Substrate processing method and substrate processing apparatus

Abstract

Provided is a substrate processing method for processing a substrate by supplying a gas from a gas supply unit into a substrate processing space in a substrate processing apparatus. The gas supply unit comprises a plurality of gas sources, a flow path for circulating the gas from the plurality of the gas sources to the substrate processing space, and a valve provided in the flow path to switch between opening and closing of the circulation of the gas. Pulse control is performed to cause the circulation of the gas to pulsate by alternately repeating the opening and closing of the circulation of the gas in the valve, wherein the duration of continuation of the pulse control and the number of times of opening the circulation of the gas in the duration of continuation are controlled to control the flow volume of the gas.

Description

Substrate processing method and substrate processing apparatus

[0001] The present disclosure relates to a substrate processing method and a substrate processing apparatus.

[0002] Patent Document 1 discloses a method for switching between two or more types of process gases in a semiconductor substrate etching apparatus, in which the gas supply is pulsed by switching between a path for supplying the gas to a substrate processing space and a path for exhausting the gas by an exhaust system by opening and closing a valve.

[0003] JP 2015-144249 A

[0004] The technology according to the present disclosure reduces gas waste during substrate processing and simplifies the substrate processing apparatus.

[0005] One aspect of the present disclosure is a substrate processing method in a substrate processing apparatus, in which gas is supplied from a gas supply unit to a substrate processing space to process a substrate, the gas supply unit including a plurality of gas sources, a flow path for circulating the gas from the plurality of gas sources to the substrate processing space, and a valve provided in the flow path for switching between opening and closing the flow of the gas, wherein pulse control is performed in the valve to pulse the flow of the gas by alternately opening and closing the flow of the gas, and the flow rate of the gas is controlled by controlling the duration of the pulse control and the number of times the flow of the gas is opened during the duration.

[0006] According to the present disclosure, gas waste during substrate processing can be reduced and the substrate processing apparatus can be simplified.

[0007] FIG. 1 is an explanatory diagram showing an example of the configuration of a plasma processing system according to an embodiment. FIG. 2 is a cross-sectional view showing an example of the configuration of a plasma processing apparatus according to an embodiment. FIG. 3 is a plan view showing an example of the configuration of an upper baffle plate according to an embodiment. FIG. 4 is a plan view showing an example of the configuration of a lower baffle plate according to an embodiment. FIG. 5 is a plan view showing an example of the arrangement of an upper baffle plate and a lower baffle plate. FIG. 6 is a side view showing an example of a gas flow during exhaust through an upper baffle plate and a lower baffle plate. FIG. 1 is an explanatory diagram showing an example of the configuration of a plasma processing system according to an embodiment. FIG. 2 is a flowchart showing an overview of a substrate processing method according to an embodiment. FIG. 3 is an explanatory diagram showing an overview of pulse control in a substrate processing method according to another embodiment. FIG. 4 is a flowchart showing an overview of a substrate processing method according to another embodiment. FIG. 5 is a schematic diagram showing an overview of a conventional gas supply system. FIG. 6 is a diagram showing an overview of valve opening and closing control when gas is supplied using a conventional gas supply system.

[0008] In the manufacturing process of semiconductor devices, a substrate processing space containing semiconductor wafers (hereinafter referred to as "substrates") is decompressed and various processing steps are performed on the substrates. Gas processing is performed in these processing steps.

[0009] In a semiconductor dry process, which is a predetermined process performed in a substrate processing apparatus, two or more process gases may be repeatedly switched between at high speed. For example, Patent Document 1 discloses a means for switching between a path for supplying gas to a substrate processing space and a path for discharging the gas by exclusively controlling a valve. Specifically, a gas supply system such as the one shown in FIG. 12 is employed.

[0010] 12 is a schematic diagram showing an outline of a conventional gas supply system capable of switching between two or more types of gases using the method disclosed in Patent Document 1. The conventional gas supply system includes a gas box BR that supplies one mixed gas (GR) and a gas box BL that supplies another mixed gas (GL). The gas boxes BR and BL are connected to flow paths CR and CL, respectively. The flow paths CR and CL are equipped with flow rate controllers FCR and FCL, respectively. The flow path CR branches into an exhaust flow path ER that connects to an exhaust system ES and a supply flow path SR that connects to a substrate processing space PS. The flow path CL branches into an exhaust flow path EL that connects to the exhaust system and a supply flow path SL that connects to the substrate processing space PS. The exhaust flow paths ER and EL are equipped with exhaust valves VER and VEL, respectively, and the supply flow paths SR and SL are equipped with supply valves VSR and VSL, respectively.

[0011] 13 is a diagram showing an outline of valve opening / closing control when gas is supplied using the conventional gas supply system shown in FIG. In the conventional gas supply system, when one mixed gas (GR) and another mixed gas (GL) are supplied separately and alternately, the exhaust valve VER and the supply valve VSL are closed when supplying the one mixed gas GR, and the supply valve VSR and the exhaust valve VEL are opened. As a result, the one mixed gas GR is supplied to the substrate processing space PS, and the other mixed gas GL is discharged by the exhaust system ES. Furthermore, when the other mixed gas GL is supplied, the exhaust valve VEL and the supply valve VSR are closed, and the supply valve VSL and the exhaust valve VER are opened. As a result, the other mixed gas GL is supplied to the substrate processing space PS, and the one mixed gas GR is discharged by the exhaust system ES. By alternately repeating this process, the one mixed gas (GR) and the other mixed gas (GL) are supplied separately and alternately to the substrate processing space PS.

[0012] However, when changing the flow rate using the flow rate controllers FCR and FCL, it takes time for the flow rate to stabilize. Specifically, a response time of approximately 500 ms is required for the flow rate to stabilize. This is slow and impractical when considering high-speed processes. In view of this, the gas supply system of Patent Document 1 shortens the switching time by switching the mixed gas without changing the flow rate. While this gas switching mechanism can shorten the switching time, it has the problem of constantly disposing of gas that is not supplied to the substrate processing space PS, which is uneconomical. Furthermore, to achieve the desired flow rate of the gas supplied to the substrate processing space PS, flow rate controllers FCR and FCL must be installed downstream of the gas boxes BR and BL for reasons described below. This necessitates an increase in the overall size of the gas supply system due to the size of the flow rate controllers. Note that "system size" includes not only the occupied area (volume) but also the structural complexity of the system.

[0013] Therefore, the technology disclosed herein uses a pulse-controllable valve to supply gas, eliminating the need for constant gas waste during gas switching and minimizing gas waste. Furthermore, by eliminating the need for flow rate controllers, which were required for each gas downstream of the gas box in conventional gas supply systems, the gas supply unit and, ultimately, the substrate processing apparatus are simplified. Note that "simplifying" the gas supply unit and substrate processing apparatus includes reducing the occupied area (volume) and / or simplifying the structure relative to conventional technologies.

