Ignition control method and substrate processing apparatus

Abstract

The invention provides an ignition control method and a substrate processing apparatus for improving the precision of a preset value of a variable reactor. The ignition control method is performed in a substrate processing apparatus including: a pair of electrodes within a processing container; an impedance matching device having a variable reactor and an electronic circuit for controlling a current flowing through the variable reactor; an RF power supply connected to the pair of electrodes via an impedance matching device; the ignition control method includes measuring first information indicating inter-electrode voltages corresponding to each of a plurality of adjustment positions of the variable reactor when the temperature of the variable reactor is set to a first temperature and a high-frequency voltage is applied to the electrode from the RF power source, and measuring second information indicating inter-electrode voltages corresponding to each of a plurality of adjustment positions of the variable reactor when the high-frequency voltage is applied to the electrode from the RF power source. And a control unit that determines a preset value of the variable reactor on the basis of the measured first information, and, when the detected temperature of the variable reactor is set to a second temperature and the second temperature is different from the first temperature, controls the electronic circuit to correct the current flowing through the variable reactor so that the adjustment position of the variable reactor becomes the determined preset value.

Description

Technical Field

[0001] The invention relates to an ignition control method and a substrate processing device. Background Art

[0002] Immediately before applying the high-frequency voltage, the adjustment position of the variable capacitor or the variable reactor included in the impedance matching device is set to an appropriate position (preset value), thereby stably igniting the plasma.

[0003] For example, Patent Document 1 discloses an electronic matching device that can perform impedance matching at high speed without including any mechanical elements.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2017-118434 Summary of the invention

[0007] Technical problem to be solved by the invention

[0008] The present invention provides a technology capable of improving the accuracy of a preset value of a variable reactor.

[0009] Technical solutions for solving technical problems

[0010] According to a technical solution of the present invention, an ignition control method is performed in a substrate processing device, which includes: a processing container for accommodating substrates; a pair of electrodes formed in the processing container; an impedance matching device, which has a variable inductor and an electronic circuit for controlling the current flowing through the variable inductor; an RF power supply, which is connected to the pair of electrodes via the impedance matching device; and a temperature sensor, which detects the temperature of the variable inductor. The ignition control method includes: step (a), measuring first information, wherein the first information indicates the voltage between the electrodes corresponding to each of the plurality of adjustment positions of the variable reactor when a high-frequency voltage of a specified frequency is applied from the RF power supply to the pair of electrodes when the temperature of the variable reactor is set to a first temperature; step (b), determining a preset value of the variable reactor based on the measured first information; step (c), obtaining the temperature of the variable reactor detected by the temperature sensor as a second temperature; and step (d), when the first temperature and the second temperature are different, correcting the current flowing through the variable reactor by controlling the electronic circuit so that the adjustment position of the variable reactor becomes the determined preset value at the second temperature.

[0011] Effects of the Invention

[0012] According to one aspect, the accuracy of the preset value of the variable reactor can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a diagram showing a configuration example of a substrate processing apparatus according to one embodiment.

[0014] Figure 2 It is a diagram showing a configuration example of an impedance matching device and a plasma box according to one embodiment.

[0015] Figure 3 It is a diagram showing an overview of the operation of a variable reactor.

[0016] Figure 4 It is a diagram for explaining the temperature change of the variable reactor and the technical problems at the time of plasma ignition.

[0017] Figure 5 This is an explanatory diagram of a gas supply source, a control unit, and a controller of a substrate processing apparatus according to an embodiment.

[0018] Figure 6 is a flow chart of an ignition control method according to an embodiment.

[0019] Figure 7 This is an example of the voltage between electrodes at various adjustment positions of the variable reactor.

[0020] Figure 8 Yes means Figure 6 A flowchart of an example of correction processing.

[0021] Fig. 9 This is an example of a control current table of a variable reactor according to an embodiment.

[0022] Fig.10 Yes means Figure 6 A flowchart of an example of a film forming process.

[0023] Fig.11 Yes means Fig.10 A timing diagram of an example of a film forming process.

[0024] Description of Reference Numerals

[0025] 10 Film forming device

[0026] 11. Processing Container

[0027] 19 Plasma Box

[0028] 53 Impedance matching device

[0029] 55 RF Power Supply

[0030] 58 First variable reactor

[0031] 59 Second variable reactor

[0032] 80 Controller

[0033] 90 Constant temperature bath

[0034] 91, 92 Electrode

[0035] 100 Control Department. DETAILED DESCRIPTION

[0036] Hereinafter, the mode for implementing the present invention will be described with reference to the accompanying drawings. In each of the drawings, the same components are denoted by the same reference numerals, and duplicate descriptions may be omitted.

[0037] [first]

[0038] Film formation using plasma requires high film quality and film formation speed. In addition, from plasma processing using a single gas to plasma processing using multiple gases, multiple gases are used in the generation of plasma.

[0039] It can be seen from the Paschen's Curve that the minimum ignition voltage of various gases is different depending on the different gases used. Therefore, due to the use of different gases, the minimum ignition voltage required for plasma ignition is different. Therefore, stable plasma ignition without reflected waves is required for various gases. In addition, in order to improve the film quality after film formation, it is also necessary to deal with the temperature changes caused by plasma, the influence of reaction products generated by film formation, and the influence of regular cleaning in the processing container for removing reaction products.

[0040] In order to control them at high speed, a variable reactor is provided in the impedance matching device, and the impedance is matched by using the impedance matching device using the variable reactor. When plasma is ignited, it is necessary to set the adjustment position of the variable reactor to an appropriate position (called a preset value) in the impedance matching device to match the impedance, but the temperature of the variable reactor changes due to the ambient temperature and the operation of the device, and the appropriate preset value changes. Therefore, in this embodiment, an ignition control method and a substrate processing device are provided, which can improve the accuracy of the preset value of the variable reactor according to the temperature of the variable reactor and perform stable plasma ignition.

[0041] Below, refer to Figure 1 , a substrate processing device that executes the ignition control method of this embodiment is described, and then the ignition control method of this embodiment is described.

