Device and method for exhaust gas purification at a CVD reactor

Abstract

Method for operating a reactor (3), in particular as a control program stored in a data storage device, into which different process gases are fed in different process steps and in which different exhaust gases are discharged from the reactor (3) through an exhaust gas line (5) in the different process steps, wherein in a first process step a first exhaust gas device (10) is flow-connected to the exhaust gas line (5) by means of a first shut-off valve (11) of a valve arrangement (11, 21) and at least a second exhaust gas device (20) is separated from it by a second shut-off valve (21), wherein a first of the two exhaust gases is treated with a first cleaning element (18) of the first exhaust gas device (10) and by means of a first gas injection device (12) having in particular a first mass flow controller (12') between the valve arrangement (11,21) and the first cleaning element (18) is supplied with a first compensating gas and the total pressure (P, F ) in the first exhaust gas device (10), wherein in a second process step a second exhaust gas device (20) is connected to the exhaust gas line (5) by means of the second shut-off valve (21) of the valve arrangement (11, 21) and at least the first exhaust gas device (10) is separated from it by the first shut-off valve (11), wherein a second of the two exhaust gases is treated with a second cleaning element (28) of the second exhaust gas device (20) and a second compensating gas is fed in between the valve arrangement (11, 21) and the second cleaning element (28) by means of a second gas feed device (22) having in particular a second mass flow controller (22') and the total pressure (P) is measured with a second pressure sensor (23). T) in the second exhaust system (20), whereby the pressure difference between the total pressure (P) is determined by means of a control device (9). F ) in the first exhaust device (10) and the total pressure (P T ) in the second exhaust device (20) at least when switching the valve arrangement during which the two shut-off valves (11, 21) of the two valve arrangements 11, 21) are simultaneously open are regulated to zero.

Description

[0001] Devices with a reactor into which different process gases can be fed in separate process steps, or processes in which different process gases are fed into a reactor in separate process steps, are known in the prior art. For example, US Patent 7,647,886 B2 describes a process chamber into which different process gases are fed from several gas sources in separate process steps. The process gases enter the process chamber through a gas inlet. A substrate to be coated is located on a heated susceptor in the process chamber. During this process, the process gases decompose, particularly pyrolytically, forming a coating and an exhaust gas. The exhaust gas exits the process chamber through an exhaust pipe and is cleaned in a first exhaust gas cleaning device.When using a second process gas, for example a cleaning gas intended to etch parasitic deposits from the walls of the process gases, a second exhaust gas cleaning system is used. The two exhaust gas cleaning systems have separate cleaning elements, each filtering out a different exhaust gas or reaction product.

[0002] US patents 2007 / 0207625 A1 and 2012 / 0304930 A1 each disclose a CVD reactor with a gas outlet connected to an exhaust gas cleaning system. The exhaust gas cleaning system has two parallel branches that can be used selectively for cleaning the exhaust gas.

[0003] From JP H07-142392 A, a CVD reactor is known in which a process gas flows vertically through a process chamber. To ensure a uniform layer thickness of the deposited layer, the coating process is divided into two halves, with the gas flow reversing direction during the half-cycle. A differential pressure measuring device is provided in the exhaust system to measure the pressure difference between two different exhaust gas branches.

[0004] US 2013 / 0237063 A1 also describes an arrangement of exhaust gas cleaning devices comprising two pumps and a common cleaning device.

[0005] US Patent 4,817,557 A describes a process chamber arrangement for carrying out a CVD process, wherein a ballast gas can be fed into an exhaust line via a mass flow controller, with which the total pressure in the process chamber can be varied or controlled while the suction power of the pump arrangement is kept at a fixed value.

[0006] During the operation of a CVD reactor, a process gas is fed into the process chamber of the CVD reactor through a gas inlet device. The process gas can consist of reacting individual gases; for example, the process gas can contain a metal-organic III component and a III hydride. For example, a metal-organic gallium compound, a metal-organic indium compound, or a metal-organic aluminum compound can be fed into the process chamber. To deposit III-V layers, a hydride, such as arsine, phosphine, or ammonia, is additionally fed in. The chemical reaction products form a preferably single-crystal layer on the substrate resting on a heated susceptor in the process chamber. Gaseous reaction products or undiluted process gases are discharged from the process chamber, which is located inside the gas-tight reactor, through an exhaust line.During the growth step, a first exhaust system with a first cleaning device, such as a particulate filter, is connected to the exhaust line. The particulate filter removes particles that form in the process chamber or in the gas outlet through reactions between the process gases. During the deposition process, not only does a layer form on the one or more substrates, but parasitic deposits also form on the walls of the process chamber and, in particular, on the areas of the heated susceptor surface not covered by the substrates. In a cleaning step, performed after the coating step and once the substrates have been removed from the process chamber, a cleaning gas is introduced into the chamber. This cleaning gas is typically chlorine.The cleaning gas removes parasitic deposits from the surfaces of the walls or the susceptor of the process chamber. The exhaust gas line carries not only the reaction product between the cleaning gas and the deposits, such as gallium chloride, but also Cl₂. To prevent the cleaning gas from reacting with the residues in the filter, or to remove the cleaning gas from the exhaust stream, a valve assembly separates the first exhaust gas unit from the exhaust gas line. This valve assembly connects a second exhaust gas unit to the exhaust gas line, which contains a second cleaning element. A cold trap cooled to 77 K, for example, can be used to freeze the cleaning gas.In such a method or device, the valve arrangement alternately connects either the first or the second exhaust gas unit to the exhaust line. However, crosstalk can occur during switching. This means that, for example, chlorine gas enters the exhaust gas cleaning unit used to purify the process gas during the separation process, or that NH3 enters the exhaust gas cleaning unit used to freeze the cleaning gas. In both cases, this results in a reaction of Cl with NH3 to form NH4Cl, thus reducing the service life of the cleaning elements.Such cross-contamination occurs in a prior art device if, for safety reasons, both shut-off valves connecting the respective exhaust device to the exhaust pipe are briefly open when switching the valve arrangement.

