JP2004062897A - Control method of gas system and its device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control pressure, etc. of gas according to each state of flow rate load, etc. due to presence/absence of gas flow to be used. <P>SOLUTION: A gas control device is provided with mass flow controllers 78a to 78c which are disposed in supply ducts 72a to 72c which supply the gas to a processing chamber 71 and detects the flow rate load of the gas, a control valve 80 disposed in an exhaust duct 73 connected with the processing chamber for adjusting pressure in the processing chamber, a monochrometer 83 which detects presence/absence of plasma generated in the processing chamber by a plasma generation means and a CPU 40A which preliminarily stores a control coefficient according to presence/absence of gas flow and presence/absence of plasma generation. The flow rate load of gas is detected by the mass flow controllers, presence/absence of the plasma generated in the processing chamber is detected by the monochrometer, these detection signals are transmitted to the CPU and a control valve is controlled so that pressure of the processing chamber is at a specified level based on a control signal from the CPU. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for controlling a gas system used in, for example, a semiconductor manufacturing process.
[0002]
[Prior art]
Generally, in a manufacturing process of a semiconductor manufacturing apparatus, an object to be processed (hereinafter, referred to as a wafer or the like) such as a semiconductor wafer or LCD glass is sequentially immersed in a processing tank in which a processing liquid such as a chemical solution or a rinsing liquid (cleaning liquid) is stored. A cleaning treatment method for performing cleaning is widely adopted. In such a cleaning process, a surface of a wafer or the like after cleaning is brought into contact with a dry gas composed of a vapor of a volatile organic solvent such as IPA (isopropyl alcohol) to condense or adsorb the vapor of the dry gas. Then, a drying process for removing and drying the moisture of the wafer and the like is performed.
[0003]
This type of conventional drying apparatus includes a supply section for supplying an inert gas such as a carrier gas such as nitrogen (N2), a steam generator for heating a drying gas such as IPA (isopropyl alcohol) to generate steam, The supply line is provided with an on-off valve for supplying steam, that is, a drying gas generated by the generator, to the drying processing chamber, and a heater for heating the supply line. Therefore, in the drying process, since the temperature control of the N2 gas, the drying gas, and the like to be used is important, conventionally, the heater provided in the N2 gas supply pipe, the dry gas supply pipe, or the steam generator is used. Temperature control.
[0004]
Further, in a semiconductor manufacturing process, a dry etching technique is indispensable for forming a fine pattern on a wafer or the like. In the dry etching, a plasma is generated using a reactive gas in a vacuum, and various materials on a wafer or the like are etched using ions, neutral radicals, atoms, and molecules in the plasma. Therefore, various gases are used depending on the etching material.
[0005]
Generally, in this type of etching apparatus, an etching gas introduction unit is provided in a container having a closed processing chamber, and a vacuum exhaust port for forming a predetermined reduced-pressure atmosphere (vacuum) in the processing chamber is formed. A high-frequency power source is connected to one of the flat electrodes which also serve as a susceptor and the other flat electrode is grounded to the container. Then, a plasma discharge is generated between the two electrodes by a high-frequency power while the processing chamber is kept at a predetermined reduced pressure atmosphere depending on the type of the material to be etched and the type of reactive gas to be used, and ions, electrons and medium in the generated plasma are generated. Etching of a wafer or the like is performed by the active species having a nature. Therefore, in the etching process, since pressure control for bringing the processing chamber into a predetermined reduced-pressure atmosphere is important, conventionally, pressure adjusting means is provided in an exhaust pipe connected to a vacuum exhaust port to provide a pressure adjusting means in the processing chamber. Controlling pressure.
[0006]
[Problems to be solved by the invention]
However, in this type of conventional drying processing and etching processing, temperature control and pressure control are not performed by changing control constants for each type of gas and gas supply state. For this reason, for example, it is good to control the state where the heat or pressure load is moderate by using the control constant of the state where the heat or pressure load is severe. However, if the reverse situation occurs, the control will fail immediately. was there. In this case, it is still better if the load is light, but there is a disadvantage that the control constants cannot be basically shared between the completely different load states.
[0007]
The present invention has been made in view of the above circumstances, and stores a control constant corresponding to a load depending on the presence or absence of a gas flow to be used in advance, and controls a temperature or a pressure by selecting a control constant according to each state. It is an object of the present invention to provide a method and an apparatus for controlling a gas system as described above.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is characterized in that a control constant corresponding to a flow rate load depending on the presence or absence of a predetermined gas flow and a presence or absence of plasma generation of plasma generated in a processing chamber by a plasma generation unit. The control constant corresponding thereto is stored in advance, and based on the detection signal of the flow rate load of the gas, the pressure control means for selecting the control constant and adjusting the pressure of the processing chamber is controlled. The pressure of the processing chamber is adjusted by selecting the control constant based on the detection signal of the flow rate load and the detection signal of the presence or absence of the plasma.