[0042] [Substrate processing device]

[0043] Figure 11 is a diagram showing a substrate processing apparatus 10 according to an embodiment. The substrate processing apparatus 10 is an ALD (Atomic Layer Deposition) apparatus that accommodates a plurality of wafers 2 in a processing container 11 and forms a predetermined film such as a nitride film on the plurality of wafers 2. The substrate processing apparatus 10 is a batch-type vertical heat treatment apparatus that processes a plurality of wafers. The substrate processing apparatus 10 is an example of an apparatus that executes an ignition control method according to an embodiment described later.

[0044] In the substrate processing apparatus 10 of the present embodiment, for example, a silicon nitride film (SiN) is formed, but the type of film to be formed is not limited thereto. The silicon nitride film is formed on the wafer 2 by alternately supplying a source gas (e.g., dichlorosilane gas) and a plasma of a nitride gas (e.g., ammonia (NH3) gas) to the wafer. In this film forming method, there is a tendency that the film thickness of the nitride film formed in the surface of the wafer 2 becomes thicker at the edge of the wafer 2. In order to suppress this, the film thickness at the edge of the wafer 2 is suppressed by supplying a plasma of a nitrogen (N2) gas before the step of supplying a plasma of ammonia gas.

[0045] The substrate processing device 10 includes: a processing container 11 that accommodates a wafer 2 and forms a space for processing the wafer 2; a cover 20 that hermetically closes the opening at the lower end of the processing container 11; and a substrate holder 30 that holds the wafer 2. The wafer 2 is, for example, a semiconductor substrate, and more specifically, a silicon wafer. The substrate holder 30 is also called a wafer boat.

[0046] The processing container 11 has a processing container body 12 in a cylindrical shape with a top and an open lower end. The processing container body 12 is formed of, for example, quartz. A flange portion 13 is formed at the lower end of the processing container body 12. In addition, the processing container 11 has, for example, a cylindrical manifold 14. The manifold 14 is formed of, for example, stainless steel. A flange portion 15 is formed at the upper end of the manifold 14, and the flange portion 13 of the processing container body 12 is provided on the flange portion 15. A sealing component 16 such as an O-ring is arranged between the flange portion 15 and the flange portion 13.

[0047] The cover 20 is airtightly mounted to the opening at the lower end of the manifold 14 via a sealing member 21 such as an O-ring. The cover 20 is formed of, for example, stainless steel. A through hole is formed in the central portion of the cover 20, which passes through the cover 20 in the vertical direction. A rotating shaft 24 is arranged in the through hole. The gap between the cover 20 and the rotating shaft 24 is sealed by a magnetic fluid sealing portion 23. The lower end of the rotating shaft 24 is rotatably supported by an arm 26 of a lifting portion 25. A rotating plate 27 is provided at the upper end of the rotating shaft 24. A substrate holder 30 is provided on the rotating plate 27 via a heat-retaining table 28.

[0048] The substrate holder 30 holds a plurality of wafers 2 at intervals in the vertical direction. The plurality of wafers 2 are held horizontally, respectively. The substrate holder 30 is formed of, for example, quartz (SiO2) or silicon carbide (SiC). When the lifting portion 25 is raised, the cover 20 and the substrate holder 30 are raised, and the substrate holder 30 is sent into the processing container 11, and the opening at the lower end of the processing container 11 is sealed by the cover 20. In addition, when the lifting portion 25 is lowered, the cover 20 and the substrate holder 30 are lowered, and the substrate holder 30 is sent out of the processing container 11. In addition, when the rotating shaft 24 is rotated, the substrate holder 30 rotates together with the rotating plate 27.

[0049] The substrate processing device 10 has three gas supply pipes 40A, 40B, and 40C. The gas supply pipes 40A, 40B, and 40C are formed of, for example, quartz (SiO2). The gas supply pipes 40A, 40B, and 40C supply gas to the interior of the processing container 11. The types of gas will be described later. In addition, one gas supply pipe may release one or more gases in sequence. In addition, multiple gas supply pipes may release the same type of gas.

[0050] The gas supply pipes 40A, 40B, and 40C include horizontal pipes 43A, 43B, and 43C that horizontally penetrate the manifold 14, and vertical pipes 41A, 41B, and 41C that are vertically arranged inside the processing container 11. The vertical pipes 41A, 41B, and 41C include a plurality of gas supply ports 42A, 42B, and 42C that are spaced apart in the vertical direction. The gas supplied to the horizontal pipes 43A, 43B, and 43C is transported to the vertical pipes 41A, 41B, and 41C, and is horizontally released from the plurality of gas supply ports 42A, 42B, and 42C. The vertical pipe 41C is arranged in the plasma box 19. The vertical pipes 41A and 41B are arranged in the processing container 11.

[0051] The substrate processing device 10 has an exhaust pipe 45. The exhaust pipe 45 is connected to an exhaust device not shown in the figure. The exhaust device includes a vacuum pump to exhaust the interior of the processing container 11. An exhaust port 18 is formed in the processing container body 12. The exhaust port 18 is arranged in a manner opposite to the gas supply ports 42A, 42B, and 42C. The gas released horizontally from the gas supply ports 42A, 42B, and 42C passes through the exhaust port 18 and is discharged from the exhaust pipe 45. The exhaust device sucks the gas inside the processing container 11 and sends it to the detoxification device. The detoxification device releases the exhaust gas into the atmosphere after removing the harmful components of the exhaust gas.

[0052] The substrate processing apparatus 10 further includes a heating unit 60. The heating unit 60 is disposed outside the processing container 11 and heats the inside of the processing container 11 from the outside of the processing container 11. For example, the heating unit 60 is formed in a cylindrical shape so as to surround the processing container body 12. The heating unit 60 is composed of, for example, an electric heater. The heating unit 60 heats the inside of the processing container 11 to improve the processing capacity of the gas supplied into the processing container 11.

[0053] [Plasma box]

[0054] Figure 2 1 is a diagram showing a configuration example of an impedance matching device 53 and a plasma box 19 according to an embodiment. Figure 1 and Figure 2 As shown, an opening 17 is formed in a part of the circumference of the processing container body 12. A plasma box 19 is formed on the side of the processing container 11 so as to surround the opening 17. The plasma box 19 is formed to protrude radially outward from the processing container body 12, for example, to be formed in a substantially U shape when viewed in the vertical direction.