[0014] The configuration of the substrate processing system according to this embodiment will be described below with reference to the drawings. In this specification, elements having substantially the same functional configuration are designated by the same reference numerals, and redundant description will be omitted.

[0015] FIG. 1 is a diagram illustrating an exemplary configuration of a plasma processing system. In one embodiment, the plasma processing system includes a plasma processing apparatus 1 and a control unit 2. The plasma processing system is an example of a substrate processing system, and the plasma processing apparatus 1 is an example of a substrate processing apparatus. The plasma processing apparatus 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 substrate processing space 10s. The plasma processing chamber 10 also has at least one gas supply port for supplying at least one processing gas to the substrate processing space 10s and at least one gas exhaust port for exhausting gas from the substrate processing space 10s. 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 within the substrate processing space 10s and has a substrate support surface for supporting a substrate.

[0016] The plasma generating unit 12 is configured to generate plasma from at least one processing gas supplied into the substrate processing space 10s. The plasma generated in the substrate processing space 10s may be capacitively coupled plasma (CCP), inductively coupled plasma (ICP), electron-cyclotron-resonance plasma (ECR plasma), helicon wave plasma (HWP), surface wave plasma (SWP), or the like. Various types of plasma generators may be used, including alternating current (AC) plasma generators and direct current (DC) plasma generators. In one embodiment, the AC signal (AC power) used in the AC plasma generator has a frequency in the range of 100 kHz to 10 GHz. Thus, AC signals include radio frequency (RF) signals and microwave signals. In one embodiment, the RF signal has a frequency in the range of 100 kHz to 150 MHz.

[0017] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform various processes described in this disclosure. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to perform various processes described herein. In one embodiment, part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The control unit 2 may be implemented by, for example, a computer 2a. The processing unit 2a1 may be configured to read a program from the storage unit 2a2 and execute the read program to perform various control operations. This program may be stored in the storage unit 2a2 in advance or may be acquired via a medium when needed. The acquired program is stored in the storage unit 2a2 and read from the storage unit 2a2 by the processing unit 2a1 for execution. The medium may be various storage media readable by the computer 2a or a communication line connected to the communication interface 2a3. The processing unit 2a1 may be a CPU (Central Processing Unit). 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).

[0018] An example of the configuration of a capacitively coupled plasma processing apparatus 1 as an example of a substrate processing apparatus will be described below. FIG. 2 is a diagram for explaining an example of the configuration of the capacitively coupled plasma processing apparatus 1.

[0019] The capacitively coupled 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 gas inlet is configured to introduce at least one process gas into the plasma processing chamber 10. The gas inlet includes a showerhead 13. The substrate support 11 is disposed within the plasma processing chamber 10. The showerhead 13 is disposed above the substrate support 11. In one embodiment, the showerhead 13 forms at least a portion of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a substrate processing space 10s 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 housing of the plasma processing chamber 10.

[0020] The substrate support 11 includes a main body 111 and a ring assembly 112. The main body 111 has a central region 111a for supporting a substrate W and an annular region 111b for supporting the ring assembly 112. The annular region 111b of the main body 111 surrounds the central region 111a of the main body 111 in a plan view. The substrate W is disposed on the central region 111a of the main body 111, and the ring assembly 112 is disposed on the annular region 111b of the main body 111 so as to surround the substrate W on the central region 111a of the main body 111. Therefore, the central region 111a is also called a substrate support surface for supporting the substrate W, and the annular region 111b is also called a ring support surface for supporting the ring assembly 112.

[0021] In one embodiment, the main body 111 includes a base 1110 and an electrostatic chuck 1111. The base 1110 includes a conductive member. The conductive member of the base 1110 can function as a lower electrode. The electrostatic chuck 1111 is disposed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic electrode 1111b disposed within the ceramic member 1111a. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Note that the annular region 111b may also be provided by another member surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member. In this case, the ring assembly 112 may be disposed on the annular electrostatic chuck or the annular insulating member, or may be disposed on both the electrostatic chuck 1111 and the annular insulating member. Furthermore, at least one RF / DC electrode coupled to an RF power supply 31 and / or a DC power supply 32, which will be described later, may be disposed within the ceramic member 1111a. 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, which will be 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 1110 and the at least one RF / DC electrode may function as multiple lower electrodes. Furthermore, the electrostatic electrode 1111b may function as a lower electrode. Therefore, the substrate support 11 includes at least one lower electrode.

[0022] The ring assembly 112 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.

[0023] The substrate support 11 may also include a temperature adjustment module configured to adjust at least one of the electrostatic chuck 1111, the ring assembly 112, and the substrate W to a target temperature. The temperature adjustment module may include a heater, a heat transfer medium, a flow passage 1110a, or a combination thereof. A heat transfer fluid such as brine or a gas flows through the flow passage 1110a. In one embodiment, the flow passage 1110a is formed in the base 1110, and one or more heaters are disposed in the ceramic member 1111a of the electrostatic chuck 1111. The substrate support 11 may also include a heat transfer gas supply configured to supply a heat transfer gas to a gap between the back surface of the substrate W and the central region 111a.

[0024] The showerhead 13 is configured to introduce at least one process gas from the gas supply unit 20 into the substrate processing space 10s. The showerhead 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and multiple gas inlets 13c. The process gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the substrate processing space 10s from the multiple gas inlets 13c. The showerhead 13 also includes at least one upper electrode. In addition to the showerhead 13, the gas inlet may also include one or more side gas injectors (SGIs) attached to one or more openings formed in the sidewall 10a.

[0025] The gas supply unit 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply unit 20 is configured to supply at least one process gas from a corresponding gas source 21 to the showerhead 13 via a corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Furthermore, the gas supply unit 20 may include at least one flow modulation device that modulates or pulses the flow rate of the at least one process gas. In this specification, the gas source is described as being upstream of the gas flow, and the substrate processing space 10s is described as being downstream. Details of the gas supply unit 20 and the substrate processing space 10s will be described later.

[0026] The power supply 30 includes an RF power supply 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power supply 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 substrate processing space 10s. Therefore, the RF power supply 31 can function as at least a part of the plasma generating unit 12. Furthermore, by supplying a bias RF signal to the at least one lower electrode, a bias potential is generated on the substrate W, thereby attracting ion components in the formed plasma to the substrate W.

[0027] 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 multiple 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.

[0028] The second RF generator 31b is coupled to at least one lower electrode via at least one impedance matching circuit and is 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 generator 31b may be configured to generate multiple bias RF signals having different frequencies. The generated one or more bias RF signals are supplied to at least one lower electrode. In various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0029] 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 the 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 the 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.