[0007] The invention is based on the objective of improving a device or method for exhaust gas purification of a CVD system in a way that is advantageous for use.

[0008] The problem is solved by a device comprising a reactor into which different process gases can be fed in different process steps and which has an exhaust line through which different exhaust gases can be discharged from the reactor in the different process steps, a first exhaust device which can be connected to and disconnected from the exhaust line by means of a valve arrangement, a first cleaning element for treating exhaust gas generated in a first of the different process steps, a first gas injection device arranged between the valve arrangement and the first cleaning element for injecting a first compensating gas, a first pressure sensor for determining the total pressure in the first exhaust device, and in particular a first mass flow controller for adjusting the mass flow of the compensating gas.and with a second exhaust gas device, which can be connected to and separated from the exhaust gas line by means of the valve arrangement, with a second cleaning element for treating exhaust gas generated in a second of the different process steps, with a second gas injection device arranged between the valve arrangement and the second cleaning element for injecting a second compensating gas, with a second pressure sensor for determining the total pressure in the second exhaust gas device, and in particular with a second mass flow controller for adjusting the mass flow of the second compensating gas, wherein a control device is provided whose controlled variable is the pressure difference between the total pressure in the first exhaust gas device and the total pressure in the second exhaust gas device, and which is configured such that the pressure difference is initially controlled to zero when the valve arrangement is switched.

[0009] The problem is further solved by a method or a control program stored in a data storage device for operating a reactor into which different process gases are fed in different process steps and in which different exhaust gases are discharged from the reactor through an exhaust gas line in different process steps, wherein in a first process step a first exhaust gas device is flow-connected to the exhaust gas line by means of a valve arrangement and at least a second exhaust gas device is separate from it.wherein the first exhaust gas is treated with a first cleaning element of the first exhaust gas device and a first compensating gas is fed in between the valve arrangement and the first cleaning element by means of a first gas injection device, in particular having a first mass flow controller, and the total pressure in the first exhaust gas device is determined with a first pressure sensor, wherein in a second process step a second exhaust gas device is flow-connected to the exhaust gas line by means of the valve arrangement and at least the first exhaust gas device is separated from it,wherein the second exhaust gas is treated with a second cleaning element of the second exhaust gas device, and a second compensating gas is fed in between the valve arrangement and the second cleaning element by means of a second gas supply device, in particular having a second mass flow controller, and the total pressure in the second exhaust gas device is determined by means of a second pressure sensor, wherein the pressure difference between the total pressure in the first exhaust gas device and the total pressure in the second exhaust gas device is initially regulated to zero by means of a control device during the switching of the valve arrangement. In a preferred embodiment of the invention, a pressure sensor is provided with which the total pressure in the process chamber can be determined. Furthermore, at least one vacuum pump is provided,with which the process chamber can be evacuated through one of the exhaust systems. Upstream of the at least one vacuum pump is a throttle valve. The throttle valve has an actuator driven by the control unit. The actuator allows the opening cross-section of the throttle valve, and thus the pump output, to be varied. During the process step, the total pressure within the process chamber, measured by the pressure sensor, is regulated to a setpoint, for example, by varying the position of the throttle valve. However, the mass flow of the compensating gas, which acts here as ballast gas, can also be used to regulate the total pressure in the process chamber.The procedure described above is used at least during the switchover from one process step to the next. At the beginning of the switchover phases, the total pressures in the two exhaust gas systems are regulated to a common value by varying the position of the throttle valve and / or by varying the mass flow of the compensating or ballast gas into the two exhaust gas systems.

