Plasma processing apparatus

Abstract

An exemplary embodiment of the plasma treatment method of the present invention includes the step of generating plasma from a film-forming gas within a chamber of a plasma treatment apparatus by supplying high-frequency power from a high-frequency power source. The plasma treatment method further includes the step of forming a protective film on the inner wall surface of the chamber by depositing chemical species from the plasma onto the inner wall surface of the chamber's sidewall. In the step of forming the protective film, a pulsed negative DC voltage is periodically applied from a DC power source to the upper electrode of the plasma treatment apparatus.

Description

Technical Field

[0001] Exemplary embodiments of the present invention relate to a plasma processing method and a plasma processing apparatus. Prior Art

[0002] The plasma processing device is used for performing plasma processing on a substrate. Before performing plasma processing on a substrate, a protective film is formed on the inner wall surface of a chamber of the plasma processing device. Japanese Patent Publication No. 2014-138027 and Japanese Patent Publication No. 2016-12712 disclose technologies for forming a protective film on the inner wall surface of a chamber. The technologies disclosed in each of these documents form a protective film on the inner wall surface of a chamber, thereby generating plasma containing silicon gas in the chamber. Summary of the invention

[0003] The present invention provides a technology for suppressing the increase of the thickness of a protective film formed on an upper electrode of a capacitively coupled plasma processing device and controlling the thickness of the protective film formed on the inner wall surface of the side wall of a chamber.

[0004] In an exemplary embodiment, a plasma processing method is provided. The plasma processing method is performed using a plasma processing device. The plasma processing device includes a chamber, a substrate holder, an upper electrode, a high-frequency power supply, and a direct current power supply device. The chamber includes a side wall having an inner wall surface. The substrate holder includes a lower electrode disposed in the chamber. The upper electrode is disposed above the substrate holder. The high-frequency power supply is used to generate plasma in the chamber. The direct current power supply device is electrically connected to the upper electrode. The direct current power supply device is configured to periodically generate a pulsed negative-polarity direct current voltage. The plasma processing method includes a step of generating plasma from a film-forming gas in the chamber by supplying high-frequency power from the high-frequency power supply. The plasma processing method further includes a step of forming a protective film on the inner wall surface by depositing chemical species from the plasma on the inner wall surface. In the step of forming the protective film, a pulsed negative-polarity direct current voltage is periodically applied from the direct current power supply device to the upper electrode.

[0005] According to an exemplary embodiment, the thickness increase of a protective film formed on an upper electrode of a capacitively coupled plasma processing apparatus can be suppressed, and the thickness of the protective film formed on the inner wall surface of a side wall of a chamber can be controlled. Simple diagram description

[0006] FIG. 1 is a flow chart of a plasma processing method according to an exemplary embodiment. FIG. 2 is a diagram schematically showing a plasma processing apparatus according to an exemplary embodiment. FIG. 3 is a diagram showing an example of the structure of a DC power supply device of the plasma processing apparatus shown in FIG. 2 . FIG. 4 is a timing diagram related to a plasma processing method according to an exemplary embodiment. FIG5 is a graph showing the experimental results. Implementation

[0007] Various exemplary implementations are described below.

[0008] In an exemplary embodiment, a plasma processing method is provided. The plasma processing method is performed using a plasma processing device. The plasma processing device includes a chamber, a substrate support, an upper electrode, a high-frequency power supply, and a direct current power supply device. The chamber includes a side wall having an inner wall surface. The substrate support includes a lower electrode disposed in the chamber. The upper electrode is disposed above the substrate support. The high-frequency power supply is used to generate plasma in the chamber. The direct current power supply device is electrically connected to the upper electrode. The direct current power supply device is configured to periodically generate a pulsed negative-polarity direct current voltage. The plasma processing method includes a step of generating plasma from a film-forming gas in the chamber by supplying high-frequency power from the high-frequency power supply. The plasma processing method further includes a step of depositing chemical species from the plasma on the inner wall surface to form a protective film on the inner wall surface. In the step of forming the protective film, a pulsed negative-polarity direct current voltage is periodically applied from the direct current power supply device to the upper electrode.

