GAS SUPPLY SYSTEM, PLASMA PROCESSING APPARATUS, AND GAS SUPPLY METHOD

Abstract

To appropriately supply a gas into a processing chamber in consideration of the influence of an additive gas mixed into a main gas.SOLUTION: Provided is a gas supply system for supplying a gas into a processing chamber. A controller included in the system executes: a control of calculating a flow rate of a main gas flowing through each of a plurality of gas supply flow paths; a control of acquiring a flow rate of an additive gas that flows through an additive gas flow path and is mixed with the main gas flowing through each of the plurality of gas supply flow paths; a control of calculating a total flow rate of the flow rate of the main gas and the flow rate of the additive gas, in each of the plurality of gas supply flow paths; a control of calculating an internal pressure of each of the plurality of gas supply flow paths by using the total flow rate calculated in each of the plurality of gas supply flow paths, and relationships between a previously-acquired flow rate and a previously-acquired pressure of the main gas and between a previously-acquired flow rate and a previously-acquired pressure of the additive gas; a control of calculating a ratio of the internal pressures calculated in each of the plurality of gas supply flow paths; and a control of proportionally controlling openings of a plurality of flow rate control valves based on the ratio of the internal pressures.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a gas supply system, a plasma processing apparatus, and a gas supply method. [Background technology]

[0002] Patent Document 1 discloses a partial pressure control system having two valves that variably control the working gas, pressure sensors connected in series to each of the valves to detect the pressure of the working gas, and a controller that relatively controls the output pressure of each valve based on the detection results of the pressure sensors. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-000723 A Summary of the Invention [Problem to be solved by the invention]

[0004] The technology according to the present disclosure takes into consideration the influence of the additive gas mixed into the main gas and appropriately supplies gas into the processing chamber. [Means for solving the problem]

[0005] One aspect of the present disclosure is a gas supply system for supplying gas into a processing chamber, the system including a plurality of gas supply flow paths configured to be able to independently supply a main gas to the processing chamber, a flow control valve disposed in each of the plurality of gas supply flow paths, an additive gas flow path connected to a downstream side of the flow control valve in at least one of the gas supply flow paths, an additive valve disposed in the additive gas flow path, and a controller for controlling operation of the flow control valve and the additive valve, the controller being configured to perform control for calculating a flow rate of a main gas flowing through each of the plurality of gas supply flow paths, and a control for calculating a flow rate of the main gas flowing through the additive gas flow path and each of the gas supply flow paths. The control device executes the following controls: control for acquiring a flow rate of the additive gas to be mixed; control for calculating a total flow rate, which is the sum of the flow rate of the main gas and the flow rate of the additive gas, for each of the multiple gas supply flow paths; control for calculating an internal pressure of each of the multiple gas supply flow paths using the total flow rate calculated for each of the multiple gas supply flow paths, a first relationship between a gas flow rate and a gas pressure of the main gas that has been acquired in advance, and a second relationship between a gas flow rate and a gas pressure of the additive gas that has been acquired in advance; control for calculating a ratio of the internal pressures calculated for each of the multiple gas supply flow paths; and control for proportionally controlling an opening degree of the multiple flow control valves based on the ratio of the internal pressures. Effect of the Invention

[0006] According to the present disclosure, the influence of the additive gas mixed with the main gas is taken into consideration and the gas is appropriately supplied into the processing chamber. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is an explanatory diagram illustrating a configuration example of a wafer processing system according to an embodiment. [Diagram 2] 1 is a cross-sectional view showing a configuration example of a plasma processing apparatus according to an embodiment; [Diagram 3] FIG. 3 is a schematic explanatory diagram showing main elements of a gas supply unit in FIG. 2. [Figure 4]FIG. 2 is a flow chart showing main steps of flow rate control according to the embodiment. [Figure 5A] FIG. 1 is an explanatory diagram showing an example of a PQ characteristic. [Figure 5B] FIG. 1 is an explanatory diagram showing an example of PQ characteristics of various gases. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] In the manufacturing process of semiconductor devices, various gas processes such as etching, film formation, cleaning, etc. are performed on a semiconductor substrate (hereinafter simply referred to as "substrate") placed in the internal space of a chamber under a desired gas atmosphere. In these gas processes, in order to obtain the desired processing results for the substrate to be processed, it is important to independently control the supply of gas to multiple regions on the substrate and precisely control the flow rate of the gas supplied to these multiple regions.

[0009] Patent Document 1 discloses a partial pressure control system for uniformly controlling the flow rate of an operating gas supplied to two different regions on a substrate, specifically, a center region and an edge region. The partial pressure control system described in Patent Document 1 detects the gas pressures output from two valves arranged corresponding to the center region and the edge region, respectively, and proportionally controls the operation of the two valves based on the detection results, thereby relatively controlling the output pressures of the two valves (pressure ratio control).

[0010] During these gas processes, other process gases (hereinafter referred to as "additive gases") may be mixed with the main process gas (hereinafter referred to as "main gas") used in the gas process to assist the gas process (to improve efficiency, etc.). Such additive gases may be mixed independently with the main gas supplied to each of the above-mentioned multiple regions. In other words, the supply of additive gas to each of the above-mentioned multiple regions on the substrate may be controlled independently.

[0011] Incidentally, when an additive gas is mixed into a main gas in gas processing, in order to obtain a desired gas processing result for a substrate, it is necessary to perform gas flow control taking into consideration the additive gas. That is, in a pressure-controlled flow control system such as that described in Patent Document 1, for example, it is necessary to perform gas flow control taking into consideration the pressure increase caused by mixing the additive gas. However, Patent Document 1 does not describe taking into consideration the pressure increase caused by the additive gas when controlling the flow rate, much less mixing the additive gas into the main gas.

[0012] The technology disclosed herein has been made in consideration of the above circumstances, and takes into account the influence of the additive gas mixed into the main gas, and appropriately supplies gas into the processing chamber. Hereinafter, the substrate processing system according to the present embodiment will be described with reference to the drawings. In this specification and the drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, and duplicated description will be omitted.

[0013] <Plasma processing system> In one embodiment, the plasma processing system includes a plasma processing device 1 and a control unit 2 as shown in FIG. 1. The plasma processing system is an example of a substrate processing system, and the plasma processing device 1 is an example of a substrate processing device. The plasma processing device 1 includes a plasma processing chamber 10, a substrate support unit 11, and a plasma generation unit 12. The plasma processing chamber 10 has a plasma processing space. The plasma processing chamber 10 also has at least one gas supply port for supplying at least one processing gas to the plasma processing space, and at least one gas exhaust port for exhausting the processing gas from the plasma processing space. The gas supply port is connected to a gas supply unit 20 described later, and the gas exhaust port is connected to an exhaust system 40 described later. The substrate support unit 11 is disposed in the plasma processing space and has a substrate support surface for supporting a substrate.