[0010] This occurs during an operating state in which one exhaust system is connected to the gas discharge via an open shut-off valve, and the other exhaust system is separated from the exhaust line by a closed shut-off valve. After the total pressures in both exhaust systems have stabilized, the previously closed shut-off valve is opened, so that both exhaust systems are flow-connected to the exhaust line. Because the total pressure in both exhaust systems is maintained at a common value, the cross-flow that is problematic in prior art is prevented. Nevertheless, it is ensured that the process chamber is continuously extracted, as all shut-off valves are never closed at any one time. Shortly after the shut-off valve of, for example, the second exhaust system opens, the shut-off valve of the first exhaust system closes.In the subsequent process step, the control unit again works in conjunction with the pressure sensor, which determines the total pressure in the process chamber, to maintain the total pressure in the process chamber at a setpoint. Since the shut-off valves are generally not 100% airtight, the pressure difference between the total pressures in the two exhaust gas systems is kept as constant as possible during the process steps, particularly by varying the mass flow rates of the first and / or second compensating gas. In the exhaust gas system that is separate from the exhaust line, pressure control can be achieved by varying the mass flow rate of the injected compensating gas. The compensating gas is preferably an inert gas, such as nitrogen. However, hydrogen or a suitable noble gas can also be used. The injection takes place in a section of the exhaust gas system located between the valve assembly and the respective cleaning element.The total pressure is preferably determined in this area. The cleaning element can be a particle filter or a cold trap. Preferably, the first cleaning element is a particle filter and the second is a cold trap for freezing out chlorine. A pressure sensor can also be arranged downstream of the cleaning element. This pressure sensor measures a reduced total pressure due to the pressure drop in the cleaning element. Each of the one or more exhaust gas devices can have a throttle valve with which the pumping capacity of a vacuum pump located downstream of the throttle valve can be regulated. To regulate the total pressure within the exhaust gas device, the throttle valve can be held in a fixed position. This results in the pump operating at a constant delivery rate.However, it is also possible to regulate the total pressure using the respective throttle valve and to feed a constant ballast flow into the exhaust system. In a preferred embodiment of the invention, at the beginning of the switching phase, the compensating gas flow into the exhaust system, which is still separated from the exhaust line but will be connected to it at the end of the switching phase, is increased to a value corresponding to the gas flow through the exhaust system that is connected to it at the beginning of the switching phase but will be separated after the switching phase. Both exhaust systems each have a throttle valve with which the total pressure in the process chamber can be adjusted. These two throttle valves then have approximately the same valve position immediately before the closed shut-off valve opens.After opening the previously closed shut-off valve and closing the previously open shut-off valve, only the flow of compensating gas into the exhaust system, now connected to the exhaust line, needs to be reduced. This can be done more quickly than by adjusting the throttle valve. This results in only a slight pressure increase within the process chamber when the shut-off valve is closed. The total pressure within the exhaust system is regulated by determining the total pressure using the pressure sensor and the control unit, which varies the mass flow of the compensating gas via the mass flow controller. In a variant of the invention, only one vacuum pump is provided, to which two or more exhaust systems are connected.Furthermore, each exhaust gas unit may be equipped with its own vacuum pump, which may be located upstream or downstream of the cleaning device. In any case, the total pressure is determined directly downstream of the valve assembly, ensuring that no cross-flow occurs when all valves of the assembly are open. Each of the two or more exhaust gas units may have its own shut-off valve, which is part of the valve assembly. Upstream of the shut-off valve, the exhaust gas unit is connected to the reactor's exhaust line. Preferably, at least one gas cleaning system in the form of a scrubber is provided. A common scrubber may be provided that cleans each gas stream exiting the vacuum pumps or the vacuum pump. However, it is also possible for each exhaust gas unit to have its own individually assigned scrubber.Furthermore, it may be provided that each exhaust system has a throttle valve. However, it may also be provided that at least one exhaust system does not have an adjustable throttle valve, but only a fixed throttle, so that the total pressure within this exhaust system is regulated exclusively via the compensating gas.

[0011] Exemplary embodiments of the invention are explained below with reference to the accompanying drawings. These show: Fig. 1 as a block diagram a first embodiment with two exhaust gas purification devices 10, 20 arranged in parallel to each other, Fig. 2 a representation according to Fig. 1, however with three exhaust gas purification devices arranged parallel to each other 10, 20, 30, Fig. 3 a representation according to Fig. 1 of a third embodiment, in which a common vacuum pump 16 is arranged downstream of each of a throttle valve 15, 25, Fig. 4 a fourth embodiment of the invention, in which the cleaning elements 18, 28 are arranged downstream of the vacuum pumps 16, 26 and Fig. 5 a fifth embodiment in which only an adjustable throttle valve 15 is provided and a fixed-value throttle 25 is located in the exhaust gas purification device 20.