[0009] In the above embodiment, the raw material in the plasma formed by the film-forming gas forms a protective film on the surface of the upper electrode and the inner wall surface of the side wall of the chamber. When forming the protective film, since a pulsed negative-polarity DC voltage is periodically applied to the upper electrode, ion sputtering is generated for the protective film formed on the surface of the upper electrode. As a result, the increase in thickness of the protective film formed on the surface of the upper electrode is suppressed. On the other hand, the thickness of the protective film formed on the inner wall surface of the side wall of the chamber is adjusted according to the effective value of the voltage applied from the DC power supply device to the upper electrode when forming the protective film. Therefore, according to the above embodiment, the increase in thickness of the protective film formed on the upper electrode of the capacitive coupling type plasma processing device can be suppressed, and the thickness of the protective film formed on the inner wall surface of the side wall of the chamber can be controlled.

[0010] In an exemplary embodiment, the film-forming gas may also contain a silicon-containing gas. In an exemplary embodiment, the silicon-containing gas may also be a silicon halogenated gas. In an exemplary embodiment, the silicon halogenated gas may also be a silicon tetrachloride gas. In an exemplary embodiment, the film-forming gas may also contain a carbon-containing gas. In an exemplary embodiment, the carbon-containing gas may also be a hydrocarbon gas or a fluorocarbon gas.

[0011] In an exemplary embodiment, the output voltage of the DC power supply device can be a pulsed negative polarity DC voltage in the first period of the cycle and zero volt in the remaining second period of the cycle.

[0012] In an exemplary embodiment, the effective value of the output voltage of the DC power supply device in the step of forming the protective film can be less than 0 V and greater than -848 V. The effective value is the product of the square root of the duty ratio and the value of the pulsed negative DC voltage in the first period. The duty ratio is the ratio of the duration of the first period to the duration of the cycle.

[0013] In an exemplary embodiment, the plasma treatment method may further include a step of performing plasma treatment on the substrate in the chamber after the step of forming the protective film. In the step of performing the plasma treatment, plasma is generated from the processing gas in the chamber by supplying high-frequency power from the high-frequency power supply. In the step of performing the plasma treatment, the effective value of the output voltage of the DC power supply device is set to a value smaller than the effective value in the step of forming the protective film. In the step of performing the plasma treatment, the substrate is treated by chemical species from the plasma generated by the processing gas.

[0014] In an exemplary embodiment, the plasma treatment method may further include a step of removing the protective film. In the step of removing the protective film, plasma is generated from the cleaning gas in the chamber by supplying high-frequency power from the high-frequency power supply. In the step of removing the protective film, the effective value of the output voltage of the DC power supply device is set to a value greater than the effective value in the step of forming the protective film. In the step of removing the protective film, the protective film is treated by chemical species from the plasma generated by the cleaning gas.

[0015] In another exemplary embodiment, a plasma processing device is provided. The plasma processing device includes a chamber, a substrate holder, an upper electrode, a high-frequency power supply, a direct current power supply device, and a control unit. The chamber includes a side wall having an inner wall surface. The substrate holder includes a lower electrode disposed in the chamber. The upper electrode is disposed above the substrate holder. The high-frequency power supply is used to generate plasma in the chamber. The direct current power supply device is electrically connected to the upper electrode. The control unit is configured to control the high-frequency power supply and the direct current power supply device. The direct current power supply device is configured to periodically generate a pulsed negative-polarity direct current voltage. In order to generate plasma from a film-forming gas in the chamber, the control unit controls the high-frequency power supply in a manner of supplying high-frequency power. In order to cause chemical species from the plasma to accumulate on the inner wall surface and form a protective film on the inner wall surface, the control unit controls the direct current power supply device in a manner of periodically applying a pulsed negative-polarity direct current voltage to the upper electrode.

[0016] In an exemplary embodiment, the film-forming gas may also contain a silicon-containing gas. In an exemplary embodiment, the silicon-containing gas may also be a silicon halogenated gas. In an exemplary embodiment, the silicon halogenated gas may also be a silicon tetrachloride gas. In an exemplary embodiment, the film-forming gas may also contain a carbon-containing gas. In an exemplary embodiment, the carbon-containing gas may also be a hydrocarbon gas or a fluorocarbon gas.