[0014] The plasma generating unit 12 is configured to generate plasma from at least one processing gas supplied into the plasma processing space. The plasma formed in the plasma processing space may be a capacitively coupled plasma (CCP), an inductively coupled plasma (ICP), an electron-cyclotron-resonance plasma (ECR plasma), a helicon wave plasma (HWP), or a surface wave plasma (SWP), etc. Also, various types of plasma generating units may be used, including an alternating current (AC) plasma generating unit and a direct current (DC) plasma generating unit. In one embodiment, the AC signal (AC power) used in the AC plasma generating unit has a frequency in the range of 100 kHz to 10 GHz. Thus, the AC signal includes a radio frequency (RF) signal and a microwave signal. In one embodiment, the RF signal has a frequency in the range of 200 kHz to 150 MHz.

[0015] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to execute various steps described in the present disclosure. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to execute various steps described herein. In one embodiment, a part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include, for example, a computer 2a. The computer 2a may include, for example, a processing unit (CPU: Central Processing Unit) 2a1, a storage unit 2a2, and a communication interface 2a3. The processing unit 2a1 may be configured to perform various control operations based on a program stored in the storage unit 2a2. The storage unit 2a2 may include a random access memory (RAM), a read only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a local area network (LAN). The above program may be recorded in a storage medium readable by the computer 2a and installed in the control unit 2 from the storage medium. Furthermore, the storage medium may be either temporary or non-temporary.

[0016] <Plasma processing equipment> Next, a configuration example of a capacitively coupled plasma processing apparatus 1 will be described as an example of the above-mentioned plasma processing apparatus 1. Fig. 2 is a vertical cross-sectional view showing an outline of the configuration of the plasma processing apparatus 1. In the following description, the side of a main gas box 100 described below in the flow direction of the processing gas may be referred to as the primary side (upstream side), and the side of a shower head 13 (plasma processing chamber 10) described below in the flow direction may be referred to as the secondary side (downstream side).

[0017] The plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply 20, a power supply 30, and an exhaust system 40. The plasma processing apparatus 1 also includes a substrate support 11 and a gas inlet. The substrate support 11 is disposed within the plasma processing chamber 10. The gas inlet is configured to introduce at least one processing gas into the plasma processing chamber 10. The gas inlet includes a showerhead 13. The showerhead 13 is disposed above the substrate support 11. In one embodiment, the showerhead 13 forms at least a part of a ceiling of the plasma processing chamber 10. Inside the plasma processing chamber 10, a plasma processing space 10s is formed, which is defined by the showerhead 13, a sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 is grounded. The showerhead 13 and the substrate support 11 are electrically insulated from the plasma processing chamber 10.

[0018] The substrate support 11 includes a main body 11a and a ring assembly 11b. The upper surface of the main body 11a has a central region (substrate support surface) for supporting a substrate (wafer) W, and an annular region (ring support surface) for supporting the ring assembly 11b. The wafer is an example of a substrate W. The annular region surrounds the central region in a plan view. The substrate W is disposed on the central region, and the ring assembly 11b is disposed on the annular region so as to surround the substrate W on the central region.

[0019] In one embodiment, the main body 11a includes a base and an electrostatic chuck. The base includes a conductive member. The conductive member of the base may function as a lower electrode. The electrostatic chuck is disposed on the base. The electrostatic chuck includes a ceramic member and an electrostatic electrode disposed within the ceramic member. The upper surface of the ceramic member constitutes the central region (substrate support surface) and the annular region (ring support surface) described above. Note that other members surrounding the electrostatic chuck, such as the annular electrostatic chuck or the annular insulating member, may have the annular region. In this case, the ring assembly may be disposed on the annular electrostatic chuck or the annular insulating member, or may be disposed on both the electrostatic chuck and the annular insulating member. Also, at least one RF / DC electrode coupled to an RF power source 31 and / or a DC power source 32 described later may be disposed within the ceramic member. In this case, the at least one RF / DC electrode functions as a lower electrode. When a bias RF signal and / or a DC signal described later is supplied to the at least one RF / DC electrode, the RF / DC electrode is also called a bias electrode. Note that the conductive member of the base and the at least one RF / DC electrode may function as multiple lower electrodes. Also, an electrostatic electrode may function as the bottom electrode. Thus, the substrate support 11 includes at least one bottom electrode.

[0020] The ring assembly 11b includes one or more annular members. In one embodiment, the one or more annular members include one or more edge rings and at least one cover ring. The edge rings are formed of a conductive or insulating material, and the cover rings are formed of an insulating material.

[0021] Although not shown, the substrate support 11 may also include a temperature adjustment module configured to adjust at least one of the ring assembly 11b, the electrostatic chuck, and the substrate W to a target temperature. The temperature adjustment module may include a heater, a heat transfer medium, a flow path, or a combination thereof. A heat transfer fluid such as brine or gas flows through the flow path. In one embodiment, the flow path is formed in the base, and one or more heaters are disposed in a ceramic member of the electrostatic chuck. The substrate support 11 may also include a heat transfer gas supply configured to supply a heat transfer gas (backside gas) to a gap between the back surface of the substrate W and the top surface of the electrostatic chuck.

[0022] The showerhead 13 is configured to introduce at least one process gas from a gas supply 20 into the plasma processing space 10s. The showerhead 13 includes at least one upper electrode.

[0023] The shower head 13 has a plurality of gas supply ports 14c and 14e (two in this embodiment), a plurality of gas diffusion chambers 15c and 15e (two in this embodiment), and a plurality of gas inlets 16. Gas supplied from the gas supply unit 20 to the gas supply port 14c passes through the gas diffusion chamber 15c and is supplied from the plurality of gas inlets 16 toward a central region of the substrate W supported by the substrate support unit 11. Gas supplied from the gas supply unit 20 to the gas supply port 14e passes through the gas diffusion chamber 15e and is supplied from the plurality of gas inlets 16 toward a peripheral region of the substrate W supported by the substrate support unit 11.

[0024] The number of gas supply ports 14 and gas diffusion chambers 15 formed in the shower head 13 is not limited to this. For example, when the shower head 13 is provided with three gas supply ports 14 and three gas diffusion chambers 15, the processing gas from the gas supply section 20 can be supplied toward the center region, the edge region, and the middle region between the center region and the edge region of the substrate W. For example, when the shower head 13 is provided with four gas supply ports 14 and four gas diffusion chambers 15, the processing gas from the gas supply section 20 can be supplied toward the center region, middle region, edge region, and outer end region (belly edge) outside the edge region of the substrate W. In this way, a plurality of gas supply ports 14, i.e., any number of two or more, and gas diffusion chambers 15 can be formed in the shower head 13. In this case, the arrangement of the plurality of gas supply ports 14 and gas diffusion chambers 15 can also be designed arbitrarily.