[0055] A pair of electrodes (electrode pair) 91, 92 facing each other are arranged so as to sandwich the plasma box 19. The electrodes 91, 92 are a pair of parallel electrodes (parallel electrodes) disposed face to face with the outside of the plasma box 19. The electrodes 91, 92 face each other and are formed to be elongated in the vertical direction similarly to the vertical tube 41C. The RF power supply 55 is connected to the electrodes 91, 92 via the impedance matching device 53, and applies a high-frequency voltage of a predetermined frequency to the electrodes 91, 92.

[0056] The impedance matching device 53 is connected in series between the RF power supply 55 and the electrodes 91 and 92 via the voltage supply lines 51, 52 and 54. The impedance matching device 53 includes a first variable reactor 58, a second variable reactor 59, electronic circuits 75a and 75b, capacitors 56 (C1) and 57 (C2), a coil (L1) and a coil (L2). The electronic circuit 75a changes the inductance of the first variable reactor 58 by controlling the current flowing through the first variable reactor 58. The electronic circuit 75b changes the inductance of the second variable reactor 59 by controlling the current flowing through the second variable reactor 59.

[0057] When high-frequency electric power is supplied from the RF power source 55 to the load side (the plasma box 19 side), the impedance matching device 53 matches the impedance between the RF power source 55 and the load, thereby improving the supply efficiency of the high-frequency electric power.

[0058] The stability of plasma ignition is improved by responding quickly from plasma excitation to stabilization and ending in a short time. In addition, the stability of plasma ignition is achieved by stabilizing the high-frequency electric power used for plasma to suppress plasma fluctuations. Therefore, it is necessary to perform impedance matching at high speed to suppress reflected waves.

[0059] In the ignition control method of the present embodiment, the current flowing through the first variable reactor 58 and the second variable reactor 59 in the impedance matching device 53 is controlled by the electronic circuit 75a, 75b, so that the inductance of each variable reactor changes, and impedance matching is performed. The speed of change of the inductance of the first variable reactor 58 and the second variable reactor 59 depends on the operation speed of the electronic circuit 75a, 75b, and the time until the impedance matching is achieved is in the μs (microsecond) order. Therefore, by using the impedance matching device 53 having the first variable reactor 58 and the second variable reactor 59, impedance matching can be performed at a high speed in a short time (for example, within 1 second) just before the plasma is ignited.

[0060] The impedance matching device 53 includes a first Vpp sensor 70 for detecting a voltage between electrodes 91 and 92, a second Vpp sensor 71 for detecting a voltage between electrode 91 and the ground, and a third Vpp sensor 72 for detecting a voltage between electrode 92 and the ground. In addition, the impedance matching device 53 has a temperature sensor (TC) 73a for detecting a temperature of the first variable reactor 58 and a temperature sensor (TC) 73b for detecting a temperature of the second variable reactor 58.

[0061] Furthermore, the impedance matching device 53 includes a controller 80. The controller 80 obtains the detection values ​​of the first Vpp sensor 70, the second Vpp sensor 71, and the third Vpp sensor 72, and the detection values ​​of the temperature sensors 73a and 73b. The controller 80 obtains the inter-electrode voltage from the first Vpp sensor 70 and the temperature of the first variable reactor 58 from the temperature sensor 73a, and controls the current flowing through the electronic circuit 75a based on these information. Thus, the inductance of the first variable reactor 58 is changed. In addition, the controller 80 obtains the inter-electrode voltage from the first Vpp sensor 70 and the temperature of the second variable reactor 59 from the temperature sensor 73b, and controls the current flowing through the electronic circuit 75b based on these information. Thus, the inductance of the second variable reactor 59 is changed. In the above manner, the controller 80 can control the impedance matching at a high speed without going through the control unit 100.

[0062] However, the controller 80 may control the impedance matching in cooperation with the control unit 100 that controls the entire substrate processing apparatus 10. The controller 80 and the control unit 100 are constituted by, for example, a computer.

[0063] [Overview of variable reactor operation]

[0064] Reference Figure 3 , the operation outline of the first variable reactor 58 and the second variable reactor 59 in the impedance matching device 53 will be described. The second variable reactor 59 has the same structure as the first variable reactor 58, so the first variable reactor 58 will be described here.

[0065] The first variable reactor 58 has a structure in which a control winding A between T3 and T4 and an AC winding B between T1 and T2 are wound around an annular magnetic core 74. An electronic circuit 75a (see Figure 2 ). The direct current I flowing through the control winding A is variably controlled by the electronic circuit 75a. As a result, the inductance changes.

[0066] In the first variable reactor 58, when the temperature of the magnetic core 74 rises due to the ambient temperature, the magnetic permeability μ rises and the inductance rises. When the temperature of the magnetic core 74 drops, the magnetic permeability μ drops and the inductance drops. Therefore, when the temperature of the first variable reactor 58 changes, when the same current flows through the control winding A before and after the temperature change, the preset value deviates, and the reflected wave changes when the plasma is ignited, which affects the film formation depending on the process. In particular, it is known from experiments that the variable capacitor is not easily affected by the temperature change, while the variable reactor is easily affected by the temperature change and the preset value is easily changed.

[0067] The magnetic permeability μ[H / m] is a parameter that numerically indicates how easily the magnetic core 74 can be magnetized. The relationship between the magnetic field intensity H and the magnetic flux density B is represented by B=μH. Figure 3 The cross-sectional area S [m 2 ], the number of turns N of the control winding A and the AC winding B, and the length l[m] passing through the center of the magnetic core 74 are expressed by equation (1). Therefore, when the magnetic permeability μ increases, the inductance L increases.

[0068] L=μSN 2 / l[H]……(1)

[0069] Immediately before applying a high frequency voltage from the RF power supply 55 to the electrodes 91 and 92, the adjustment positions of the first variable reactor 58 and the second variable reactor 59 of the impedance matching device 53 are set to preset values. In this way, the reflected wave is controlled and the plasma is stably ignited.