[0017] In an exemplary embodiment, the output voltage of the DC power supply device may be a pulsed negative-polarity DC voltage during the first period of the cycle and zero volt during the remaining second period of the cycle.

[0018] In an exemplary embodiment, the control unit can control the DC power supply device in such a manner that the effective value of the output voltage is set to a value less than 0 V and greater than -848 V when the protective film is formed. The effective value is the product of the square root of the duty ratio and the value of the pulsed negative-polarity DC voltage in the first period. The duty ratio is the ratio of the duration of the first period to the duration of the cycle.

[0019] In an exemplary embodiment, in order to generate plasma from the processing gas in the chamber when performing plasma processing of the substrate in the chamber after forming the protective film, the control unit controls the high-frequency power supply in a manner of supplying high-frequency power. The control unit may also control the DC power supply device in a manner of setting the effective value of the output voltage of the DC power supply device to a value smaller than the effective value set when forming the protective film when performing the plasma processing of the substrate.

[0020] In an exemplary embodiment, the control unit may control the high frequency power supply so as to generate plasma from the cleaning gas in the chamber when removing the protective film. The control unit may also control the DC power supply device so as to set the effective value of the output voltage of the DC power supply device to a value greater than the effective value set when forming the protective film when removing the protective film.

[0021] Hereinafter, various exemplary embodiments will be described in detail with reference to the drawings. In addition, in each drawing, the same or corresponding parts are marked with the same reference numerals.

[0022] FIG. 1 is a flow chart of a plasma processing method according to an exemplary embodiment. The plasma processing method shown in FIG. 1 (hereinafter referred to as "method MT") is performed using a capacitively coupled plasma processing apparatus. FIG. 2 is a diagram schematically showing a plasma processing apparatus according to an exemplary embodiment. The plasma processing apparatus 1 shown in FIG. 2 is a capacitively coupled plasma processing apparatus. The plasma processing apparatus 1 can be used to perform method MT.

[0023] The plasma processing apparatus 1 includes a chamber 10. The chamber 10 provides an internal space 10s therein. The chamber 10 includes a chamber body 12. The chamber body 12 has a substantially cylindrical shape. The internal space 10s is provided inside the chamber body 12. The chamber body 12 is formed of a conductor such as aluminum. The chamber body 12 is grounded. A corrosion-resistant film is applied to the inner wall surface of the chamber body 12. The corrosion-resistant film may be a film formed of ceramics such as aluminum oxide and yttrium oxide.

[0024] A passage 12p is formed on the side wall of the chamber body 12. The substrate W passes through the passage 12p when being transported between the internal space 10s and the outside of the chamber 10. The passage 12p can be opened and closed by a gate valve 12g. The gate valve 12g is provided along the side wall of the chamber body 12.

[0025] A support portion 13 is provided on the bottom of the chamber body 12. The support portion 13 is formed of an insulating material. The support portion 13 has a substantially cylindrical shape. The support portion 13 extends upward from the bottom of the chamber body 12 in the internal space 10s. The support portion 13 supports a substrate holder 14. The substrate holder 14 is configured to support a substrate W in the chamber 10, that is, in the internal space 10s.

[0026] The substrate holder 14 has a lower electrode 18 and an electrostatic chuck 20. The lower electrode 18 and the electrostatic chuck 20 are disposed in the chamber 10. The substrate holder 14 may further have an electrode plate 16. The electrode plate 16 is formed of a conductor such as aluminum and has a substantially disc shape. The lower electrode 18 is disposed on the electrode plate 16. The lower electrode 18 is formed of a conductor such as aluminum and has a substantially disc shape. The lower electrode 18 is electrically connected to the electrode plate 16.

