EP2377151A1

EP2377151A1 - Method for lowering the pressure in a charge-discharge lock and associated equipment

Info

Publication number: EP2377151A1
Application number: EP09805742A
Authority: EP
Inventors: Julien Bounouar; Jean-Marie Foray
Original assignee: Adixen Vacuum Products SAS
Current assignee: Pfeiffer Vacuum SAS
Priority date: 2008-12-19
Filing date: 2009-12-18
Publication date: 2011-10-19
Also published as: KR20110099041A; JP2012513111A; WO2010070240A1; FR2940322A1; FR2940322B1; CN102282663A; US20120024394A1

Abstract

The invention relates to a method for lowering the pressure in a device charge-discharge lock from atmospheric pressure to a sub-atmospheric transfer pressure, said lock comprising a chamber in which at least one substrate is arranged at atmospheric pressure, said method comprising: a first step (101), in which first primary pumping is carried out from atmospheric pressure to a first characteristic threshold, using a primary pump with limited pumping rate, while isolating a turbomolecular pumping of said chamber; a second step (102) following said first step (101), in which a second primary pumping is carried out, faster than in said first step, to a second characteristic threshold, maintaining the isolation of the turbomolecular pumping; a third step (103) following said second step (102), in which secondary pumping is performed using said turbomolecular pumping upstream from the first pumping, and the primary pump chamber is isolated. The invention also relates to a device for implementing the method.

Description

Pressure lowering method in a loading and unloading chamber and associated equipment

The present invention relates to a method of descent pressure in a lock of loading and unloading a substrate (or "load-lock" in English) from an atmospheric pressure to a low pressure for the loading and unloading of the substrate in a treatment chamber maintained at low pressure. The invention also relates to equipment comprising a loading and unloading lock, adapted for the implementation of the method, for example a semiconductor component manufacturing equipment.

In some manufacturing processes, an important step is to treat a substrate under controlled atmosphere at very low pressure in a process chamber of equipment.

For example, in semiconductor component manufacturing processes, it is desired to maintain the semiconductor substrate at a very low pressure to effect plasma deposition or etching.

To maintain an acceptable rate and to avoid the presence of any impurity and any pollution, the atmosphere surrounding the substrate is first lowered at low pressure by a loading lock and unloading communicating with the process chamber.

For this purpose, the loading and unloading chamber comprises a sealed enclosure, the first door of which communicates the interior of the enclosure with an atmospheric pressure zone, such as a clean room or a mini-equipment environment, for loading at least one substrate. The chamber of the chamber is connected to a gas pumping system, allowing the pressure in the chamber to be lowered to a suitable low pressure similar to that in the process chamber so that the substrate can be transferred to the chamber. process chamber. The airlock further includes a second door for discharging the substrate into the process chamber or into the transfer chamber after being evacuated.

In the case of equipment comprising several process chambers, the loading and unloading chamber is placed in communication with a transfer chamber maintained at low pressure, which then distributes the substrate in the various process chambers. The loading and unloading chamber thus makes it possible to reduce the time required to go from atmospheric pressure to low transfer pressure. It also reduces pollution in the process or transfer chamber.

The descent pressure in the airlock is generally carried out gradually by two successive steps. In the first step, a slow primary pumping is carried out since the pressure atmospheric up to a first characteristic threshold. Slow pumping is essential to prevent the solidification of certain gaseous species present in the gaseous atmosphere of the airlock surrounding the substrate, for example to prevent the appearance of water crystals.