[0012] The exemplary embodiments describe an exhaust gas purification device for cleaning the various exhaust gases generated during a CVD growth process. The CVD growth process takes place in a reactor 3. The reactor 3 is a gas-tight sealed housing containing a gas inlet element 6. The showerhead-shaped gas inlet element 6 has gas outlet openings through which process gases supplied by gas sources 1, 2, 2' enter a process chamber, the bottom of which is formed by a heated susceptor 7. One or more substrates 8, for example III-V substrates or IV substrates, such as silicon substrates, are placed on the susceptor 7. III-V layers, for example gallium arsenide, indium arsenide, indium phosphide, or gallium nitrite layers, are deposited on the substrates 8.Generally speaking, layers containing gallium, indium, aluminum, phosphorus, arsenic, and / or nitrogen are deposited within the process chamber. These layers can also be doped with other materials. Process gases in the form of organometallic compounds or hydrides, such as NH3, are used. The process gases, along with a carrier gas, are introduced into the process chamber through the gas inlet. Hydrogen, nitrogen, or a noble gas can be used as the carrier gas.

[0013] After depositing one or more layers with different compositions onto the substrates 8 and removing the substrates 8 from the process chamber, the process chamber must be cleaned. For this purpose, a cleaning gas is introduced into the process chamber. A typical cleaning gas is chlorine. The cleaning gas is introduced into the process chamber together with a carrier gas. Nitrogen is particularly suitable as the carrier gas when using chlorine.

[0014] The process gases or exhaust gases are discharged from the reactor 3 through an exhaust pipe 5. A pressure sensor 4 is located in the exhaust pipe 5 to measure the total pressure P. Rto be measured within the exhaust gas line or within the process chamber. The exhaust gas line 5 branches to a first shut-off valve 11 of a first exhaust gas cleaning device 10. This is an exhaust gas cleaning device that includes a cleaning element 18 in the form of a particulate filter. Immediately downstream of the first shut-off valve 11 is a gas injection point 12 for injecting a compensating gas, for example N2. The mass flow of the compensating gas is controllable via a mass flow controller 12'. Immediately downstream of the shut-off valve 11, i.e., between the cleaning element 18 and the shut-off valve 11, is a pressure sensor 13 with which the total pressure P is measured. F within the exhaust system 10, it is preferably the total pressure immediately downstream of the shut-off valve 11.

[0015] By means of a second pressure sensor 13', the total pressure P can be determined. Fcan be determined downstream of the cleaning organ 18.

[0016] Downstream of the cleaning element 18 is an adjustable throttle valve 15, with which the suction power of the vacuum pump 16 located downstream of the throttle valve 15 can be adjusted. Downstream of the vacuum pump 16 is a scrubber 17 for gas cleaning.

[0017] The exhaust line 5 further branches to a second exhaust device 20, which has a similar design to the first exhaust device 10. It has a second shut-off valve 21 and a second inlet 22 located immediately downstream of the shut-off valve 21 for introducing a second compensating gas, the mass flow of which is adjusted via a second mass flow controller 22'. The total pressure P is measured by means of a second pressure sensor 23. TThe location is determined immediately downstream of the second shut-off valve 21. The shut-off valve 21, which can be operated independently of the shut-off valve 11, allows the second exhaust device 20 to be connected to or disconnected from the exhaust line 5.

[0018] The second exhaust device 20 has a second cleaning element 18 in the form of a cold trap, which can be cooled to 77°K to freeze out the cleaning gas. Downstream of the second cleaning element 28 is another pressure sensor 23' to measure the total pressure P T to be determined within the exhaust system 20.

[0019] An adjustable throttle valve 25 is located upstream of a second vacuum pump 26 to adjust the pumping capacity of the second vacuum pump 26. A second scrubber 27 is located downstream of the second vacuum pump.

[0020] During the separation process, the second shut-off valve 21 is closed and the first shut-off valve 11 is open, allowing the exhaust gas, which contains NH3 in particular, to flow through the exhaust line 5 into the first exhaust gas cleaning unit 10. Particles present in the exhaust gas stream are filtered out in the particulate filter 18. Undissolved residual gas passes through the vacuum pump 16 into the gas cleaning unit 17. During the separation process, the two pressure sensors 13 and 23 transmit pressure values ​​for the total pressure in the first exhaust gas unit 10 and the second exhaust gas unit 20 to a control unit 9. The control unit 9 also receives the total pressure P from the pressure sensor. R within the process chamber. By varying the position of the throttle valve of the throttle valve 15, the total pressure in the process chamber is maintained at a setpoint.

[0021] After the separation process, a switching phase takes place. The purpose of the switching phase is to disconnect the first exhaust gas device 10 from the exhaust gas line 5 by disconnecting the shut-off valve 11 and to connect the second exhaust gas device 20 to the exhaust gas line 5 by opening the shut-off valve 21.

[0022] At the beginning of the switching phase, the control variable for the pressure regulation is changed. Instead of the total pressure P R In the trial chamber, the total pressure P is now being measured. F in the first exhaust system, the value is kept constant. This is achieved either by varying the mass flow of the compensating gas supplied by the mass flow controller 12' or by varying the position of the throttle valve of the throttle valve 15.