[0030] 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 thereof pulse waveform. In one embodiment, a waveform generator for generating the 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 either positive or negative polarity. Furthermore, the sequence of voltage pulses may include one or more positive voltage pulses and one or more negative voltage pulses within one period. The first and second DC generating units 32a and 32b may be provided in addition to the RF power supply 31, or the first DC generating unit 32a may be provided instead of the second RF generating unit 31b.

[0031] 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 in the substrate processing space 10s is regulated by the pressure regulating valve. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0032] In one embodiment, the exhaust system 40 includes an upper baffle plate 41 and a lower baffle plate 42. The upper baffle plate 41 and the lower baffle plate 42 are provided with through-holes 43 and 44, respectively. The upper baffle plate 41 and the lower baffle plate 42 form a boundary between the substrate processing space 10s and the exhaust system 40.

[0033] 3 is a plan view of the upper baffle plate 41 as viewed from the ceiling side of the plasma processing chamber 10. As shown in the figure, the upper baffle plate 41 has through-holes 43 in addition to the plate portion indicated by hatching. Gas can flow through the through-holes 43, and specifically, gas flows from the substrate processing space 10s to the exhaust system 40 via the through-holes 43.

[0034] 4 is a plan view of the lower baffle plate 42 as viewed from the ceiling side of the plasma processing chamber 10. As shown in the figure, the lower baffle plate 42 has through-holes 44 in addition to the plate portion indicated by hatching. Gas can flow through the through-holes 44, and specifically, gas flows from the substrate processing space 10s to the exhaust system 40 through the through-holes 44.

[0035] 5 is a plan view of the upper baffle plate 41 and the lower baffle plate 42 viewed from the top to show their relative positions. As shown in the figure, the upper baffle plate 41 and the lower baffle plate 42 are arranged so that the positions of their respective through holes 43, 44 are offset from each other. In the example shown in the figure, the hatched plate portion of the upper baffle plate 41 overlaps with the through hole 44 of the lower baffle plate 42, and the hatched plate portion of the lower baffle plate 42 overlaps with the through hole 43 of the upper baffle plate 41.

[0036] FIG. 6 is a side view of the upper baffle plate 41 and the lower baffle plate 42 as viewed from the chamber sidewall 10a. In FIG. 6, the gas flow is indicated by bold arrows. The relative magnitude of the gas flow is indicated by the thickness of the bold arrows. When at least one of the upper baffle plate 41 and the lower baffle plate 42 moves up and down and approaches each other, the distance between the through holes 43 and 44 is shortened, thereby suppressing the flow of gas through the through holes 43 and 44. In addition to the above configuration, the gas flow can also be changed by rotating at least one of the upper baffle plate 41 and the lower baffle plate 42, thereby changing the distance between the through holes 43 and 44. With this configuration, the volume of the substrate processing space 10s can be limited by using the upper baffle plate 41 and the lower baffle plate 42. Therefore, even when the pumping speed is increased, the substrate processing space 10s can be evacuated while maintaining a uniform pressure.

[0037] Next, the gas supply unit 20 and the substrate processing space 10s according to this embodiment will be described in detail with reference to Fig. 7. Fig. 7 is a schematic diagram showing the gas supply unit 20 and the substrate processing space 10s according to this embodiment, and an outline of a flow path connecting these.

[0038] 7, the gas supply unit 20 includes gas boxes 200a and 200b and flow paths. The gas box 200a includes gas sources 21a, 21b, and 21c and corresponding flow rate controllers 22a, 22b, and 22c. The gas box 200b includes gas sources 21d, 21e, and 21f and corresponding flow rate controllers 22d, 22e, and 22f. The flow paths include a plurality of first flow paths 204a and 204b and a second flow path 206. The downstream sides of the plurality of gas sources 21a to 21f are connected to the upstream sides of the corresponding plurality of flow rate controllers 22a to 22f. The downstream sides of the plurality of flow rate controllers 22a to 22f are connected to the first flow paths 204a and 204b. The downstream sides of the first flow paths 204a and 204b merge into the second flow path 206. The downstream of the second flow path 206 is connected to the substrate processing space 10s. The downstream of the second flow path 206 may be connected to a gas inlet and connected to the substrate processing space 10s via the shower head 13 described above. The gas box 200 is not limited to the illustrated configuration. For example, a gas box including a gas source for supplying a mixed gas of multiple gases mixed in a desired ratio may supply the mixed gas to one of the first flow paths 204a, 204b. The combination or number of the gas sources 21, flow rate controllers 22, and first flow paths 204a, 204b is not limited to the illustrated configuration. For example, the number of multiple flow rate controllers 22 merging into one of the first flow paths 204a, 204b and the corresponding gas sources 21 may be increased or decreased as desired. Alternatively, a configuration may be adopted in which a desired combination of multiple gas sources 21 can be switched to merge, and the gases may be controlled to be mixed in a desired ratio in one of the first flow paths 204a, 204b.

[0039] In one embodiment, buffer tanks 210a and 210b are provided in the first flow paths 204a and 204b, respectively. The buffer tanks 210a and 210b each have a pressure sensor P1 or P2 capable of measuring the internal pressure. The buffer tanks 210a and 210b may be configured so that the area (hereinafter referred to as the flow path cross-section) of a cross section perpendicular to the gas flow path direction (hereinafter referred to as the flow path cross-section) is larger than the flow path cross-sectional area of ​​the piping that constitutes the first flow paths 204a and 204b. In this case, the flow path cross-sectional area of ​​the buffer tanks 210a and 210b may be three or more times the flow path cross-sectional area of ​​the first flow paths 204a and 204b. Furthermore, in this case, the length of the buffer tanks 210a and 210b in the flow path direction may be equal to or longer than the diameter of the flow path cross-section of the buffer tanks 210a and 210b.

[0040] In one embodiment, the volume of the buffer tank 210a is configured to be sufficiently larger than the target value (volume value) of the supply amount of the mixed gas Gα in step ST12 for one pulse set described later, and the volume of the buffer tank 210b is configured to be sufficiently larger than the target value (volume value) of the supply amount of the mixed gas Gβ in step ST16 for one pulse set described later. In this case, the volumes of the buffer tanks 210a and 210b are preferably 5 times or more, and more preferably 10 times or more, the target values ​​of the supply amounts of the mixed gases Gα and Gβ, respectively.

[0041] In another embodiment, the volumes of the buffer tanks 210a, 210b are configured to be variable. For example, controllable pistons are provided to change the buffer tanks 210a, 210b to the desired volume.

[0042] In another embodiment, the temperature of the buffer tanks 210 a, 210 b is configured to be variable. For example, a controllable temperature adjustment mechanism is connected to the buffer tanks 210 a, 210 b so that the gas inside the buffer tanks 210 a, 210 b can be adjusted to a desired temperature. In this case, the temperature adjustment mechanism may be a heater that heats the gas inside the buffer tanks 210 a, 210 b.