[0025] In addition to the shower head 13, the gas introduction part may include one or more side gas injectors (SGI) attached to one or more openings formed in the side wall 10a.

[0026] The gas supply unit 20 includes a main gas box 100 including multiple gas sources (not numbered), a flow rate control unit 110 that controls the flow rate of the process gas sent from the main gas box 100, and a splitter 120 that splits the main gas output from the flow rate control unit 110. In one embodiment, the gas supply unit 20 is configured to mix different types of process gases output from the multiple gas sources included in the main gas box 100 after controlling their flow rates with the flow rate control unit 110, and supply the mixed gas to the shower head 13 (plasma processing chamber 10) via the splitter 120 as the main gas.

[0027] 2, the flow rate control unit 110 is connected to the main gas box 100 via a primary-side supply pipe 130. A primary-side valve 131 is disposed in the primary-side supply pipe 130, and the supply of gas from each gas source in the main gas box 100 to the flow rate control unit 110 can be arbitrarily switched by opening and closing the primary-side valve 131. Note that any type of valve, such as an air-operated valve or an electromagnetic valve, can be used as the primary-side valve 131, but from the viewpoint of improving responsiveness in gas supply, it is preferable to use, for example, an electromagnetic valve.

[0028] The flow control unit 110 includes a plurality of flow controllers 111 provided in the main gas box 100, a plurality of flow controllers 111 corresponding to each of the three gas sources in the illustrated example, three in the illustrated example. The three flow controllers 111 are respectively connected to ends of primary side supply pipes 130 extending from each of the gas sources of the main gas box 100. Since the three flow controllers 111 provided in the flow control unit 110 have the same configuration, the configuration of one flow controller 111 will be described as a representative in the following description. Also, in the numbering in the figure, the numbering of some of the components of the flow controllers 111 may be omitted.

[0029] The flow rate controller 111 includes an internal supply pipe 112, an orifice 113, two pressure sensors 114 and 115, a control valve 116, and a control circuit 117. The internal supply pipe 112 also includes a primary internal supply pipe 112a on the upstream side and a secondary internal supply pipe 112b on the downstream side, with the orifice 113 as a boundary.

[0030] The primary side of the primary side internal supply pipe 112a is connected to the above-mentioned primary side supply pipe 130, and the secondary side is connected to the orifice 113. The primary side of the secondary side internal supply pipe 112b is connected to the orifice 113, and the secondary side is connected to the below-mentioned secondary side supply pipe 140. In other words, the orifice 113 is provided between the primary side internal supply pipe 112a and the secondary side internal supply pipe 112b.

[0031] Two pressure sensors 114, 115 measure the internal pressures of the primary internal supply pipe 112a and the secondary internal supply pipe 112b, ie, the pressures upstream and downstream of the orifice 113, respectively.

[0032] The control valve 116, with its opening controlled by the control circuit 117, controls the flow rate of the main gas flowing through the internal supply pipe 112 and supplied into the plasma processing chamber 10 (shower head 13). Specifically, the control circuit 117 controls the opening of the control valve 116 to adjust the internal pressure of the primary side internal supply pipe 112a, thereby controlling the flow rate of the main gas flowing downstream of the orifice 113 (secondary side internal supply pipe 112b) to be kept at a desired value determined according to the purpose of substrate processing in the plasma processing chamber 10.

[0033] Furthermore, the control valve 116 may function as a flow rate modulation device that modulates or pulses the flow rate of the main gas under the control of the control circuit 117.

[0034] Returning to the description of the gas supply unit 20, Each flow rate controller 111 is connected to the splitter 120 via a secondary side supply pipe 140. The splitter 120 includes branch supply pipes 121c, 121e provided corresponding to the gas supply ports 14c, 14e of the shower head 13, control valves 122c, 122e provided corresponding to the branch supply pipes 121c, 121e, and sensor groups 123c, 123e provided corresponding to the branch supply pipes 121c, 121e, respectively.

[0035] The primary sides of the branch supply pipes 121c and 121e are connected to the secondary supply pipe 140 described above, and the secondary sides are connected to the gas supply ports 14c and 14e of the shower head 13. In other words, the shower head 13 is connected to the secondary supply pipe 140 via the splitter 120.

[0036] As shown in the figure, the sensor groups 123c and 123e each include a pressure sensor and a temperature sensor, for example. The sensor groups 123c and 123e measure the internal pressure and internal temperature of the branch supply pipes 121c and 121e, respectively. More specifically, they measure the internal pressure and internal temperature downstream of the control valves 122c and 122e, which will be described later.

[0037] The control valves 122c and 122e are provided corresponding to the branch supply pipes 121c and 121e, respectively. The control valves 122c and 122e control the flow rate of the main gas flowing through the branch supply pipes 121c and 121e and supplied to the gas diffusion chambers 15c and 15e of the shower head 13 by controlling the opening degree by a control circuit (not shown). Specifically, the control circuits provided in the branch supply pipes 121c and 121e proportionally control the opening degree of each of the control valves 122c and 122e based on the pressure ratio of the branch supply pipes 121c and 121e (more specifically, the pressure ratio of the gas diffusion chambers 15c and 15e) measured by the respective sensor groups 123c and 123e. This relatively controls the flow rate of the main gas supplied from the splitter 120 to the gas supply ports 14c and 14e of the shower head 13 (the center region and the edge region of the substrate W).

[0038] In one embodiment, one end of additive gas supply pipes 151c and 151e is connected to the branch supply pipes 121c and 121e downstream of the corresponding control valves 122c and 122e. The other end of the additive gas supply pipe 151 is connected to an additive gas box 150. In other words, the main gas supplied from the gas supply unit 20 to the shower head 13 via the flow rate control unit 110 and the splitter 120 may be further mixed with the additive gas from the additive gas box 150.

[0039] Further, the additive gas supply pipes 151c, 151e are provided with corresponding additive valves 152c, 152e, respectively, and by opening and closing the additive valve 152, it is possible to arbitrarily switch the mixing of the additive gas with the main gas supplied to each of the gas supply ports 14c, 14e of the shower head 13. Note that, as the additive valve 152, any type of valve, such as an air-operated valve or an electromagnetic valve, can be used, but from the viewpoint of improving responsiveness in gas supply, it is preferable to use, for example, an electromagnetic valve.

[0040] The additive gas box 150 may include at least one gas source and at least one flow controller. In one embodiment, the additive gas box 150 is configured to supply at least one process gas as an additive gas from a corresponding gas source through a corresponding flow controller to the showerhead 13. Each flow controller may include, for example, a mass flow controller or a pressure-controlled flow controller.