[0023] At the beginning of the switching phase, the mass flow of the compensating gas, which is fed into the second exhaust gas device 20 by the mass flow controller 22' at the feed point 22, is set to a value corresponding to the mass flow flowing through the throttle valve 15 of the first exhaust gas device 10. When the compensating flow is small, this is essentially the same mass flow that also flows through the process chamber of the reactor 3. The total pressure P T In the second exhaust device 20, the total pressure P is then applied. F the first exhaust device 10 is regulated. In other words, the total pressures P F , P T In both exhaust systems 10, 20 are regulated to the same value.

[0024] As soon as the total pressures P F , P TOnce the pressure in both exhaust devices 10 and 20 has stabilized, the shut-off valve 21 can be opened. As soon as the valve 21 is fully open, the shut-off valve 11 of the first exhaust device 10 is closed. For a brief moment, both exhaust devices 10 and 20 are thus connected to the exhaust pipe 5. Due to the identical total pressures on both sides, only minimal cross-flow occurs.

[0025] Simultaneously with the closing of the first shut-off valve 11 of the first exhaust device, the mass flow of the compensating gas, which is fed into the second exhaust device 20 at the feed point 22, is reduced to a minimum, so that when the valve arrangement is switched, i.e. when the second shut-off valve 21 is opened and when the first shut-off valve 11 is closed, the positions of the two throttle valves 15, 25 are essentially the same.

[0026] Due to the pressure equality, no cross-flows occur during switching. The chlorine used in cleaning the process chamber is frozen out in the cold trap 28. During the cleaning step, the total pressure in the first exhaust system 10 is maintained at the same level as the total pressure in the second exhaust system 20 by injecting compensating gas at the injection point 12 into the first exhaust system.

[0027] After the switching process is completed, the control device 9 receives the total pressure in the process chamber again as a reference variable, so that the pressure P determined by the pressure regulator 4 R is used to control the throttle valve 25. Here too, it is possible to keep the throttle valve 25 at a constant value and to carry out pressure control by varying the mass flow of the compensating gas.

[0028] After completion of the cleaning step, another switching phase occurs, in which the total pressure within the active exhaust system 20 is first regulated to a constant value, and the total pressure of the inactive exhaust system 10 is regulated to the same total pressure. Once pressure stability is reached, i.e., a state in which the same total pressure prevails in both exhaust systems 10 and 20, the shut-off valve 11 of the passive exhaust system is opened, and as soon as it is open, the shut-off valve 21 of the active exhaust system 20 is closed. The process then switches back to regulating the total pressure within the process chamber.

[0029] In the passive exhaust system, the mass flow of the compensating flow fed in at the feed points 22 or 12 is maintained at a minimum value. However, the control device 9 maintains the total pressure within the passive exhaust system at the same value as the total pressure in the active exhaust system.

[0030] In the Fig. The second embodiment shown in 2 is the one described in the Fig. The embodiment shown in Figure 1 is supplemented by a third exhaust gas purification device 30, the construction of which essentially corresponds to that of the first exhaust gas purification device 10. The third exhaust gas purification device 30 has a third shut-off valve 31, which is connected in parallel to the shut-off valves 11 and 21. At an inlet point 32, a third compensating gas is fed into the exhaust gas purification device 30 by means of a third mass flow controller 32', with mass flow control. The third exhaust gas purification device 30 has a particulate filter as its third purification element 38. Upstream of the particulate filter 38 is a third pressure sensor 33 for determining the total pressure within the third exhaust gas purification device. The third pressure sensor 33 provides its value to the control unit, which in turn controls the third mass flow controller 32' such that the total pressure within the exhaust gas purification device 30 corresponds to the total pressure of the two other exhaust gas purification devices 10 and 20.

[0031] Downstream of the cleaning element 38 is another pressure sensor 33'. Downstream of the cleaning element 38 is also a third throttle valve 35, which determines the pumping capacity of a third vacuum pump 36. The third throttle valve 35 is also adjustable. Downstream of the third vacuum pump 36 is a third scrubber 37.

[0032] In the Fig. In the third embodiment shown in Figure 3, unlike in the first embodiment, only one vacuum pump 16 is used. The single vacuum pump 16 is arranged downstream of the two throttle valves 15, 25. Downstream of the vacuum pump 16 is a common scrubber 17.

[0033] In the Fig. In the fourth embodiment shown in Figure 4, the vacuum pumps 16, 26 are located upstream of the cleaning elements 18, 28, but downstream of the gas supply points 12, 22. The vacuum pumps 16, 26 operate at a constant pumping capacity. The pressure downstream of the shut-off valves 11, 21 is adjusted by varying the mass flows of the two compensating gases.

[0034] The one in Fig. The embodiment shown in Figure 4 can be modified such that upstream of the vacuum pump 16 or upstream of the vacuum pump 26, but downstream of the measuring points where the total pressure P is measured, the measuring points are located. F or P T A throttle valve 11, 21 is arranged, with which the total pressure can be controlled by the control device 9.

