FR2946736A1 - Station for drying and/or degassing e.g. vaccine, or photomask transport chamber e.g. face opening unified pod transport chamber, has gas species analyzer comprising output signal for determining advancement characteristics parameter - Google Patents

Abstract

The station (1) has a sealed chamber (2) receiving a substrate transport chamber (3). A pumping device (6) includes a gas inlet port (7) connected to the sealed chamber. A central processing unit (9) controls an advancement characteristics parameter of drying and/or degassing of the transport chamber. Output signal of a gas species analyzer (10) is related to operation of the central processing unit for determining the advancement characteristics parameter of drying and/or degassing of the transport chamber. The gas species analyzer is a hygrometer or a volatile organic compound trace detector. An independent claim is also included for a method for drying and/or degassing a product or a transport chamber to transfer and atmospheric-store a substrate.

Description

Station and method for drying and / or degassing a product or a transport enclosure for conveying and atmospheric storage of substrates

The present invention relates to a drying station and / or degassing a transport chamber for conveying and atmospheric storage of substrates, such as semiconductor wafers or photomasks. The invention also relates to a drying station and / or degassing a food or pharmaceutical product (vaccine, serum, drug) or bio-industry (leaven) for a lyophilization treatment.

The present invention further extends to a corresponding drying and / or degassing process.

The transport and storage enclosures determine a confined space under atmospheric pressure, separate from the environment of use and transport of the substrate, for transporting and storing one or more substrates. In the semiconductor manufacturing industry, these enclosures make it possible to transport substrates such as semiconductor wafers or photomasks from one equipment to another or to store the substrates between two manufacturing steps. In particular, there are standardized speakers for transporting and storing side opening plates of the FOUP type (Front Opening Unified Pod in English) or FOSB (Front Opening Shipping Box), or opening by the bottom type SMIF Pod (Standard Mechanical Interface Pod in English), and standard RSP (Reticle SMIF Pod) photomasks storage and storage enclosures. These transport enclosures are made of materials such as polycarbonate, which can in some cases concentrate contaminants and in particular organic, amine or acidic contaminants. Indeed, at the output of the processing processes for the manufacture of semiconductors, the substrates are loaded with process gas. These gases escape from the substrates and can charge the walls and the interior environment of the transport enclosures that are thus contaminated. These walls exposed to these contaminated atmospheres BRT0421 FR (804697) can then release these harmful gases later while the enclosures contain semiconductor substrates. It is therefore expected frequent degassing stages of the transport enclosures by placing them under vacuum in sealed chambers.

In addition, polluting particles can form and lodge in these same walls. The particles stuck on the walls can then peel off, fall back on the substrates stored in these enclosures and damage them. It is therefore also expected regular cleaning of these enclosures by washing with a liquid such as pure water. The washing step is followed by a drying step comprising, for example, a phase in which the transport chambers are heated by infrared radiation and centrifuged, followed by a phase in which the transport chamber has finished being dried by a dehumidification step. During this step, the transport chamber is placed in a sealed chamber and said chamber is subjected to a sub-atmospheric pressure to promote the evaporation of liquids on the walls of said transport chamber and accelerate the desorption. In the food or pharmaceutical industry, vacuum product drying methods are also used to remove by sublimation most of the water contained in the product. The problem is to determine as precisely as possible the transition from one step to another and the end of the operation.

The stability of a product preserved under these conditions is extremely sensitive to a very small variation in the amount of residual water that it contains. A cycle too short, if it reduces costs, leads to a product too wet output. There is usually a rapid deterioration in the quality of the product. Conversely, a too long operating cycle risks causing the product to deteriorate due to overheating, to which unnecessary additional costs are added. As well as for a degassing step or for a vacuum drying stage of the transport chambers, or for monitoring the dehydration kinetics of a product during lyophilization, it is necessary to be able to precisely follow the evolution of the product. process so that the end of these steps can be checked. In particular, the monitoring of the dehydration kinetics during freeze-drying is essential to control manufacturing costs, but also to obtain a freeze-dried product of quality. BRT0421 EN (804697) In the field of semiconductors, document WO2009021941 is known, a post-processing station comprising a central unit enabling the control of a characteristic parameter of the progress of the dehumidification of the transport enclosure .

The characteristic parameter may be a predefined duration, characteristic of the type of transport enclosure from which the transport enclosure is subjected to a sub-atmospheric pressure. The predefined duration is determined by experimentation. However, the preset duration does not guarantee the reproducibility of the results on all the treated speakers.