[0009]
In the invention described in claim 1, the pressure can be adjusted even if the gas is a plurality of gases of different types (claim 2).
[0010]
Further, when it is determined that there is a flow of the gas based on the detection signal of the flow rate load of the gas, a control constant is selected according to the magnitude of the detected flow rate load to control the pressure adjusting means. (Claim 3).
[0011]
Further, based on the detection signal of the flow rate load of the gas and the detection signal of the presence / absence of the plasma generation, when it is determined that the gas flow is present and the plasma generation is not performed, a control constant stored in advance is used. It is possible to select and adjust the pressure of the processing chamber (claim 4).
[0012]
Further, based on the detection signal of the flow rate load of the gas and the detection signal of the presence / absence of the plasma generation, when it is determined that the gas flow is present and the plasma generation is present, a control constant stored in advance is determined. It is possible to select and adjust the pressure of the processing chamber (claim 5).
[0013]
According to a sixth aspect of the present invention, there is provided a supply pipe for supplying gas into the processing chamber, a discharge pipe connected to the processing chamber, and a pressure interposed in the discharge pipe for adjusting the pressure in the processing chamber. Adjusting means; gas load detecting means interposed in the supply conduit for detecting the flow rate load of the gas; and plasma generation presence / absence detection for detecting the presence / absence of plasma generation of plasma generated in the processing chamber by the plasma generation means Means, and control means for storing in advance a control constant according to the presence or absence of the flow of the gas and the presence or absence of plasma generation of plasma generated in the processing chamber. In addition to detecting the flow load, the presence / absence of plasma generated in the processing chamber is detected by the plasma generation presence / absence detection means, and these detection signals are transmitted to the control means. Rutotomoni, based on the control signal from the control means for controlling said pressure adjusting means so that the processing chamber reaches a predetermined pressure, characterized in that.
[0014]
According to the first, third to sixth aspects of the present invention, the control constant according to the flow rate load depending on the presence or absence of the predetermined gas flow and the presence or absence of plasma generation of the plasma generated in the processing chamber by the plasma generation means. The control constants are stored in advance, and based on the detection signal of the gas flow load, the control means selects a control constant and controls the pressure adjusting means for adjusting the pressure of the processing chamber. By selecting a control constant and adjusting the pressure of the processing chamber based on the detection signal of the generation or non-production, the control is performed based on the detection result of the flow rate load of the gas supplied to the processing chamber and the detection result of the plasma generation or not. By selecting a constant, the pressure in the processing chamber can be controlled to an optimum state. In this case, the pressure can be controlled even if the gases are a plurality of different types of gases.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
◎ Reference embodiment
FIG. 1 is a configuration diagram when a gas control apparatus according to the present invention is applied to a semiconductor wafer cleaning / drying processing system.
[0016]
The cleaning / drying system includes an N2 gas heater 3 (hereinafter simply referred to as a heater) as N2 gas heating means connected to a supply source 1 of a carrier gas, for example, nitrogen (N2) gas via a supply pipe 2a. A steam generator 5 as a mixed gas (steam) generating means connected to the heater 3 via a supply pipe 2b and connected to a supply source 4 for a drying gas liquid such as IPA via a supply pipe 2c. And a flow control means 7 provided in a supply pipe 2 d connecting the steam generator 5 and a drying processing chamber 6 (hereinafter simply referred to as a processing chamber). In this case, an on-off valve 8a is interposed in the supply pipe line 2a connecting the N2 gas supply source 1 and the heater 3. Further, an on-off valve 8b is provided in a supply pipe 2c connecting the IPA supply source 4 and the steam generator 5, and an on-off valve 8b side of the on-off valve 8b is provided via a branch passage 9 and an on-off valve 8c. The IPA collection unit 10 is connected. As shown by a two-dot chain line in FIG. 1, a drain pipe 5a of IPA is connected to the steam generator 5 as necessary, and a drain valve 5c is interposed in the drain pipe 5a, and a check valve is provided. A branch path 5b interposed by 5d is connected. By connecting the drain pipe 5c, the drain valve 5d, and the like in this manner, it becomes convenient to discharge a cleaning liquid or the like when cleaning the inside of the steam generator 5.
[0017]
As shown in FIG. 2 (a), the heater 3 is provided between an introduction pipe 11 communicating with a supply pipe 2 a for N 2 gas and an inner wall surface of the introduction pipe 11 inserted into the introduction pipe 11. The main part is constituted by a flow path forming tube 13 forming the spiral flow path 12 and a heating means, for example, a cartridge heater 14 inserted inside the flow path forming tube 13. In this case, the introduction pipe 11 has an inflow port 11a connected to the supply pipe 2a at one end, and an outflow port 11b connected to the supply pipe 2b at a side surface of the other end. As shown in FIG. 2 (b), the channel forming tube 13 is formed with a spiral uneven groove 15 such as a trapezoidal screw on its outer peripheral surface, and the spiral uneven groove 15 and the introduction pipe 11 are formed. A spiral flow path 12 is formed with the inner wall surface 11c. The spiral flow channel 12 does not necessarily need to have such a structure, and for example, a spiral uneven groove may be formed on the inner wall surface of the introduction pipe 11, and the outer peripheral surface of the flow channel forming pipe 13 may be a flat surface. The spiral flow path may be formed by forming spiral grooves on both the inner wall surface of the introduction pipe 11 and the outer peripheral surface of the flow path forming pipe 13, or the spiral flow path 12 may be formed by using a coil sponge. It may be formed.