[0027] The electrostatic chuck 20 is disposed on the lower electrode 18. The substrate W is placed on the upper surface of the electrostatic chuck 20. The electrostatic chuck 20 has a body and an electrode. The body of the electrostatic chuck 20 is formed of a dielectric. The electrode of the electrostatic chuck 20 is a film-shaped electrode, which is disposed in the body of the electrostatic chuck 20. The electrode of the electrostatic chuck 20 is connected to a DC power supply 20p via a switch 20s. When a voltage from the DC power supply 20p is applied to the electrode of the electrostatic chuck 20, an electrostatic attraction is generated between the electrostatic chuck 20 and the substrate W. The generated electrostatic attraction causes the substrate W to be attracted by the electrostatic chuck 20 and held by the electrostatic chuck 20.

[0028] An edge ring ER is disposed on the substrate holder 14. The edge ring ER is not limited and may be formed of silicon, silicon carbide, or quartz. When the substrate W is processed in the chamber 10, the substrate W is disposed on the electrostatic chuck 20 and in the area surrounded by the edge ring ER.

[0029] A flow path 18f is provided inside the lower electrode 18. A heat exchange medium (e.g., a refrigerant) is supplied from a cooler unit 22 to the flow path 18f via a pipe 22a. The cooler unit 22 is provided outside the chamber 10. The heat exchange medium supplied to the flow path 18f returns to the cooler unit 22 via a pipe 22b. In the plasma processing apparatus 1, the temperature of the substrate W placed on the electrostatic chuck 20 is adjusted by heat exchange between the heat exchange medium and the lower electrode 18.

[0030] The plasma processing apparatus 1 may further include a gas supply line 24. The gas supply line 24 supplies a heat transfer gas (eg, He gas) to a gap between the upper surface of the electrostatic chuck 20 and the back surface of the substrate W. The heat transfer gas is supplied to the gas supply line 24 from a heat transfer gas supply mechanism.

[0031] The plasma processing apparatus 1 further includes an upper electrode 30. The upper electrode 30 is disposed above the substrate holder 14. The upper electrode 30 is supported on the upper portion of the chamber body 12 via a member 32. The member 32 is formed of an insulating material. The upper electrode 30 and the member 32 close the upper opening of the chamber body 12.

[0032] The upper electrode 30 may include a top plate 34 and a support 36. The lower surface of the top plate 34 is the lower surface on the side of the internal space 10s, and defines and forms the internal space 10s. The top plate 34 is formed of a silicon-containing material. The top plate 34 is formed of, for example, silicon or silicon carbide. A plurality of gas injection holes 34a are formed in the top plate 34. The plurality of gas injection holes 34a penetrate the top plate 34 in the plate thickness direction.

[0033] The support body 36 supports the top plate 34 in a detachable manner. The support body 36 is formed of a conductive material such as aluminum. A gas diffusion chamber 36a is provided inside the support body 36. A plurality of pores 36b are formed in the support body 36. The plurality of pores 36b extend downward from the gas diffusion chamber 36a. The plurality of pores 36b are respectively connected to the plurality of gas injection holes 34a. A gas inlet 36c is formed in the support body 36. The gas inlet 36c is connected to the gas diffusion chamber 36a. A gas supply pipe 38 is connected to the gas inlet 36c.

[0034] The gas source group 40 is connected to the gas supply pipe 38 via the valve group 41, the flow controller group 42 and the valve group 43. The gas source group 40, the valve group 41, the flow controller group 42 and the valve group 43 constitute the gas supply unit GS. The gas source group 40 includes a plurality of gas sources. Each of the valve group 41 and the valve group 43 includes a plurality of on-off valves. The flow controller group 42 includes a plurality of flow controllers. Each of the plurality of flow controllers of the flow controller group 42 is a mass flow controller or a pressure-controlled flow controller. Each of the plurality of gas sources of the gas source group 40 is connected to the gas supply pipe 38 via the corresponding on-off valve of the valve group 41, the corresponding flow controller of the flow controller group 42, and the corresponding on-off valve of the valve group 43.