[0043] Pulse valves 220a and 220b are provided in the first flow paths 204a and 204b. Orifices 222a and 222b are provided downstream of the pulse valves 220a and 220b. The pulse valves 220a and 220b can be instantaneously switched between open and closed. Specifically, although not particularly limited, it is preferable to use valves that can switch between open and closed gas flow so that the pulse interval is at least less than 50 ms. At the above speed, gas can be supplied at a sufficiently accurate flow rate and switching speed in the flow control using the pulse valves 220a and 220b described below. In this specification, the control of alternately opening and closing the pulse valves 220a and 220b is referred to as pulse control. In pulse control, one gas flow from a closed state to opening the pulse valves 220a and 220b and then switching them back to the closed state is referred to as one pulse PL.

[0044] A chamber monitor 224 is provided on the chamber sidewall 10a as a detector capable of detecting plasma emission or gas composition in the substrate processing space 10s. The chamber monitor 224 may be, for example, an optical emission spectrometer (OES) capable of detecting plasma emission in the substrate processing space 10s from the chamber sidewall 10a. Alternatively, the chamber monitor 224 may be a known detector capable of detecting the gas composition in the substrate processing space 10s from the chamber sidewall 10a. In one embodiment, the chamber monitor 224 transmits information on the detected plasma emission (including the amount of emission or the emission intensity ratio) or gas composition (including the amount or ratio of gas present, including products resulting from dissociation of gas components) to the controller 2. The controller 2 performs calculations based on the information, updates the target value of the gas supply rate, and transmits the target value to the controller 226. The controller 226 controls the pulse valves 220a and 220b based on the target value, and increases or decreases the flow rate in the pulse valves 220a and 220b.

[0045] 7, the buffer tanks 210a and 210b are preferably provided, but this is not essential, and the buffer tanks 210a and 210b may not be provided. In this case, for example, a portion of the piping constituting the first flow paths 204a and 204b may be expanded to have the same dimensions as the buffer tanks 210a and 210b. Although the second flow path 206 is provided, this is not essential. In this case, the downstream of the first flow paths 204a and 204b may be directly connected to a gas inlet, for example, the shower head 13. Furthermore, although the chamber monitor 224 is provided, this is not essential.

[0046] Next, the substrate processing method according to this embodiment will be described with reference to FIGS. 8 to 11. FIG. 8 is an explanatory diagram illustrating the opening and closing control of the pulse valve in the substrate processing method MT1 according to one embodiment. FIG. 9 is a flowchart illustrating an outline of the substrate processing method MT1 according to one embodiment. FIG. 10 is an explanatory diagram illustrating an outline of another example of pulse control in the substrate processing method MT1 according to one embodiment. FIG. 11 is a flowchart illustrating an outline of the substrate processing method MT2 according to another embodiment. The substrate processing methods MT1 and MT2 according to this embodiment can be performed, for example, in the above-described plasma processing system. In the substrate processing methods MT1 and MT2, the flow rate of gas supplied to the substrate processing space 10s is controlled by pulse control of the pulse valves 220a and 220b.

[0047] In the following description of the substrate processing methods MT1 and MT2, a case will be described in which, in the plasma processing system shown in FIG. 7 , gas species a to c are supplied from gas sources 21 a to 21 c to first flow path 204 a via flow rate controllers 22 a to 22 c, respectively, and gas species d to f are supplied from gas sources 21 d to 21 f to first flow path 204 b via flow rate controllers 22 d to 22 f. Note that gas species a to f may be known gases used in processes such as etching or deposition, or known gases for diluting these processes. Prior to the execution of the substrate processing methods MT1 and MT2, gas species a to c are mixed in first flow path 204 a to form mixed gas Gα, which is stored in buffer tank 210 a at a desired pressure. Gas species d to f are mixed in first flow path 204 b to form mixed gas Gβ, which is stored in buffer tank 210 b at a desired pressure.

[0048] The following describes a case in which the gas supply is started in the substrate processing method MT1 according to this embodiment, in which the mixed gas Gα and the mixed gas Gβ are supplied separately and alternately. In FIGS. 8 and 9 , pulse control is first initiated for the pulse valve 220a provided on the first flow path 204a. During pulse control, the pulse valve 220a is repeatedly switched from a closed state to an open state and then closed again. During this period, the pulse valve 220b is kept closed (step ST10). After that, when the supply rate of the mixed gas Gα reaches a target value, the pulse control for the pulse valve 220a is terminated, and the supply of the mixed gas Gα is stopped (step ST12). Subsequently, the same pulse control is similarly performed for the pulse valve 220b provided on the first flow path 204b, during which the pulse valve 220a is kept closed (step ST14). After that, when the supply rate of the mixed gas Gβ reaches a target value, the pulse control for the pulse valve 220b is terminated, and the supply of the mixed gas Gβ is stopped (step ST16). Thereafter, the pulse control of the pulse valve 220a and the pulse valve 220b is alternately repeated until the desired process is completed (step ST18).

[0049] As shown in FIG. 10 , a delay time DT may be provided when terminating the pulse control of the mixed gas Gα and initiating the control of the mixed gas Gβ, or vice versa (hereinafter, these are collectively referred to as mixed gas switching). That is, for example, after terminating the pulse control of the mixed gas Gα, the control of the mixed gas Gβ may be initiated after the delay time DT has elapsed. When switching the mixed gas, gas is exhausted from the first flow paths 204a, 204b, the second flow path 206, and the substrate processing space 10s downstream of the pulse valves 220a, 220b. Therefore, the delay time DT is provided as the time until the exhaust is completed. Specifically, the delay time DT is preferably set to 10 ms to 1 s.

[0050] The target value of the supply amount of the mixed gas may be determined in advance for each process and read in. The start and end of the pulse control may be performed by the control unit 2 sending a start command and an end command to the controller 226 based on the target value, and the controller 226 controlling the pulse valves 220 a and 220 b.

[0051] Pulse control will be described in more detail. The duration of pulse control and the number of pulses PL during the duration may be determined based on the target values ​​of the flow rate per pulse PL and the supply rate of the mixed gas. Specifically, the number of pulses is first determined so that the product of the flow rate per pulse PL and the number of pulses equals the target value of the supply rate. For example, if the target value of the supply rate in the process is 100 and the flow rate of the mixed gas per pulse PL is 1, setting the number of pulses to 100 will allow the supply rate of 100 to be supplied. After determining the number of pulses, the duration of pulse control may be determined so that pulse control can be performed at the desired pulse interval. Note that the flow rate per pulse PL may be measured in advance under process conditions.