[0018]
As described above, the spiral flow path 12 is provided between the introduction pipe 11 connected to the supply pipe 2a on the side of the N2 gas supply source 1 and the flow path forming pipe 13 or the coil spring inserted into the introduction pipe 11. Is formed, and the cartridge heater 14 is inserted into the flow path forming tube 13 to increase the length of the flow path where the N2 gas flow path and the cartridge heater 14 come into contact with each other and to form a spiral flow. , The flow velocity can be increased as compared with the case without the above, as a result, the Reynolds number (Re number) and the Nusselt number (Nu number) are increased, the boundary layer is put into the turbulent flow region, Improvement can be achieved. Therefore, the N2 gas can be efficiently heated to a predetermined temperature, for example, 200 ° C. by one cartridge heater 14, so that the heater 3 can be downsized. When it is necessary to further increase the heating temperature, an outer tube heater may be provided outside the introduction pipe 11.
[0019]
As shown in FIG. 3, the steam generator 5 is formed of, for example, a stainless steel pipe-shaped main body 20 connected to the carrier gas supply pipe 2b. The Laval nozzle 21 is formed by a tapered nozzle portion 21a that gradually narrows along the flow direction of the carrier gas, and a divergent nozzle portion 21c that gradually expands from the narrow portion 21b of the tapered nozzle portion 21a along the flow direction. ing. In the Laval nozzle 21, a shock wave is formed by a pressure difference between the inflow side pressure (primary pressure) and the outflow side pressure (secondary pressure) of the Laval nozzle 21. For example, a shock wave can be formed by appropriately selecting the primary pressure (Kgf / cm2G) and the flow rate of the N2 gas (Nl / min). In this case, a pressure regulating valve 23 is provided in a branch 22 connecting the primary side and the secondary side of the Laval nozzle 21, and the conditions for generating a shock wave are appropriately set by adjusting the pressure regulating valve 23. If the primary pressure can be increased, the shock wave can be formed without using the pressure regulating valve 23.
[0020]
If the pressure or flow rate of the N2 gas can be adjusted in a predetermined high pressure range on the primary side, the shock wave can be formed without using the pressure adjusting valve 23. That is, as shown in FIG. 11, the branch passage 22 and the pressure regulating valve 23 can be removed by connecting the N2 gas supply source 1 to the N2 gas pressure regulating means 1a for regulating the pressure or flow rate of the N2 gas. In this case, the N2 gas supply source 1 needs to be able to supply N2 gas at a higher pressure than usual so that N2 gas in a predetermined high pressure range can be supplied. By adjusting the high pressure level of the N2 gas supplied from the N2 gas supply source 1 by the N2 gas pressure adjusting means 1a, the inflow side pressure (primary pressure) and the outflow side pressure (secondary pressure) of the shock wave forming part 21 are reduced. And the conditions for generating shock waves can be set as appropriate.
[0021]
An IPA supply port 24 is opened in the middle of the divergent nozzle portion 21c of the Laval nozzle 21 thus formed. The IPA supply source 4 is connected to the supply port 24 via an IPA supply pipe, that is, a supply pipe 2c. Further, an inner tube heater 25 is inserted into the pipe-shaped main body 20 on the outflow side of the divergent nozzle portion 21c, and an outer tube heater 26 is disposed outside the inner tube heater 25. The heating means of the steam generator 5 is constituted. In this case, a heater may be provided near the Laval nozzle 21 and the IPA supply port 24.
[0022]
With the above configuration, when the IPA supplied from the IPA supply source 4 is supplied from the supply port 24 of the Laval nozzle 21, the IPA is atomized by the shock wave formed by the Laval nozzle 21 and then the heater 25, 26 The heating produces IPA vapor.
[0023]
In the above description, the case where the supply port 24 is provided on the secondary side of the Laval nozzle 21, that is, on the side after the generation of the shock wave is described. However, such a configuration is not necessarily required, and the supply port 24 may be provided on the primary side of the Laval nozzle 21. That is, it may be provided at a position before the shock wave is generated, and after the N2 gas and the IPA are mixed, the mixture is atomized by the shock wave.
[0024]
As shown in FIG. 1, the flow rate control means 7 includes an opening adjustment valve such as a diaphragm valve 30 provided in the supply pipe 2d, and a pressure sensor 31 which is a detection means for detecting the pressure in the processing chamber 6. Control means for comparing and calculating a signal from the microcomputer and information stored in advance, for example, a control valve for controlling the operating pressure of the diaphragm valve 30 based on a signal from a CPU 40 (central processing unit), for example, a micro valve 32. Become.