[0041] In one embodiment, the operation of the gas supply unit 20 is controlled by the above-mentioned control unit 2. Specifically, for example, the control unit 2 is configured to be able to independently control the opening degree of various valves (primary side valve 131, secondary side valve 141, and additive valve 152) included in the gas supply unit 20. As a result, the gas supply unit 20 controls the type of process gas mixed with the main gas supplied to the gas supply ports 14c and 14e, independently controls the supply of the main gas from the splitter 120 to the gas supply ports 14c and 14e, and independently controls the mixing of the additive gas from the additive gas supply pipes 151c and 151e to the corresponding branch supply pipes 121c and 121e.

[0042] A pressure sensor 160 for measuring the internal pressure of the primary side of the splitter 120 , that is, the secondary side supply pipe 140 , may be provided on the primary side of the splitter 120 .

[0043] Returning to the explanation of the plasma processing apparatus 1, The power source 30 includes an RF power source 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power source 31 is configured to supply at least one RF signal (RF power) to at least one lower electrode and / or at least one upper electrode. This causes a plasma to be formed from at least one processing gas supplied to the plasma processing space 10s. Thus, the RF power source 31 can function as at least a part of the plasma generating unit 12. In addition, by supplying a bias RF signal to the at least one lower electrode, a bias potential is generated on the substrate W, and ion components in the formed plasma can be attracted to the substrate W.

[0044] In one embodiment, the RF power supply 31 includes a first RF generating unit 31a and a second RF generating unit 31b. The first RF generating unit 31a is coupled to at least one lower electrode and / or at least one upper electrode via at least one impedance matching circuit, and is configured to generate a source RF signal (source RF power) for plasma generation. In one embodiment, the source RF signal has a frequency in the range of 10 MHz to 150 MHz. In one embodiment, the first RF generating unit 31a may be configured to generate a plurality of source RF signals having different frequencies. The generated one or more source RF signals are supplied to at least one lower electrode and / or at least one upper electrode.

[0045] The second RF generating unit 31b is coupled to at least one lower electrode via at least one impedance matching circuit and configured to generate a bias RF signal (bias RF power). The frequency of the bias RF signal may be the same as or different from the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency lower than the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 100 kHz to 60 MHz. In one embodiment, the second RF generating unit 31b may be configured to generate a plurality of bias RF signals having different frequencies. The generated one or more bias RF signals are supplied to at least one lower electrode. Also, in various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0046] The power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generator 32a and a second DC generator 32b. In one embodiment, the first DC generator 32a is connected to at least one lower electrode and configured to generate a first DC signal. The generated first DC signal is applied to the at least one lower electrode. In one embodiment, the second DC generator 32b is connected to at least one upper electrode and configured to generate a second DC signal. The generated second DC signal is applied to the at least one upper electrode.

[0047] In various embodiments, the first and second DC signals may be pulsed. In this case, a sequence of voltage pulses is applied to at least one lower electrode and / or at least one upper electrode. The voltage pulses may have a rectangular, trapezoidal, triangular or combination of these pulse waveforms. In one embodiment, a waveform generator for generating a sequence of voltage pulses from the DC signal is connected between the first DC generator 32a and at least one lower electrode. Thus, the first DC generator 32a and the waveform generator constitute a voltage pulse generator. When the second DC generator 32b and the waveform generator constitute a voltage pulse generator, the voltage pulse generator is connected to at least one upper electrode. The voltage pulses may have a positive polarity or a negative polarity. Also, the sequence of voltage pulses may include one or more positive polarity voltage pulses and one or more negative polarity voltage pulses in one period. The first and second DC generating units 32a, 32b may be provided in addition to the RF power supply 31, or the first DC generating unit 32a may be provided in place of the second RF generating unit 31b.

[0048] The exhaust system 40 may be connected to, for example, a gas exhaust port 10e provided at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure regulating valve regulates the internal pressure of the plasma processing space 10s. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0049] Although various exemplary embodiments have been described above, the present invention is not limited to the above-described exemplary embodiments, and various additions, omissions, substitutions, and modifications may be made. In addition, elements in different embodiments can be combined to form other embodiments.

[0050] For example, in the above embodiment, the splitter 120 in the gas supply unit 20 includes the branch supply pipe 121, the control valve 122, and the sensor group 123. However, the configuration of the splitter 120 is not limited to this, and for example, the sensor group 123 may be provided outside the splitter 120, that is, between the splitter 120 and the shower head 13 in the branch supply pipes 121c and 121e.

[0051] <Flow rate control method> The plasma processing apparatus 1 according to this embodiment is configured as described above. In the plasma processing apparatus 1, the main gas from the main gas box 100 is supplied to the gas diffusion chambers 15c and 15e of the shower head 13 via a flow rate control unit 110 and a splitter 120. A flow rate controller 111 relatively controls the flow rates of the process gases output from the gas sources of the main gas box 100, in other words, the flow rates of the process gases mixed as the main gas. Furthermore, the main gas output from the flow rate controller 111 and supplied via the splitter 120 to each of the gas diffusion chambers 15c and 15e can be mixed with an additive gas from an additive gas box 150 independently. The processing gases (main gas and additive gas) supplied to the gas diffusion chambers 15c and 15e are respectively supplied toward the center region and edge region of the substrate W held on the substrate support 11, thereby subjecting the substrate W to the desired gas processing.

[0052] Next, a method for controlling the flow rate of the main gas supplied from the gas supply unit 20 to each of the gas diffusion chambers 15c and 15e will be described in detail. FIG. 3 is a schematic explanatory diagram showing main elements extracted from the gas supply unit 20 shown in FIG. 2. The flow rates Q and pressures P of various process gases used in the following description are plotted at corresponding positions.

[0053] In order to control the flow rate of the main gas split and output by the splitter 120, a PQ characteristic serving as a reference for calculating the main gas flow rate (hereinafter referred to as the "reference PQ characteristic") is acquired prior to gas processing in the plasma processing apparatus 1, for example, during start-up (setup) of the plasma processing apparatus 1 (step St0-1 in FIG. 4). The acquired reference PQ characteristic is output to the control unit 2. In the technology disclosed herein, the "PQ characteristic" refers to a characteristic that indicates the relationship between the gas flow rate (Q) and the gas pressure (P) of a certain gas (for example, a certain main gas or a certain additive gas as described above), and is sometimes called the "pressure-flow characteristic."