The station also provides a device for measuring gaseous species that can operate at sub-atmospheric pressures. However, these measuring devices are not always accurate at sub-atmospheric pressures, or are far too expensive. The station also provides that the characteristic parameter may be the total or partial pressure of the gas in the chamber. However, this measurement technique lacks precision because the desorption flows are relatively low. Moreover, when a purge is injected into the chamber, the desorption flow signal may be flooded with that of the purge flow. Another method is to remove the enclosure from the enclosure once a predetermined time has elapsed and complete this step by visually inspecting the condition of the walls of the substrate enclosure. When the operator finds that drying and / or degassing is not complete, a new cycle of drying and / or degassing is started. However, this method is not accurate and can not be easily integrated into an industrial process.

The present invention aims at providing a station and a method for drying and / or degassing a transport chamber for the conveying and the atmospheric storage of semiconductor substrates, more precise and less expensive than the devices of the state of the art. the technique. BRT0421 EN (804697) For this purpose, the invention relates to a drying station and / or degassing a product or a transport chamber for conveying and atmospheric storage of substrates, comprising: a sealed chamber intended to receive at least one product or a substrate transport enclosure, a pumping device comprising a gas suction connected to said sealed chamber, a central unit for on the one hand the subatmospheric pressure management of said chamber by via the pumping device and secondly, for controlling a characteristic parameter of the progress of drying and / or degassing of the product and / or of the transport enclosure, at least one analyzer of gaseous species connected to a discharge outlet of the gases of said pumping device and whose output signal is connected to said central unit for the determination of said characteristic parameter of the advance of the dryer age and / or degassing of the product and / or the transport enclosure.

The concentration of the gaseous species at the discharge outlet of the gases is characteristic of the progress of the dehumidification and / or the drying of the product and / or the enclosure as well as the concentration of these species at the suction of the device. pumping. However, the concentration of gaseous species at the gas discharge outlet has the advantage of being accessible at a higher pressure so that real-time, quantitative, more accurate and less expensive gas analyzers can be used to monitor the evolution of the dehumidification and / or drying of the product and / or the enclosure.

According to one or more characteristics of the station, taken alone or in combination, said gaseous species analyzer is connected to a discharge pipe of a primary vacuum pump of said pumping device, gaseous species analyzer is connected downstream of a check valve of said primary vacuum pump, in the direction of gas flow, - said gaseous species analyzer is connected to an output of a vacuum stage primary of said device of - said gaseous species analyzer is a trace detector of volatile organic compounds, said gaseous species analyzer is configured to measure the mobility of ions of the gaseous species, said gaseous species analyzer has a measurement sensitivity lower or of the order of 1 ppm.

The subject of the invention is also a process for drying and / or degassing a product or a transport enclosure for conveying and atmospheric storage of substrates, comprising a drying and / or degassing step in which the product or the transport chamber is placed in said chamber of a drying and / or degassing station as described above, said chamber is subjected to a sub-atmospheric pressure via said pumping device the concentration of gaseous species present in said chamber is monitored by means of said gaseous species analyzer connected to said discharge outlet of the gases of said pumping device. It can further be provided that during the drying process of a product, the end of the sublimation of the water contained in products subjected to freeze-drying treatment is determined by controlling the concentration of gaseous species. present in said chamber by means of said gaseous species analyzer connected to a discharge outlet of the gases of said pumping device. BR0421 EN (804697) 10 of a pump pump, said gaseous species analyzer is a hygrometer, Other advantages and characteristics will become apparent on reading the description of the invention, as well as the appended drawings in which: FIG. 1 represents a schematic view of a drying and / or degassing station of a product or a transport enclosure; FIG. 2 represents a flowchart of the various steps of the drying and / or degassing process of a a product or a transport enclosure, and - Figure 3 shows a graph of the evolution of the measured humidity of a transport enclosure as a function of time during a vacuum. In these figures, the identical elements bear the same reference numbers.

For the sake of clarity, the process steps are numbered starting from 100.

FIG. 1 represents a station for drying and / or degassing 1 of a product or a transport enclosure. Drying or dehumidification is the operation to reduce or eliminate liquids and / or steam, such as water. Degassing is the operation to remove gases from the walls by desorption. The station 1 comprises a chamber 2 for receiving at least one product such as a food or pharmaceutical product, such as a vaccine, a serum or a drug, or a bio-industry product, such as leaven.

The chamber 2 may also be intended to receive at least one substrate transport enclosure. The transport chamber is a means of conveying and atmospheric storage of substrates such as platelets and photomasks of semiconductors. Atmospheric pressure is the pressure that substrate enclosures have in their environment of use, such as atmospheric pressure in the clean room.