[0070] However, as described above, the accuracy of the preset value may deteriorate due to the change in inductance caused by the change in temperature of the first variable reactor 58 and the second variable reactor 59. Figure 4 , further illustrating the temperature change of the variable inductor and the technical problems during plasma ignition. Figure 4 It is a diagram for explaining the temperature change of the variable reactor and the technical problems at the time of plasma ignition.

[0071] Figure 4 The horizontal axis of the graph (a) represents the temperature of the variable reactor, and the vertical axis represents the magnetic permeability μ. Therefore, when the temperature of the variable reactor rises, the magnetic permeability μ rises. According to formula (1), when the magnetic permeability μ rises, the inductance increases, so when the temperature of the variable reactor rises, the inductance of the variable reactor increases. However, when the temperature of the variable reactor becomes Figure 4 (a) Curie temperature T k When the temperature is around or above , the proportional relationship of the increase in magnetic permeability μ with the increase in temperature is destroyed. Therefore, the temperature of the first variable reactor 58 and the second variable reactor 59 is preferably controlled to be 100° C. or less.

[0072] In this embodiment, the current flowing through the control winding A (see Figure 3 ) of the direct current I. Thus, the magnetic permeability μ in the magnetic core 74 is made variable, and the inductance of each of the first variable reactor 58 and the second variable reactor 59 is changed. As a result, it is possible to prevent the preset value from changing due to the temperature change of the variable reactor.

[0073] In order to control the temperature of the first variable reactor 58 and the second variable reactor 59 to be 100° C. or less, the impedance matching device 53 includes a temperature adjustment unit for adjusting the temperature of the first variable reactor 58 and the second variable reactor 59. Figure 2 In the embodiment, as an example of a temperature adjustment unit, a thermostatic tank 76 is provided which surrounds the first variable reactor 58 and the second variable reactor 59 and can adjust the temperature of each variable reactor. The thermostatic tank 76 controls the temperature of the first variable reactor 58 and the second variable reactor 59 to a temperature of at least 100° C. or less. However, the thermostatic tank 76 also causes a certain degree of variation in the temperature of the first variable reactor 58 and the second variable reactor 59. In addition, the thermostatic tank 76 may surround the entire impedance matching device 53.

[0074] As another example of the temperature control unit, a fan may be installed near the first variable reactor 58 and the second variable reactor 59. Also, as another example of the temperature control unit, a piping structure for flowing a temperature control medium may be formed near the first variable reactor 58 and the second variable reactor 59, and the temperature of the first variable reactor 58 and the second variable reactor 59 may be controlled by controlling the temperature of the temperature control medium.

[0075] Figure 4The horizontal axis of the graph (b) represents the intensity H of the magnetic field, and the vertical axis represents the magnetic flux density B. As described above, the magnetic permeability μ is represented by B=μH. Figure 4 (b) shows the case where the temperature of the variable reactor is 25°C, 50°C, and 100°C. The higher the temperature of the variable reactor, the lower the saturation magnetic flux density Bs. Therefore, in order to minimize the saturation magnetic flux density Bs, it is preferable to control the temperature of the variable reactor to a temperature lower than 100°C.

[0076] Figure 4 The horizontal axis of the graph (c) represents the temperature of the variable reactor, and the vertical axis represents the rate of change of the inductance. When the temperature of the variable reactor rises, the rate of change of the inductance increases even if the same current flows through the variable reactor. Therefore, when the temperature of the variable reactor rises, the deviation of the preset value becomes larger. Therefore, it is preferable to reduce the temperature of the variable reactor to reduce the rate of change of the inductance.

[0077] Figure 4 The horizontal axis of the graph (d) represents the current flowing through the control winding A (refer to Figure 3 ) of DC current, and the vertical axis represents inductance. Figure 4 (d) shows the case where the temperature of the variable reactor is 25°C, 50°C, and 100°C. The higher the temperature of the variable reactor, the smaller the range (amplitude) of the current value in which the inductance is a certain value relative to the DC current flowing through the control winding A, the greater the ratio of the inductance change relative to the DC current flowing through the control winding A, and the greater the deviation from the preset value.

[0078] As shown above, the inductance changes due to the temperature change of the variable reactor caused by the surrounding environment and the operating conditions of the device, and the greater the temperature rise of the variable reactor, the greater the rate of change of the inductance. As a result, the preset value changes before the high-frequency electric power is input from the RF power supply 55, and the reflected wave changes when the plasma is ignited just after the high-frequency electric power is input. As a result, the film forming state is adversely affected. Therefore, in the ignition control method of this embodiment, the inductance is changed by controlling the current flowing through the control winding A according to the temperature change of the variable reactor, thereby improving the accuracy of the preset value of the variable reactor. According to the above content, since a high-precision preset value can be set, the reflected wave and the inter-electrode voltage during plasma ignition can be stably controlled, and a substrate processing device 10 capable of stable film forming control can be provided.

[0079] Next, refer to Figure 5 , the gas supply source, the control unit 100, and the controller 80 are described. Figure 5 It is a diagram for explaining a gas supply source, a control unit 100, and a controller 80 of a substrate processing apparatus 10 according to an embodiment.

[0080] In the substrate processing apparatus 10, the gas supply unit includes a raw gas supply source 90, a reforming gas supply source 93, and a nitriding gas supply source 96. The raw gas supply source 90 supplies raw gas into the processing container 11. The raw gas contains an element to be nitrided (eg, silicon).

[0081] As the raw material gas, for example, dichlorosilane (DCS: SiH2Cl2) gas is used. It should be noted that the raw material gas in this embodiment is DCS gas, but the technology of the present invention is not limited to this.

[0082] The raw material gas piping 91 connects the raw material gas supply source 90 to the gas supply pipes 40A and 40B, and supplies the raw material gas from the raw material gas supply source 90 to the gas supply pipes 40A and 40B. The raw material gas is released horizontally from the gas supply ports 42A and 42B of the vertical pipes 41A and 41B toward the wafer 2. The raw material gas flow control valve 92 is provided in the middle of the raw material gas piping 91 to control the flow rate of the raw material gas.

[0083] The reforming gas supply source 93 reforms the Si-containing layer by supplying reforming gas into the processing container 11. The reforming of the Si-containing layer includes, for example, removing halogen contained in the Si-containing layer. The reforming gas may be nitrogen, hydrogen, ammonia, or a gas containing any of these gases.