[0035] In the Fig.In the embodiment shown in Figure 5, only one adjustable throttle valve 15 is used upstream of a single vacuum pump 16. This throttle valve 15 essentially only allows the total pressure in the first exhaust system 10 to be influenced. The second exhaust system 20 has a throttle valve 25 set to a fixed value. Here, too, a compensating gas regulated by a controller 9 is fed into inlet points 12 and 22 in order to adjust the total pressure in the exhaust system, which is separate from the exhaust line 5.

[0036] The foregoing statements serve to explain the inventions covered by the application as a whole, which each independently advance the prior art at least through the following combinations of features, namely: A device characterized in that different process gases can be fed into a reactor 3 in different process steps, and the reactor 3 has an exhaust gas line 5 through which different exhaust gases can be discharged from the reactor 3 in the different process steps, comprising a first exhaust gas device 10 which can be connected to and disconnected from the exhaust gas line 5 by means of a valve arrangement 11, 21, comprising a first cleaning element 10 for treating exhaust gas generated in a first of the different process steps, comprising a first gas injection device 12 arranged between the valve arrangement 11, 21 and the first cleaning element 18 for injecting a first compensating gas, and comprising a first pressure sensor 13 for determining the first total pressure P Fin the first exhaust gas device 10 and with a second exhaust gas device 20, which can be connected to and separated from the exhaust gas line 5 by means of the valve arrangement 11, 21, with a second cleaning element 28 for treating exhaust gas generated in a second of the different process steps, with a second gas injection device 22 arranged between the valve arrangement 11, 21 and the second cleaning element 28 for injecting a second compensating gas, with a second pressure sensor 23 for determining the second total pressure P T in the second exhaust device 20, wherein a control device 9 is provided, the controlled variable of which is the pressure difference between the total pressure P F in the first exhaust device 10 and the total pressure P T in the second exhaust device 20, and which is arranged in such a way that the pressure difference is regulated to zero at least when the valve arrangement 11, 21 is switched.

[0037] A method or control program characterized in that a reactor 3 is operated in which different process gases are fed into it in different process steps and different exhaust gases are discharged from the reactor 3 through an exhaust gas line 5 in different process steps, wherein in a first process step a first exhaust gas device 10 is connected to the exhaust gas line 5 by means of a valve arrangement 11, 21 and at least a second exhaust gas device 20 is separate from it, wherein the first exhaust gas is treated with a first cleaning element 18 of the first exhaust gas device 10 and a first compensating gas is fed in between the valve arrangement 11, 21 and the first cleaning element 18 by means of a first gas feed device 12, which in particular has a first mass flow controller 12', and the total pressure P is measured with a first pressure sensor 13 Fin the first exhaust gas device 10, wherein in a second process step a second exhaust gas device 20 is flow-connected to the exhaust gas line 5 by means of the valve arrangement 11, 21 and at least the first exhaust gas device 10 is separated from it, wherein the second exhaust gas is treated with a second cleaning element 28 of the second exhaust gas device 20 and a second compensating gas is fed in between the valve arrangement 11, 21 and the second cleaning element 28 by means of a second gas feed device 22, which in particular has a second mass flow controller 22', and the total pressure P is measured with a second pressure sensor 23 T in the second exhaust system 20 is determined, whereby the pressure difference between the total pressure P is determined by means of a control device 9. F in the first exhaust device 10 and the total pressure P T in the second exhaust device 20, at least when the valve arrangement is switched to zero.

[0038] A device or method characterized in that the first or second compensating gas is an inert gas, in particular nitrogen.

[0039] A device or method characterized in that the actuators of the control device 9 are the mass flow controllers 12', 22' and / or one or more throttle valves 16, 26 arranged upstream of a pump 16, 26.

[0040] A device or method characterized in that the first cleaning element 18 is a filter and / or the second cleaning element 28 is a cold trap.

[0041] A control device for controlling the sequence of a process, characterized in that a process step, in particular the first process step, is a substrate coating step in which a hydride, in particular NH3, is fed into the reactor 3.

[0042] A control device characterized in that a process step, in particular the second process step, is a cleaning step in which a cleaning gas, in particular a halogen-containing gas, in particular Cl2, is fed into the reactor 3.

[0043] A device or method characterized by a third exhaust gas device 30, which can be connected to and separated from the exhaust gas line 5 by means of the valve arrangement 11, 21, and which has a third cleaning element 38, a third gas supply device 32, in particular a third mass flow controller 32', for supplying a third compensating gas and a third pressure sensor 33 for determining the total pressure in the third exhaust gas device 30, wherein the control device 9 regulates the total pressure in the third exhaust gas device 30 against the total pressure in the first or second exhaust gas device 10, 20.

[0044] A device or method characterized in that all of the exhaust devices 10, 20, 30 each have a throttle valve 15, 25, 35 and / or that at least one exhaust device 10, 20, 30 does not have a throttle valve 15, 25, 35.