The enclosure is for example a standardized transport enclosure type FOUP, SMIF Pod or RSP. FIG. 1 shows a chamber containing four products or substrates of substrates 3. The chamber 2 is impervious and adapted for vacuum resistance, that is to say that it is adapted to withstand a lower pressure. at 1000 mbar, and preferably of the order of 100 mbar or of the order of 10 mbar. For this, the chamber 2 is for example of form BRT0421 FR (804697) cylindrical and stainless steel. It further comprises an opening that can be closed by a closure cap and door seals disposed on the periphery of the opening so as to seal the chamber 2 when the cover is in the closed position (not shown).

As can be seen in the diagram of FIG. 1, the chamber 2 comprises a means for introducing neutral gas 4, such as means for introducing dry nitrogen, for returning the internal atmosphere of the chamber 2 to atmospheric pressure. The chamber 2 also comprises at least one pressure sensor 5 for determining the pressure in the chamber 2.

The evacuation in the chamber 2 is performed by means of a pumping device 6 of the station 1. The pumping device 6 comprises a primary vacuum pump. In the application of the degassing and / or drying of the enclosures, it can be provided that the pumping device 6 further comprises a secondary vacuum pump mounted in shunt and upstream of the primary vacuum pump so as to be isolated from the primary pumping and thus be able to switch from primary pumping to secondary pumping (not shown). Thus, to evacuate more quickly and at a still lower level the degassing flow, the chamber is subjected to a secondary vacuum for which the subatmospheric pressure is less than 0.1 mbar and preferably of the order of 0.001 mbar.

The primary vacuum pump comprises a gas suction 7 connected to the sealed chamber 2 via an isolation valve 8. In the case of the freeze-drying process monitoring, the isolation valve 8 may comprise regulating means for regulating the pressure in the chamber 2. The station 1 further comprises a central unit 9, configured to firstly manage the sub-atmospheric pressure of the chamber 2 by means of the pumping device 6 and secondly to control a characteristic parameter of the progress of the dehumidification and / or the degassing of the product and / or of the transport enclosure 3. Thus, the central unit 9 may comprise a control device for controlling in particular the control valve. isolation 8 upstream of the pumping device 6 for evacuation of the chamber 2 (Figure 1), for example depending on the signals of the pressure sensor 5. BRT0421 EN (804697) The central unit 9 is also able to inject or cut r injection of a gas into the chamber 2 by controlling the neutral gas introduction means 4. The injection of neutral gas allows for example to return the internal atmosphere of the chamber 2 at atmospheric pressure in flight from method or to adapt the internal pressure of the chamber 2 according to the value of the characteristic parameter followed during the process, for example during a drying process to prevent condensation or solidification of the gases. The central unit 9 may also be able to control the pumping speed of the pumping device 6 for example to control the internal pressure of the chamber 2 by varying the pumping speed of the pumping device 6 according to the characteristic parameter followed. The central unit 9 is also able to store at least one reference threshold and furthermore comprises means for comparing the characteristic parameter with the reference. Furthermore, the central unit 9 is connected to a gaseous species analyzer 10 of station 1 for the control of the evolution of drying and / or degassing. The gaseous species analyzer 10 is connected to a discharge outlet of the gases of the pumping device 6 for the control of gaseous species at the pump outlet. The concentration of the gaseous species at the outlet of the discharge of the gases is characteristic of the progress of the dehumidification and / or the drying of the product and / or the enclosure in the same way as the concentration of these species at the suction 7 of the device However, the concentration of gaseous species at the outlet of the gas discharge has the advantage of being accessible at a higher pressure, so that real-time, quantitative, more accurate and less expensive gas analyzers can be used. used to follow the evolution of the dehumidification and / or drying of the product and / or the chamber 3. The available input pressure of the gaseous species analyzer 10 is a function of its position in the outlet of the discharge of the 6. For example, the gaseous species analyzer 10 is fluidly connected to a delivery line 11 of the primary vacuum pump of the pumping device 6, downstream of a key. non-return valve of the primary vacuum pump (not visible) in the direction of flow of gases (see arrow 12). The available pressure at the inlet of the gaseous species analyzer 10 is then greater than the atmospheric pressure. Alternatively, and not shown, the gaseous species analyzer 10 is connected to an output of a discharge stage of the primary vacuum pump of the pumping device 6. The available pressure at the inlet of the gaseous species analyzer 10 is then greater than the primary vacuum pressure prevailing in chamber 2 but below atmospheric pressure. A gas-sensitive gaseous species analyzer is chosen which is to be evacuated from the product or enclosure, such as water vapor, volatile organic compounds, ammonia (NH 3) and / or acids. . A gaseous species analyzer that is sensitive to one or more gaseous species or several gaseous species-sensitive gaseous species analyzers may be chosen depending on the need for process monitoring. The gaseous species analyzer 10 is for example a hygrometer, sensitive to water vapor at atmospheric pressure. The gaseous species analyzer 10 can also be a trace detector of volatile organic compounds. Volatile organic compounds, such as acetone, propane, butane, isobutene (or isobutylene or 2-methyl propene), ethanol, methanol, benzene, butene, propene, ethylene or PGMEA (or propylene glycol monomethyl ether acetate or 1-methoxy-2-acetoxypropane or 1-methoxy-2-propanol acetate) are in gaseous form at atmospheric pressure and comprise carbon atoms. Simple analyzers of volatile organic compounds having a very high sensitivity of measurement at atmospheric pressure, of the order of 1 ppb (part per billion in English or billionth in French, or 10-) or lower, are commercially available. The gaseous species analyzer 10 can also be configured to measure the mobility of the ions of the gaseous species according to the principle of the IMS instrumentation (Ion Mobility Spectrometer in English) or according to the IAMS (Ion Attachment Mass Spectrometer) technology. These analyzers are suitable for detecting very low levels of gaseous contamination in the trace state (of the order of ppb). BRT0421 EN (804697) It is thus easy to choose a gaseous species analyzer having a lower measurement sensitivity or of the order of 1 ppm (part per million in English or millionth in French, ie 10-6). FIG. 2 illustrates a diagram of a drying and / or degassing process 100 of a product or of a transport enclosure for conveying and atmospheric storage of substrates. The drying and / or degassing process 100 comprises a drying and / or degassing step in which the product or the transport enclosure 3 is first placed in the chamber 2 of the drying and / or degassing station 1 (step 101).