[0052] In switching the mixed gas, in addition to switching to the supply of one mixed gas when the supply rate of the other mixed gas reaches a target value as described above, a method MT2 described below can also be employed. That is, the state within the substrate processing space 10s is monitored by the chamber monitor 224, and the supply of the mixed gas is started or stopped based on the monitoring results. Specifically, the state within the substrate processing space 10s is monitored by the chamber monitor 224, such as an OES, by detecting the emission wavelength ratio, amplitude, wavelength correlation, etc. of the plasma emission of the gases. In this case, the detection results detected by the chamber monitor 224 are first transmitted to the control unit 2. Next, the control unit 2 determines whether process α using mixed gas Gα or process β using mixed gas Gβ has been completed based on the detection results. If it is determined that process α or process β has been completed, a command is transmitted to the controller 226 to switch the mixed gas, and the pulse valves 220a and 220b are controlled.

[0053] FIG. 11 illustrates an example of monitoring the gas state in the substrate processing space 10s using an OES and controlling the pulse valves 220a and 220b based on the monitoring results. As an example, consider a case where the mixed gas Gα being supplied is an etching gas containing fluorine, and the closed mixed gas Gβ is a deposition gas. First, the pulse valve 220a is pulse-controlled to supply the mixed gas Gα (step ST20). At this time, the supply of the mixed gas Gα forms an etching gas plasma in the substrate processing space 10s, and etching of the substrate W as the workpiece progresses. During etching, the fluorine in the mixed gas Gα is consumed in the etching, so the amount of fluorine emitted by the plasma is low. On the other hand, as the etching approaches completion, the fluorine in the mixed gas Gα is no longer consumed in the etching, and its amount in the substrate processing space 10s increases. This increases the fluorine plasma emission, and the amount detected by the OES increases. That is, if an increase in the amount of fluorine-related plasma emission detected by the OES is detected, it can be determined that the etching is approaching completion (step ST22). In this embodiment, if the plasma emission intensity is below the threshold, the supply of the mixed gas Gα continues. If the plasma emission intensity reaches or exceeds the threshold, etching is determined to be complete, and the supply of the mixed gas Gα is stopped. This prevents excess mixed gas Gα from being supplied into the substrate processing space 10s. The pulse valve 220a is then closed and pulse-controlled to execute the next process (step ST24). The process β using the mixed gas Gβ is also monitored in the same manner as above to determine whether the process β is complete (step ST26). If the process β is determined to be complete, the pulse control of the pulse valve 220a is resumed, or the process is terminated (step ST28). The threshold for the plasma emission intensity may be determined in advance as a process condition, and the emission intensity of a wavelength that serves as an indicator of the progress of the process may be stored in a memory unit and read during the process.

[0054] While the detection target described above is the amount of plasma emission from fluorine in the etching gas, the detection is not limited thereto. The progress of the process may be determined by detecting the amount of gas present or the gas ratio, which are indicators of the progress of the process. The gases detected here include not only the gas components themselves but also products resulting from the dissociation of the gas components. In this case, a threshold value may be determined in advance for each indicator gas under the process conditions, stored in a memory unit, and loaded during the process. While the plasma emission value is monitored and compared with the threshold value in the above example, this is not limiting. For example, the intensity ratio of light of multiple wavelengths detected by the OES may be monitored and compared with a threshold value to determine the progress of the etching. In this case, the comparison with the threshold value may be performed by continuing the supply of the mixed gas Gα when the intensity ratio is less than the threshold value and stopping the supply of the mixed gas Gα when the intensity ratio is equal to or greater than the threshold value. Furthermore, the comparison with the threshold value may be performed by continuing the supply of the mixed gas Gα when the intensity ratio is equal to or greater than the threshold value and stopping the supply of the mixed gas Gα when the intensity ratio is less than the threshold value. The threshold value for the intensity ratio may be determined in advance as a process condition, and stored in a storage unit as an intensity ratio of light of wavelengths that is an index of the progress of the process, and then read when the process is executed.

[0055] Although the above describes an example in which pulse control and switching control are performed on two types of mixed gases, Gα and Gβ, similar control is possible when three or more types of mixed gases are supplied to the substrate processing space 10s through three or more first flow paths. In this case, while pulse control for one mixed gas is being performed, the pulse valves for the other mixed gases are closed to stop their supply. A delay time DT may also be provided between the switching of each mixed gas.

[0056] Next, the significance of configuring the plasma processing apparatus 1 and the substrate processing methods MT1 and MT2 as described above in the present disclosure will be described in detail.

[0057] As described with reference to FIG. 12 , in a conventional method and configuration for switching between two or more types of gases, the switching time was shortened by switching between a path supplied to the substrate processing space PS and a path exhausted by the exhaust system ES. In addition to the cost issue of continuously wasting gas that was not supplied to the substrate processing space PS, the conventional configuration also had the following problem. That is, in the conventional configuration, when one gas is being supplied, the supply valves VSR and VSL are maintained in an open state. In this state, the flow rate of the gas supplied through the supply valves VSR and VSL is limited to a certain value depending on the specifications of the supply valves VSR and VSL. Therefore, in order to supply the gas at a desired flow rate, it was necessary to provide flow rate controllers FCR and FCL on the flow paths CR and CL. In contrast, in the technology disclosed herein, the gas is supplied using pulse control by pulse valves 220 a and 220 b. The advantages of supplying gas using pulse control rather than supplying gas with the valves open are as follows. That is, by changing the density, number, interval, and duration of the pulse control of the pulses PL to desired values, it is possible to control the supplied gas to a desired flow rate. In other words, the pulse control of the present disclosure allows the flow rate of the gas supplied to the substrate processing space 10s to be controlled to a desired value. That is, the gas supply unit 20 of the present disclosure does not require a flow rate controller for each mixed gas. This allows the system size of the gas supply unit to be smaller than that of conventional configurations.

[0058] Next, the significance of the buffer tanks 210a, 210b and the orifices 222a, 222b that are provided as a preferred configuration in the present disclosure will be described.

[0059] When pulse control is performed using pulse valves 220 a and 220 b, the flow rate of the gas passing through the valves is not constant but may change periodically depending on the pulse control conditions. In this specification, such periodic changes in flow rate are referred to as flow rate pulsation. Flow rate pulsation can occur not only downstream of pulse valves 220 a and 220 b but also upstream of them.