[0035] In the plasma processing apparatus 1, a shield 46 is detachably provided along the inner wall surface of the chamber body 12. The shield 46 is also provided on the outer periphery of the support portion 13. The shield 46 prevents the byproducts of the plasma processing from adhering to the chamber body 12. The shield 46 is grounded. The shield 46 is formed, for example, by forming a corrosion-resistant film on the surface of a member formed of aluminum. The corrosion-resistant film may be a film formed of ceramics such as yttrium oxide. Furthermore, in one embodiment, the shield 46 provides an inner wall surface 10w of the side wall of the chamber 10. The inner wall surface 10w includes a first region 10a and a second region 10b. The first region 10a extends to the side of the internal space 10s. The second region 10b extends above the internal space 10s and to the side of the upper electrode 30. The first area 10a and the second area 10b may be provided not only by the mask 46 but also by one or more other components, such as the chamber body 12.

[0036] A baffle plate 48 is provided between the support portion 13 and the side wall of the chamber body 12. The baffle plate 48 is formed by, for example, forming a corrosion-resistant film on the surface of a member formed of aluminum. The corrosion-resistant film may be a film formed of ceramics such as yttrium oxide. A plurality of through holes are formed in the baffle plate 48. An exhaust port 12e is provided below the baffle plate 48 and at the bottom of the chamber body 12. An exhaust device 50 is connected to the exhaust port 12e via an exhaust pipe 52. The exhaust device 50 has a pressure regulating valve and a vacuum pump such as a turbomolecular pump.

[0037] The plasma processing apparatus 1 further includes a first high-frequency power source 62 and a second high-frequency power source 64. The first high-frequency power source 62 is a power source for generating a first high-frequency power. In one example, the first high-frequency power has a frequency suitable for generating plasma. The frequency of the first high-frequency power is, for example, a frequency in the range of 27 MHz to 100 MHz. The first high-frequency power source 62 is connected to the upper electrode 30 via an integrator 66. The integrator 66 has a circuit for integrating the impedance of the load side (the upper electrode 30 side) of the first high-frequency power source 62 with the output impedance of the first high-frequency power source 62. Furthermore, the first high-frequency power source 62 can also be connected to the lower electrode 18 via the integrator 66 and the electrode plate 16.

[0038] The second high-frequency power source 64 is a power source for generating a second high-frequency power. The second high-frequency power has a frequency lower than the frequency of the first high-frequency power. The second high-frequency power can be used as a bias high-frequency power for pulling ions toward the substrate W. The frequency of the second high-frequency power is, for example, a frequency in the range of 400 kHz to 40 MHz. The second high-frequency power source 64 is connected to the lower electrode 18 via the integrator 68 and the electrode plate 16. The integrator 68 has a circuit for integrating the impedance of the load side (lower electrode 18 side) of the second high-frequency power source 64 with the output impedance of the second high-frequency power source 64.

[0039] The plasma processing device 1 further includes a DC power supply device 70. The DC power supply device 70 is electrically connected to the upper electrode 30. The DC power supply device 70 is configured to periodically generate a pulsed negative DC voltage. FIG. 3 is a diagram showing an example of the configuration of the DC power supply device of the plasma processing device shown in FIG. 2 . FIG. 4 is a timing diagram of a plasma processing method performed using a plasma processing device of an exemplary embodiment. In FIG. 4 , the horizontal axis represents time. In FIG. 4 , the vertical axis represents the supply of high-frequency power (the first high-frequency power and / or the second high-frequency power) and the output voltage of the DC power supply device 70. In FIG. 4 , the high-frequency power is at a high level, which means that the high-frequency power is supplied. In FIG. 4 , the high-frequency power is at a low level, which means that the high-frequency power is not supplied. Hereinafter, reference is made to FIG. 2 , FIG. 3 , and FIG. 4 together.

[0040] In one embodiment, the DC power supply device 70 includes a variable DC power supply 70a and a switching element 70b. The variable DC power supply 70a is configured to continuously generate a negative DC voltage. The level of the negative DC voltage output by the variable DC power supply 70a can be controlled by the control unit 80 described later. The switching element 70b switches the connection and disconnection between the variable DC power supply 70a and the upper electrode 30 by switching its conduction state. The switching of the conduction state of the switching element 70b can also be controlled by the control unit 80.