[0045] A device or method characterized in that the valve arrangement 11, 21, 31 has two or three separately switchable individual valves 11, 21, 31, which are connected upstream to the exhaust line 5 and downstream to the exhaust device 10, 20, 30.

[0046] A device or method characterized in that the pressure sensor 13, 23, 33 is arranged upstream of the cleaning element 18, 28, 38 and in particular between the gas supply device 12, 22, 32 and the cleaning element 18, 28, 38.

[0047] A device or method characterized by a further pressure sensor 13', 23', 33' arranged downstream of the cleaning element 18, 28, 38, for determining a total pressure in the exhaust system 10, 20, 30.

[0048] A device or method characterized in that each of the exhaust gas devices 10, 20, 30 has a gas cleaning system 17, 27, 37 downstream of the respective vacuum pump 16, 26, 36 in the direction of flow.

[0049] A control device for controlling the sequence of a process, characterized in that during the first process step, the control device 9 determines a process chamber pressure P from a pressure sensor 4. R in particular by varying the position of a throttle valve 15 to a setpoint value, so that before switching from the first process step to the second process step the total pressure P Fthe first exhaust device 10 and the total pressure P T The second exhaust device 20 is each regulated to the same setpoint value, so that after stabilization of the total pressures P F , P T In the two exhaust gas devices 10, 20, first a shut-off valve 21 of the valve arrangement connecting the second exhaust gas device 20 to the exhaust gas line 5 is opened, and subsequently a shut-off valve 11 of the valve arrangement connecting the first exhaust gas device 10 to the exhaust gas line 5 is closed, and then the control device 9 applies the process chamber pressure P determined by the pressure sensor 4. R by varying the position of a throttle valve 25 to a setpoint value.

[0050] All disclosed features are essential to the invention (individually, but also in combination with one another). The disclosure of this application also fully incorporates the disclosure content of the associated / attached priority documents (copy of the earlier application), also for the purpose of including features of these documents in the claims of the present application. The dependent claims, with their features, characterize independent inventive developments of the prior art, in particular for the purpose of filing divisional applications on the basis of these claims. Reference symbol list: 1 Gas source 2 Gas source 2' Gas source 3 Reactor 4 pressure sensor 5 Exhaust pipe 6 Gas inlet device 7 Susceptor 8 Substrat 9 Control unit 10 Exhaust gas purification system 11 Shut-off valve / valve assembly 12 Gas feed device 12' Mass flow regulator 13 Pressure sensor 13' Pressure sensor 14 15 Throttle valve 16 Vacuum pump 17 Gas cleaning / scrubber 18 Filter / Cleaning element 19 20 Exhaust gas purification system 21 Shut-off valve / valve assembly 22 Gas feed device 22' Mass flow regulator 23 Pressure sensor 23' Pressure sensor 24 25 Fixed-value throttle / throttle valve 26 Vacuum pump 27 Gas cleaning / scrubber 28 Cold trap / cleaning device 29 30 Exhaust gas purification system 31 Shut-off valve / valve assembly 32 Gas feed device 32' Mass flow regulator 33 Pressure sensor 33' Pressure sensor 34 35 Throttle valve 36 Vacuum pump 37 Gas cleaning / scrubber 38 Filter / Cleaning element P F first total pressure P R Process chamber pressure P T second total pressure

