EP1194610A1 - Method and system for pumping semiconductor equipment from transfer chambers - Google Patents

Method and system for pumping semiconductor equipment from transfer chambers

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Publication number
EP1194610A1
EP1194610A1 EP01928018A EP01928018A EP1194610A1 EP 1194610 A1 EP1194610 A1 EP 1194610A1 EP 01928018 A EP01928018 A EP 01928018A EP 01928018 A EP01928018 A EP 01928018A EP 1194610 A1 EP1194610 A1 EP 1194610A1
Authority
EP
European Patent Office
Prior art keywords
pumping
transfer chamber
gas
gases
pressure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP01928018A
Other languages
German (de)
French (fr)
Inventor
Marc Lagedamont
Roland Bernard
Eric Chevalier
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Alcatel Lucent SAS
Original Assignee
Alcatel CIT SA
Alcatel SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Alcatel CIT SA, Alcatel SA filed Critical Alcatel CIT SA
Publication of EP1194610A1 publication Critical patent/EP1194610A1/en
Withdrawn legal-status Critical Current

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Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/67005Apparatus not specifically provided for elsewhere
    • H01L21/67011Apparatus for manufacture or treatment
    • H01L21/67017Apparatus for fluid treatment
    • CCHEMISTRY; METALLURGY
    • C23COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23CCOATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/56Apparatus specially adapted for continuous coating; Arrangements for maintaining the vacuum, e.g. vacuum locks
    • C23C14/564Means for minimising impurities in the coating chamber such as dust, moisture, residual gases
    • CCHEMISTRY; METALLURGY
    • C23COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23CCOATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/56Apparatus specially adapted for continuous coating; Arrangements for maintaining the vacuum, e.g. vacuum locks
    • C23C14/564Means for minimising impurities in the coating chamber such as dust, moisture, residual gases
    • C23C14/566Means for minimising impurities in the coating chamber such as dust, moisture, residual gases using a load-lock chamber
    • CCHEMISTRY; METALLURGY
    • C23COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23CCOATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/44Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
    • C23C16/4412Details relating to the exhausts, e.g. pumps, filters, scrubbers, particle traps

Definitions

  • the present invention relates to methods and devices ensuring the pumping of gases in an airlock or a semiconductor transfer chamber to a process chamber.
  • an important step consists in treating a semiconductor substrate under a controlled atmosphere at very low pressure in a process chamber, for example for plasma deposition of layers of different materials.
  • the atmosphere In the process chamber, the atmosphere must be controlled to avoid the presence of any impurity and pollution. For this, the substrate must arrive in the process chamber in a satisfactory state of purity.
  • controlled valves are provided to limit the inflow and outflow of air into the process chamber in order to reduce the risk of pollution resulting from the detachment of particles previously deposited on the walls of the process chamber.
  • the substrates in the form of slices, are packaged and brought in succession into the process chamber, by means of a transfer chamber inside which the atmosphere is gradually brought to a similar suitable pressure. of that prevailing in the process chamber.
  • a gas pumping system is used for this, comprising a primary pump biased by drive means and connected by a pumping circuit to the airlock or to the transfer chamber to pump the gases until the appropriate pressure is reached.
  • the pumping speed is determined to reach the appropriate pressure at the end of a conditioning period which does not delay the transfer of the substrate into the process chamber.
  • the conditioning of the substrate is often insufficient, and there is the appearance of pollution and impurities in the process chamber.
  • Document EP 0 776 026 A teaches to reduce the pollution resulting from particles depositing on the walls of a transfer chamber. Controlled valves are used for this which reduce the pumping speed of the gases out of the transfer chamber, in order to avoid condensation or solidification of the gases in the transfer chamber. The reduction of the risks of pollution is however insufficient, probably because of the presence of controlled valves, which increase the surfaces on which particles can be deposited. Also, the device is more complex.
  • An object of the invention is to more effectively avoid the introduction of impurities and pollution into the process chamber.
  • Another object of the invention is therefore to improve the degassing of the substrates during their packaging in the airlock or the transfer chamber, without delaying the transfer of the substrate into the process chamber.
  • a gas pumping system in a semiconductor equipment transfer chamber, comprises a primary pump biased by drive means and connected by a pumping circuit to the transfer chamber for pump the gases out of the transfer chamber until an appropriate pressure is reached; the drive means are adapted to drive the primary pump at a variable speed, thereby ensuring variable speed pumping; a turbomolecular secondary pump is interposed in the pumping circuit between the primary pump and the transfer chamber; gas control means are provided to control one or more appropriate characteristic parameters of the pumped gases and to produce control signals acting on the drive means to adapt the speed of the primary pump in order to avoid any condensation or solidification of the gas in the transfer chamber.
  • the permanent control of the gases pumped by acting on the speed of the pump makes it possible, on the one hand, to avoid the appearance of any condensation or solidification of the gases, and therefore the introduction of any pollution into the process chamber.
  • This control also makes it possible to avoid the risks of additional pollution and the complications linked to the presence of control valves.
  • This control also makes it possible to optimize the pressure descent speed, in order to reach the fastest possible average speed, so that the conditioning time is not increased and that it even becomes possible, at the same conditioning time. , to lower the pressure to a lower value which promotes degassing of the substrate.
  • the gas control means may include a temperature sensor sensitive to the temperature of the pumped gases, and / or a gas analyzer.
  • the gas analyzer can advantageously be adapted to detect and measure the humidity line.
  • the gas analyzer can be advantageously suitable for detecting and measuring lines of hydrocarbons.
  • the gas pumping system can further comprise means for measuring the pressure in a process chamber to which the transfer chamber is connected. It is thus possible to control the pressure in the transfer chamber so as to avoid or limit the transfer of pollutants from the process chamber to the transfer chamber. It is thus possible to increase the speed of conditioning of the next substrate in the same transfer chamber, this conditioning not being disturbed by the pollution coming from the process chamber.
  • the turbomolecular secondary pump can be of a robust type capable of operating from the start of the pumping step by discharging the gases at atmospheric pressure.
  • the turbomolecular pump is not associated with any bypass pipe for starting pumping, and it constitutes the only pumping element connected to the transfer chamber. This reduces the risk of pollution of the atmosphere in the transfer chamber, and therefore in the process chamber.
  • the speed of the primary pump which extracts the gases out of the transfer chamber is adapted according to a or several parameters characteristic of the gases pumped, so as to avoid or limit the condensation or solidification of the gases in the transfer chamber.
  • the speed of the pump can be optimized to reach the appropriate pressure in a shorter time, and continue pumping until reaching and maintaining momentarily, for example until the end of the conditioning period, a lower residual pressure. at the appropriate operating pressure of the transfer chamber, thereby promoting degassing of the substrate.
  • the atmosphere of the process chamber can be monitored simultaneously.
  • FIG. 1 schematically illustrates the general structure of a gas pumping system according to an embodiment of the present invention
  • FIG. 2 illustrates the pressure descent curves, a first curve illustrating the pressure descent with a device according to the present invention, a second curve illustrating the pressure descent with a known device with dry primary pump;
  • FIG. 3 schematically illustrates the general structure of a gas pumping system according to an embodiment further comprising a cryogenic trap.
  • the pumping system allows the pumping of gases in an airlock or transfer chamber 1 which is connected to a process chamber 2 by means allowing the passage of a semiconductor substrate.
  • the gas pumping system comprises a primary pump 3 solicited by integrated drive means and connected by a pumping circuit 12 comprising a pipe 4 to the airlock or to the transfer chamber 1 to pump the gases until reaching a pressure suitable close to that present in the process chamber 2.
  • the drive means integrated in the primary pump 3 are adapted to ensure pumping at variable speed, the speed being controlled by a control device 5 which may be of a type known per se.
  • a turbomolecular secondary pump 6 is interposed in the pumping circuit 12 between the pipe 4 connected to the primary pump 3 and the airlock or transfer chamber 1.