[0041] In order to periodically output a pulsed negative DC voltage, the output voltage of the DC power supply device 70 is a negative DC voltage in the first period P1 of the period PT. In one embodiment, in the first period P1 of the period PT, the conduction state of the switching element 70b is switched in such a way that the variable DC power supply 70a and the upper electrode 30 are connected to each other. The output voltage of the DC power supply device 70 is zero volt in the remaining second period P2 of the period PT. In one embodiment, in the second period P2 of the period PT, the conduction state of the switching element 70b is switched in such a way that the connection between the variable DC power supply 70a and the upper electrode 30 is blocked.

[0042] In one embodiment, the frequency f, which is the inverse of the period PT, may be 400 kHz or more. In one embodiment, the frequency f may be 1 MHz or less. When the frequency f is 1 MHz or less, the behavior of ions in the chamber 10 has a high degree of independent control over the generation of free radicals.

[0043] The plasma processing device 1 further includes a control unit 80. The control unit 80 may be a computer including a processor, a memory unit such as a memory, an input device, a display device, a signal input and output interface, and the like. The control unit 80 controls each unit of the plasma processing device 1. In the control unit 80, an operator may use an input device to input instructions in order to manage the plasma processing device 1. In addition, in the control unit 80, a display device may be used to display a visualized operating status of the plasma processing device 1. Furthermore, a control program and process recipe data are stored in the memory unit of the control unit 80. In order to perform various processes using the plasma processing device 1, the control program is executed by the processor of the control unit 80. The processor of the control unit 80 executes the control program to control each unit of the plasma processing device 1 according to the process recipe data, thereby performing the method MT using the plasma processing device 1.

[0044] 1 again, the method MT will be described by taking the case where the method is performed using the plasma processing apparatus 1 as an example. In addition, each part of the plasma processing apparatus 1 controlled by the control unit 80 will also be described.

[0045] The method MT includes step ST1 and step ST2. During the execution of step ST1 and step ST2, a substrate (such as a dummy substrate) may be placed on the substrate holder 14, or may not be placed.

[0046] In step ST1, plasma is generated from the film-forming gas in the chamber 10. In order to generate plasma from the film-forming gas in the chamber 10, in step ST1, the film-forming gas is supplied from the gas supply unit GS into the chamber 10. The film-forming gas system contains a gas of a raw material of the protective film to be formed on the inner wall surface 10w. The film-forming gas may contain a silicon-containing gas as a raw material gas. In this case, a silicon-containing film is formed as a protective film. The silicon-containing gas may also be a silicon halide gas. The silicon halide gas may also be a silicon tetrachloride gas. In step ST1, one or more other gases may be supplied to the chamber 10 in addition to the raw material gas. That is, in step ST1, a mixed gas containing the raw material gas may also be supplied to the chamber 10. One or more other gases may be oxygen and a rare gas (such as argon). In the case where the film-forming gas contains oxygen, a silicon oxide film is formed as a protective film. Furthermore, the film-forming gas may not contain the silicon-containing gas but may contain other raw material gases. For example, the film-forming gas may contain a carbon-containing gas as the raw material gas. In this case, a carbon-containing film is formed as a protective film. The carbon-containing gas may be a hydrocarbon gas such as CH 4 gas or a fluorocarbon gas such as C 4F 6 gas. Furthermore, in step ST1, in order to form plasma from the film-forming gas in the chamber 10, the first high-frequency power and / or the second high-frequency power are supplied. As a result, plasma is generated from the film-forming gas in the chamber 10. Furthermore, in step ST1, the second high-frequency power may not be supplied.

[0047] In order to execute step ST1, the control unit 80 controls the gas supply unit GS so as to supply the film forming gas into the chamber 10. In order to execute step ST1, the control unit 80 controls the exhaust device 50 so as to set the pressure in the chamber 10 to a specified pressure. In order to execute step ST1, the control unit 80 controls the first high frequency power source 62 and / or the second high frequency power source 64 so as to supply the first high frequency power and / or the second high frequency power.