Claims

[1] A method for operating a reactor (3), in particular as a control program stored in a data storage device, into which different process gases are fed in different process steps and in which different exhaust gases are discharged from the reactor (3) through an exhaust gas line (5) in the different process steps, wherein in a first process step a first exhaust gas device (10) is flow-connected to the exhaust gas line (5) by means of a first shut-off valve (11) of a valve arrangement (11, 21) and at least a second exhaust gas device (20) is separated from it by a second shut-off valve (21), wherein a first of the two exhaust gases is treated with a first cleaning element (18) of the first exhaust gas device (10) and by means of a first gas injection device (12) having in particular a first mass flow controller (12') between the valve arrangement (11,21) and the first cleaning element (18) is supplied with a first compensating gas and the total pressure (P, F ) in the first exhaust gas device (10), wherein in a second process step a second exhaust gas device (20) is connected to the exhaust gas line (5) by means of the second shut-off valve (21) of the valve arrangement (11, 21) and at least the first exhaust gas device (10) is separated from it by the first shut-off valve (11), wherein a second of the two exhaust gases is treated with a second cleaning element (28) of the second exhaust gas device (20) and a second compensating gas is fed in between the valve arrangement (11, 21) and the second cleaning element (28) by means of a second gas feed device (22) having in particular a second mass flow controller (22') and the total pressure (P) is measured with a second pressure sensor (23). T) in the second exhaust system (20), whereby the pressure difference between the total pressure (P) is determined by means of a control device (9). F ) in the first exhaust device (10) and the total pressure (P T ) in the second exhaust device (20) at least when switching the valve arrangement during which the two shut-off valves (11, 21) of the two valve arrangements 11, 21) are simultaneously open are regulated to zero. [2] Method according to claim 1, characterized by that the first or second compensating gas is inert gas, in particular nitrogen. [3] Method according to any one of the preceding claims, characterized by , that a process step, in particular the first process step, is a substrate coating step in which a hydride, in particular NH3, is fed into the reactor (3). [4] Method according to any one of the preceding claims, characterized by, that a process step, in particular the second process step, is a cleaning step in which a cleaning gas, in particular a halogen-containing gas, in particular Cl2, is fed into the reactor (3). [5] Method according to any one of the preceding claims, characterized by , that during the first process step a process chamber pressure (P) determined by a pressure sensor (4) R ) in particular by varying the position of a throttle valve (15) at a setpoint value, so that before switching from the first process step to the second process step the total pressure (P F ) of the first exhaust device (10) and the total pressure (P T ) of the second exhaust device (20) are each regulated to the same setpoint value, so that after stabilization of the total pressures (P F , P T) in the two exhaust gas devices (10, 20) first the second shut-off valve (21) of the valve arrangement connecting the second exhaust gas device (20) to the exhaust gas line (5) is opened and subsequently the first shut-off valve (11) of the valve arrangement connecting the first exhaust gas device (10) to the exhaust gas line (5) is closed, and that afterwards the control device (9) applies the process chamber pressure (P) determined by the pressure sensor (4). R ) by varying the position of a throttle valve (25) to a setpoint. [6] Device comprising a reactor (3) into which different process gases can be fed in different process steps and which has an exhaust gas line (5) through which different exhaust gases can be discharged from the reactor (3) in the different process steps, comprising a first exhaust gas device (10) which can be connected to and disconnected from the exhaust gas line (5) by means of a first shut-off valve (11) of a valve arrangement (11, 21), comprising a first cleaning element (10) for treating a first exhaust gas generated in a first of the different process steps, comprising a first gas injection device (12) arranged between the valve arrangement (11, 21) and the first cleaning element (18) for injecting a first compensating gas, comprising a first pressure sensor (13) for determining the first total pressure (P F) in the first exhaust gas device (10) and with a second exhaust gas device (20), which can be connected to and separated from the exhaust gas line (5) by means of a second shut-off valve (21) of the valve arrangement (11, 21), with a second cleaning element (28) for treating a second exhaust gas generated in a second of the different process steps, with a second gas injection device (22) arranged between the valve arrangement (11, 21) and the cleaning element (28) for injecting a second compensating gas, with a second pressure sensor (23) for determining the second total pressure (P T ) in the second exhaust device (20), wherein a control device (9) is provided, the controlled variable of which is the pressure difference between the total pressure (P F ) in the first exhaust device (10) and the total pressure (P T) in the second exhaust device (20), and which is arranged in such a way that the pressure difference is regulated to zero at least when switching the valve arrangement (11, 21) during which the two shut-off valves (11, 21) of the valve arrangement (11, 21) are simultaneously open. [7] Device according to claim 6, characterized by , that the actuators of the control device (9) are the mass flow controllers (12', 22') and / or one or more throttle valves (16, 26) arranged upstream of a pump (16, 26). [8] Device according to one of claims 6 or 7, characterized by , that the first cleaning element (18) is a filter and / or the second cleaning element (28) is a cold trap. [9] Device according to any one of claims 6 to 8, characterized bya third exhaust gas device (30) which can be connected to and separated from the exhaust gas line (5) by means of the valve arrangement (11, 21), with a third cleaning element (38), with a third gas supply device (32) which in particular has a third mass flow controller (32') for supplying a third compensating gas and a third pressure sensor (33) for determining the total pressure in the third exhaust gas device (30), wherein the control device (9) regulates the total pressure in the third exhaust gas device (30) against the total pressure in the first or second exhaust gas device (10, 20). [10] Device according to any one of claims 6 to 9, characterized by , that each of the exhaust devices (10, 20, 30) has a throttle valve (15, 25, 35) or that at least one exhaust device (10, 20, 30) does not have a throttle valve (15, 25, 35). [11] Device according to any one of claims 6 to 10, characterized by, that the valve arrangement (11, 21, 31) has two or three separately switchable individual valves (11, 21, 31) which are connected upstream to the exhaust pipe (5) and downstream to the exhaust device (10, 20, 30). [12] Device according to any one of claims 6 to 11, characterized by , that the pressure sensor (13, 23, 33) is located upstream of the cleaning element (18, 28, 38) and in particular between the gas supply device (12, 22, 32) and the cleaning element (18, 28, 38). [13] Device according to any one of claims 6 to 12, characterized by a further pressure sensor (13', 23', 33') arranged downstream of the cleaning element (18, 28, 38) for determining a total pressure in the exhaust system (10, 20, 30). [14] Device according to any one of claims 6 to 13, characterized by, that each of the exhaust gas devices (10, 20, 30) has a gas cleaning system (17, 27, 37) downstream of the respective vacuum pump (16, 26, 36) in the direction of flow.

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