[0025]
In this case, as shown in FIG. 4, for example, the micro valve 32 communicates a discharge path 34 with an inflow path 33 of a working fluid, for example, air of the diaphragm valve 30, and a flexible member is provided on a surface facing the discharge path 34. A chamber 37 for accommodating a control liquid, for example, a heat-stretchable oil 36, is formed via 35, and a plurality of resistance heaters 38 provided on a surface of the chamber 37 facing the flexible member 35 are provided. . In this case, the flexible member 35 has a middle member 35b interposed between the upper member 35a and the lower member 35c, and has a pedestal 35d joined to the lower member 35c. The middle member 35 b is configured to be able to open and close the discharge path 34 by the bending deformation of 35. The entirety of the microvalve 32 is formed of silicon.
[0026]
With this configuration, when the signal from the CPU 40 is converted from digital to analog and transmitted to the resistance heater 38, the resistance heater 38 is heated and the control liquid, that is, the oil 36 expands and contracts. The flexible member 35 moves to the inflow side and the upper part of the discharge path 34 is opened, so that the control fluid, that is, the gas pressure can be adjusted. Therefore, the diaphragm valve 30 is operated by the fluid, that is, the air delayed by the micro valve 32, and the pre-stored information is compared with the pressure in the processing chamber 6, and the operation of the diaphragm valve 30 is controlled to process the N2 gas. It can be supplied into the chamber 6 and time control of the pressure recovery in the processing chamber 6 can be performed.
[0027]
Further, as shown in FIG. 5, the processing chamber 6 stores (contains) a cleaning solution such as a chemical solution such as hydrofluoric acid or pure water and immerses the wafer W in the stored cleaning solution. The cover 51 is attached to the opening 50a for loading / unloading the wafer W provided thereabove so as to be openable and closable. Further, between the processing chamber 6 and the cleaning tank 50, holding means, for example, a wafer boat 52 for holding a plurality of, for example, 50 wafers W and moving the wafers W into the cleaning tank 50 and the processing chamber 6 is provided. Have been. Further, a cooling pipe 53 for cooling the IPA gas supplied into the processing chamber 6 may be provided in the processing chamber 6. The cleaning tank 50 includes an inner tank 55 having a discharge port 54 at the bottom, and an outer tank 56 for receiving the cleaning liquid overflowing from the inner tank 55. In this case, the wafer W is immersed in the chemical or pure water supplied and stored in the inner tub 55 from the supply nozzle 57 of the chemical or pure water disposed below the inner tub 55 and washed. ing. A discharge pipe 56b is connected to a discharge port 56a provided at the bottom of the outer tank 56. With such a configuration, the cleaned wafer W is moved into the processing chamber 6 by the wafer boat 52 and comes into contact with the IPA gas supplied into the processing chamber 6 to condense or adsorb the vapor of the IPA gas. Thus, the removal and drying of the water of the wafer W are performed.
[0028]
In addition, a filter 60 is interposed in the supply pipe line 2d on the downstream side (secondary side) of the diaphragm valve 30, so that a dry gas with few particles can be supplied. Further, a heater 62 for keeping heat is provided outside the supply pipe 2d so that the temperature of the IPA gas can be maintained constant. Further, an IPA gas temperature sensor 61 (temperature detecting means) is disposed on the processing line 6 side of the supply line 2d so that the temperature of the IPA gas flowing through the supply line 2d is measured. .
[0029]
On the other hand, as shown in FIG. 1, a gas load detecting means for detecting a load based on the presence or absence of the flow of the N2 gas flowing through the supply pipe 2a, for example, a flow rate detection sensor 41 (hereinafter referred to as a flow rate sensor 41) is provided in the supply pipe 2a. A gas load detecting means for detecting a load based on the presence or absence of the flow of the IPA gas flowing through the supply pipe 2d, for example, a flow rate detection sensor 42 (hereinafter referred to as a flow rate sensor 42) is provided in the supply pipe 2d. Is interposed. Further, an IPA supply pump 43 (fluid flow detection means) capable of detecting the presence or absence of the flow of IPA is provided in the IPA supply line 2c.
[0030]
The load detection signals detected by the flow rate detection sensors 41 and 42 and the IPA supply pump 43 are transmitted to the CPU 40, and are stored in the CPU 40 in accordance with the flow rate load based on the presence or absence of the flow of N2 gas, IPA gas and IPA. Information, that is, a plurality of control modes corresponding to the presence or absence of a gas flow, and a PID control constant (control constant) including three operations of a proportional operation, an integral operation, and a differential operation adopted for each control mode. The N2 gas heater 3, the heaters 25 and 26 of the steam generator 5, and the heat retaining heater 62 are controlled by the control signal. PID control constants (hereinafter referred to as PID constants) are stored in a data table in the CPU 40.