  • a valve insulation 7 is interposed between the turbomolecular secondary pump 6 and the airlock or transfer chamber 1.
  • Gas control means are provided to control one or more appropriate characteristic parameters of the pumped gases and to produce control signals sent by one or more transmission lines such as the transmission lines 9 or 14 to the control device 5 to act on the drive means and thus adapt the pumping speed of the primary pump 3 in order to avoid any condensation or solidification of the gases in the airlock or the transfer chamber 1.
  • the gas control means one can for example provide a temperature sensor 8 for measuring the temperature in the pipe 4, and / or a pressure sensor 16 for measuring the pressure in the airlock or transfer chamber 1. The measurement is then sent respectively by the transmission line 14 or by the transmission line 15 in the control device 5. It is indeed known that the condensations or solidifications occur only below a determined temperature threshold, and l 'It is then possible to maintain the pumping speed at a value low enough to remain above the temperature threshold.
  • the gas monitoring means comprise a gas analyzer 10, for example a mass spectrometer, which can be adapted to detect and measure certain lines of characteristic elements in the gases present in the pipe 4.
  • a gas analyzer 10 for example a mass spectrometer, which can be adapted to detect and measure certain lines of characteristic elements in the gases present in the pipe 4.
  • the gas analyzer 10 can be adapted to detect and measure the humidity line, and to send signals to the control device 5 by the transmission line 9 making it possible to fix the pumping speed at a value such that the humidity is kept below a permissible threshold.
  • Another frequent source of pollution is the condensation or solidification of hydrocarbons.
  • the gas analyzer 10 can be adapted to detect and measure the lines of hydrocarbons, and to send to the control device 5 by the transmission line 9 the signals necessary to maintain the lines of hydrocarbons at a value below a permissible threshold. In the embodiment illustrated in FIG.
  • the system further comprises means for measuring the pressure 13 in the process chamber 2 to which the airlock or the transfer chamber 1 is connected.
  • An isolation valve 17 is interposed between the airlock or transfer chamber 1 and the process chamber 2, allowing the passage of the sample by opening / closing the airlock of the process chamber 2.
  • the pressure measurement signal is sent by a transmission line 11 to the control device 5, to control the pumping speed of the primary pump 3 in order to establish the appropriate pressure in the airlock or the transfer chamber 1 to a value slightly higher than that of the process chamber 2, so as to avoid or limit the transfer of polluting materials from the process chamber 2 to the airlock or the transfer chamber 1 during the transfer of the semiconductor substrate to be treated.
  • the gases exit the primary pump 3 through a pipe 19.
  • FIG. 1 illustrates a particularly advantageous embodiment of the present invention comprising isolation means making it possible to further reduce the disturbances provided by the pumping device on the transfer chamber 1, or even on the process chamber 2.
  • the primary pump 3, the gas analyzer means 10 and the control device 5 are enclosed together in an isolation enclosure 18.
  • the isolation enclosure 18 is a sealed enclosure which forms a mechanically rigid assembly and may comprise a device for controlling and regulating the temperature or an active vibration compensation means (not shown).
  • turbomolecular secondary pump 6 of a type capable of operating from the start of the pumping stage by discharging the gases at atmospheric pressure.
  • this solution saves space, in terms of floor space, very interesting.
  • the turbomolecular secondary pump 6 is only associated with no bypass line for starting pumping, outside of valve 7, and it constitutes the only pumping element connected to the airlock or to the transfer chamber 1.
  • a reference pump ATH 30 sold by the ALCATEL company.
  • Such a pump also has the advantage of being compact, so that the system can be placed in the immediate vicinity of the transfer chamber 1, which simplifies all the electrical connections and the pipes.
  • the system thus designed is capable of descending from atmospheric pressure to pressures of the order of 10 ⁇ 3 Pascal in about thirty seconds.
  • the pumping speed is subject to the expansion of the gases in order to avoid any solidification or condensation phenomenon in the airlock or the transfer chamber 1.
  • the pumping speed of the gases is adapted from the airlock or from the transfer chamber 1 as a function of one or more parameters characteristic of the pumped gases, so as to avoid or limit condensation or solidification of gases in the airlock or transfer chamber 1.
  • the pressure is first of all relatively slowly reduced during a step A1, to avoid condensation or solidification gases, then the pressure descent speed accelerates during a step A2 and can become faster than the speed usually chosen in known systems with only primary pump driven at constant speed.
  • the lowest pressure level reached, or pressure P2 is much lower than the conditioning pressure PI.
  • the condensation and solidification of the gases are likely to occur essentially during the first stage A1, when the pressures are still relatively high. Thanks to the adaptation of the pumping speed as a function of characteristic parameters of the pumped gases, the pressure drop can be faster than in known systems, which makes it possible to very quickly reach a much lower pressure P2.
  • the method according to the invention makes it possible to optimize the pumping speed by substantially accelerating the pumping during step A2 when the pressure is already low, so to reach the appropriate transfer or conditioning pressure PI more quickly, then to reach a minimum residual pressure P2, and after a possible rise A3 to temporarily maintain the residual pressure according to a level A5 at a value P3 lower than the conditioning pressure PI of the airlock or of the transfer chamber 1.
  • the degassing of the substrate is favored and the pollution which the substrate is liable to introduce into the medium is reduced. process chamber 2.
  • the pressure bearing A5 P3 can advantageously be maintained up to the vicinity of the instant t0 of transf ert a semiconductor substrate to be treated from the transfer chamber 1 to the process chamber 2.
  • the pressure Pi is then restored according to the rise A6.
  • the transfer pressure Pi established according to known systems requires, after the substrate has entered the process chamber 2, a pressure reduction up to the operating pressure of the said process chamber 2. This pressure reduction requires a time of relatively long pumping, which must be undertaken before each treatment cycle.
  • the invention provides for lowering the transfer pressure to bring it closer to the treatment pressure.
  • provision is made for example to fix the pressure P3 at a value substantially equal to the treatment pressure in the process chamber 2, and to carry out the transfer at this pressure P3, without going back to the pressure PI of the devices of the art prior.
  • This example is illustrated by the continuation A7 of the stage A6 until the instant t0 in FIG. 2. This then results in an appreciable saving in pumping time, and a significant acceleration of the treatment cycle in the process chamber 2.
  • the gas pumping system further comprises, interposed in the pumping circuit 4 between the secondary pump 6 and the transfer chamber 1, a cryogenic trap composed of a refrigeration device 20 cooling a cold finger 21 and an active surface 22 in contact with the gases pumped in the pumping circuit 4.
  • the cryogenic trap can be a mechanical cooler of the Stirling type.
  • the active surface 22 can be a cylindrical metallic part inside the pipe conducting the pumped gases. The typical temperature of this active surface 22 is approximately 140 ° K.
  • the water vapor at this temperature is trapped and condenses in the form of ice on the active surface 22. It is possible to reach partial water pressures of less than 10 ⁇ 5 Pa. Gradually, the thickness of ice grows on the active surface 22. It is then desirable to regenerate the trap by heating the active surface 22 by Joule effect: the ice vaporizes and is pumped by the pumping circuit 12. Means are provided for this to periodically heat the active surface 22 so as to remove the ice deposited on the active surface 22.

Abstract

The invention concerns a method which consists in pumping the gases present in a transfer chamber (1) using a primary pump (3) driven by variable speed driving means, mounted in series with a turbomolecular secondary pump (6), and associated with gas controlling means (8, 10, 13, 16) to control one or several appropriate characteristic parameters of the pumped gases and to produce control signals acting on the means driving the primary pump (3) to adapt its pumping speed so as to avoid any condensation or solidification in the airlock or transfer chamber (1). Thus the pressure drop speed can be optimised thereby reducing pollution introduced into the process chamber (2).