Then, in the second step, the gaseous atmosphere is brought to the appropriate low transfer pressure by faster primary pumping. However, it is observed that the partial pressure of water vapor present in the residual gaseous mixture at the transfer pressure is not very well evacuated by the primary pumping system. Water vapor can be relatively detrimental to the substrates, and can thus reduce the production yield, in particular by corrosion of the metal layers of the substrate in semiconductor manufacturing processes. In addition, during the descent in pressure of the atmosphere in the loading chamber and unloading, it necessarily occurs a degassing of the substrate, and it is important that degassing is sufficient before the substrate is introduced into the chamber. processes. In the absence of this, the degassing continues in the process chamber and the gases from this subsequent degassing constitute an additional source of pollution during the treatment. It is known from WO 01/81651, a gas pumping system comprising a primary pump connected by a pumping circuit to the loading and unloading lock for pumping the gases to a suitable transfer pressure. A turbomolecular pump is interposed in the pumping circuit between the primary pump and the loading and unloading chamber. Gas control means are provided to adapt the speed of the primary pump to prevent any condensation or solidification of the gases in the loading chamber and unloading. The turbomolecular pump is the only pumping element connected to the loading and unloading chamber. However, it can be seen that the pumping through the turbomolecular pump from the atmospheric pressure can cause problems of reliability of the turbomolecular pump and makes the pumping relatively noisy. In addition, the drive means of the primary pump for adjusting the speed of the pump are complicated to implement.

The invention therefore aims to solve the problems of the state of the art by proposing a method of descent pressure in a lock of loading and unloading equipment, simple, inexpensive to implement, compact, to prevent the solidification of certain gaseous species at high pressure and making it possible to reduce the amount of residual water vapor so as to prevent its propagation in the process or low-pressure transfer chamber, without delaying the transfer of the substrate into the chamber of processes. The method also aims to improve the degassing of the substrates at the transfer pressure. The invention also provides equipment for implementing the method. For this purpose, the subject of the invention is a method of descent in pressure in an airlock for loading and unloading equipment from an atmospheric pressure to a sub-atmospheric transfer pressure, said airlock comprising an enclosure in which the at least one atmospheric pressure substrate, and a gas pumping system comprising a primary pump and a turbomolecular pump whose suction is connected to the enclosure via a first isolation valve and whose discharge is connected upstream of said pump primary by a primary pumping circuit, said gas pumping system further comprising a branch circuit of said turbomolecular pump placed in communication on the one hand with said enclosure upstream of said first isolation valve and on the other hand with said primary pumping circuit, said branch circuit comprising a second isolation valve comprising means for limiting the flow of acti and said primary pumping circuit having a third isolation valve disposed between the delivery of the turbomolecular pump and the bypass circuit, said method comprising: a first step in which the first and third isolation valves are closed and opens said second isolation valve for which the flow limitation means are activated, to perform a first primary pumping from the atmospheric pressure to a first characteristic threshold through said branch circuit of said primary pump whose pumping rate is limited, by isolating said suction of said turbomolecular pump in operation, from said chamber and by isolating said discharge of said turbomolecular pump, from the primary pump, a second step following said first step in which the flow limiting means are deactivated of said second isolation valve for realizing er a second primary pumping, faster than in said first step, up to a second characteristic threshold, while maintaining the isolation of the turbomolecular pumping and, a third step following said second step, in which said first and third isolation valve and closing said second isolation valve to perform secondary pumping through said turbomolecular pumping upstream of the primary pumping by isolating the enclosure of said primary pump.

This results in a rapid decrease in the total pressure in the chamber of the chamber and therefore in the partial pressure of water vapor. In addition, the turbomolecular pump is constantly maintained at full throttle and at low pressure, which increases its service life and allows immediate pumping inside the enclosure as soon as the isolation valves are opened. According to one or more characteristics of the process, taken alone or in combination, the method comprises a fourth step following said third step, in which said first isolation valve is closed and said second isolation valve is opened for which the means of flow limitation are disabled, to restore primary pumping by isolating the turbomolecular pumping when a third characteristic threshold is reached, injecting a neutral gas during said fourth step, - said first and / or said second and / or said third characteristic threshold are predetermined durations, said first and / or second and / or said third characteristic threshold are predetermined pressure values, said second primary pumping is restored when said lock receives a substrate unloading request signal.