[0054] The reference PQ characteristic indicates the relationship between the flow rate Q and the pressure P when nitrogen (N2) gas as the reference gas is supplied from the main gas box 100 to the plasma processing apparatus 1 (the shower head 13). The reference PQ characteristic is thus found based on the relationship between the flow rate Q and pressure P of the reference gas, but the flow rate Q and pressure P of the reference gas may change due to their influence on the conductance of the shower head 13 (gas diffusion chamber 15). In addition, the conductance of the shower head 13 (gas diffusion chamber 15) may change depending on, for example, the shape of the gas diffusion chamber 15 and the number and shape of the gas inlets 16 formed in the shower head 13. From this viewpoint, the reference PQ characteristics are obtained on the primary side of the splitter 120, the secondary side of the control valve 122c in the splitter 120 (gas diffusion chamber 15c side: center region side), and the secondary side of the control valve 122e in the splitter 120 (gas diffusion chamber 15e side: edge region side). Figure 5A is a graph showing the reference PQ characteristics of the primary side of splitter 120 (solid line in Figure 5A), the reference PQ characteristics of the secondary side of control valve 122e in splitter 120 (edge ​​area side of substrate W) (dashed line in Figure 5A), and the reference PQ characteristics of the secondary side of control valve 122c in splitter 120 (center area side of substrate W) (dotted line in Figure 5A).

[0055] The reference PQ characteristics at each point in the gas supply unit 20 can be automatically measured and further parameterized by the plasma processing apparatus 1. In other words, the output of the main gas from the main gas box 100, the measurement of the flow rate Q and the pressure P, the acquisition of the PQ characteristic curve, and the output to the control unit 2 can be automatically performed simply by issuing a signal to start acquiring the reference PQ characteristics, without any operation by an operator in between.

[0056] In order to control the flow rate of the main gas output from the splitter 120, the flow factors of various process gases used in the gas process are acquired prior to the gas process in the plasma processing apparatus 1 (step St0-2 in FIG. 4). The acquired flow factors are output to the control unit 2.

[0057] The flow factor applied in the technology according to the present disclosure can be calculated based on the PQ characteristics of various process gases as shown in FIG. 5B, and can be a numerical value indicating the change in flow rate display depending on the type of the various process gases relative to N2 as a reference gas. That is, the flow factor of various process gases can be a relative constant when the flow rate display (PQ characteristic) of N2 as a reference gas is set to "1" as an example. Note that the types of process gases shown in FIG. 5B are examples, and the types of process gases used in the plasma processing apparatus 1 according to the embodiment are not limited to the illustrated example. The flow factor includes characteristic values ​​such as density, specific heat ratio, and gas constant corresponding to N2 and various process gases. As an example, the flow factor may be a coefficient defined by the international standard IEC60534-1 (corresponding to the Japanese Industrial Standard JIS B 2005-1). The flow factor may be a value that is set to 1 when the flow rate of an orifice through which 60°F air flows at a flow rate of 1 gallon / min per minute with a pressure difference of 1 psi.

[0058] When the reference PQ characteristics and the flow factors of various process gases are acquired as preparations for gas processing in the plasma processing apparatus 1, the operation of determining the supply flow rates of the process gases (main gas and additive gas) for gas processing is then started.

[0059] When determining the supply flow rate of the processing gas, first, based on the process recipe for the gas processing, the type and total flow rate Qm of the main gas output from the main gas box 100 and the supply flow rate ratio (Qmc / Qme) of the processing gas to each of the center region and edge region required to obtain the desired gas processing result on the substrate W are obtained (input). The control unit 2 calculates the main gas flow rate Qmc output to the center region (gas diffusion chamber 15c) and the main gas flow rate Qme output to the edge region (gas diffusion chamber 15e) based on the acquired total flow rate Qm of the main gas and the supply flow rate ratio (Qmc / Qme) (step St1 in FIG. 4).

[0060] Next, based on the gas processing process recipe, the flow rate of the additive gas output from the additive gas box 150, more specifically, the type and flow rate Qac of the additive gas mixed with the main gas output to the center region (gas diffusion chamber 15c) and the type and flow rate Qae of the additive gas mixed with the main gas output to the edge region (gas diffusion chamber 15e) are respectively obtained (input) (step St2 in Figure 4).

[0061] Here, in the splitter 120, the openings of the control valves 122c, 122e provided in the branch supply pipes 121c, 121e, respectively, are proportionally controlled based on the pressure ratio (Pc / Pe) of the process gases supplied to the gas diffusion chambers 15c, 15e of the shower head 13, thereby relatively controlling the output main gas flow rates Qmc, Qme. However, when an additive gas is mixed into the main gas as described above, and particularly when the main gas and the additive gas are different types, there is a risk that the proportional control of the flow rate based on the pressure ratio cannot be appropriately performed depending on various conditions such as differences in the physical properties of the main gas and the additive gas to be mixed.

[0062] In this embodiment, the flow rate Qm of the main gas and the flow rate Qa of the additive gas calculated in steps St1 and St2 are converted into a reference gas (N2) value using the flow factor acquired in step St0-2 (step St3-1 in FIG. 4). This makes it possible to unify the pressure P of the process gas (main gas + additive gas) that serves as the basis for flow rate control by converting it into the reference gas, and as a result, even if the main gas and the additive gas are different types, it is possible to appropriately perform proportional control of the flow rate based on the pressure ratio.

[0063] In addition, in the case where a temperature difference occurs between the center region and the edge region of the substrate W to which the processing gas is supplied, the flow factor used in step St3-1 may reflect such temperature dependency. In other words, the converted flow rate QmN2 of the main gas and the converted flow rate QaN2 of the additive gas converted into the reference gas (step St3-1) may be fine-tuned / optimized by a temperature correction coefficient ΔT based on the temperature dependency of the flow factor (step St3-2 in FIG. 4). More specifically, as an example, the above-mentioned flow factor at the reference temperature of N2 gas (for example, room temperature) may be set to "1", and the flow factor of N2 gas at various temperatures may be corrected.

[0064] Next, a total converted flow rate Q(m+a)N2 is calculated, which is the sum of the converted flow rate QmN2 of the main gas calculated in step St3 and the converted flow rate QaN2 of the additive gas (step St4 in FIG. 4). The total converted flow rate is calculated independently for each of the process gases supplied to the center region and the edge region of the substrate W.

[0065] Next, based on the total converted flow rate Qc(m+a)N2 on the center region side and the total converted flow rate Qe(m+a)N2 on the edge region side calculated in step St4, and the reference PQ characteristic acquired in step St0-1, the converted pressure Pc(m+a)N2 on the center region side, which serves as the reference pressure for flow rate control of the main gas, and the converted pressure Pe(m+a)N2 on the edge region side are calculated (step St5 in Figure 4).