Description

PROCEDE ET SYSTEME DE POMPAGE DES CHAMBRES DE TRANSFERT D'EQUIPEMENT DE SEMI-CONDUCTEUR METHOD AND SYSTEM FOR PUMPING SEMICONDUCTOR EQUIPMENT TRANSFER CHAMBERS
DOMAINE TECHNIQUE DE L'INVENTION La présente invention concerne les procédés et dispositifs assurant le pompage des gaz dans un sas ou une chambre de transfert de semi-conducteurs vers une chambre de procédés .TECHNICAL FIELD OF THE INVENTION The present invention relates to methods and devices ensuring the pumping of gases in an airlock or a semiconductor transfer chamber to a process chamber.
Dans la fabrication des composants électroniques à semiconducteur, une étape importante consiste à traiter un substrat semi-conducteur sous atmosphère contrôlée à très basse pression dans une chambre de procédés, par exemple pour des dépôts par plasma de couches de différents matériaux.In the manufacture of semiconductor electronic components, an important step consists in treating a semiconductor substrate under a controlled atmosphere at very low pressure in a process chamber, for example for plasma deposition of layers of different materials.
Dans la chambre de procédés, l'atmosphère doit être contrôlée pour éviter la présence de toute impureté et de toute pollution. Pour cela, le substrat doit arriver dans la chambre de procédés dans un état de pureté satisfaisant.In the process chamber, the atmosphere must be controlled to avoid the presence of any impurity and pollution. For this, the substrate must arrive in the process chamber in a satisfactory state of purity.
Dans le document EP 0 385 709 A, on prévoit des vannes commandées pour limiter les flux d'entrée et de sortie d'air dans la chambre de procédés afin de réduire le risque de pollution résultant du détachement de particules préalablement déposées sur les parois de la chambre de procédés.In document EP 0 385 709 A, controlled valves are provided to limit the inflow and outflow of air into the process chamber in order to reduce the risk of pollution resulting from the detachment of particles previously deposited on the walls of the process chamber.
Dans une production industrielle, les substrats, sous forme de tranches, sont conditionnés et amenés en succession dans la chambre de procédés, au moyen d'une chambre de transfert à l'intérieur de laquelle l'atmosphère est progressivement amenée à une pression appropriée similaire de celle régnant dans la chambre de procédés. On utilise pour cela un système de pompage des gaz comprenant une pompe primaire sollicitée par des moyens d'entraînement et raccordée par un circuit de pompage au sas ou à la chambre de transfert pour pomper les gaz jusqu'à atteindre la pression appropriée.In industrial production, the substrates, in the form of slices, are packaged and brought in succession into the process chamber, by means of a transfer chamber inside which the atmosphere is gradually brought to a similar suitable pressure. of that prevailing in the process chamber. A gas pumping system is used for this, comprising a primary pump biased by drive means and connected by a pumping circuit to the airlock or to the transfer chamber to pump the gases until the appropriate pressure is reached.
Dans le document US 4 379 743 A, on évite la transmission d'impuretés depuis une chambre de prétraitement vers une chambre de traitement en établissant une surpression différentielle gazeuse dans la chambre de traitement après le prétraitement d'un substrat.In document US Pat. No. 4,379,743 A, the transmission of impurities from a pretreatment chamber to a treatment chamber is avoided by establishing a gas differential overpressure in the treatment chamber after the pretreatment of a substrate.
Dans les installations connues, lorsqu'on utilise une pompe primaire sèche à vitesse variable de pompage des gaz de la chambre de transfert, on détermine la vitesse de pompage pour atteindre la pression appropriée à l'issue d'une durée de conditionnement qui ne retarde pas le transfert du substrat dans la chambre de procédés. Toutefois, le conditionnement du substrat est souvent insuffisant, et l'on constate l'apparition de pollution et d'impuretés dans la chambre de procédés.In known installations, when using a dry primary pump with variable speed for pumping gases from the transfer chamber, the pumping speed is determined to reach the appropriate pressure at the end of a conditioning period which does not delay the transfer of the substrate into the process chamber. However, the conditioning of the substrate is often insufficient, and there is the appearance of pollution and impurities in the process chamber.
Le document EP 0 776 026 A enseigne de réduire la pollution résultant des particules se déposant sur les parois d'une chambre de transfert. On utilise pour cela des vannes commandées qui réduisent la vitesse de pompage des gaz hors de la chambre de transfert, afin d'éviter la condensation ou la solidification des gaz dans la chambre de transfert. La réduction des risques de pollution est toutefois insuffisante, vraisemblablement à cause de la présence des vannes commandées, qui augmentent les surfaces sur lesquelles des particules peuvent se déposer. Egalement, le dispositif est plus complexe.Document EP 0 776 026 A teaches to reduce the pollution resulting from particles depositing on the walls of a transfer chamber. Controlled valves are used for this which reduce the pumping speed of the gases out of the transfer chamber, in order to avoid condensation or solidification of the gases in the transfer chamber. The reduction of the risks of pollution is however insufficient, probably because of the presence of controlled valves, which increase the surfaces on which particles can be deposited. Also, the device is more complex.
EXPOSE DE L'INVENTION Un but de l'invention est d'éviter de façon plus efficace l'introduction d'impuretés et de pollution dans la chambre de procédés .PRESENTATION OF THE INVENTION An object of the invention is to more effectively avoid the introduction of impurities and pollution into the process chamber.
Egalement, lors de la descente en pression de l'atmosphère dans le sas ou la chambre de transfert, il se produit nécessairement un dégazage du substrat, et il est important que ce dégazage soit suffisant avant que le substrat soit introduit dans la chambre de procédés. A défaut de cela, le dégazage se poursuit dans la chambre de procédés et les gaz provenant de ce dégazage postérieur constituent une source supplémentaire de pollution pendant le traitement. Ainsi, l'invention a pour autre but d'améliorer le dégazage des substrats lors de leur conditionnement dans le sas ou la chambre de transfert, sans pour autant retarder le transfert du substrat dans la chambre de procédés.Also, during the pressure drop of the atmosphere in the airlock or the transfer chamber, there is necessarily degassing of the substrate, and it is important that this degassing is sufficient before the substrate is introduced into the process chamber. . Otherwise, degassing continues in the process chamber and the gases from this posterior degassing constitute an additional source of pollution during treatment. Another object of the invention is therefore to improve the degassing of the substrates during their packaging in the airlock or the transfer chamber, without delaying the transfer of the substrate into the process chamber.
Pour atteindre ces objets ainsi que d'autres, l'invention prévoit de contrôler efficacement et de manière simple la descente en pression de l'atmosphère dans le sas ou la chambre de transfert pendant le conditionnement, de façon à éviter l'apparition de toute humidité ou de toute solidification des gaz. Ainsi, un système de pompage des gaz selon l'invention, dans une chambre de transfert d'équipement de semi-conducteurs, comprend une pompe primaire sollicitée par des moyens d'entraînement et raccordée par un circuit de pompage à la chambre de transfert pour pomper les gaz hors de la chambre de transfert jusqu'à atteindre une pression appropriée ; les moyens d'entraînement sont adaptés pour entraîner la pompe primaire selon une vitesse variable, assurant ainsi un pompage à vitesse variable ; une pompe secondaire turbomoléculaire est interposée dans le circuit de pompage entre la pompe primaire et la chambre de transfert ; des moyens de contrôle de gaz sont prévus pour contrôler un ou plusieurs paramètres caractéristiques appropriés des gaz pompés et pour produire des signaux de commande agissant sur les moyens d'entraînement pour adapter la vitesse de la pompe primaire afin d'éviter toute condensation ou solidification des gaz dans la chambre de transfert.To achieve these and other objects, the invention provides for effectively and simply controlling the pressure drop in the atmosphere in the airlock or the transfer chamber during conditioning, so as to avoid the appearance of any humidity or any solidification of gases. Thus, a gas pumping system according to the invention, in a semiconductor equipment transfer chamber, comprises a primary pump biased by drive means and connected by a pumping circuit to the transfer chamber for pump the gases out of the transfer chamber until an appropriate pressure is reached; the drive means are adapted to drive the primary pump at a variable speed, thereby ensuring variable speed pumping; a turbomolecular secondary pump is interposed in the pumping circuit between the primary pump and the transfer chamber; gas control means are provided to control one or more appropriate characteristic parameters of the pumped gases and to produce control signals acting on the drive means to adapt the speed of the primary pump in order to avoid any condensation or solidification of the gas in the transfer chamber.