The invention also relates to equipment for carrying out the pressure descent method as described above, comprising a loading and unloading chamber comprising an enclosure for the descent into pressure of the environment of at least one substrate from atmospheric pressure to a sub-atmospheric transfer pressure and at least one treatment chamber in communication with said loading and unloading lock for transfer of the substrate into the transfer pressure treatment chamber, said airlock comprising a gas pumping system comprising a primary pump and a turbomolecular pump whose suction is connected to the chamber via a first isolation valve and whose discharge is connected upstream of said primary pump by a primary pumping circuit said gas pumping system further comprising a bypass circuit of said turbomolecular pump in communication with each other; one part with said enclosure upstream of said first isolation valve and secondly with said primary pumping circuit, said bypass circuit comprising a second isolation valve comprising activatable flow limitation means and said pumping circuit primary circuit comprising a third isolation valve disposed between the discharge of the turbomolecular pump and the bypass circuit, said gas pumping system further comprising means for controlling said isolation valves.

According to one or more characteristics of the equipment, taken alone or in combination, the second isolation valve comprises a first main valve having a first conductance and a second restriction valve bypassing said main valve and having a second conductance lower than said first conductance, the equipment comprises a processing unit for controlling said first valves as a function of at least one output signal of a sensor of a characteristic parameter of the gases of said enclosure, said third valve is integrated in a peripheral envelope of said turbomolecular pump to cooperate with a delivery port of said turbomolecular pump .

Other advantages and characteristics will appear on reading the description of the invention, as well as the appended drawings in which: FIG. 1 is a schematic view of a loading and unloading chamber and a treatment chamber; Figure 2 is a schematic side view of a semiconductor component manufacturing equipment, Figure 3 is a schematic view of a pressure descent process in a loading and unloading chamber. FIG. 4 is a graph showing a pressure descent curve in a loading and unloading lock as a function of time.

In these figures, the identical elements bear the same reference numbers. For the sake of clarity, the elements referring to the process are numbered starting from 100.

By "low primary vacuum pressure" is defined a pressure that is lower than a pressure of the order of 0.1 Pascal, obtained by primary pumping. By "secondary vacuum pressure" is defined a pressure of less than 0.1 Pascal, obtained by secondary turbomolecular pumping.

FIG. 1 represents an equipment item 1 comprising a loading and unloading chamber 2 comprising an enclosure 3 for lowering the pressure of the environment of at least one substrate 4 from atmospheric pressure to a subatmospheric transfer pressure. The sub-atmospheric transfer pressure is for example a low primary vacuum pressure, of the order of 0.01 Pascal.

The equipment 1 furthermore comprises at least one treatment chamber 5 in communication with the loading and unloading chamber 2 via a first airlock door 6, for the transfer of the substrate 4 into the treatment chamber 5 at the transfer pressure. , according to arrow 7.

The lock 2 and the treatment chamber 5 comprise a substrate holder 8 and handling robots (not shown) for including the maintenance and transfer of the substrate 4.

The enclosure 3, sealed, comprises a second airlock door 9 communicating the interior of the chamber 3 with an atmospheric pressure zone, such as a clean room or a mini-equipment environment (or "Equipment"). Front End Module (English)), for loading at least one substrate 4 according to the arrow 10.

The lock 2 also comprises means for restoring the atmospheric pressure (not shown) to replace the inside of the chamber 3 at atmospheric pressure, either while waiting for the loading of a new substrate or after having loaded a substrate that has been treated by the treatment chamber 2.

The loading and unloading lock 2 thus makes it possible to reduce the time required to pass from the atmospheric pressure to the sub-atmospheric transfer pressure and makes it possible to reduce the pollution in the process or transfer chamber. The equipment 1 is for example a semiconductor component manufacturing equipment. The treatment chamber 5 is then a process chamber or a transfer chamber.

In the case of a simple equipment (or "stand alone" in English), the processing chamber 5 is a process chamber in which for example a deposit or etching of layers of the substrate 4 of semiconductors under an atmosphere is carried out. controlled at a secondary vacuum pressure, for example of the order of 10 ³ Pascal.