[0084] The modified gas pipe 94 connects the modified gas supply source 93 and the gas supply pipe 40C, and supplies the modified gas from the modified gas supply source 93 to the gas supply pipe 40C. The modified gas is released horizontally from the gas supply port 42C of the vertical pipe 41C toward the wafer 2. The modified gas flow control valve 95 is provided in the middle of the modified gas pipe 94 to control the flow rate of the modified gas.

[0085] The nitriding gas supply source 96 nitrides the Si-containing layer by supplying a nitriding gas into the processing container 11. As the nitriding gas, for example, ammonia (NH3) gas, organic hydrazine compound gas, amine gas, NO gas, N2O gas or NO2 gas is used.

[0086] The nitriding gas pipe 97 connects the nitriding gas supply source 96 to the gas supply pipe 40C, and supplies the nitriding gas from the nitriding gas supply source 96 to the gas supply pipe 40C. The nitriding gas is released horizontally from the gas supply port 42C of the vertical pipe 41C toward the wafer 2. The nitriding gas flow control valve 98 is provided in the middle of the nitriding gas pipe 97 to control the flow rate of the nitriding gas.

[0087] Furthermore, a purge gas supply source (not shown) may be provided. By supplying a purge gas into the processing container 11, the raw material gas, the reforming gas, and the nitriding gas remaining in the processing container 11 are removed. As the purge gas, for example, an inert gas is used. As the inert gas, a rare gas such as Ar gas or N2 gas is used.

[0088] like Figure 5 As shown, the substrate processing apparatus 10 has a control unit 100 for controlling the substrate processing apparatus 10. The control unit 100 includes a CPU (Central Processing Unit) 101, a memory 102, an input interface 103, and an output interface 104. The memory 102 stores a program for controlling various processes performed in the substrate processing apparatus 10. The control unit 100 controls the operation of the entire substrate processing apparatus 10 by causing the CPU 101 to execute the program stored in the memory 102. The control unit 100 receives a signal from the outside through the input interface 103 and sends a signal to the outside through the output interface 104.

[0089] The program may be stored in a computer-readable medium and installed from the medium into the memory 102 of the control unit 100. Examples of the computer-readable medium include a hard disk (HD), a floppy disk (FD), a compact disk (CD), a magneto-optical disk (MO), a memory card, etc. In addition, the program may be downloaded from a server via the Internet and installed into the memory 102 of the control unit 100.

[0090] The controller 80 includes a processor 81 and a memory 82. The memory 82 stores an ignition control program, an inter-electrode voltage table 83 (see Figure 7 ) and control current meter 84 (refer to Fig. 9 The controller 80 uses various tables stored in the memory 102 to cause the processor 81 to execute an ignition control program, thereby controlling the operation of the impedance matching device 53 including current control of the electronic circuits 75a and 75b.

[0091] The ignition control program may be stored in a medium readable by the processor 81 and installed from the medium into the memory 82 of the controller 80 .

[0092] [Ignition control method]

[0093] The ignition control method of this embodiment controls the current flowing to each variable reactor based on the temperature change of the first variable reactor 58 and the second variable reactor 59, sets a high-precision preset value, and thus performs stable plasma ignition. As a result, the controllability of the film thickness and film quality of the wafer 2 can be improved, and a high-quality film can be formed.

[0094] Reference Figure 6 and Figure 7 , the ignition control method of this embodiment is described. Figure 6 is a flowchart showing an ignition control method according to an embodiment. Figure 7 The ignition control method of the embodiment is controlled by the controller 80 or the control unit 100. In this example, when the RF power source 55 is turned on, a high-frequency voltage of a predetermined frequency (for example, 13.56 MHz) is applied. Figure 7 This is an example of a table of inter-electrode voltages at adjustment positions VL1 and VL2 of the inductance of each variable reactor when, for example, an RF of 13.56 MHz is applied.

[0095] exist Figure 6 When the power of the substrate processing apparatus 10 is turned on, the idle mode is executed in step S1. In the idle mode, the high frequency voltage from the RF power supply 55 is turned off. In this state, the control unit 100 supplies nitrogen gas from the plurality of gas supply ports 42A, 42B, and 42C of the vertical pipes 41A, 41B, and 41C.

[0096] In step S2, the control unit 100 carries the wafer 2 placed on the substrate holder 30 into the processing container 11 to prepare for film forming. First, outside the processing container 11, the conveying device carries a plurality of wafers 2 on the substrate holder 30. The substrate holder 30 holds the plurality of wafers 2 horizontally at intervals in the vertical direction. Next, the lifting unit 25 is raised to raise the cover 20 and the substrate holder 30. The wafer 2 is carried into the processing container 11 together with the substrate holder 30, and the opening at the lower end of the processing container 11 is sealed by the cover 20.

[0097] In step S3, the control unit 100 sets the processing type of the processing to be performed on the wafer 2. The processing type is identification information for determining the processing conditions of the substrate to be applied according to the frequency of the high frequency output from the RF power source 55, the type of gas supplied into the processing container 11, and the temperature and pressure in the processing container 11.

[0098] In step S4, the control unit 100 sets the temperature of the first variable reactor 58 and the second variable reactor 59 to a first temperature (e.g., 25° C.). The RF power source 55 supplies a high-frequency electric power of a low electric power level (e.g., 100 W) with a frequency of, for example, 13.56 MHz, which does not generate plasma discharge (ignition), and the control unit 100 obtains first information indicating the inter-electrode voltage corresponding to each of the plurality of adjustment positions of the first variable reactor 58 and the second variable reactor 59 at this time. The first Vpp sensor 70 measures (detects) the inter-electrode voltage corresponding to each of the plurality of adjustment positions of the first variable reactor 58 and the second variable reactor 59, and sends it to the controller 80. Thus, the measurement is performed to indicate the voltage between the electrodes at each 5%. Figure 7The scanning pattern of the inter-electrode voltage at each adjustment position of the matrix shown in FIG. 8 is a scanning pattern of the inter-electrode voltage at each adjustment position VL1 and VL2 in the range of 0 to 100%. That is, the controller 80 scans the range of 0 to 100% of each adjustment position VL1 and VL2 at every 5%, for example, to generate Figure 7 The table of the first information as shown is the inter-electrode voltage table 83. After the measurement, the output of low electric power from the RF power source 55 is stopped. The inter-electrode voltage table 83 is an example of the first information.