Le contrôle permanent des gaz pompés par action sur la vitesse de la pompe permet d'une part d'éviter l'apparition de toute condensation ou solidification des gaz, et donc l'introduction de toute pollution dans la chambre de procédés. Ce contrôle permet d'autre part d'éviter les risques de pollution supplémentaires et les complications liées à la présence de vannes de commande. Ce contrôle permet aussi d'optimiser la vitesse de descente en pression, pour atteindre la vitesse moyenne la plus rapide possible, de sorte que le temps de conditionnement n'est pas augmenté et qu'il devient même possible, dans le même temps de conditionnement, de descendre la pression à une valeur plus faible qui favorise le dégazage du substrat.The permanent control of the gases pumped by acting on the speed of the pump makes it possible, on the one hand, to avoid the appearance of any condensation or solidification of the gases, and therefore the introduction of any pollution into the process chamber. This control also makes it possible to avoid the risks of additional pollution and the complications linked to the presence of control valves. This control also makes it possible to optimize the pressure descent speed, in order to reach the fastest possible average speed, so that the conditioning time is not increased and that it even becomes possible, at the same conditioning time. , to lower the pressure to a lower value which promotes degassing of the substrate.
Les moyens de contrôle de gaz peuvent comprendre un capteur de température sensible à la température des gaz pompés, et/ou un analyseur de gaz.The gas control means may include a temperature sensor sensitive to the temperature of the pumped gases, and / or a gas analyzer.
Une source fréquente de pollution est l'humidité contenue dans l'atmosphère pompée, qui tend à se condenser ou à cristalliser. Dans ce cas, l'analyseur de gaz peut avantageusement être adapté pour détecter et mesurer la raie d'humidité.A frequent source of pollution is the humidity contained in the pumped atmosphere, which tends to condense or crystallize. In this case, the gas analyzer can advantageously be adapted to detect and measure the humidity line.
Une autre source de pollution est fréquemment la présence d'hydrocarbures. Dans ce cas, l'analyseur de gaz peut être avantageusement adapté pour détecter et mesurer des raies d 'hydrocarbures .Another source of pollution is frequently the presence of hydrocarbons. In this case, the gas analyzer can be advantageously suitable for detecting and measuring lines of hydrocarbons.
Selon un mode de réalisation avantageux, le système de pompage de gaz peut comprendre en outre des moyens de mesure de la pression dans une chambre de procédés à laquelle est raccordée la chambre de transfert. On peut ainsi asservir la pression dans la chambre de transfert de manière à éviter ou à limiter le transfert de matières polluantes depuis la chambre de procédés vers la chambre de transfert. On peut ainsi augmenter la vitesse de conditionnement du substrat suivant dans la même chambre de transfert, ce conditionnement n'étant pas perturbé par les pollutions provenant de la chambre de procédés .According to an advantageous embodiment, the gas pumping system can further comprise means for measuring the pressure in a process chamber to which the transfer chamber is connected. It is thus possible to control the pressure in the transfer chamber so as to avoid or limit the transfer of pollutants from the process chamber to the transfer chamber. It is thus possible to increase the speed of conditioning of the next substrate in the same transfer chamber, this conditioning not being disturbed by the pollution coming from the process chamber.
De préférence, la pompe secondaire turbomoléculaire peut être d'un type robuste capable de fonctionner dès le début de l'étape de pompage en refoulant les gaz à la pression atmosphérique. De la sorte, la pompe turbomoléculaire n'est associée a aucune canalisation de dérivation pour démarrage du pompage, et elle constitue le seul élément de pompage raccordé à la chambre de transfert. On réduit ainsi les risques de pollution de l'atmosphère dans la chambre de transfert, et donc dans la chambre de procédés.Preferably, the turbomolecular secondary pump can be of a robust type capable of operating from the start of the pumping step by discharging the gases at atmospheric pressure. In this way, the turbomolecular pump is not associated with any bypass pipe for starting pumping, and it constitutes the only pumping element connected to the transfer chamber. This reduces the risk of pollution of the atmosphere in the transfer chamber, and therefore in the process chamber.
Dans un procédé de pompage des gaz selon 1 ' invention, dans une chambre de transfert de semi-conducteurs vers une chambre de procédés, on adapte la vitesse de la pompe primaire qui extrait les gaz hors de la chambre de transfert en fonction d'un ou plusieurs paramètres caractéristiques des gaz pompés, de manière à éviter ou à limiter la condensation ou la solidification des gaz dans la chambre de transfert.In a method of pumping gases according to the invention, in a semiconductor transfer chamber to a process chamber, the speed of the primary pump which extracts the gases out of the transfer chamber is adapted according to a or several parameters characteristic of the gases pumped, so as to avoid or limit the condensation or solidification of the gases in the transfer chamber.
Avantageusement, on peut optimiser la vitesse de la pompe pour atteindre la pression appropriée en un temps plus court, et poursuivre le pompage jusqu'à atteindre et maintenir momentanément, par exemple jusqu'à la fin de la durée de conditionnement, une pression résiduelle inférieure à la pression appropriée de fonctionnement de la chambre de transfert, favorisant ainsi le dégazage du substrat. Par l'analyse des gaz pompés au moyen d'un analyseur de gaz, on peut contrôler simultanément l'atmosphère de la chambre de procédés.Advantageously, the speed of the pump can be optimized to reach the appropriate pressure in a shorter time, and continue pumping until reaching and maintaining momentarily, for example until the end of the conditioning period, a lower residual pressure. at the appropriate operating pressure of the transfer chamber, thereby promoting degassing of the substrate. By analyzing the gases pumped by means of a gas analyzer, the atmosphere of the process chamber can be monitored simultaneously.
DESCRIPTION SOMMAIRE DES DESSINS D'autres objets, caractéristiques et avantages de la présente invention ressortiront de la description suivante de modes de réalisation particuliers, faite en relation avec les figures jointes, parmi lesquelles:SUMMARY DESCRIPTION OF THE DRAWINGS Other objects, characteristics and advantages of the present invention will emerge from the following description of particular embodiments, made in relation to the attached figures, among which:
- la figure 1 illustre schématiquement la structure générale d'un système de pompage des gaz selon un mode de réalisation de la présente invention ;- Figure 1 schematically illustrates the general structure of a gas pumping system according to an embodiment of the present invention;
- la figure 2 illustre les courbes de descente en pression, une première courbe illustrant la descente en pression avec un dispositif selon la présente invention, une seconde courbe illustrant la descente en pression avec un dispositif connu à pompe primaire sèche ; et- Figure 2 illustrates the pressure descent curves, a first curve illustrating the pressure descent with a device according to the present invention, a second curve illustrating the pressure descent with a known device with dry primary pump; and
- la figure 3 illustre schématiquement la structure générale d'un système de pompage des gaz selon un mode de réalisation comportant en outre un piège cryogénique. DESCRIPTION DES MODES DE REALISATION PREFERES- Figure 3 schematically illustrates the general structure of a gas pumping system according to an embodiment further comprising a cryogenic trap. DESCRIPTION OF THE PREFERRED EMBODIMENTS
Dans le mode de réalisation illustré sur la figure 1, le système de pompage selon 1 ' invention permet le pompage des gaz dans un sas ou chambre de transfert 1 qui est raccordé à une chambre de procédés 2 par des moyens permettant le passage d'un substrat semi- conducteur .In the embodiment illustrated in FIG. 1, the pumping system according to the invention allows the pumping of gases in an airlock or transfer chamber 1 which is connected to a process chamber 2 by means allowing the passage of a semiconductor substrate.