[0066] Finally, based on the converted pressure P(m+a)N2 calculated in step St5, the pressure ratio Pc / Pe=Pc(m+a)N2 / Pe(m+a)N2=α, which is the basis for gas flow rate control in the splitter 120, is calculated (step St6 in FIG. 4). The pressure ratio α is a calculated value obtained by converting the process gas pressures output from the branch supply pipes 121c and 121e, respectively, that is, a calculated value of the internal pressures of the branch supply pipes 121c and 121e, respectively. The calculated pressure ratio α is output to the control unit 2.

[0067] Thereafter, during gas processing in the plasma processing apparatus 1, the openings of the control valves 122c, 122e corresponding to the branch supply pipes 121c, 121e, respectively, are proportionally controlled based on the pressure ratio α calculated in this manner, thereby relatively controlling the flow rates of the processing gases (main gas + additive gas) supplied to the gas diffusion chambers 15c, 15e of the shower head 13, respectively. More specifically, the openings of the control valves 122c and 122e are adjusted so that the flow rate ratio Qc / Qe of the process gases output from the branch supply pipes 121c and 121e approximately matches the pressure ratio α, that is, so that the flow rate ratio Qc / Qe=α.

[0068] The process gas is split by the splitter 120 according to the technique of the present disclosure, that is, the flow rates of the process gas output from each of the branch supply pipes 121c and 121e are controlled in the manner described above.

[0069] During gas processing in the plasma processing apparatus 1, it is desirable that the downstream pressure of the splitter 120, i.e., the internal pressure of the branch supply pipes 121c, 121e (secondary side pressure of the control valves 122c, 122e), be lower than the upstream pressure of the splitter 120, i.e., the internal pressure of the secondary supply pipe 140 (primary side pressure of the control valves 122c, 122e), and preferably be less than twice the primary side pressure. In other words, in the flow rate control according to the technology of the present disclosure, it is desirable to set the converted pressure P(m+a)N2 calculated in step St5 lower than the total flow rate Qm in the gas processing process recipe, and preferably to set it to less than twice the primary side pressure. If the internal pressure of the branch supply pipes 121c, 121e is equal to or greater than the internal pressure of the secondary side supply pipe 140, when the control valve 116 is opened during gas processing, the processing gas may flow back from the secondary side supply pipe 140 to the secondary side supply pipe 140, which may cause a malfunction of the gas supply unit 20. In this regard, in the present embodiment, the reduced pressure P(m+a)N2 is set lower than the total flow rate Qm, so that the backflow of the processing gas can be appropriately suppressed.

[0070] At this time, the pressures upstream and downstream of the splitter 120 can be measured by the pressure sensor 160 and the sensor groups 123c and 123e, respectively. The pressure upstream of the splitter 120 may be measured using the pressure sensor 115 of the flow rate controller 111 instead of the pressure sensor 160 .

[0071] <Example> The main gas division and flow rate control according to the present disclosure are performed as described above. Next, a calculation example will be shown using specific values ​​for the above-mentioned series of flow rate control methods. Note that the types and flow rates of the process gases used in the following description are merely examples. In other words, the types and flow rates of the process gases applied to the technology of the present disclosure are not limited to the following calculation examples. In the following calculation example, it is assumed that the above-mentioned reference PQ characteristic and flow factor have been output in advance to the control unit 2. In other words, it is assumed that the above-mentioned steps St0-1 and St0-2 have been executed in advance.

[0072] In step St1, first, the type and total flow rate Qm of the main gas output from the main gas box 100, and the supply flow rate ratio (Qmc / Qme) of the process gas to the center region and the edge region are input. In this calculation example, the main gas output from the main gas box 100 is Ar gas, and the total flow rate Qm and the supply flow rate ratio are set to the values ​​shown below. Total flow rate Qm [Ar] = Qmc + Qme = 1000sccm Supply flow ratio (Qmc / Qme) =1.0

[0073] The control unit 2 calculates the main gas flow rates to be output to the center region and the edge region, based on the total flow rate Qm of the input Ar gas and the supply flow rate ratio (Qmc / Qme). Flow rate Qmc[Ar]=500sccm Flow rate Qme[Ar]=500sccm

[0074] In step St2, the flow rates Qac and Qae of the additive gas output from the additive gas box 150 to the center region and the edge region, respectively, are input. In this calculation example, the additive gas output from the additive gas box 150 to the center region is O2 gas, and the additive gas output to the edge region is C4F8 gas, and the flow rates Qa of each are as follows: Flow rate Qac[O2] =100sccm Flow rate Qae[C4F8] =5sccm

[0075] In step St3-1, the flow rate Qm of the main gas and the flow rate Qa of the additive gas calculated in steps St1 and St2 are converted into N2 using a flow factor previously acquired. The flow factors of Ar as the main gas and O2 and C4F8 as the additive gas are as shown below in one example. Ar = 1.1 O2=1.1 C4F8=1.9 Then, in step St3-1, the converted flow rate of each process gas is calculated based on this. Converted flow rate QmcN2[Ar] =500×1.1=550sccmN2 Converted flow rate QmeN2[Ar] =500×1.1=550sccmN2 Converted flow rate QacN2[O2] =100×1.1=110sccmN2 Converted flow rate QaeN2[C4F8] =5 ×1.9=9.5sccmN2

[0076] As described above, when a temperature difference occurs between the center region and the edge region of the substrate W, which are the target positions of the supply of the processing gas, the calculated converted flow rate may be finely adjusted / optimized by further reflecting the temperature dependency in the calculated converted flow rate (step St3-2). In other words, the temperature correction coefficient ΔT may be further integrated with the calculated converted flow rates QmN2 and QaN2. In this calculation example, consideration of such temperature dependency is omitted. In other words, it is assumed that there is no temperature difference between the center region and the edge region of the substrate W.

[0077] In step St4, the total converted flow rate of the processing gas supplied to the center region and the total converted flow rate of the processing gas supplied to the edge region are calculated. Total converted flow rate Qc(m+a)N2=550+110=660sccmN2 Total converted flow rate Qe(m+a)N2=550+9.5≒560sccmN2

[0078] In step St5, a converted pressure for calculating the pressure ratio serving as a reference for the main gas division, i.e., flow rate control, is calculated based on the total converted flow rate calculated in step St4 and a reference PQ characteristic acquired in advance. Total conversion flow rate Qc(m+a)N2 → conversion pressure Pc(m+a)N2 = 25TorrN2 Total conversion flow rate Qe(m+a)N2 → conversion pressure Pe(m+a)N2 = 40TorrN2

[0079] Finally, in step St6, a pressure ratio α serving as a reference for gas flow rate control is calculated based on the converted pressure calculated in step St5. Pressure ratio α = Pc(m+a)N2 / Pe(m+a)N2 = 25 / 40 = 0.625

[0080] In the plasma processing apparatus 1, during gas processing of the substrate W, the opening of the control valve 116 is adjusted so that the flow rate ratio Qc / Qe of the processing gas output from the splitter 120 to each of the gas diffusion chambers 15c, 15e approximately matches the pressure ratio α, i.e., so that the flow rate ratio Qc / Qe = 0.625.