[0031]
Next, temperature control of N2 gas, IPA and IPA gas (dry gas; mixed gas) in the above-mentioned cleaning / drying processing system will be described with reference to the flowcharts of FIGS.
[0032]
☆ N2 gas heater temperature control
As shown in FIG. 6, first, after confirming a process mode in which the flow rate and supply timing of the N2 gas in the N2 gas heater 3 are set (step A), the flow sensor 41 determines whether or not the N2 gas is flowing. Confirm (step B). When the N2 gas is not flowing, the heat-up mode is set by the control signal from the CPU 40 (step C), and the N2 gas heater 3 is heated up based on the PID constants (P11, I11, D11) obtained by the auto-tuning in advance. Temperature control for the mode is performed (steps D and E). In this way, it is determined whether or not the process mode has ended (step F). If the process mode has ended, the temperature control for the heat-up mode is ended. If not, the process mode is checked again (step F). A).
[0033]
On the other hand, when the N2 gas is flowing through the supply pipe 2a, the N2 gas flow mode is set (step G), and the N2 gas heater 3 is set based on the PID constants (P21, I21, D21) obtained by auto-tuning in advance. Is subjected to temperature control in the N2 gas flow mode (steps H and I). In this way, it is determined whether or not the process mode has ended (step J). If the process mode has ended, the temperature control for the N2 gas flow mode is ended. If not, the process mode is checked again. (Step A), the above procedure is repeated to control the temperature of the N2 gas heater.
[0034]
Therefore, depending on whether or not N2 gas has been supplied from the N2 gas supply source 1 to the supply line 2a, a PID constant (control constant) stored in advance is selected to preheat the N2 gas heater 3 or The temperature of the N2 gas can be adjusted to an optimum state by heating.
[0035]
In the above description, in the N2 gas flow mode (steps H and I), only the PID constants (P21, I21, D21) based on the presence or absence of the flow of the N2 gas detected by the flow rate sensor 41 are previously stored in the data table. Although the example of the case of storing is shown, the PID constant may be stored in advance in multiple stages according to the magnitude of the flow load detected by the flow sensor 41, that is, the magnitude of the flow rate of the N2 gas. . As a result, since the PID constant adopted according to the magnitude of the flow load of the N2 gas is stored in the data table in advance, a highly accurate PID constant is set in multiple stages according to the magnitude of the flow load. The N2 gas heater 3 can be controlled with high accuracy based on the selected PID constant, and the temperature of the N2 gas can be controlled with high accuracy to an optimum state.
[0036]
☆ Steam generator temperature control
As shown in FIG. 7, first, after confirming a process mode in which the flow rates and supply timings of N2 gas and IPA in the steam generator 5 are set (step A), the flow sensor 41 determines whether or not N2 gas is flowing. Is confirmed (Step B). When the N2 gas is not flowing, the heat-up mode is set according to a control signal from the CPU 40 (step C), and the heater 25 of the steam generator 5 is set based on the PID constants (P12, I12, D12) obtained in advance by auto-tuning. The temperature control for the heat-up mode is performed (steps D and E). In this way, it is determined whether or not the process mode has ended (step F). If the process mode has ended, the temperature control for the heat-up mode is ended. If not, the process mode is checked again (step F). A).
[0037]
On the other hand, when the N2 gas is flowing through the supply pipe 2a, it is next determined whether or not the IPA supply pump 43 is driven to determine whether or not the IPA is supplied (step G), and the IPA is not supplied. In this case, the N2 gas flow mode is set by a control signal from the CPU 40 (step H), and the heater 25 of the steam generator 5 through which the N2 gas passes based on the PID constants (P22, I22, D22) obtained in advance by auto-tuning. The temperature control for the N2 gas flow mode is performed (steps I and J). In this way, it is determined whether or not the process mode has ended (step K). If the process mode has ended, the heating is ended. If not, the process mode is checked again (step A).
[0038]
Further, when IPA is flowing through the supply pipe 2c, the flow enters the N2 + IPA flow mode by a control signal from the CPU 40 (step L), and is based on the PID constants (P32, I32, D32) obtained in advance by auto-tuning. To heat the heaters 25 and 26 of the steam generator 5 (steps M and N). In this way, it is determined whether or not the process mode has ended (step O). If the process mode has ended, the heating is ended. If not, the process mode is checked again (step A). Is repeated to perform temperature control of the heaters 25 and 26 of the steam generator 5 in the N2 + IPA flow mode.