Le système de pompage des gaz comprend une pompe primaire 3 sollicitée par des moyens d'entraînement intégrés et raccordée par un circuit de pompage 12 comportant une canalisation 4 au sas ou à la chambre de transfert 1 pour pomper les gaz jusqu'à atteindre une pression appropriée voisine de celle présente dans la chambre de procédés 2. Les moyens d'entraînement intégrés à la pompe primaire 3 sont adaptés pour assurer un pompage à vitesse variable, la vitesse étant pilotée par un dispositif de commande 5 qui peut être d'un type connu en soi. Une pompe secondaire turbomoléculaire 6 est interposée dans le circuit de pompage 12 entre la canalisation 4 reliée à la pompe primaire 3 et le sas ou chambre de transfert 1. Une vanne d'isolation 7 est interposée entre la pompe secondaire turbomoléculaire 6 et le sas ou chambre de transfert 1.The gas pumping system comprises a primary pump 3 solicited by integrated drive means and connected by a pumping circuit 12 comprising a pipe 4 to the airlock or to the transfer chamber 1 to pump the gases until reaching a pressure suitable close to that present in the process chamber 2. The drive means integrated in the primary pump 3 are adapted to ensure pumping at variable speed, the speed being controlled by a control device 5 which may be of a type known per se. A turbomolecular secondary pump 6 is interposed in the pumping circuit 12 between the pipe 4 connected to the primary pump 3 and the airlock or transfer chamber 1. A valve insulation 7 is interposed between the turbomolecular secondary pump 6 and the airlock or transfer chamber 1.
Des moyens de contrôle de gaz sont prévus pour contrôler un ou plusieurs paramètres caractéristiques appropriés des gaz pompés et pour produire des signaux de commande envoyés par une ou plusieurs lignes de transmission telles que les lignes de transmission 9 ou 14 au dispositif de commande 5 pour agir sur les moyens d'entraînement et adapter ainsi la vitesse de pompage de la pompe primaire 3 afin d'éviter toute condensation ou solidification des gaz dans le sas ou la chambre de transfert 1.Gas control means are provided to control one or more appropriate characteristic parameters of the pumped gases and to produce control signals sent by one or more transmission lines such as the transmission lines 9 or 14 to the control device 5 to act on the drive means and thus adapt the pumping speed of the primary pump 3 in order to avoid any condensation or solidification of the gases in the airlock or the transfer chamber 1.
Parmi les moyens de contrôle des gaz, on peut prévoir par exemple un capteur de température 8 pour mesurer la température dans la canalisation 4, et/ou un capteur de pression 16 pour mesurer la pression dans le sas ou chambre de transfert 1. La mesure est alors envoyée respectivement par la ligne de transmission 14 ou par la ligne de transmission 15 dans le dispositif de commande 5. On sait en effet que les condensations ou solidifications n'interviennent qu'en dessous d'un seuil de température déterminé, et l'on peut alors maintenir la vitesse de pompage à une valeur suffisamment faible pour rester en dessus du seuil de température.Among the gas control means, one can for example provide a temperature sensor 8 for measuring the temperature in the pipe 4, and / or a pressure sensor 16 for measuring the pressure in the airlock or transfer chamber 1. The measurement is then sent respectively by the transmission line 14 or by the transmission line 15 in the control device 5. It is indeed known that the condensations or solidifications occur only below a determined temperature threshold, and l 'It is then possible to maintain the pumping speed at a value low enough to remain above the temperature threshold.
De préférence, les moyens de contrôle de gaz comprennent un analyseur de gaz 10, par exemple un spectromètre de masse, que l'on peut adapter pour détecter et mesurer certaines raies d'éléments caractéristiques dans les gaz présents dans la canalisation 4.Preferably, the gas monitoring means comprise a gas analyzer 10, for example a mass spectrometer, which can be adapted to detect and measure certain lines of characteristic elements in the gases present in the pipe 4.
Par exemple, une source fréquente de condensation et de solidification dans les atmosphères de traitement est la vapeur d'eau. Ainsi, l'analyseur de gaz 10 peut être adapté pour détecter et mesurer la raie d'humidité, et pour envoyer au dispositif de commande 5 par la ligne de transmission 9 des signaux permettant de fixer la vitesse de pompage à une valeur telle que la raie d'humidité soit maintenue à une valeur inférieure à un seuil admissible. Une autre source de pollution fréquente est la condensation ou solidification d'hydrocarbures. Pour éviter cela, l'analyseur de gaz 10 peut être adapté pour détecter et mesurer les raies d'hydrocarbures, et pour envoyer au dispositif de commande 5 par la ligne de transmission 9 les signaux nécessaires pour maintenir les raies d'hydrocarbures à une valeur inférieure à un seuil admissible. Dans le mode de réalisation illustré sur la figure 1, le système comprend en outre des moyens de mesure de la pression 13 dans la chambre de procédés 2 à laquelle est raccordé le sas ou la chambre de transfert 1. Une vanne d'isolation 17 est interposée entre le sas ou chambre de transfert 1 et la chambre de procédés 2, permettant le passage d'échantillon par l'ouverture/fermeture du sas de la chambre de procédés 2. Le signal de mesure de pression est envoyé par une ligne de transmission 11 au dispositif de commande 5, pour asservir la vitesse de pompage de la pompe primaire 3 afin d'établir la pression appropriée dans le sas ou la chambre de transfert 1 à une valeur un peu supérieure à celle de la chambre de procédés 2, de manière à éviter ou à limiter le transfert de matières polluantes depuis la chambre de procédés 2 vers le sas ou la chambre de transfert 1 lors du transfert du substrat semi-conducteur à traiter. Les gaz sortent de la pompe primaire 3 par une canalisation 19.For example, a frequent source of condensation and solidification in treatment atmospheres is water vapor. Thus, the gas analyzer 10 can be adapted to detect and measure the humidity line, and to send signals to the control device 5 by the transmission line 9 making it possible to fix the pumping speed at a value such that the humidity is kept below a permissible threshold. Another frequent source of pollution is the condensation or solidification of hydrocarbons. To avoid this, the gas analyzer 10 can be adapted to detect and measure the lines of hydrocarbons, and to send to the control device 5 by the transmission line 9 the signals necessary to maintain the lines of hydrocarbons at a value below a permissible threshold. In the embodiment illustrated in FIG. 1, the system further comprises means for measuring the pressure 13 in the process chamber 2 to which the airlock or the transfer chamber 1 is connected. An isolation valve 17 is interposed between the airlock or transfer chamber 1 and the process chamber 2, allowing the passage of the sample by opening / closing the airlock of the process chamber 2. The pressure measurement signal is sent by a transmission line 11 to the control device 5, to control the pumping speed of the primary pump 3 in order to establish the appropriate pressure in the airlock or the transfer chamber 1 to a value slightly higher than that of the process chamber 2, so as to avoid or limit the transfer of polluting materials from the process chamber 2 to the airlock or the transfer chamber 1 during the transfer of the semiconductor substrate to be treated. The gases exit the primary pump 3 through a pipe 19.
La figure 1 illustre un mode de réalisation particulièrement avantageux de la présente invention comprenant des moyens d' isolement permettant de réduire encore les perturbations apportées par le dispositif de pompage sur la chambre de transfert 1, voire sur la chambre de procédés 2. Pour cela, la pompe primaire 3, le moyen analyseur de gaz 10 et le dispositif de commande 5 sont enfermés ensemble dans une enceinte d'isolement 18.FIG. 1 illustrates a particularly advantageous embodiment of the present invention comprising isolation means making it possible to further reduce the disturbances provided by the pumping device on the transfer chamber 1, or even on the process chamber 2. For this, the primary pump 3, the gas analyzer means 10 and the control device 5 are enclosed together in an isolation enclosure 18.