[0081] <Action and effect> According to the above embodiment, the total flow rate of the main gas and the auxiliary gas supplied to the showerhead 13 is converted into a single total flow rate of the reference gas using the flow factor as described above. As a result, even if the main gas and the auxiliary gas are different types, it is possible to calculate a converted pressure that takes into account the difference in the physical properties of these process gases, and as a result, it is possible to appropriately proportionally control the flow rate of the process gas output from the splitter 120.

[0082] Furthermore, according to the technology disclosed herein, the pressure increase due to the additive gas mixed with the main gas can be known in advance simply by acquiring (inputting) the types of main gas and additive gas and the recipe flow rate prior to gas processing in the plasma processing apparatus 1, and the flow ratio of the main gas split by the splitter 120 (pressure ratio between the center region side and the edge region side) can be maintained at a desired value. As a result, the desired gas processing result can be appropriately obtained for the substrate W to be processed in the plasma processing apparatus 1.

[0083] Furthermore, according to the technology disclosed herein, as described above, overshoot control is possible for the pressure increase caused by the added gas, and the pressure ratio α can be stabilized at higher speed.

[0084] In the above embodiment, nitrogen (N2) gas is used as the reference gas for flow rate control, but the gas used as the reference gas is not limited to N2, and any gas can be used as the reference gas. However, nitrogen (N2) gas is commonly used in various plasma processing apparatuses used in the manufacturing process of semiconductor devices. In other words, gas sources and gas supply lines for supplying nitrogen gas are pre-installed in various plasma processing apparatuses. Therefore, by using nitrogen gas as a reference gas, it is not necessary to install a new gas supply line for supplying the reference gas even in plasma processing apparatuses with different purposes, and the reference PQ characteristics and flow factor can be obtained under approximately the same conditions. In view of this, it is desirable to use nitrogen (N2) gas as the reference gas.

[0085] In the above embodiment, an example has been described in which the gas supply unit 20 has two gas flow paths, i.e., the splitter 120 divides the main gas into two flows and supplies processing gas independently to two regions (center region and edge region) of the substrate W. However, the number of gas flow paths provided in the gas supply unit 20 is not limited to this. As described above, the gas supply unit 20 may include three gas flow paths when supplying processing gas to three regions (center region, middle region, and edge region) of the substrate W. Also, when supplying processing gas to four regions (center region, middle region, edge region, and very-edge region) of the substrate W, the gas supply unit 20 may include four gas flow paths. In this manner, the gas supply unit 20 of the plasma processing apparatus 1 according to the present disclosure may include a plurality of gas flow paths, at least two or more, depending on the number of processing gas supply regions formed on the substrate W.

[0086] In the above embodiment, an example has been described in which the additive gas is mixed with both the main gas supplied to the center region (gas diffusion chamber 15c) and the main gas supplied to the edge region (gas diffusion chamber 15e). However, the additive gas may be mixed with the main gas in only one of the regions. That is, as shown in the above embodiment, an additive gas flow path may be connected to all of the multiple gas flow paths, and the additive gas may be mixed with only the main gas flowing through at least one of the gas flow paths by opening and closing an additive valve arranged in the additive gas flow path. Alternatively, the additive gas flow path may be connected to at least one of the multiple gas flow paths provided in the gas supply unit 20.

[0087] As described above, the reference PQ characteristic acquired in step St0-1 may change depending on the conductance of the showerhead 13 (gas diffusion chamber 15), for example, the shape of the gas diffusion chamber 15 and the number of gas inlets 16. In addition, the operation of forming the gas inlets 16 during production of the showerhead 13 is prone to processing errors, that is, machine differences are likely to occur between different showerheads 13. In view of this, it is preferable to obtain the reference PQ characteristic in step St0-1 for each individual plasma processing apparatus 1 or each individual shower head 13.

[0088] Furthermore, the shower head 13 is worn out by repeated plasma processing performed by the plasma processing apparatus 1, which may change the average diameter and depth of the gas inlet 16. In other words, the conductance of the shower head 13 (gas diffusion chamber 15) changes over time due to repeated plasma processing, which may cause the reference PQ characteristic to change over time. In consideration of this, in the plasma processing apparatus 1, the reference PQ characteristics acquired in step St0-1 (such as when the plasma processing apparatus 1 is started up) may be stored in the control unit 2 as "initial data," and the reference PQ characteristics may be acquired periodically (for example, for each series of plasma processing) in the plasma processing apparatus 1. Then, by comparing the reference PQ characteristics thus acquired periodically with the "initial data" stored in the control unit 2, the deterioration over time (amount of wear) of the shower head 13 can be inspected, and as a result, the time to replace the shower head 13 can be appropriately determined. The reference PQ characteristics may be periodically obtained, for example, when the substrate W is being transported after completion of plasma processing on the substrate W in the plasma processing apparatus 1. In other words, the PQ characteristics to be compared with the reference PQ characteristics as "initial data" may be referred to as "post-processing PQ characteristics" after gas processing in the plasma processing apparatus 1.

[0089] In the above embodiment, the flow factor serving as the basis for flow rate control is determined and finely modified / optimized based on the type of processing gas (step St3-1) and the temperature dependency (step St3-2). However, the flow factor may also change depending on the conductance of the shower head 13 (gas diffusion chamber 15) in the same manner as the reference PQ characteristic. In view of this, similarly to the reference PQ characteristics, the flow factors of the various process gases may be fine-tuned / optimized for each individual plasma processing apparatus 1 or each individual shower head 13.

[0090] In the above embodiment, in order to appropriately perform proportional control of the flow rate based on the pressure ratio, particularly when the main gas and the additive gas are of different types, the main gas flow rate Qm and the additive gas flow rate Qa are converted into a reference gas (N2) flow rate (step St3) using a flow factor. However, even when the main gas and the additive gas are of different types, for example, when there is no large difference in the physical property values ​​of the main gas and the additive gas, or when the difference in the physical property values ​​falls within an allowable value, it is not necessarily necessary to perform the reference gas conversion using the flow factor.

[0091] Specifically, instead of acquiring the reference PQ characteristics in step St0-1, the PQ characteristics of various process gases used in the gas process are acquired in advance. Then, the pressure ratio (Pc / Pe) can be calculated from the supply flow rate ratio (Qmc / Qme) of various process gases calculated using the process recipe and the PQ characteristics corresponding to the various process gases, and the proportional control of the control valves 122c and 122e is performed using the pressure ratio.