[0048] Step ST2 is performed during the process of generating plasma in step ST1. In step ST2, a protective film is formed on the inner wall surface 10w by depositing chemical species from the plasma generated by the film forming gas in step ST1 on the inner wall surface 10w. In step ST2, a pulsed negative-polarity DC voltage is periodically applied from the DC power supply device 70 to the upper electrode 30. As described above, the output voltage of the DC power supply device 70 is a pulsed negative-polarity DC voltage in the first period P1 within the period PT. The output voltage of the DC power supply device 70 is zero volts in the remaining second period P2 within the period PT.

[0049] In one embodiment, the effective value of the output voltage of the DC power supply device 70 in step ST2 is less than 0 V and greater than -848 V. The effective value is the product of the square root of the duty ratio (expressed as a decimal) of the pulse-shaped negative polarity DC voltage and the value of the pulse-shaped negative polarity DC voltage in the first period P1. The duty ratio is the ratio (expressed as a decimal) of the duration of the first period P1 to the duration of the period PT. In one embodiment, the duty ratio of the pulse-shaped negative polarity DC voltage can be greater than 0.2 and less than 0.5. In one embodiment, the value of the pulse-shaped negative polarity DC voltage in the first period P1 can be less than 0 V and greater than -1200 V.

[0050] In order to perform step ST2, the control unit 80 controls the DC power supply device 70 so as to periodically apply a pulsed negative DC voltage to the upper electrode 30. In one embodiment, the control unit 80 controls the DC power supply device 70 so as to set the effective value of the output voltage of the DC power supply device 70 to a value less than 0 V and not less than -848 V.

[0051] In the method MT, the raw material in the plasma formed by the film forming gas forms a protective film on the surface of the upper electrode 30 and the inner wall surface 10w of the side wall of the chamber 10. When forming the protective film, a pulsed negative polarity DC voltage is periodically applied to the upper electrode 30, so that sputtering of ions to the protective film formed on the surface of the upper electrode 30 occurs. As a result, the increase in thickness of the protective film formed on the surface of the upper electrode 30 is suppressed. On the other hand, the thickness of the protective film formed on the inner wall surface 10w is adjusted according to the effective value of the voltage applied from the DC power supply device 70 to the upper electrode 30 when forming the protective film. Therefore, according to the method MT, the increase in thickness of the protective film formed on the upper electrode 30 of the capacitive coupling type plasma processing device 1 can be suppressed, and the thickness of the protective film formed on the inner wall surface 10w can be controlled.

[0052] In one embodiment, the method MT may further include a step ST3. Step ST3 is performed after step ST2. In step ST3, a plasma treatment of the substrate is performed in the chamber 10. During the execution of step ST3, the substrate is placed on the substrate holder 14 and held by the electrostatic chuck 20. The plasma treatment performed in step ST3 may be plasma etching. The plasma treatment performed in step ST3 may also be other plasma treatments.

[0053] In step ST3, a processing gas is supplied from the gas supply unit GS into the chamber 10. The processing gas is appropriately selected according to the plasma treatment applied to the substrate. In step ST3, in order to generate plasma from the processing gas in the chamber 10, the first high-frequency power and / or the second high-frequency power are supplied. As a result, plasma is generated from the processing gas in the chamber 10. In step ST3, the substrate is processed by chemical species from the plasma generated by the processing gas. In step ST3, the effective value of the output voltage of the DC power supply device 70 is set to a value smaller than the effective value in step ST2. As a result, the reduction of the protective film during the execution of step ST3 is suppressed.

[0054] In order to perform step ST3, the control unit 80 controls the gas supply unit GS so as to supply the processing gas into the chamber 10. In order to perform step ST3, the control unit 80 controls the exhaust device 50 so as to set the pressure in the chamber 10 to a specified pressure. In order to perform step ST3, the control unit 80 controls the first high-frequency power source 62 and / or the second high-frequency power source 64 so as to supply the first high-frequency power and / or the second high-frequency power. Furthermore, in order to perform step ST3, the control unit 80 controls the DC power source device 70 so as to set the effective value of the output voltage of the DC power source device 70 to a value smaller than the effective value set in step ST2.

[0055] In one embodiment, the method MT may further include step ST4. In step ST4, the protective film formed in step ST2 is removed. During the execution of step ST4, the substrate (eg, dummy substrate) may be placed on the substrate holder 14 or may not be placed on the substrate holder 14.