L'enceinte d'isolement 18 est une enceinte étanche qui forme un ensemble mécaniquement rigide et peut comprendre un dispositif de contrôle et de régulation de la température ou un moyen de compensation active de vibration (non représentés) .The isolation enclosure 18 is a sealed enclosure which forms a mechanically rigid assembly and may comprise a device for controlling and regulating the temperature or an active vibration compensation means (not shown).
D'excellents résultats ont été obtenus en utilisant une pompe secondaire turbomoléculaire 6 d'un type capable de fonctionner dès le début de l'étape de pompage en refoulant les gaz à la pression atmosphérique. Avantageusement, cette solution permet un gain de place, en termes de surface au sol, très intéressant. De la sorte, la pompe secondaire turbomoléculaire 6 n'est associée à aucune canalisation de dérivation pour le démarrage du pompage, en dehors de la vanne 7, et elle constitue le seul élément de pompage raccordé au sas ou à la chambre de transfert 1. On peut par exemple utiliser une pompe de référence ATH 30 vendue par la société ALCATEL. Une telle pompe présente en outre l'avantage d'être peu encombrante,' de sorte que le système peut être placé à proximité immédiate de la chambre de transfert 1, ce qui simplifie toutes les liaisons électriques et les canalisations.Excellent results have been obtained by using a turbomolecular secondary pump 6 of a type capable of operating from the start of the pumping stage by discharging the gases at atmospheric pressure. Advantageously, this solution saves space, in terms of floor space, very interesting. In this way, the turbomolecular secondary pump 6 is only associated with no bypass line for starting pumping, outside of valve 7, and it constitutes the only pumping element connected to the airlock or to the transfer chamber 1. One can for example use a reference pump ATH 30 sold by the ALCATEL company. Such a pump also has the advantage of being compact, so that the system can be placed in the immediate vicinity of the transfer chamber 1, which simplifies all the electrical connections and the pipes.
Le système ainsi conçu est capable de descendre depuis la pression atmosphérique jusqu'à des pressions de l'ordre de 10~3 Pascal en une trentaine de secondes. La vitesse de pompage est asservie à la détente des gaz afin d'éviter tout phénomène de solidification ou de condensation dans le sas ou la chambre de transfert 1. Dans un procédé de pompage des gaz selon l'invention, dans un sas ou une chambre de transfert 1 de semi-conducteurs vers une chambre de procédés 2, on adapte la vitesse de pompage des gaz hors du sas ou de la chambre de transfert 1 en fonction d'un ou plusieurs paramètres caractéristiques des gaz pompés, de manière à éviter ou à limiter la condensation ou la solidification des gaz dans le sas ou la chambre de transfert 1.The system thus designed is capable of descending from atmospheric pressure to pressures of the order of 10 ~ 3 Pascal in about thirty seconds. The pumping speed is subject to the expansion of the gases in order to avoid any solidification or condensation phenomenon in the airlock or the transfer chamber 1. In a gas pumping process according to the invention, in an airlock or a chamber transfer 1 of semiconductors to a process chamber 2, the pumping speed of the gases is adapted from the airlock or from the transfer chamber 1 as a function of one or more parameters characteristic of the pumped gases, so as to avoid or limit condensation or solidification of gases in the airlock or transfer chamber 1.
Par exemple, en se référant à la courbe A en traits pleins de la figure 2, partant de la pression atmosphérique Pa, on diminue tout d'abord relativement lentement la pression au cours d'une étape Al, pour éviter la condensation ou solidification des gaz, puis la vitesse de descente en pression s'accélère au cours d'une étape A2 et peut devenir plus rapide que la vitesse habituellement choisie dans les systèmes connus à pompe primaire seule entraînée à vitesse constante. Le niveau de pression le plus bas atteint, ou pression P2, est nettement inférieur à la pression de conditionnement PI. En effet, la condensation et la solidification des gaz risquent de se produire essentiellement au cours de la première étape Al, lorsque les pressions sont encore relativement élevées. Grâce à l'adaptation de la vitesse de pompage en fonction de paramètres caractéristiques des gaz pompés, la descente en pression peut être plus rapide que dans les systèmes connus, ce qui permet d'atteindre très rapidement une pression P2 très inférieure. Puis la remontée en pression se fait par A3 et A4, rejoignant le palier B3 à la pression de conditionnement Pi qui correspond au cas selon l'art antérieur où seulement une pompe primaire 3 est présente. A contrario, en se référant à la courbe B en pointillés de cette même figure 2, dans les systèmes connus à pompe entraînée à vitesse constante, la vitesse de pompage est plus faible car elle est limitée par la vitesse maximale admissible au delà de laquelle apparaissent des phénomènes de condensation ou solidification lors de la première étape de pompage. La pression est lentement diminuée au cours de l'étape Bl, puis plus fortement au cours de l'étape B2 jusqu'à atteindre un niveau de pression le plus bas sensiblement égal à la pression de conditionnement PI, puis la légère remontée B4 est suivie d'un palier B3. Selon une variante avantageuse de l'invention représentée en traits mixtes sur la figure 2, le procédé selon l'invention permet d'optimiser la vitesse de pompage en accélérant sensiblement le pompage pendant l'étape A2 lorsque la pression est déjà basse, de façon à atteindre plus rapidement la pression appropriée PI de transfert ou de conditionnement, puis à atteindre une pression résiduelle minimale P2, et après une éventuelle montée A3 à maintenir momentanément la pression résiduelle selon un palier A5 à une valeur P3 inférieure à la pression PI de conditionnement du sas ou de la chambre de transfert 1. Pendant la période au cours de laquelle la pression résiduelle P3 inférieure à Pi est appliquée au substrat, on favorise le dégazage de substrat et on réduit la pollution que le substrat est susceptible d'introduire dans la chambre de procédés 2. Le palier A5 de pression P3 peut avantageusement être maintenu jusqu'au voisinage de l'instant tO de transfert d'un substrat semiconducteur à traiter depuis la chambre de transfert 1 vers la chambre de procédés 2. La pression Pi est alors rétablie selon la remontée A6. Par le fait que le début du palier A5 est anticipé grâce à une descente contrôlée et plus rapide de pression, et par le fait que la pression P3 peut être inférieure à Pi et maintenue pendant un palier A5 de durée maximisée, on a pu réduire sensiblement, par exemple selon un facteur 2, la fréquence des interventions nécessaires de dépollution de la chambre de procédés 2. En d'autres termes, on augmente d'un facteur 2 le temps moyen entre deux opérations de nettoyage (MTBC) .For example, by referring to curve A in solid lines in FIG. 2, starting from atmospheric pressure P a , the pressure is first of all relatively slowly reduced during a step A1, to avoid condensation or solidification gases, then the pressure descent speed accelerates during a step A2 and can become faster than the speed usually chosen in known systems with only primary pump driven at constant speed. The lowest pressure level reached, or pressure P2, is much lower than the conditioning pressure PI. Indeed, the condensation and solidification of the gases are likely to occur essentially during the first stage A1, when the pressures are still relatively high. Thanks to the adaptation of the pumping speed as a function of characteristic parameters of the pumped gases, the pressure drop can be faster than in known systems, which makes it possible to very quickly reach a much lower pressure P2. Then the pressure build-up takes place via A3 and A4, joining the bearing B3 at the conditioning pressure Pi which corresponds to the case according to the prior art where only a primary pump 3 is present. Conversely, by referring to the dotted curve B of this same figure 2, in the known systems with pump driven at constant speed, the pumping speed is lower because it is limited by the maximum admissible speed beyond which appear condensation or solidification phenomena during the first pumping step. The pressure is slowly reduced during step B1, then more sharply during step B2 until reaching a lowest pressure level substantially equal to the conditioning pressure PI, then the slight rise B4 is followed of a bearing B3. According to an advantageous variant of the invention shown in dashed lines in FIG. 2, the method according to the invention makes it possible to optimize the pumping speed by substantially accelerating the pumping during step A2 when the pressure is already low, so to reach the appropriate transfer or conditioning pressure PI more quickly, then to reach a minimum residual pressure P2, and after a possible rise A3 to temporarily maintain the residual pressure according to a level A5 at a value P3 lower than the conditioning pressure PI of the airlock or of the transfer chamber 1. During the period during which the residual pressure P3 lower than Pi is applied to the substrate, the degassing of the substrate is favored and the pollution which the substrate is liable to introduce into the medium is reduced. process chamber 2. The pressure bearing A5 P3 can advantageously be maintained up to the vicinity of the instant t0 of transf ert a semiconductor substrate to be treated from the transfer chamber 1 to the process chamber 2. The pressure Pi is then restored according to the rise A6. By the fact that the start of the plateau A5 is anticipated thanks to a controlled and faster pressure descent, and by the fact that the pressure P3 can be less than Pi and maintained during a plateau A5 of maximized duration, it has been possible to reduce appreciably , for example according to a factor 2, the frequency of necessary interventions to clean up the process chamber 2. In other words, the average time between two cleaning operations (MTBC) is increased by a factor of 2.