[0039]
Therefore, whether N2 gas has been supplied from the N2 gas supply source 1 to the supply line 2a, or whether IPA has been supplied from the IPA supply source 4 to the steam generator 5 via the supply line 2c. In accordance with the above, a pre-stored PID constant (control constant) is selected to control the temperature of the heaters 25 and 26 of the N2 gas heater 3 or the steam generator 5 to optimize the temperature of the N2 gas and the temperature of the dry gas. Can be
[0040]
In the above description, in the N2 + IPA flow mode (step L), the PID constants (P32, I32, D32) based on the presence or absence of the flow of the N2 gas detected by the flow rate sensor 41 and the presence or absence of the driving of the IPA supply pump 43. ) Is previously stored in the data table, but it is also possible to store the PID constants in advance in multiple stages according to the magnitude of the flow rate of the N2 gas and the magnitude of the IPA supply amount. . Accordingly, the PID constants used in accordance with the magnitude of the flow load of the N2 gas and the magnitude of the IPA supply amount are previously stored in the data table. High-precision PID constants can be set and selected in multiple stages, and the heaters 25 and 26 of the steam generator 5 can be controlled with high accuracy based on the selected PID constants. Temperature can be controlled to an optimum state with high accuracy.
[0041]
☆ Dry gas temperature control
As shown in FIG. 8, first, after confirming a process mode in which the flow rates and supply timings of N2 gas and IPA in the steam generator 5 are set (step A), the flow sensor 41 determines whether or not N2 gas is flowing. Is confirmed (Step B). When the N2 gas is not flowing, the heat-up mode is set by the control signal from the CPU 40 (step C), and the heat retention heater 62 is set to the heat-up mode based on the PID constants (P13, I13, D13) obtained in advance by auto-tuning. Temperature control is performed (steps D and E). In this way, it is determined whether or not the process mode has ended (step F). If the process mode has ended, the temperature control for the heat-up mode is ended. If not, the process mode is checked again (step F). A).
[0042]
On the other hand, when the N2 gas is flowing through the supply pipe 2a, it is next determined whether or not the IPA supply pump 43 is driven to determine whether or not the IPA is supplied (step G), and the IPA is not supplied. In this case, the N2 gas flow mode is set according to the control signal from the CPU 40 (step H), and the heat retaining heater 62 through which the N2 gas passes is set to the N2 gas flow mode based on the PID constants (P23, I23, D23) obtained by the automatic tuning in advance. (Steps I and J). In this way, it is determined whether or not the process mode has ended (step K). If the process mode has ended, the temperature control for the N2 gas flow mode is ended. If not, the process mode is checked again ( Step A).
[0043]
Further, when the IPA is flowing through the supply pipe 2c, the passage of the drying gas (N2 + IPA) is detected by the flow rate sensor 42, and the flow is set to the N2 + IPA flow mode by the control signal from the CPU 40 (step L). Based on the PID constants (P33, I33, D33) obtained by the tuning, the temperature control of the heat retaining heater 62 in the N2 + IPA flow mode is performed (steps M and N). In this way, it is determined whether or not the process mode has ended (Step O). If the process mode has ended, the temperature control for the N2 + IPA flow mode is ended. If not, the process mode is checked again ( Step A), the above procedure is repeated to control the temperature of the heat retaining heater 62.
[0044]
Therefore, a state as to whether or not N2 gas is supplied from the N2 gas supply source 1 to the supply line 2a, and a state as to whether or not IPA is supplied from the IPA supply source 4 to the steam generator 5 through the supply line 2c. Alternatively, a PID constant (control constant) stored in advance is selected to control the temperature of the N2 gas heater 3 and the steam generator 5 according to whether the dry gas is flowing through the supply pipe 2d. The temperature of the N2 gas and the temperature of the dry gas can be optimized by controlling the temperature of the heaters 25 and 26 or the temperature of the heat retaining heater 62.
[0045]
In the above description, in the N2 + IPA flow mode (step L), only the PID constants (P33, I33, D33) based on the presence or absence of the passage of the drying gas (N2 + IPA) by the flow sensor 42 are stored in the data table in advance. Although an example of the case has been described, the PID constant may be stored in advance in multiple stages according to the magnitude of the flow rate of the dry gas (N2 + IPA) by the flow rate sensor 42. As a result, the data table stores in advance the PID constants employed in accordance with the magnitude of the flow rate of the dry gas (N2 + IPA). It is possible to set and select a highly accurate PID constant, and to control the heat retention heater 62 with high accuracy based on the selected PID constant, and to precisely and precisely control the temperature of the N2 gas and the temperature of the dry gas. Can be controlled.
[0046]
◎ Embodiment
FIG. 9 is a schematic configuration diagram of an embodiment of a gas-based control device according to the present invention. The embodiment is a case where the gas control device according to the present invention is applied to pressure control of an etching device.
[0047]
The etching apparatus includes a gas supply pipe line 72a to 72c for connecting a container 70 having a process chamber 71 that can be closed and a gas supply source (not shown) of a different type from a gas introduction unit provided in the container 70. And an exhaust pipe or exhaust pipe 73 connected to a vacuum exhaust port provided in the processing chamber 71, and a vacuum exhaust device such as a vacuum pump 74 connected to the exhaust pipe 73.