In the case of a multiple equipment (or "cluster" in English), the equipment may include one or more process chambers. The treatment chamber 5 is then a transfer chamber. In operation, the transfer chamber is maintained at a transfer pressure of the order of that of the process chamber, for example of the order of 10 ² Pascal. The atmosphere of the transfer chamber is maintained by a primary pump or a secondary pump under a controlled atmosphere of neutral gas, such as nitrogen. The transfer chamber receives the substrate 4 from the loading and unloading chamber 2 at the transfer pressure and distributes it into the appropriate process chamber. FIG. 2 illustrates an example of a multiple equipment for manufacturing semiconductor components comprising a mini-equipment environment 11, a loading and unloading lock 2, a transfer chamber 5 and a process chamber 12.

The airlock 2 comprises a gas pumping system 13 (FIG. 1) in communication with the enclosure 3 for the descent of pressure inside the enclosure.

The gas pumping system 13 comprises a primary pump 14 and a turbomolecular pump 15 upstream of the primary pump 14 in the direction of circulation of the pumped gases, represented by the arrow 16. The primary pump 14 may be a pump dedicated to the airlock 2 or may also be the primary pump of another chamber of the equipment 1, such as the transfer chamber 5.

The suction 17 of the turbomolecular pump 15 is connected to the chamber 3 via a first isolation valve 18. The discharge 19 of the turbomolecular pump 15 is connected upstream of the suction of the primary pump 14 by a circuit of primary pumping 20.

The gas pumping system 13 further comprises a bypass circuit 21 of the turbomolecular pump 15 placed in communication on the one hand with the enclosure 3, upstream of the first isolation valve 18 and on the other hand with the primary pumping circuit 20.

The branch circuit 21 comprises a second isolation valve 22 comprising activatable flow limitation means. When they are activated, the flow limiting means make it possible to limit the pumping speed of the primary pump 14 mechanically. For example, the second isolation valve 22 comprises a first main valve having a first conductance and a second bypass restriction of the main valve and having a second conductance lower than the first conductance.

The primary pumping circuit 20 further comprises a third isolation valve 23 disposed between the delivery 19 of the turbomolecular pump 15 and the bypass circuit 21. It can also be provided that the third valve 23 is integrated in a peripheral envelope of the turbomolecular pump 15 so that the shutter of the third valve 23 cooperates directly with the discharge port of the turbomolecular pump.

For example, a small turbomolecular pump ATH30 sold by Alcatel Lucent is used. Such a pump has the advantage of being compact so that it can be easily disposed near the enclosure 3.

It is then possible by closing the first and the third valve 18, 23, to completely isolate the turbomolecular pump 15 in operation, the suction 17 and the discharge 19, which allows, in particular, to ensure a low primary vacuum pressure to the discharge 19 of the turbomolecular pump 15. This low discharge pressure 19 allows the pump Turbomolecular 15 operates at full speed, without over-consumption of power and without risk of failure.

The gas pumping system 13 further comprises means for controlling, in opening and closing, the isolation valves 18, 22, 23, as a function of characteristic thresholds. For this, the equipment 1 comprises a processing unit 24. For example, the processing unit 24 controls the opening and / or closing of the valves 18, 22, 23, depending on the flow of predetermined times.

According to another example, the processing unit 24 controls the valves 18, 22, 23 as a function of at least one output signal 26 of a sensor 25 connected to the enclosure 3 for the measurement of a parameter characteristic of the gas from the enclosure 3 of the airlock 2. The output signal 26 of the sensor 25 is connected to the processing unit 24 for controlling the valves 18, 22, 23 as a function of the characteristic threshold values provided by the output signal 26.

For example, the sensor 25 is a pressure sensor for indicating the pressure in the chamber 3. It can also be envisaged that the sensor 25 can provide an indication of the partial pressure of the gases inside the chamber. For example, the sensor 25 makes it possible to give an indication of the partial pressure of water vapor inside the enclosure 3.