[0060] When flow pulsation occurs, it is thought that it may cause loads on structural components and destabilize measurements by various sensors such as pressure sensors. It is known that the degree of the effect of flow pulsation depends on the volume of the flow path, which is the space where the flow pulsation occurs. Specifically, the smaller the volume of the flow path, the greater the effect of flow pulsation, and the larger the volume of the flow path, the less the effect of flow pulsation. For this reason, in one embodiment of the present disclosure, buffer tanks 210a and 210b are provided. That is, the buffer tanks 210a and 210b expand the volume of the space where flow pulsation occurs and have the effect of buffering the flow pulsation. Furthermore, the orifices 222a and 222b have the effect of uniforming the flow rate downstream. The buffer tanks 210a and 210b reduce the magnitude of the flow pulsation and sufficiently suppress the above-mentioned effect. To maximize this effect, the buffer tanks 210a, 210b are preferably configured such that their cross-sectional area is three or more times the cross-sectional area of ​​the first flow paths 204a, 204b, and their lengths in the flow path direction are equal to or greater than the cross-sectional diameter of the buffer tanks 210a, 210b. On the other hand, if the volumes of the buffer tanks 210a, 210b are too large, it will take a long time to fill the buffer tanks 210a, 210b with gas to the desired pressure. Furthermore, since the piping including the buffer tanks 210a, 210b is evacuated at the end of the process, this gas is wasted. Therefore, it is undesirable for the buffer tanks 210a, 210b to be unnecessarily large.

[0061] After careful consideration, the inventors have found that when a buffer tank is provided, it is important for more precise control of the gas supply amount that the pressure in the buffer tank during pulse control be kept substantially constant from the time the supply of the mixed gas starts until the supply amount of the mixed gas reaches the target value and the supply ends.

[0062] In the following description, a series of pulse controls from the start of the supply of the mixed gas until the supply is terminated when the supply amount of the mixed gas reaches the target value is referred to as one pulse set. The series of controls from the start of the pulse control of the pulse valve 220 a in process ST10 to the closing of the pulse valve 220 a in process ST14 is an example of one pulse set.

[0063] In the present disclosure, if the mixed gas supplied is considered to be an ideal gas, then, when the pressure inside the buffer tank is P, the volume of the buffer tank is V, the amount of mixed gas supplied (amount of substance) in one pulse set is n, the gas constant is R, and the absolute temperature of the mixed gas is T, then P = nRT / V holds from the gas state equation.

[0064] From this perspective, as described above, in one embodiment, the volume of the buffer tank is configured to be sufficiently larger than the target value (volume value) of the mixed gas supply amount in one pulse set. During gas supply in a pulse set, the mixed gas in the buffer tank decreases by a maximum of the mixed gas supply amount n. At this time, since the volume V of the buffer tank is sufficiently large relative to the gas volume decreasing from the buffer tank (i.e., a function of the supply amount n), the pressure P in the buffer tank can be kept constant. Note that the pressure P being constant also includes not falling below a desired threshold value, as described below.

[0065] In another embodiment, the volume of the buffer tank is variable. During gas supply in the pulse set, the mixed gas in the buffer tank decreases by a maximum of the mixed gas supply amount n. By controlling the volume of the buffer tank to decrease by the amount of mixed gas decreased from the buffer tank at this time, it is possible to maintain, for example, the ratio n / V of the supply amount n to the volume V substantially constant, and the pressure P in the buffer tank can be kept constant.

[0066] In another embodiment, the temperature of the buffer tank is variable. During gas supply in the pulse set, the mixed gas in the buffer tank decreases by a maximum of the mixed gas supply amount n. However, by increasing the absolute temperature T of the gas by the amount of mixed gas decreased from the buffer tank at this time, the product nT of the supply amount n and the absolute temperature T can be kept approximately constant, and the pressure P in the buffer tank can be kept constant.

[0067] Here, it is more preferable that the pressure P in the buffer tank be kept substantially constant throughout the duration of pulse control from the start to the end of one pulse set, but in one embodiment, the pressure P in the buffer tank may be reduced to a value greater than a desired threshold value, for example, 80% of the value of the pressure P at the start of the pulse set.

[0068] Although the buffer tanks 210a and 210b are shown in FIG. 7 to be located on the first flow paths 204a and 204b upstream of the pulse valves 220a and 220b, this is not limiting. For example, they may be located on the first flow paths 204a and 204b downstream of the pulse valves 220a and 220b. Even in this case, the effects of the flow rate pulsation described above can be reduced. However, since the first flow paths 204a and 204b downstream of the pulse valves 220a and 220b are exhausted when the mixed gas is switched, if the buffer tanks 210a and 210b are large, the exhaust time will be correspondingly longer. From this perspective, it is more preferable to install the buffer tanks 210a and 210b on the first flow paths 204a and 204b upstream of the pulse valves 220a and 220b.

[0069] Next, the significance of the chamber monitor 224 provided as a preferred configuration in the present disclosure will be described.

[0070] In processes such as deposition and etching, the required amount of deposition gas or etching gas depends on the conditions of the substrate W to be processed and the conditions of the apparatus. Examples of the conditions of the substrate W include the surface area and surface properties of the substrate W. Examples of the conditions of the apparatus include the degree of wear of consumable parts and the amount of processing residue (deposit) present in the chamber or piping. Therefore, it is preferable to change the gas supply amount depending on the substrate conditions and the conditions of the apparatus. According to the substrate processing method MT2, by monitoring the conditions in the substrate processing space 10s using the chamber monitor 224, the mixed gas can be switched when the process is actually completed.

[0071] Next, the significance of providing the delay time DT and the exhaust system 40 as described above in the present disclosure will be described.

[0072] In the case where the mixed gas Gα and the mixed gas Gβ are supplied separately and alternately as described above, both the mixed gas Gα and the mixed gas Gβ flow through the second flow path 206 and the substrate processing space 10s downstream of the pulse valve 220a or the pulse valve 220b, which may result in unintended mixing of these gases. In contrast, the delay time DT according to the present embodiment makes it possible to control the supply of either the mixed gas Gα or the mixed gas Gβ to start when the supply of the other mixed gas has finished and the evacuation of the second flow path 206 and the substrate processing space 10s has been completed.

[0073] From the viewpoint of throughput, it is preferable to make the delay time DT as short as possible without causing mixing of the mixed gases. In order to shorten the delay time DT, it is preferable to sufficiently increase the exhaust speed of the substrate processing space 10s. When performing such high-speed exhaust, it is preferable to improve the pressure uniformity within the substrate processing space 10s and the exhaust system 40. As a specific example of such an exhaust system 40, it is preferable to adopt a configuration including an upper baffle plate 41 and a lower baffle plate 42 shown in FIGS. 2 to 6.

[0074] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope of the appended claims, the configuration examples that fall within the technical scope of the present disclosure described below, and the spirit thereof. For example, the components of the above-described embodiments may be arbitrarily combined. Such an arbitrary combination naturally provides the functions and effects of each of the components involved in the combination, as well as other functions and effects that would be apparent to a person skilled in the art from the description of this specification.

[0075] Furthermore, the effects described herein are merely descriptive or exemplary and are not limiting. In other words, the technology according to the present disclosure may achieve other effects that are apparent to those skilled in the art from the description of this specification, in addition to or in place of the above-described effects.