[0048]
In this case, an upper plate electrode 75 facing the upper and lower sides, which also serves as a gas supply to the processing chamber 71, and a lower plate electrode 76, which also serves as a susceptor, are arranged in the container 70. A high frequency power supply 77 is connected to the plate electrode 76, and the upper plate electrode 75 is grounded via a container 70.
[0049]
The gas supply pipes 72a to 72c are provided with mass flow controllers 78a to 78c and air operation on-off valves 79a to 79c for detecting and controlling various gas flow rates, respectively. The detected detection signal is transmitted to control means, for example, the CPU 40A.
[0050]
On the other hand, a control valve 80 as a pressure adjusting means in the processing chamber 71 is provided on the vacuum exhaust port side of the exhaust pipe 73, and a turbo molecular pump 81 is provided on the downstream side thereof. In this case, the control valve 80 is configured such that the opening is adjusted based on a control signal from the CPU 40A.
[0051]
Further, a window 82 for monitoring the inside of the processing chamber 71 is provided on a side wall of the container 70, and outside the window 82, plasma emission generated by application of high-frequency power from the high-frequency power supply 77 is provided. A monochromator 83 for detecting the presence or absence is provided, and a detection signal detected by the monochromator 83 is transmitted to the CPU 40A. In addition, between the turbo molecular pump 81 and the vacuum pump 74 in the container 70 and the exhaust pipe 73, pressure gauges 84 and 85 for measuring the pressure of each part are respectively installed.
[0052]
In the etching apparatus configured as described above, after the wafer W is mounted on the lower plate electrode 76 by the transfer means (not shown), the control valve 80 is adjusted based on the control signal from the CPU 40A, and the vacuum pump is driven. The inside of the processing chamber 71 is set to a predetermined reduced-pressure atmosphere, and a gas is supplied from a predetermined gas supply source into the processing chamber 71, while high-frequency power is applied from a high-frequency power supply 77 to generate a plasma discharge between the electrodes 75 and 76. Is generated, and the wafer W is etched by the ions, electrons, and neutral active species in the generated plasma.
[0053]
At this time, the pressure in the processing chamber 71 changes due to the flow rates of various gases and the ignition of plasma. Therefore, in the present invention, the processing pressure is controlled to the optimum pressure by selecting the PID constant (control constant) corresponding to the load depending on the flow rate of each gas stored in the CPU 40A in advance and controlling the control valve 80. ing. That is, similarly to the above-described reference embodiment, a plurality of corresponding control modes, a PID constant including three operations of a proportional operation, an integral operation, and a differential operation adopted for each control mode in accordance with the presence or absence of a gas flow, as in the above-described reference embodiment. An arithmetic process is performed based on the (control constant), and the control signal controls the pressure in the processing chamber 71 to an optimum pressure.
[0054]
Next, a mode of pressure control according to the embodiment will be described with reference to a flowchart of FIG. First, after confirming the process mode in which the type, flow rate, supply timing and the like of the gas to be used are set (step A), it is confirmed by the mass flow controllers 78a to 78c whether or not the gas is flowing (step B). If the gas is not flowing, a vacuum reaching mode (a mode for checking whether the leak in the processing chamber 71 is normal) is set by a control signal from the CPU 40A (step C), and a PID constant (P1) previously obtained by auto-tuning. , I1, D1), the opening of the control valve 80 is adjusted (steps D, E). In this way, it is determined whether or not the process mode has ended (step F). If the process mode has ended, the opening adjustment of the control valve 80 is ended. If not, the process mode is confirmed again ( Step A).
[0055]
On the other hand, when the gas is flowing through the gas supply pipes 72a to 72c, it is next determined by the monochromator 83 whether or not plasma is generated by application of the high frequency power of the high frequency power supply 77 (step G). If no plasma is generated, the gas flow mode is set by the control signal from the CPU 40A (step H), and the opening of the control valve 80 is adjusted based on the PID constants (P2, I2, D2) obtained in advance by auto-tuning (step H). Steps I and J). In this way, it is determined whether or not the process mode has ended (step K). If the process mode has ended, the opening adjustment of the control valve 80 is ended. If not, the process mode is confirmed again ( Step A).
[0056]
Further, when plasma emission is confirmed by the monochromator 83 and plasma is generated, the plasma mode is set (step L), and the control valve is set based on the PID constants (P3, I3, D3) obtained in advance by auto tuning. The opening of 80 is adjusted (steps M and N). In this way, it is determined whether or not the process mode has ended (step O). If the process mode has ended, the opening adjustment of the control valve 80 is ended. If not, the process mode is checked again. (Step A) The above procedure is repeated to adjust the opening of the control valve 80.
[0057]
Therefore, it is stored in advance according to the state of whether the gas is supplied from the gas supply source into the processing chamber 71 through the supply pipes 72a to 72c, or whether the plasma is generated. The processing pressure in the processing chamber 71 can be optimized by selecting a PID constant (control constant) and adjusting the opening of the control valve 80.