In a particular embodiment, the sensor 25 comprises a derived excitation cell and an electromagnetic excitation antenna powered by a power generator, arranged around the cell so as to form a plasma inside thereof. The light radiation emitted by the plasma is then captured and transmitted to an optical spectrometer. The transmission can be provided by an optical fiber, or a suitable connector. The optical spectrometer generates an output signal 26 of the detected optical spectrum, which is transmitted to the processing unit 24. In another embodiment, the sensor 25 is a mass spectrometer.

The pressure drop in the loading and unloading chamber 2 of equipment 1 from the atmospheric pressure to a low transfer pressure is progressively achieved by at least three consecutive steps (see the method 100 shown in FIG.

3). We begin by having at least one substrate 4 at atmospheric pressure in the enclosure

3. The first and second isolation valves 18, 22 are closed. It is also possible to close the third isolation valve 23. The primary 14 and turbomolecular pumps 15 are in operation. During a first step 101, a first primary pumping is performed from the atmospheric pressure to a first characteristic threshold. The pumping is performed through the bypass circuit 21 of the primary pump 14, the pumping rate is limited. The suction 17 of the turbomolecular pump 15 in operation is isolated from the chamber 3 and the discharge 19 of the turbomolecular pump 15 is isolated from the primary pump 14. For this, in the example considered in FIG. first and third isolation valves 18, 23 and opens the second isolation valve 22 whose flow limitation means are activated, for example by having a second lower conductance, until crossing a first threshold feature. Thus, during the first step 101, the turbomolecular pump 15 is completely isolated from the gases of the enclosure 3 and the bypass circuit 21, the pressure between the atmospheric pressure and a first sub-atmospheric primary pressure could damage the turbomolecular pump 15.

This first step 101 makes it possible to carry out a slow primary pumping from the atmospheric pressure to the first characteristic threshold, for which the risk of pollution by too rapid primary pumping no longer exists. Slow pumping prevents the solidification of certain gaseous species present in the gaseous atmosphere surrounding the substrate 4.

Then, in a second step 102 consecutive to the first step 101, a second primary pumping is performed, which is faster than in the first step 101, up to a second characteristic threshold, while maintaining the isolation of the turbomolecular pumping.

For this, the first and third isolation valves 18, 23 are kept closed. The second isolation valve 22 is kept open and the flow limiting means are deactivated, for example with an isolation valve 22 presenting a first conductance greater than the second conductance, until a second characteristic threshold is crossed. The pumping rate of the primary pump 14 is no longer limited.

The second characteristic threshold corresponds to the threshold for which the suction pressure 17 of the turbomolecular pump 15 is sufficiently low so as not to affect its operation.

Thus, during the second step 102, when the pressure inside the chamber 3 is between the first sub-atmospheric pressure and a second primary low primary vacuum pressure, the turbomolecular pump 15 remains isolated to the suction 17 and discharge 19, which limits the power consumption of the turbomolecular pump 15 and extend its life. Then, in a third step 103 consecutive to the second step 102, secondary pumping is performed through the turbomolecular pumping upstream of the primary pumping and the enclosure 3 is isolated from the primary pumping. For this purpose, the first and third isolation valves 18, 23 are opened and the second isolation valve 22 is closed. This third step 103 makes it possible to reduce the partial pressure of water vapor present in the residual gaseous mixture and to accelerate the degassing of the substrates, which makes it possible to increase the yield of production.

Thus, during the third step 103, when the pressure inside the chamber 3 is sufficiently low, the turbomolecular pump 15, whose operation at full speed has been preserved, can immediately lower the pressure inside. of the enclosure 3.

The method 100 may comprise a fourth step 104 consecutive to the third step

103 in which a primary pumping is restored by isolating the turbomolecular pumping when a third characteristic threshold is reached. For example, primary pumping is restored when the lock 2 receives a request signal for discharging the substrate 4, which can be generated by the treatment chamber 5.