The initial concentration of gaseous species present in the chamber 2 can then be controlled by means of the gaseous species analyzer 10 connected to a discharge outlet of the pumping device 6. For example, the initial vapor concentration of water. Then, the internal atmosphere of the chamber 2 is reduced to a sub-atmospheric pressure via the pumping device 6 (step 102) and the concentration of gaseous species present in the chamber 2 is monitored by means of the analyzer gaseous species 10 connected to a discharge outlet of the pumping device 6 (step 103). This drying and / or degassing process 100 applies, for example, to a transport chamber having undergone prior cleaning with a liquid, such as washing with pure water. Thus, in operation, the possible evaporation of the liquids on the walls of the transport chamber is promoted and the desorption is accelerated by the evacuation of the gases contained in the chamber 2 by means of the pumping device 6. , Vacuuming the walls optimizes the degassing of the walls and to obtain a satisfactory level of drying after only a few tens of minutes. The end of the drying and / or degassing step can be determined according to the result of the comparison of the evolution of the gaseous species concentration at the pump outlet with a reference threshold. The reference threshold is for example a predetermined concentration. FIG. 3 illustrates an example of monitoring the drying step of a first and a second wet transport enclosure 13, 14 and of a dry transport enclosure 15 when empty (BR0421). The graph represents the evolution of the concentration of water vapor in ppm by volume as a function of time, at the discharge outlet of the pumping device 6. The reference threshold 16 is, for example, predefined at about 13000 ppmv. The wet transport chambers (curves 13 and 14) have initial levels substantially equivalent in moisture, of the order of 46000 ppmv. It is found that the reference threshold is reached after 12 minutes for the second wet chamber (curve 14) and after 15 minutes for the first damp chamber (curve 13). The dry transport chamber (curve 15) has an initial content of about 32000 ppmv. The reference threshold is reached after only 8 minutes.

The reference threshold may also be a predetermined slope. The slope of the gaseous species concentration is then calculated and compared with an associated reference threshold. When the slope of the evolution of the concentration becomes lower than a predetermined threshold slope, the efficiency of the drying step and / or degassing becomes limited and it is decided to interrupt the drying step and / or degassing.

It is therefore possible to easily and accurately determine the end of the drying step by a hygrometer-type gas analyzer. We can then choose, either to raise the pressure in the chamber 2 and to leave the enclosure, or to store the enclosure under vacuum so that it continues to desorb its walls while waiting to be reused, or to free up the place in bedroom 2.