La pression de transfert Pi établie selon les systèmes connus nécessite, après l'entrée du substrat en chambre de procédés 2, un abaissement de pression jusqu'à la pression de fonctionnement de ladite chambre de procédés 2. Cet abaissement de pression nécessite un temps de pompage relativement long, qu'il faut entreprendre avant chaque cycle de traitement. Selon un mode de réalisation particulièrement avantageux, l'invention prévoit d'abaisser la pression de transfert pour la rapprocher de la pression de traitement. Ainsi, on prévoit par exemple de fixer la pression P3 à une valeur sensiblement égale à la pression de traitement dans la chambre de procédés 2, et de réaliser le transfert à cette pression P3, sans remonter à la pression PI des dispositifs de l'art antérieur. Cet exemple est illustré par la poursuite A7 du palier A6 jusqu'à l'instant tO sur la figure 2. Il en résulte alors un gain de temps de pompage appréciable, et une accélération sensible du cycle de traitement dans la chambre de procédés 2.The transfer pressure Pi established according to known systems requires, after the substrate has entered the process chamber 2, a pressure reduction up to the operating pressure of the said process chamber 2. This pressure reduction requires a time of relatively long pumping, which must be undertaken before each treatment cycle. According to a particularly advantageous embodiment, the invention provides for lowering the transfer pressure to bring it closer to the treatment pressure. Thus, provision is made for example to fix the pressure P3 at a value substantially equal to the treatment pressure in the process chamber 2, and to carry out the transfer at this pressure P3, without going back to the pressure PI of the devices of the art prior. This example is illustrated by the continuation A7 of the stage A6 until the instant t0 in FIG. 2. This then results in an appreciable saving in pumping time, and a significant acceleration of the treatment cycle in the process chamber 2.
En se référant à nouveau à la figure 1, on comprend que, par l'analyse des gaz pompés au moyen de l'analyseur de gaz 10, on peut contrôler simultanément l'atmosphère de la chambre de procédés 2. En effet, à chaque transfert d'un substrat du sas ou de la chambre de transfert 1 vers la chambre de procédés 2, une portion des gaz présents dans la chambre de procédés 2 peut passer dans le sas ou la chambre de transfert 1, et est ensuite pompée par le système selon l'invention, de sorte que l'analyseur de gaz 10 peut déceler, analyser et quantifier les gaz de cette portion de gaz et fournir ainsi à l'utilisateur des informations utiles pour contrôler le traitement.Referring again to FIG. 1, it is understood that, by analyzing the gases pumped by means of the gas analyzer 10, it is possible to simultaneously control the atmosphere of the process chamber 2. In fact, at each transfer of a substrate from the airlock or from the transfer chamber 1 to the process chamber 2, a portion of the gases present in the process chamber 2 can pass into the airlock or the transfer chamber 1, and is then pumped by the system according to the invention, so that the gas analyzer 10 can detect, analyze and quantify the gases of this portion of gas and thus provide the user with information useful for monitoring the treatment.
Par exemple, on peut concevoir que l'utilisateur compense ensuite 1 ' atmosphère de la chambre de procédés 2 par 1 ' introduction d'éléments appropriés dans l'atmosphère du sas ou de la chambre de transfert 1 lors du conditionnement de la tranche suivante de substrat, ces éléments étant ensuite transférés avec le substrat dans la chambre de procédés 2. Dans le mode de réalisation de la figure 3, le système de pompage des gaz comprend en outre, interposé dans le circuit de pompage 4 entre la pompe secondaire 6 et la chambre de transfert 1, un piège cryogénique composé d'un dispositif de réfrigération 20 refroidissant un doigt froid 21 et une surface active 22 au contact des gaz pompés dans le circuit de pompage 4. Le piège cryogénique peut être un refroidisseur mécanique de type Stirling. La surface active 22 peut être une pièce métallique cylindrique à l'intérieur de la canalisation conduisant les gaz pompés. La température typique de cette surface active 22 est de 140°K environ. La vapeur d'eau à cette température est piégée et se condense sous forme de glace sur la surface active 22. Il est possible d'atteindre des pressions partielles d'eau inférieures à 10~5Pa. Peu à peu, l'épaisseur de glace croît sur la surface active 22. Il est alors souhaitable de régénérer le piège en chauffant par effet Joule la surface active 22 : la glace se vaporise et est pompée par le circuit de pompage 12. On prévoit pour cela des moyens pour échauffer périodiquement la surface active 22 de manière à enlever la glace déposée sur la surface active 22.For example, it is conceivable that the user then compensates for the atmosphere of the process chamber 2 by the introduction of appropriate elements into the atmosphere of the airlock or of the transfer chamber 1 during the packaging of the next section of substrate, these elements then being transferred with the substrate into the process chamber 2. In the embodiment of FIG. 3, the gas pumping system further comprises, interposed in the pumping circuit 4 between the secondary pump 6 and the transfer chamber 1, a cryogenic trap composed of a refrigeration device 20 cooling a cold finger 21 and an active surface 22 in contact with the gases pumped in the pumping circuit 4. The cryogenic trap can be a mechanical cooler of the Stirling type. The active surface 22 can be a cylindrical metallic part inside the pipe conducting the pumped gases. The typical temperature of this active surface 22 is approximately 140 ° K. The water vapor at this temperature is trapped and condenses in the form of ice on the active surface 22. It is possible to reach partial water pressures of less than 10 ~ 5 Pa. Gradually, the thickness of ice grows on the active surface 22. It is then desirable to regenerate the trap by heating the active surface 22 by Joule effect: the ice vaporizes and is pumped by the pumping circuit 12. Means are provided for this to periodically heat the active surface 22 so as to remove the ice deposited on the active surface 22.
La présente invention n'est pas limitée aux modes de réalisation qui ont été explicitement décrits, mais elle en inclut les diverses variantes et généralisations qui sont à la portée de l'homme du métier. The present invention is not limited to the embodiments which have been explicitly described, but it includes the various variants and generalizations which are within the reach of those skilled in the art.