For this, the first isolation valve 18 is closed and the second isolation valve 22 is opened for which the flow limiting means are deactivated, for example with the first higher conductance when a third characteristic threshold has been crossed. during the third step 103. It is also possible to close the third isolation valve 23 just before opening the second isolation valve 22, to ensure that the discharge 19 of the turbomolecular pump 15 is isolated. a low pressure of primary vacuum.

The fourth step 104 makes it possible to bring the gaseous atmosphere of the substrate 4 to the appropriate transfer pressure. Thus, the process steps of the treatment chamber 5 do not have to be modified to allow the entry of the substrate 4, because the same transfer pressure is maintained. It is also possible to inject a neutral gas during the fourth step 104, such as nitrogen, to ensure the flow direction of the gases to the primary pumping.

Said first and / or said second and / or said third characteristic threshold may be predetermined durations. Alternatively or in addition, said first and / or said second and / or said third characteristic threshold are predetermined pressure values. Figure 4 is a graph of a pressure drop curve dans in a loading and unloading lock 2 as a function of time.

At the initial time t0 of the graph, the atmosphere of the substrate 4 is at atmospheric pressure Pa. During the first step 101, the pressure of the environment of the substrate 4 is lowered by slow pumping at a sub-atmospheric pressure P1, through the primary pump

14 whose pumping rate is limited. The pressure P1, for example of the order of fifty Pascal, corresponds to the first characteristic threshold from which it is estimated that there is no longer a risk of pollution by too rapid primary pumping.

Then, in the second step 102, the pressure of the environment of the substrate 4 is lowered by a rapid pumping at a sub-atmospheric pressure P2, lower than the pressure P1, through the primary pump 14 whose pumping rate n ' is more limited. There is thus a slope break in the pressure drop curve at time t1 for which the fast primary pumping is started. The pressure P2, for example of the order of 0.1 Pascal, corresponds to the second characteristic threshold from which the turbomolecular pump can operate fully without risk of deterioration.

Then, in the third step 103, the pressure of the environment of the substrate 4 decreases to a sub-atmospheric pressure P3, of the order of 10 ⁴ Pascal, through the secondary pump 15. There is also a second rupture slope in the pressure drop curve at time t2 for which pumping is performed through the turbomolecular pump 15.

During the fourth step 104, at time t3 when a third characteristic threshold has been crossed, the pressure of the environment of the substrate 4 rises to a transfer pressure P4, corresponding to a low pressure of primary vacuum of the order of 10 ² Pascal. The pressure P4 is obtained by the primary pumping with an injection of neutral gas. The third characteristic threshold corresponds for example to the completion of a duration D, of the order of a few seconds, after the pressure of the chamber 3 has reached the sub-atmospheric pressure P3.

In this way, a decrease in the total pressure in the enclosure 3 and therefore in the partial pressure of water vapor is thus obtained rapidly and in masked time. Moreover, the turbomolecular pump 15 is constantly maintained at full operating speed and is only stressed for low primary vacuum pressures, which increases its service life and makes it possible to avoid any loss of time or efficiency. when placed in communication with the enclosure 3. In addition, it is possible to use a standard turbomolecular pump 15.

The pressure-lowering method is therefore simple, inexpensive to implement, and makes it possible to descend rapidly to a low pressure that is lower than the transfer pressure in order to improve the conditioning of the substrate, while meeting the industrial constraints of reliability enabling ensure the high rates of the pump cycles of the loading and unloading chambers.

Claims

1. Method of descent in pressure in a lock chamber for loading and unloading equipment from an atmospheric pressure to a sub-atmospheric transfer pressure, said lock (2) comprising an enclosure (3) in which at least one substrate is provided (4) at atmospheric pressure, and a gas pump system (13) comprising a primary pump (14) and a turbomolecular pump (15) whose suction (17) is connected to the enclosure (3) via a first isolation valve (18) whose discharge (19) is connected upstream of said primary pump (14) by a primary pumping circuit (20), said gas pumping system (13) further comprising bypass (21) of said turbomolecular pump