[0092] According to this control example, the pressure ratio can be calculated directly using the PQ characteristics corresponding to various process gases without using a reference gas, and therefore the accuracy of the flow rate control can be improved compared to the above embodiment. In this case, however, it is necessary to calculate the supply flow rate ratio, pressure ratio, and the like for each processing gas independently, which may take a lot of time for flow rate control and may not be suitable for mass production in the plasma processing apparatus 1. In view of this, in the technology according to the present disclosure, it is preferable to perform reference gas conversion using a flow factor and further perform flow rate control using the reference PQ characteristic.

[0093] That is, more specifically, the following forms may also be included in the technical scope of the technology of the present disclosure. Without using a flow factor that serves as a conversion basis for pressure P, control may be performed to calculate the internal pressure in each of a plurality of gas supply flow paths (in one example, a plurality of gas supply flow paths connected to each of the center region, edge region, and middle region of the substrate W in the above embodiment) using a total flow rate (Q) calculated for each of the plurality of gas supply flow paths, a relationship between the gas flow rate and gas pressure of the main gas that has been previously acquired (e.g., the above-mentioned PQ characteristic), and a relationship between the gas flow rate and gas pressure of the additive gas that has been previously acquired.

[0094] The embodiments disclosed herein should be considered as illustrative and not restrictive in all respects. The above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0095] 2. Control section 10 Plasma Processing Chamber 20 Gas supply section 121c Branch supply pipe 121e Branch supply pipe 122c Control Valve 122e Control valve 140 Secondary supply pipe 151 Additive gas supply pipe 152 Additive valve

Claims

1. 1. A gas delivery system for delivering gas to an interior of a processing chamber, comprising: a plurality of gas supply passages configured to independently supply a main gas to the processing chamber; a flow control valve disposed in each of the plurality of gas supply passages; an additive gas flow passage connected to a downstream side of the flow control valve in at least one of the gas supply passages; an additive valve disposed in the additive gas flow path; a control unit for controlling the operation of the flow rate control valve and the addition valve, The control unit is A control for calculating a flow rate of the main gas flowing through each of the plurality of gas supply passages; Controlling to obtain a flow rate of an additive gas flowing through the additive gas flow passage and mixed with the main gas flowing through each of the gas supply passages; a control for calculating a total flow rate, which is a sum of a flow rate of the main gas and a flow rate of the additive gas, for each of the plurality of gas supply passages; a control for calculating an internal pressure of each of the plurality of gas supply passages by using the total flow rate calculated for each of the plurality of gas supply passages, a first relationship between a gas flow rate and a gas pressure of the main gas that is previously acquired, and a second relationship between a gas flow rate and a gas pressure of the additive gas that is previously acquired; A control for calculating a ratio of the internal pressures calculated in each of the plurality of gas supply passages; and proportionally controlling the opening degrees of the plurality of flow control valves based on the ratio of the internal pressures.

2. The control unit is and further performing a control for converting the flow rate of the main gas and the flow rate of the additive gas into a flow rate converted into a reference gas using a flow factor obtained in advance. When calculating the internal pressure, 2 . The gas supply system according to claim 1 , further comprising: a gas supply passage for supplying a gas to the first gas passage and a gas pressure of the first gas passage and a gas flow rate of the first gas passage that is determined based on the reference gas.

3. the gas supply passages are configured to be capable of supplying gas to different gas supply regions within the processing chamber, The control unit is The gas supply system of claim 2 , wherein the flow factor is corrected based on a temperature difference between different gas supply regions.

4. 4. The gas supply system according to claim 2, wherein the flow factor is a numerical value determined from at least one parameter selected from the group consisting of the type, physical properties and temperature of the main gas, the type, physical properties and temperature of the additive gas, the apparatus characteristics and temperature of the processing chamber, and the apparatus characteristics and temperature of the gas supply flow path.

5. the processing chamber has a showerhead having a plurality of gas introduction holes for introducing a processing gas into the processing chamber; The gas supply system according to claim 4 , wherein the device characteristics include at least one parameter of the number, average diameter, and depth of the gas introduction holes.

6. The control unit is obtaining the third relationship for the reference gas after completion of the gas process in the process chamber; The gas supply system of claim 4 or 5, further comprising control for comparing the third relationship obtained before the gas processing is performed with the third relationship obtained after the gas processing is completed to check for changes in the device characteristics over time.

7. The gas supply system according to any one of claims 2 to 6, wherein the reference gas is nitrogen gas.

8. 8. The gas supply system according to claim 2, wherein the control unit includes a storage medium that stores the flow factor and the third relationship.

9. 9. The gas supply system according to claim 1, wherein a total value of the pressure of the main gas and the pressure of the additive gas calculated when calculating the internal pressure is equal to or less than twice the pressure on the primary side of the flow control valve.

10. a flow rate controller arranged upstream of the flow rate control valve and controlling a flow rate of the main gas; 10. The gas supply system of claim 9, further comprising: a pressure sensor disposed within the flow controller and configured to measure a pressure on the primary side.

11. A plasma processing apparatus for processing a substrate, comprising: a processing chamber; a substrate support disposed within the processing chamber; A gas supply system according to any one of claims 1 to 10, for supplying gas to an interior of the processing chamber; a plasma generating unit configured to generate a plasma from a gas in the processing chamber.

12. A gas supply method using a gas supply system, comprising: The gas supply system includes: a plurality of gas supply passages configured to be able to independently supply a main gas to the processing chamber; a flow control valve disposed in each of the plurality of gas supply passages; an additive gas flow passage connected to at least one of the gas supply passages downstream of the flow rate control valve and configured to mix an additive gas with the main gas; an additive valve disposed in the additive gas flow path; a storage medium storing a reference relationship between a gas flow rate and a gas pressure of a reference gas previously obtained in each of the plurality of gas supply passages, and flow factors of the main gas and the additive gas; (A) calculating a flow rate of a main gas flowing through each of the plurality of gas supply passages; (B) acquiring a flow rate of an additive gas flowing through the additive gas flow passage and mixed with the main gas flowing through each of the gas supply passages; (C) calculating a total flow rate, which is a sum of a flow rate of the main gas and a flow rate of the additive gas, for each of the plurality of gas supply passages; (D) converting the flow rate of the main gas and the flow rate of the additive gas into a reference gas equivalent flow rate using the flow factor; (E) calculating a total converted flow rate, which is a sum of a flow rate of the main gas converted into the reference gas and a flow rate of the additive gas converted into the reference gas, for each of the plurality of gas supply passages; (F) calculating an internal pressure of each of the plurality of gas supply channels by using the total converted flow rate and the reference relationship; (G) calculating a ratio of the internal pressures calculated in each of the plurality of gas supply channels; (H) proportionally controlling openings of the plurality of flow control valves based on the ratio of the internal pressures to supply gas from each of the plurality of gas supply passages into the processing chamber.

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