Claims

REVENDICATIONS
1 - Système de pompage des gaz dans une chambre de transfert (1) d'équipement de semi-conducteurs, comprenant une pompe primaire (3) sollicitée par des moyens d'entraînement et raccordée par un circuit de pompage (4) à la chambre de transfert1 - Gas pumping system in a transfer chamber (1) of semiconductor equipment, comprising a primary pump (3) biased by drive means and connected by a pumping circuit (4) to the chamber transfer
(1) pour pomper les gaz hors de la chambre de transfert (1) jusqu'à atteindre une pression appropriée, caractérisé en ce que :(1) for pumping the gases out of the transfer chamber (1) until an appropriate pressure is reached, characterized in that:
- les moyens d'entraînement sont adaptés pour entraîner la pompe primaire (3) selon une vitesse variable, assurant ainsi un pompage à vitesse variable,the drive means are adapted to drive the primary pump (3) at a variable speed, thus ensuring pumping at variable speed,
- une pompe secondaire turbomoléculaire (6) est interposée dans le circuit de pompage (4) entre la pompe primaire (3) et la chambre de transfert (1) ,a turbomolecular secondary pump (6) is interposed in the pumping circuit (4) between the primary pump (3) and the transfer chamber (1),
- des moyens de contrôle de gaz (8, 10, 13, 16) sont prévus pour contrôler un ou plusieurs paramètres caractéristiques appropriés des gaz pompés et pour produire des signaux de commande agissant sur les moyens d'entraînement pour adapter la vitesse de la pompe primaire (3) afin d'éviter toute condensation ou solidification des gaz dans la chambre de transfert (1) . 2 - Système de pompage des gaz selon la revendication 1, caractérisé en ce que les moyens de contrôle de gaz comprennent un capteur de température (8) sensible à la température des gaz pompés .- gas control means (8, 10, 13, 16) are provided to control one or more appropriate characteristic parameters of the pumped gases and to produce control signals acting on the drive means to adapt the speed of the pump primary (3) in order to avoid any condensation or solidification of the gases in the transfer chamber (1). 2 - gas pumping system according to claim 1, characterized in that the gas control means comprise a temperature sensor (8) sensitive to the temperature of the pumped gases.
3 - Système de pompage de gaz selon l'une des revendications 1 ou 2, caractérisé en ce que les moyens de contrôle de gaz comprennent un analyseur de gaz (10) .3 - Gas pumping system according to one of claims 1 or 2, characterized in that the gas control means comprise a gas analyzer (10).
4 - Système de pompage de gaz selon la revendication 3, caractérisé en ce que l'analyseur de gaz (10) est adapté pour détecter et mesurer la raie d'humidité. 5 - Système de pompage de gaz selon l'une des revendications 3 ou 4, caractérisé en ce que l'analyseur de gaz4 - Gas pumping system according to claim 3, characterized in that the gas analyzer (10) is adapted to detect and measure the humidity line. 5 - Gas pumping system according to one of claims 3 or 4, characterized in that the gas analyzer
(10) est adapté pour détecter et mesurer des raies d'hydrocarbures.(10) is suitable for detecting and measuring lines of oil.
6 - Système de pompage de gaz selon l'une quelconque des revendications 1 à 5, caractérisé en ce qu'il comprend en outre des moyens de mesure de la pression (13) dans une chambre de procédés6 - gas pumping system according to any one of claims 1 to 5, characterized in that it further comprises means for measuring the pressure (13) in a process chamber
(2) à laquelle est raccordée la chambre de transfert (1) , pour asservir la pression dans la chambre de transfert (1) de manière à éviter ou à limiter le transfert de matières polluantes depuis la chambre de procédés (2) vers la chambre de transfert (1) .(2) to which the transfer chamber (1) is connected, to control the pressure in the transfer chamber (1) so as to avoid or limit the transfer of pollutants from the process chamber (2) to the transfer chamber (1).
7 - Système de pompage de gaz selon l'une quelconque des revendications 1 à 6, caractérisé en ce que la pompe secondaire turbomoléculaire (6) est d'un type robuste capable de fonctionner dès le début de l'étape de pompage en refoulant les gaz à la pression atmosphérique, de sorte qu'elle n'est associée à aucune canalisation de dérivation pour démarrage du pompage et qu'elle constitue le seul élément de pompage raccordé à la chambre de transfert (1) .7 - Gas pumping system according to any one of claims 1 to 6, characterized in that the turbomolecular secondary pump (6) is of a robust type capable of operating from the start of the pumping step by driving the gas at atmospheric pressure, so that it is not associated with any bypass pipe for starting pumping and that it constitutes the only pumping element connected to the transfer chamber (1).
8 - Système de pompage de gaz selon l'une quelconque des revendications 1 à 7, caractérisé en ce qu'il comprend, interposé dans le circuit de pompage (4) entre la pompe secondaire (6) et la chambre de transfert (1), un piège cryogénique composé d'un dispositif de réfrigération (20) refroidissant un doigt froid (21) et une surface active (22) au contact des gaz pompés dans le circuit de pompage (4) .8 - Gas pumping system according to any one of claims 1 to 7, characterized in that it comprises, interposed in the pumping circuit (4) between the secondary pump (6) and the transfer chamber (1) , a cryogenic trap composed of a refrigeration device (20) cooling a cold finger (21) and an active surface (22) in contact with the gases pumped in the pumping circuit (4).
9 - Système de pompage de gaz selon la revendication 8 , caractérisé en ce qu'il comprend des moyens pour échauffer périodiquement la surface active (22) de manière à enlever la glace déposée sur la surface active (22) .9 - gas pumping system according to claim 8, characterized in that it comprises means for periodically heating the active surface (22) so as to remove the ice deposited on the active surface (22).
10 - Procédé de pompage des gaz dans une chambre de transfert (1) de semi-conducteurs vers une chambre de procédés (2) par au moins une pompe primaire (3), caractérisé en ce qu'on adapte la vitesse de la pompe primaire (3) en fonction d'un ou plusieurs paramètres caractéristiques des gaz pompés de manière à éviter ou à limiter la condensation ou la solidification des gaz dans la chambre de transfert (1) .10 - Method of pumping gases in a transfer chamber (1) of semiconductors to a process chamber (2) by at least one primary pump (3), characterized in that the speed of the primary pump is adapted (3) as a function of one or more characteristic parameters of the gases pumped so as to avoid or limit the condensation or solidification of the gases in the transfer chamber (1).
11 - Procédé selon la revendication 10, caractérisé en ce qu'on optimise la vitesse de la pompe et on poursuit le pompage jusqu'à atteindre une pression résiduelle minimale P2 et maintenir momentanément la pression résiduelle à une valeur P3 inférieure à la pression PI de fonctionnement de la chambre de transfert (1) .11 - Process according to claim 10, characterized in that the speed of the pump is optimized and the pumping is continued until a minimum residual pressure P2 is reached and momentarily maintain the residual pressure at a value P3 lower than the pressure PI of operation of the transfer chamber (1).
12 - Procédé selon l'une des revendications 10 ou 11, caractérisé en ce que, par l'analyse des gaz pompés au moyen d'un analyseur de gaz (10), on contrôle simultanément l'atmosphère de la chambre de procédés (2) . 12 - Method according to one of claims 10 or 11, characterized in that, by analyzing the gases pumped by means of a gas analyzer (10), the atmosphere of the process chamber (2) is simultaneously controlled ).
EP01928018A 2000-04-20 2001-04-20 Method and system for pumping semiconductor equipment from transfer chambers Withdrawn EP1194610A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FR0005096A FR2807951B1 (en) 2000-04-20 2000-04-20 METHOD AND SYSTEM FOR PUMPING SEMICONDUCTOR EQUIPMENT TRANSFER CHAMBERS
FR0005096 2000-04-20
PCT/FR2001/001219 WO2001081651A1 (en) 2000-04-20 2001-04-20 Method and system for pumping semiconductor equipment from transfer chambers

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EP (1) EP1194610A1 (en)
JP (1) JP2003531503A (en)
FR (1) FR2807951B1 (en)
WO (1) WO2001081651A1 (en)

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JP2003531503A (en) 2003-10-21
US6402479B1 (en) 2002-06-11
WO2001081651A1 (en) 2001-11-01
FR2807951B1 (en) 2003-05-16
FR2807951A1 (en) 2001-10-26

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