The drying and / or degassing process 100 thus makes it possible to obtain substrate enclosures whose desorbed flow level, and thus of drying, is optimized in terms of processing time and installation cost. This drying method 100 also applies to a product during which the end of the sublimation of the water it contains is determined during a lyophilization treatment. The lyophilization treatment comprises two successive operations: freezing and dehydration. The dehydration process comprises two stages corresponding to two distinct physical phenomena: on the one hand the sublimation of the ice crystals that formed during freezing, often called "primary desiccation", and on the other hand the final desorption unfrozen water, often called "secondary desiccation". BRT0421 EN (804697) Sublimation is usually carried out by supplying heat and lowering the total pressure (lyophilization under vacuum). In operation, once the freezing operation, which may have been carried out outside or inside the chamber 2, has been completed, the chamber 2 is subjected to a sub-atmospheric pressure via the pumping device. 6 (step 102). The pumping allows the lowering of the total pressure in the chamber 2, then the maintenance of the pressure reached to values compatible with the sublimation conditions throughout the dehydration operation. Sublimation is carried out by adding heat to the product, by conduction or radiation. The water vapor formed is then recovered by a trap (not shown). During the primary desiccation step, the pressure in the chamber is stabilized by means of the isolation valve 8 and its regulating means as well as the gas introduction means 4. The end of the sublimation is determined. the water contained in the products, such as the end of a primary desiccation step or a secondary desiccation step of the dehydration operation, by controlling the concentration of gaseous species present in the chamber 2 by means of the gaseous species analyzer 10 connected to the discharge outlet of the pumping device 6 (step 103). The drying and / or degassing process 100 and the drying and / or degassing station 1 have the advantage of being compatible with lyophilization plants. Indeed, they do not require any major modification of the chamber 2 and no additional pumping because the vacuum level required for the lyophilization process is a primary vacuum generally between 0.005 and 0.5 mbar. In addition, the tracking method is accurate and sterile.

The drying and / or degassing process 100 and the drying and / or degassing station 1 thus allow precise and inexpensive control of the drying and / or degassing stages by evacuation. BRT0421 FR (804697)

Claims (10)

REVENDICATIONS1. Station for drying and / or degassing a product or a transport enclosure (3) for conveying and atmospheric storage of substrates, comprising: - a sealed chamber (2) intended to receive at least one product or one substrate transport chamber (3), a pumping device (6) comprising a gas suction (7) connected to said sealed chamber (2), a central unit (9) for firstly the maintenance management subatmospheric pressure of said chamber (2) via the pumping device (6) and secondly, for the control of a characteristic parameter of the progress of drying and / or degassing of the product and / or the transport chamber (3), at least one random species analyzer (10) connected to a discharge outlet of the gases of said pump device (6) and whose output signal is connected to said central unit (9) for determining said characteristic parameter of the progress of the drying and and / or degassing of the product and / or of the transport enclosure (3). Drying and / or degassing station according to claim 1, wherein said gaseous species analyzer (10) is connected to a discharge pipe (11) of a primary vacuum pump of said pumping device (6). ). Drying and / or degassing station according to claim 2, wherein said gaseous species analyzer (10) is connected downstream of a non-return valve of said primary vacuum pump in the direction of flow. gases. 4. Drying and / or degassing station according to claim 1, wherein said gaseous species analyzer (10) is connected to an outlet of a discharge stage of a primary vacuum pump of said pump device ( 6). 5. drying station and / or degassing according to one of claims 1 to 4, wherein said gaseous species analyzer (10) is a hygrometer. 6. Drying and / or degassing station according to one of claims 1 to 4, wherein said gaseous species analyzer (10) is a trace detector of volatile organic compounds. BRT0421 EN (804697) 10 15 7. Drying and / or degassing station according to one of claims 1 to 4, wherein said gaseous species analyzer (10) is configured to measure the mobility of ions of the gaseous species. 8. drying station and / or degassing according to one of claims 1 to 7, wherein said gaseous species analyzer (10) has a lower measurement sensitivity or of the order of 1 ppm. 9. A method for drying and / or degassing a product or a transport chamber for conveying and atmospheric storage of substrates, comprising a drying and / or degassing step in which: the product or the transport chamber in said chamber of a drying and / or degassing station according to one of claims 1 to 8 (101), said chamber is subjected to a sub-atmospheric pressure via said pumping device ( 102), the concentration of gaseous species present in said chamber is monitored by means of said gaseous species analyzer connected to said gas discharge outlet of said pumping device (103). 10. A method of drying a product according to claim 9, wherein the end of the sublimation of the water contained in products subjected to freeze-drying treatment is determined by controlling the concentration of gaseous species present in the said product. chamber by means of said gaseous species analyzer connected to a gas discharge outlet of said pumping device. BRT0421 FR (804697)