[0058]
◎ Other embodiments
In the above embodiment, the case where the gas control apparatus according to the present invention is applied to a plasma etching apparatus has been described. However, various gases are supplied by controlling the etching apparatus other than the plasma processing or the processing chamber to a predetermined pressure and supplying various gases. Of course, the present invention can be applied to a processing apparatus such as a CVD apparatus and a sputtering apparatus.
[0059]
【The invention's effect】
As described above, according to the present invention, the following excellent effects can be obtained.
[0060]
A control constant corresponding to the flow rate load depending on the presence / absence of a predetermined gas flow and a control constant corresponding to the presence / absence of plasma generation of the plasma generated in the processing chamber by the plasma generation unit are stored in advance, and the gas flow rate load is stored. Based on the detection signal, a control constant is selected to control the pressure adjusting means for adjusting the pressure in the processing chamber, and a control constant is selected based on the detection signal of the gas flow load and the detection signal of the presence or absence of plasma generation. The pressure of the processing chamber is adjusted by controlling the pressure of the processing chamber by selecting a control constant based on the detection result of the flow rate load of the gas supplied to the processing chamber and the detection result of the presence / absence of plasma generation. be able to.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a reference embodiment of a gas-based control device according to the present invention.
FIG. 2A is a cross-sectional view of a carrier gas heater according to a reference embodiment, and FIG.
FIG. 3 is a cross-sectional view illustrating an example of a steam generator according to a reference embodiment.
FIG. 4 is a cross-sectional view illustrating an example of a flow rate control unit and a control valve thereof according to a reference embodiment.
FIG. 5 is a schematic sectional view showing a processing chamber in a reference embodiment.
FIG. 6 is a flowchart illustrating a method for controlling the temperature of a carrier gas heater according to the reference embodiment.
FIG. 7 is a flowchart illustrating a temperature control method of the steam generator according to the reference embodiment.
FIG. 8 is a flowchart illustrating temperature control of a dry gas supply unit according to the reference embodiment.
FIG. 9 is a schematic configuration diagram showing an embodiment of a gas control device according to the present invention.
FIG. 10 is a flowchart illustrating a pressure control method according to the embodiment.
FIG. 11 is a schematic configuration diagram showing another example of the gas-based control device shown in FIG. 1;
[Explanation of symbols]
W semiconductor wafer
40A CPU (control means)
71 Processing room
72a-72c gas supply pipeline
73 Exhaust pipe (discharge pipe)
78a-78c Mass flow controller (gas load detecting means)
80 Control valve (pressure adjusting means)
83 Monochromator (plasma generation detection means)

Claims (6)

A control constant corresponding to the flow rate load depending on the presence or absence of a predetermined gas flow and a control constant corresponding to the presence or absence of plasma generation of plasma generated in the processing chamber by the plasma generation unit are stored in advance,
Based on the detection signal of the flow rate load of the gas, to control the pressure adjustment means to select the control constant and adjust the pressure of the processing chamber,
A method for controlling a gas system, wherein the control constant is selected to adjust the pressure of the processing chamber based on the detection signal of the flow rate load of the gas and the detection signal of the presence or absence of plasma generation. The method for controlling a gas system according to claim 1,
A method for controlling a gas system, wherein the gas includes a plurality of gases of different types. The method for controlling a gas system according to claim 1,
When it is determined that there is a flow of the gas based on the detection signal of the flow rate load of the gas, controlling the pressure adjusting means by selecting a control constant according to the magnitude of the detected flow rate load. A method for controlling a gas system. The method for controlling a gas system according to claim 1,
Based on the detection signal of the flow rate load of the gas and the detection signal of the presence / absence of the plasma generation, when it is determined that the gas flow is present and the plasma generation is not performed, a pre-stored control constant is selected. A method for controlling a gas system, comprising: The method for controlling a gas system according to claim 1,
Based on the detection signal of the flow load of the gas and the detection signal of the presence / absence of the plasma generation, when it is determined that the gas flow is present and the plasma generation is present, a pre-stored control constant is selected. A method for controlling a gas system, comprising: A supply pipe for supplying gas into the processing chamber;
A discharge pipe connected to the processing chamber;
Pressure adjusting means interposed in the discharge conduit to adjust the pressure in the processing chamber;
Gas load detecting means interposed in the supply pipe and detecting a flow load of the gas,
Plasma generation presence / absence detection means for detecting the presence / absence of plasma generation of the plasma generated in the processing chamber by the plasma generation means,
Control means for storing in advance the control constant according to the presence or absence of the gas flow, the presence or absence of plasma generation of the plasma generated in the processing chamber,
The flow rate load of the gas is detected by the gas load detection means, and the presence / absence of plasma generation of the plasma generated in the processing chamber is detected by the presence / absence detection means for plasma, and these detection signals are transmitted to the control means. And a control unit for controlling the pressure of the processing chamber based on a control signal from the control unit so that the pressure of the processing chamber is maintained at a predetermined pressure.

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