(15) placed in communication on the one hand with said enclosure (3) upstream of said first isolation valve (18) and on the other hand with said primary pumping circuit (20), said branch circuit

(21) having a second isolation valve (22) including activatable flow control means and said primary pump circuit (20) having a third isolation valve (23) disposed between the pump discharge (19) turbomolecular cell (15) and the bypass circuit (21), said method comprising: a first step (101) in which said first and said third isolation valves (18, 23) are closed and said second isolation valve is opened (22) for which the flow limiting means are activated, to perform a first primary pumping from the atmospheric pressure to a first characteristic threshold through said branch circuit (21) of said primary pump (14) whose flow rate pumping is limited, by isolating said suction (17) of said turbomolecular pump (15) in operation, from said enclosure (3) and by isolating said delivery (19) of said turbomolecular pump (15), the primary pump (14), - a second step (102) following said first step (101) in which the flow limiting means of said second isolation valve (22) are deactivated to achieve a second, faster, primary pumping. in said first step, up to a second characteristic threshold, while maintaining the isolation of the turbomolecular pumping and - a third step (103) following said second step (102), in which said first and said third valve are opened isolating (18, 23) and closing said second isolation valve (22) for secondary pumping through said turbomolecular pumping upstream of the primary pumping by isolating the enclosure (3) from said primary pump (14) .

2. The pressure lowering method as claimed in claim 1, comprising a fourth step (104) following said third step (103), in which said first isolation valve (18) is closed and said second isolation valve is opened. (22) for which the flow limiting means are deactivated, to restore primary pumping by isolating the turbomolecular pumping when a third characteristic threshold is reached.

3. A method of pressure reduction according to claim 2, wherein a neutral gas is injected during said fourth step (104).

4. A pressure descent method according to any one of the preceding claims, wherein said first and / or said second and / or said third characteristic threshold are predetermined durations.

A pressure lowering method according to any one of the preceding claims, wherein said first and / or second and / or said third characteristic threshold are predetermined pressure values.

6. Pressure reduction method according to any one of the preceding claims, taken together with claim 2, characterized in that restores said second primary pumping when said lock (2) receives a substrate unloading request signal.

(4).

7. Equipment for the implementation of the pressure-lowering method according to any one of the preceding claims, comprising a loading and unloading chamber (2) comprising an enclosure (3) for the descent pressure of the environment d at least one substrate (4) from atmospheric pressure to a sub-atmospheric transfer pressure and at least one treatment chamber (5) in communication with said loading and unloading chamber (3) for substrate transfer (4) in the treatment chamber (5) at the transfer pressure, said lock (2) comprising a gas pumping system (13) comprising a primary pump (14) and a turbomolecular pump (15) whose suction (17) is connected to the enclosure (3) via a first isolation valve (18) and whose discharge (19) is connected upstream of said primary pump (14) by a primary pumping circuit (20), said gas pumping system (13) further comprising a circui t of derivation (21) of said turbomolecular pump (15) placed in communication on the one hand with said enclosure (3) upstream of said first isolation valve (18) and on the other hand with said primary pumping circuit ( 20), said bypass circuit (21) having a second isolation valve (22) including activatable flow control means and said primary pump circuit (20) having a third isolation valve (23) disposed between the delivery (19) of the turbomolecular pump (15) and the bypass circuit (21), said gas pump system (13) further comprising means for driving said isolation valves (18, 22, 23). δ.Equipment according to claim 7, wherein the second isolation valve (22) comprises a first main valve having a first conductance and a second restriction valve bypassing said main valve and having a second conductance lower than said first conductance .

9. Equipment according to any one of claims 7 or 8, comprising a processing unit (24) for controlling said valves (18, 22, 23) as a function of at least one output signal (26) of a sensor (25) a characteristic parameter of the gases of said enclosure (3). 10. Equipment according to any one of claims 7 to 9, characterized in that said third valve (23) is integrated in a peripheral envelope of said turbomolecular pump (15) to cooperate with a discharge port of said turbomolecular pump (15). ).