[0099] In step S5, the controller 80 determines the adjustment positions VL1 and VL2 for obtaining the inter-electrode voltage that is higher than the discharge voltage based on Paschen's law but not too high as preset values ​​based on the inter-electrode voltage table 83. Figure 7 The position where VL1 is 25% and VL2 is 35% is determined as the preset value P.

[0100] In step S6, the controller 80 acquires the temperatures of the first variable reactor 58 and the second variable reactor 59 detected by the temperature sensors 73a and 73b. The acquired temperature is described as the second temperature. The controller 80 determines whether at least one of the second temperature of the first variable reactor 58 and the second temperature of the second variable reactor 59 has changed from the first temperature. The first temperature is the temperature of the first variable reactor 58 and the second variable reactor 59 when the inter-electrode voltage table 83 is prepared.

[0101] In step S6 , when at least one of the second temperature of the first variable reactor 58 and the second temperature of the second variable reactor 59 has changed from the first temperature, the process proceeds to step S7 , and the controller 80 performs correction processing.

[0102] For example, relative to Figure 7 The inductance of each variable reactor changes due to the temperature change of the first variable reactor 58 and the second variable reactor 59, so the appropriate preset value deviates from the current preset value by about several percent. Therefore, due to the temperature change of the variable reactor, the set preset value P may not be an appropriate value. For example, Figure 7 The preset value P of the electrode is shifted by one unit to the position Q where VL1 is 30% and VL2 is 40% by 5%, and the inter-electrode voltage increases by about 2 times from 649V to 1111V. That is, although the inter-electrode voltage should be 629V for plasma ignition, it is ignited at 1111V. As a result, the film thickness and film quality of the wafer 2 are reduced.

[0103] Therefore, in the correction process of step S7, the controller 80 controls the electronic circuits 75a and 75b to change the current flowing in the first variable reactor 58 and the second variable reactor 59 according to the second temperature detected by the temperature sensors 73a and 73b. As a result, the inductance is changed, and a high-precision preset value can be set. In this way, even if the temperature of the variable reactor changes, a high-frequency voltage represented by the determined preset value is applied to the electrodes 91 and 92. As a result, the reflected wave and the inter-electrode voltage can be stably controlled, and stable plasma ignition can be performed. For details of the correction process, please refer to Figure 8 and Fig. 9 Explained later.

[0104] In step S8, the control unit 100 determines whether high-frequency electric power capable of igniting plasma is supplied from the RF power supply 55. For example, when the high-frequency electric power set in the treatment recipe is supplied, the control unit 100 determines that high-frequency electric power capable of igniting plasma is supplied from the RF power supply 55, and proceeds to step S9.

[0105] In step S9, the control unit 100 performs a film forming process of the set process type on the wafer 2. For the film forming process, refer to Fig.10 and Fig.11 Explained later.

[0106] In step S10, the control unit 100 determines whether the RF power source 55 is turned off. When the control unit 100 determines that the RF power source 55 is turned off, the process proceeds to step S11 to determine whether the process is finished.

[0107] In step S11, if the control unit 100 determines that the process is not completed, the control unit 100 returns to step S3 to execute the subsequent processes. In step S11, if the control unit 100 determines that the process is completed, the control unit 100 proceeds to step S12 to deliver the substrate.

[0108] After that, the process returns to step S1 and waits until the next wafer 2 is fed in (idle mode). After the next wafer 2 is fed in, the process is performed on the next wafer 2 in the same manner.

[0109] [Correction Processing]

[0110] Reference Figure 8 and Fig. 9 , describing a correction process according to one embodiment. Figure 8 It means in Figure 6 Flowchart of an example of the correction processing performed in step S7 of FIG. Fig. 9 This is an example of a control current table of a variable reactor according to an embodiment. Figure 8 The correction process is controlled by the controller 80.

[0111] In step S21 , the controller 80 determines whether the second temperature of the first varactor 58 (the temperature of the first varactor 58 detected by the temperature sensor 93 a immediately before the RF power source 55 is turned on) has changed from the first temperature.

[0112] In step S21, if the controller 80 determines that the second temperature is the same as the first temperature, the process proceeds to step S23. In step S21, if the controller 80 determines that the second temperature is different from the first temperature, the process proceeds to step S22, and determines the control current corresponding to the second temperature by referring to the control current table 84, and changes the control current of the first variable reactor 58 using the electronic circuit 75a.

[0113] In the control current table 84 , control currents of the electronic circuits 75 a and 75 b are set according to the temperatures of the respective varactors, with respect to VL1 (%) of the first varactor 58 and VL2 (%) of the second varactor 59 .

[0114] For example, in Figure 7 In the preset value P of , VL1 is 25%. When the second temperature is 50°C, the first temperature is 25°C, so the controller 80 refers to Fig. 9 The control current table 84 shown in (a) changes the current flowing through the first variable reactor 58 from 5.0 [A] to 3.8 [A].

[0115] In step S23 , the controller 80 determines whether the second temperature of the second varactor 59 (the temperature of the second varactor 59 detected by the temperature sensor 93 b immediately before the RF power source 55 is turned on) has changed from the first temperature.

[0116] In step S23, if the controller 80 determines that the second temperature is the same as the first temperature, the process ends. In step S23, if the controller 80 determines that the second temperature is different from the first temperature, the process proceeds to step S24, referring to Fig. 9 The control current table 84 shown in (b) determines the control current corresponding to the second temperature, and the control current of the second variable reactor 59 is changed using the electronic circuit 75b, and this process ends.

[0117] For example, in Figure 7 In the preset value P, VL2 is 30%. The controller 80 refers to Fig. 9 The control ammeter 84 shown in (v) changes the current flowing through the second variable reactor 59.