[0076] The following configurations also fall within the technical scope of the present disclosure: (1) A substrate processing method in a substrate processing apparatus in which a gas is supplied from a gas supply unit to a substrate processing space to process a substrate, wherein the gas supply unit includes a plurality of gas sources, a flow path for distributing the gas from the plurality of gas sources to the substrate processing space, and a valve provided in the flow path for switching between opening and closing the flow of the gas, wherein pulse control is performed in the valve to pulse the flow of the gas by alternately opening and closing the flow of the gas, and wherein the pulse control controls a flow rate of the gas by controlling a duration of the pulse control and a number of times the flow of the gas is opened during the duration. (2) The substrate processing method according to (1), wherein the flow path includes a plurality of first flow paths corresponding to a plurality of the gas sources and a second flow path where the plurality of first flow paths join, and the valve is provided in each of the plurality of first flow paths, and the pulse control is performed on the valve provided on one of the first flow paths to supply the gas to the substrate processing space and close other valves provided on other of the first flow paths. (3) The substrate processing method according to (2), wherein two or more of the plurality of gas sources correspond to one of the first flow paths of the plurality of first flow paths, and the plurality of gases are supplied from each of the plurality of gas sources and mixed in the first flow path. (4) The substrate processing method according to (2) or (3), comprising: performing the pulse control on one of the valves; then closing the flow of gas through the valve; and performing the pulse control on another of the valves after a delay time of 10 ms to 1 s has elapsed. (5) The substrate processing apparatus is provided with a detection unit that detects plasma emission in the substrate processing space, and when the gas supplied to the substrate processing space by the pulse control is an etching gas, the pulse control is continued if the amount of plasma emission is less than a threshold value while the pulse control is continuing, and the pulse control is terminated if the amount of emission becomes equal to or greater than the threshold value.(6) The substrate processing method according to any one of (1) to (5), wherein the substrate processing apparatus includes a detection unit that detects a gas component in the substrate processing space, and continues the pulse control if the amount of the component of the gas supplied to the substrate processing space by the pulse control is equal to or greater than a threshold value while the pulse control is continuing, and terminates the pulse control if the amount of the component of the gas becomes less than the threshold value. (7) The substrate processing apparatus includes a buffer tank on each of the plurality of first flow paths, wherein a flow path cross-sectional area of ​​the buffer tank is three times or more the flow path cross-sectional area of ​​the first flow path in which the buffer tank is provided, and a length of the buffer tank in the flow path direction is equal to or greater than a diameter of the flow path cross-section of the buffer tank. (8) The substrate processing method according to any one of (1) to (7), wherein the substrate processing apparatus includes an upper electrode, and wherein the gas is supplied from the gas supply unit to the vicinity of the center of the upper electrode, and the gas is diffused and supplied to the substrate processing space in a diffusion chamber provided in the upper electrode. (9) A substrate processing apparatus comprising: a processing chamber having a substrate processing space formed therein; a gas supply unit that supplies gas to the substrate processing space; and a control unit, wherein the gas supply unit comprises a plurality of gas sources, a flow path that distributes gas from the plurality of gas sources to the substrate processing space, and a valve that is provided in the flow path and switches between opening and closing the flow of the gas; wherein the control unit is configured to perform pulse control, when supplying the gas from the gas supply unit to the substrate processing space to process the substrate, to pulse the flow of the gas by alternately opening and closing the flow of the gas at the valve; and to perform a step of controlling a flow rate of the gas by controlling a duration of the pulse control and a number of times the flow of the gas is opened during the duration in the pulse control.(10) The substrate processing apparatus according to (9), wherein the flow paths include a plurality of first flow paths provided corresponding to a plurality of the gas sources and a second flow path where the plurality of first flow paths join, the valves are provided in the plurality of first flow paths, and the control unit is further configured to execute the pulse control on the valves provided on one of the first flow paths to supply the gas to the substrate processing space and close other valves provided on other of the first flow paths. (11) The substrate processing apparatus according to (10), wherein two or more of the plurality of gas sources correspond to one of the first flow paths among the plurality of first flow paths, and the control unit is further configured to execute the steps of supplying the plurality of gases from each of the plurality of gas sources and mixing the gases in the first flow path. (12) The substrate processing apparatus according to (10) or (11), wherein the control unit is further configured to be capable of executing steps including: executing the pulse control on one of the valves; thereafter closing the flow of the gas through that valve; and executing the pulse control on another of the valves after a delay time of 10 ms to 1 s has elapsed. (13) The substrate processing apparatus according to any one of (9) to (12), further comprising a detection unit that detects plasma emission in the substrate processing space, wherein the control unit is further configured to be capable of executing steps of continuing the pulse control when an amount of plasma emission is less than a threshold during the continuation of the pulse control, and terminating the pulse control when the amount of plasma emission becomes equal to or greater than the threshold, when the gas supplied to the substrate processing space by the pulse control is an etching gas. (14) A substrate processing apparatus according to any one of (9) to (13) above, further comprising a detection unit that detects gas components within the substrate processing space, wherein the control unit is further configured to be capable of executing a process of continuing the pulse control if the amount of the gas component supplied to the substrate processing space by the pulse control is equal to or greater than a threshold value while the pulse control is continuing, and terminating the pulse control if the amount of the gas component becomes less than the threshold value.(15) The substrate processing apparatus according to (10) or (11), further comprising: a buffer tank on each of the plurality of first flow paths; a flow path cross-sectional area of ​​the buffer tank being three times or more the flow path cross-sectional area of ​​the first flow path in which the buffer tank is provided; and a length of the buffer tank in the flow path direction being equal to or greater than the diameter of the flow path cross-section of the buffer tank. (16) The substrate processing apparatus according to any one of (9) to (15), further comprising: an upper electrode; and the control unit being further configured to be capable of supplying the gas from the gas supply unit to the vicinity of the center of the upper electrode, and diffusing and introducing the gas into the substrate processing space in a diffusion chamber provided in the upper electrode.

[0077] 1 Substrate processing apparatus 10s Substrate processing space 20 Gas supply unit 220a, 220b Pulse valve W Substrate PL Pulse

Claims

1. A substrate processing method for processing a substrate by supplying a gas from a gas supply unit to a substrate processing space in a substrate processing apparatus, wherein the gas supply unit includes a plurality of gas sources, a flow path for flowing the gas from the plurality of gas sources to the substrate processing space, a valve provided in the flow path for switching between opening and closing the flow of the gas, and a buffer tank provided in the flow path, performing pulse control to pulse the flow of the gas by alternately repeating opening and closing of the flow of the gas in the valve, A substrate processing method for controlling the flow rate of the gas by controlling the duration of the pulse control and the number of times of opening the flow of the gas during the duration in the pulse control.

2. wherein the flow path includes a plurality of first flow paths provided corresponding to the plurality of gas sources, and a second flow path into which the plurality of first flow paths merge, the valve is provided in each of the plurality of first flow paths, The substrate processing method according to claim 1, wherein pulse control is performed on the valve provided in one of the first flow paths to supply the gas to the substrate processing space, and the other valves provided in the other first flow paths are closed.

3. Two or more of the plurality of gas sources correspond to one of the plurality of first flow paths, The substrate processing method according to claim 2, wherein a plurality of the gases are supplied from each of the plurality of gas sources and mixed in the first flow path.

4. performing the pulse control in one of the valves, then closing the flow of the gas in the valve, After a delay time of 10 ms to 1 s has elapsed, performing the pulse control in another one of the valves, the substrate processing method according to claim 2 or 3.

5. The substrate processing apparatus includes a detection unit that detects plasma emission in the substrate processing space. When the gas supplied to the substrate processing space by the pulse control is an etching gas, during the continuation of the pulse control, if the emission amount of the plasma emission is less than the threshold value, the pulse control is continued, and if the emission amount becomes equal to or greater than the threshold value, the pulse control is terminated. The substrate processing method according to any one of claims 1 to 3.

6. The substrate processing apparatus includes a detection unit that detects a gas component in the substrate processing space. During the continuation of the pulse control, if the abundance of the component of the gas supplied to the substrate processing space by the pulse control is equal to or greater than the threshold value, the pulse control is continued, and if the abundance of the component of the gas becomes less than the threshold value, the pulse control is terminated. The substrate processing method according to any one of claims 1 to 3.

7. The substrate processing apparatus includes the buffer tank on each flow path of the plurality of the first flow paths. The cross-sectional area of the flow path of the buffer tank is 3 times or more the cross-sectional area of the first flow path where the buffer tank is provided. The length of the buffer tank in the flow path direction is equal to or greater than the diameter of the cross-section of the flow path of the buffer tank. The substrate processing method according to claim 2 or 3.

8. The buffer tank has a volume of 5 times or more the target value of the supply amount of the gas in one pulse set. The substrate processing method according to claim 7.

9. The buffer tank has a volume of 10 times or more the target value of the supply amount of the gas in one pulse set. The substrate processing method according to claim 8.

10. The buffer tank is configured such that the volume of the buffer tank is variable, and the volume of the buffer tank is decreased so that the pressure of the buffer tank is constant during the continuation time of the pulse control. The substrate processing method according to claim 1.

11. The buffer tank is configured to be able to adjust the gas temperature in the buffer tank, and raises the gas temperature in the buffer tank so that the pressure in the buffer tank is constant during the duration of the pulse control. The substrate processing method according to claim 1.

12. The substrate processing apparatus includes an upper electrode, The gas is supplied from the gas supply unit near the center of the upper electrode, and the gas is diffused and introduced into the substrate processing space in a diffusion chamber provided in the upper electrode. The substrate processing method according to any one of claims 1 to 3.

13. A substrate processing apparatus, A processing chamber in which a substrate processing space is formed inside, A gas supply unit that supplies gas to the substrate processing space, A control unit, and is provided with, The gas supply unit includes a plurality of gas sources, a flow path for allowing gas to flow from the plurality of gas sources to the substrate processing space, a valve provided in the flow path for switching the opening or closing of the gas flow, and a buffer tank provided in the flow path. The control unit, When supplying the gas from the gas supply unit to the substrate processing space to process the substrate, pulse control is executed by alternately repeating the opening and closing of the gas flow in the valve to pulse the gas flow. In the pulse control, the substrate processing apparatus is configured to be able to execute a step of controlling the gas flow rate by controlling the duration of the pulse control and the number of times of opening the gas flow during the duration.

14. The flow path includes a plurality of first flow paths provided corresponding to the plurality of gas sources, and a second flow path into which the plurality of first flow paths merge. The valve is provided in each of the plurality of first flow paths, The control unit is further configured to be capable of executing the pulse control on the valve provided in one of the first flow paths to supply the gas to the substrate processing space and closing the other valves provided in the other first flow paths. The substrate processing apparatus according to claim 13.

15. Two or more of the plurality of gas sources correspond to one of the plurality of first flow paths. The control unit is further configured to be capable of executing a process of supplying a plurality of the gases from each of the plurality of gas sources and mixing them in the first flow path. The substrate processing apparatus according to claim 14.

16. The control unit is further configured to execute the pulse control on one of the valves, and then close the flow of the gas in the valve, and after a delay time of 10 ms to 1 s has elapsed, execute the pulse control on another one of the valves. The substrate processing apparatus according to claim 13 or 14, which is configured to be capable of executing a process including this.

17. The substrate processing apparatus includes a detection unit that detects plasma emission in the substrate processing space. When the gas supplied to the substrate processing space by the pulse control is an etching gas, the control unit is further configured to be capable of executing a process of continuing the pulse control when the emission amount of the plasma emission is less than a threshold value during the continuation of the pulse control and ending the pulse control when the emission amount becomes equal to or greater than the threshold value. The substrate processing apparatus according to any one of claims 13 to 15.

18. The substrate processing apparatus includes a detection unit that detects a gas component in the substrate processing space. The control unit is further configured to be capable of executing a step of continuing the pulse control while the pulse control is ongoing when the abundance of the component of the gas supplied to the substrate processing space by the pulse control is equal to or greater than a threshold value, and ending the pulse control when the abundance of the component of the gas becomes less than the threshold value. The substrate processing apparatus according to any one of claims 13 to 15.

19. On each flow path of the plurality of first flow paths, the buffer tank is provided. The flow path cross-sectional area of the buffer tank is three times or more the flow path cross-sectional area of the first flow path in which the buffer tank is provided. The length of the buffer tank in the flow path direction is equal to or greater than the diameter of the flow path cross-section of the buffer tank. The substrate processing apparatus according to claim 14 or 15.

20. The buffer tank has a volume that is five times or more the target value of the supply amount of the gas in one pulse set. The substrate processing apparatus according to claim 19.

21. The buffer tank has a volume that is ten times or more the target value of the supply amount of the gas in one pulse set. The substrate processing apparatus according to claim 20.

22. The buffer tank is configured such that the volume of the buffer tank is variable. The control unit is further configured to be capable of executing a step of reducing the volume of the buffer tank so that the pressure of the buffer tank is constant during the continuation time of the pulse control. The substrate processing apparatus according to claim 13.

23. The buffer tank is configured to be able to adjust the gas temperature inside the buffer tank. The control unit is further configured to be capable of executing a step of increasing the gas temperature inside the buffer tank so that the pressure of the buffer tank is constant during the continuation time of the pulse control. The substrate processing apparatus according to claim 13.

24. having an upper electrode, The substrate processing apparatus according to any one of claims 13 to 15, wherein the control unit is further configured to execute a step of supplying the gas from the gas supply unit to the vicinity of the center of the upper electrode and diffusing and introducing the gas into the substrate processing space in a diffusion chamber provided in the upper electrode.