[0118] [Film forming treatment]

[0119] Reference Fig.10 and Fig.11 , a film forming process according to one embodiment is described. Fig.10 It means in Figure 6 Flowchart of an example of the film forming process performed in step S9. Fig.11 Yes means Fig.10 A timing diagram of an example of a film forming process. Fig.10 The film forming process is mainly controlled by the control unit 100, and the correction process before plasma ignition is controlled by the controller 80. Fig.10 In the process, a silicon nitride film (SiN) is formed by the ALD method.

[0120] In step S31, the control unit 100 forms a Si-containing layer on the wafer 2 held by the substrate holder 30. Step S31 Fig.11 The process is performed from time t1 to time t2. In step S31, while exhausting the interior of the processing container 11 by using an exhaust device connected to the exhaust pipe 45, a raw material gas is supplied from the raw material gas supply source 90 to the interior of the processing container 11. The raw material gas is, for example, DCS gas. Thus, a Si-containing layer is formed on the wafer 2. The time of step S31 is, for example, not less than 1 second and not more than 10 seconds.

[0121] In step S32, the control unit 100 performs a purge process. Fig.11 The process proceeds from time t2 to time t3 as shown. In step S22, while exhausting the interior of the processing container 11 by using the exhaust device, the supply of the raw material gas is stopped, and a purge gas is supplied to the interior of the processing container 11. Thus, the gas remaining in the interior of the processing container 11 is replaced by the purge gas. The purge gas can be nitrogen, argon, other inert gases, or a combination thereof. The time of step S32 is, for example, more than 3 seconds and less than 10 seconds. The purge gas can be supplied from a nitriding gas supply source 80, etc. In addition, as Fig.11 As shown, the purge gas can also be supplied continuously in all steps.

[0122] In steps S33 to S35, the controller 80 and Figure 6 The preset value is determined in the same manner as steps S5 to S7 (step S33: the same processing as step S5), it is determined whether there is a temperature change in each variable reactor (step S34: the same processing as step S6), and correction processing is performed when there is a temperature change (step S35: the same processing as step S7).

[0123] In step S36, the control unit 100 performs modification of the Si-containing layer. Fig.11The process proceeds from time t3 to time t4. In step S36, while exhausting the interior of the processing container 11 by the exhaust device, the modified gas is supplied to the interior of the processing container 11 by the modified gas supply source 93. In step S36, high-frequency electric power is supplied from the RF power supply 55, and plasma ignition is performed in the plasma box 19 to convert the modified gas into plasma. The high-frequency frequency of the RF power supply 55 is, for example, 13.56 MHz.

[0124] The modifying gas is, for example, nitrogen. The modifying gas may be hydrogen or ammonia. The modifying gas may be a gas containing nitrogen or a gas containing hydrogen. The Si-containing layer is modified by the plasma-formed modifying gas. The time of step S36 is, for example, not less than 3 seconds and not more than 60 seconds.

[0125] In step S37, the control unit 100 performs a purge. Fig.11 The process proceeds from time t4 to time t5. In step S24, while exhausting the interior of the processing container 11 by the exhaust device, the supply of the reforming gas and the high-frequency electric power is stopped, and a purge gas is supplied to the interior of the processing container 11. Thus, the gas remaining in the interior of the processing container 11 is replaced by the purge gas. The time of step S37 is, for example, not less than 3 seconds and not more than 10 seconds. The purge gas may be nitrogen gas or the like, and may be supplied from a nitriding gas supply source 80 or the like.

[0126] In steps S38 to S40, the controller 80 and Figure 6 The preset value is determined in the same manner as in steps S5 to S7 (step S38), and it is determined whether there is a temperature change in each variable reactor (step S39). If there is a temperature change, correction processing is performed (step S40).

[0127] In step S41, the control unit 100 performs nitridation of the Si-containing layer. Fig.11 The process proceeds from time t5 to time t6. In step S41, while exhausting the interior of the processing container 11 by the exhaust device, the nitriding gas is supplied to the interior of the processing container 11 by the nitriding gas supply source 96. In step S41, high-frequency electric power is supplied from the RF power supply 55, and plasma ignition is performed in the plasma box 19 to convert the nitriding gas into plasma.

[0128] The nitriding gas is, for example, ammonia gas. The Si-containing layer is nitrided by the plasma-formed ammonia gas. The time for step S41 is, for example, not less than 5 seconds and not more than 120 seconds.

[0129] In step S42, the control unit 100 performs a purge. Fig.11The process proceeds from time t6 to time t7. In step S42, while exhausting the interior of the processing container 11 by the exhaust device, the supply of the nitriding gas and the high-frequency electric power is stopped, and a purge gas is supplied to the interior of the processing container 11. Thus, the gas remaining in the interior of the processing container 11 is replaced with the purge gas. The time of step S42 is, for example, not less than 3 seconds and not more than 10 seconds. The purge gas may be nitrogen gas or the like, and may be supplied from the nitriding gas supply source 96 or the like.

[0130] In step S43, the control unit 100 determines whether the set number of repetitions has been performed. The set number of repetitions is preset. When the control unit 100 determines that the set number of repetitions has not been performed, it returns to step S31 and repeats steps S31 to S43 as a loop for a predetermined number of repetitions. In step S43, when the control unit 100 determines that the set number of repetitions has been performed, a silicon nitride film having a desired film thickness and film quality has been formed, and thus the present process is terminated. In addition, in the film forming method, the purging step can be omitted.

[0131] In the ignition control method described above, if Figure 6 Steps S5 to S7, Fig.10 As shown in steps S33 to S35 and steps S38 to S40, execute Figure 8 The correction process is performed to change the control current of the electronic circuit controlling each variable reactor according to the temperature of the first variable reactor 58 and the second variable reactor 59. As a result, the inductance of each variable reactor can be changed, and even if the temperature of each variable reactor changes, the inductance can be controlled to be constant, thereby improving the accuracy of the preset value.

[0132] In particular, in the film forming process using the ALD method, when the step of repeatedly igniting the plasma is repeated by repeatedly supplying / stopping the gas, the preset value is changed each time when the supply / stopping of the gas is repeated. Fig.10 As shown in steps S33 to S35 and steps S38 to S40, the preset value can be corrected in real time before the high frequency electric power is supplied and the plasma is ignited. Thus, it is possible to provide a substrate processing device 10 that improves the accuracy of the preset value, stably controls the reflected wave and the voltage between the electrodes, and performs stable film formation.

[0133] As described above, according to the ignition control method and substrate processing apparatus of this embodiment, since a high-precision preset value can be set, it is possible to suppress reflected waves and perform stable plasma ignition, thereby improving the controllability of film thickness and film quality and forming a high-quality film.

[0134] The ignition control method, film forming method and film forming device of the embodiments disclosed herein are illustrative in all aspects and are not restrictive. The embodiments can be deformed and improved in various ways without departing from the scope of the invention and its gist. The contents described in the above-mentioned multiple embodiments can also adopt other structures within the scope of non-contradiction, and can be combined within the scope of non-contradiction.

[0135] For example, in the present embodiment, two variable reactors are used for explanation, but the number of variable reactors included in the impedance matching device 53 is not limited thereto, and may be one. In the case where the impedance matching device 53 includes two variable reactors, one may be a variable reactor and the other may be a fixed reactor. The ignition control method of the present invention may be performed using one variable reactor or one variable reactor.

[0136] The ignition control method of the present invention can be used for all substrate processing devices that generate plasma by applying a high-frequency voltage between electrodes via an impedance matching device having a variable reactor. For example, the substrate processing device that performs the ignition control method of the present invention is not limited to the ALD device. The substrate processing device of the present invention can be an ALE (Atomic Layer Etching) device, a CVD (Chemical Vapor Deposition) device, a PVD (Physical Vapor Deposition) device, etc.

[0137] The substrate processing device of the present invention can also be applied to any type of device including capacitively coupled plasma (CCP), inductively coupled plasma (ICP), radial line slot antenna (RLSA), electron cyclotron resonance plasma (ECR), and helicon wave plasma (HWP).

[0138] The substrate processing apparatus of the present invention is not limited to a batch type substrate processing apparatus. For example, the substrate processing apparatus may be a single-wafer type apparatus that processes wafers one by one. In addition, the substrate processing apparatus may be a semi-batch type apparatus. The semi-batch type apparatus may be an apparatus that rotates a plurality of wafers arranged around the rotation center line of the turntable together with the turntable and sequentially passes through a plurality of regions to which different gases are supplied.

[0139] Examples of substrate processing performed by the substrate processing apparatus of the present invention include film formation processing and etching processing, etc. The present invention is particularly suitable for film formation using the ALD method and etching using the ALE method.

[0140] The controller 80 may be located inside the impedance matching device 53 or outside the impedance matching device 53. In the case where the controller 80 is located outside the impedance matching device 53, Figure 5 The control unit 100 and the controller 80 can be as follows Figure 5 As shown, it can be separated or integrated. In addition, the ignition control method ( Figure 6 )、Correction Processing( Figure 8 ) and film forming treatment ( Fig.10 ) are not limited to the above description and can be performed by either the control unit 100 or the controller 80.

Claims

1. An ignition control method performed in a substrate processing device, characterized in that: The substrate processing device comprises: a processing container for receiving substrates; a pair of electrodes formed in the processing container; an impedance matching device having a variable reactor and an electronic circuit for controlling a current flowing through the variable reactor; and an RF power source connected to the pair of electrodes via the impedance matching device, a temperature sensor for detecting the temperature of the variable reactor, The ignition control method comprises: Step (a), measuring first information, wherein the first information indicates a voltage between the electrodes corresponding to each of a plurality of adjustment positions of the variable reactor when a high-frequency voltage of a predetermined frequency is applied from the RF power supply to the pair of electrodes when the temperature of the variable reactor is set to a first temperature; Step (b), determining a preset value of the variable reactor based on the measured first information; Step (c), acquiring the temperature of the variable reactor detected by the temperature sensor as a second temperature; Step (d), when the first temperature and the second temperature are different, correcting the current flowing through the variable reactor by controlling the electronic circuit so that the adjustment position of the variable reactor becomes the determined preset value at the second temperature.

2. The ignition control method according to claim 1, characterized in that: In the step (d), with reference to a memory storing the current flowing through the variable reactor corresponding to each temperature of the variable reactor and a plurality of adjustment positions of the variable reactor, the current flowing through the variable reactor when the temperature of the variable reactor is the second temperature is corrected, thereby correcting the determined preset value.

3. The ignition control method according to claim 1 or 2, characterized in that: In the step (b), the first information is measured immediately before the plasma is ignited.

4. The ignition control method according to claim 1 or 2, characterized in that: In the step (b), when measuring the first information, the high-frequency electric power having an intensity that does not cause plasma ignition is supplied from the RF power supply.

5. The ignition control method according to claim 1 or 2, characterized in that: In the step (d), the current flowing through the variable reactor is corrected immediately before plasma ignition.

6. A substrate processing device, characterized in that: include: a processing container for receiving substrates; a pair of electrodes formed in the processing container; an impedance matching device having a variable reactor and an electronic circuit for controlling a current flowing through the variable reactor; and an RF power source connected to the pair of electrodes via the impedance matching device, a temperature sensor for detecting the temperature of the variable reactor; a temperature adjustment unit for adjusting the temperature of at least the variable reactor; and Control Department, The control unit controls the following processes: Process (a), measuring first information, wherein the first information indicates a voltage between the electrodes corresponding to each of a plurality of adjustment positions of the variable reactor when a high-frequency voltage of a predetermined frequency is applied from the RF power supply to the pair of electrodes when the temperature of the variable reactor is set to a first temperature; Process (b), determining a preset value of the variable reactor based on the measured first information; Process (c), obtaining the temperature of the variable reactor detected by the temperature sensor as a second temperature; and Process (d), when the first temperature and the second temperature are different, correcting the current flowing through the variable reactor by controlling the electronic circuit so that the adjustment position of the variable reactor becomes the determined preset value at the second temperature.

7. The substrate processing device according to claim 6, characterized in that: The temperature adjustment unit is any one of a thermostatic tank surrounding at least the variable reactor, a fan for adjusting the temperature of at least the variable reactor, or a piping structure through which a temperature adjustment medium for adjusting the temperature of at least the variable reactor flows.

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