[0056] In step ST4, a cleaning gas is supplied from the gas supply unit GS into the chamber 10. When the protective film is a silicon oxide film, the cleaning gas may contain a fluorocarbon gas (e.g., CF 4 gas). When the protective film is a carbon-containing film, the cleaning gas may contain an oxygen-containing gas (e.g., O 2 gas). In step ST4, in order to generate plasma from the cleaning gas in the chamber 10, the first high-frequency power and / or the second high-frequency power are supplied. As a result, plasma is generated from the cleaning gas in the chamber 10. In step ST4, the protective film is removed by chemical species from the plasma generated by the cleaning gas. In step ST4, the effective value of the output voltage of the DC power supply device 70 is set to a value greater than the effective value in step ST2. As a result, the removal efficiency of the protective film in step ST4 is improved.

[0057] In order to perform step ST4, the control unit 80 controls the gas supply unit GS so as to supply the cleaning gas into the chamber 10. In order to perform step ST4, the control unit 80 controls the exhaust device 50 so as to set the pressure in the chamber 10 to a specified pressure. In order to perform step ST4, the control unit 80 controls the first high-frequency power source 62 and / or the second high-frequency power source 64 so as to supply the first high-frequency power and / or the second high-frequency power. Furthermore, in order to perform step ST4, the control unit 80 controls the DC power source device 70 so as to set the effective value of the output voltage of the DC power source device 70 to a value greater than the effective value set in step ST2.

[0058] In one embodiment, the method MT may further include step ST5. In step ST5, it is determined whether the stop condition is satisfied. For example, when the number of executions of the program including steps ST1 to ST4 reaches a specific number of times, it is determined that the stop condition is satisfied. When it is determined in step ST5 that the stop condition is not satisfied, the program including steps ST1 to ST4 is further executed. In step ST3 of the program that is further executed, plasma treatment is further performed on the substrate that has been processed in step ST3 of the previous program, or plasma treatment is performed on other substrates. When it is determined in step ST5 that the stop condition is satisfied, the method MT ends.

[0059] Various exemplary embodiments have been described above, but various omissions, substitutions, and changes may be made without being limited to the exemplary embodiments described above. In addition, elements in different embodiments may be combined to form other embodiments.

[0060] The following describes experiments performed to evaluate the method MT and the plasma processing apparatus 1. The present invention is not limited to the experiments described below.

[0061] In the experiment, the first chip was attached to the surface of the inner space 10s side of the upper electrode 30, the second chip was attached to the first area 10a, and the third chip was attached to the second area 10b. In the experiment, the effective value of the output voltage of the DC power supply device 70 in step ST2 was set to various values. The conditions of step ST1 in the experiment are as follows. <Conditions of Step ST1> ·Pressure in chamber 10: 20 mTorr (2.666 Pa) Silicon tetrachloride gas flow rate: 5 sccm Oxygen flow rate: 50 sccm Argon gas flow rate: 250 sccm 1st high frequency power: 60 MHz, 1000 W · Second high frequency power: 0 W Frequency f (reciprocal of period PT): 400 kHz ·Duty ratio of pulsed negative DC voltage: 0.3 or 0.5 Pulse-shaped negative polarity DC voltage value: 0 V, -500 V, or -900 V

[0062] In the experiment, the film thickness of the protective film formed on each wafer was measured at each setting of the effective value of the output voltage of the DC power supply device 70. In addition, the ratio of the film thickness of the protective film formed on each wafer to the reference film thickness, i.e., the film thickness ratio (percentage), was obtained. Here, the reference film thickness is the film thickness of the protective film formed on the wafer attached to the same position when the effective value of the output voltage of the DC power supply device 70 in step ST2 is 0 V.

[0063] FIG5 shows a graph showing the results of the experiment. In the graph of FIG5 , the horizontal axis represents the effective value of the output voltage of the DC power supply device 70 in step ST2. In the graph of FIG5 , the vertical axis represents the obtained film thickness ratio. In FIG5 , the first to third film thickness ratios represent the film thickness ratios of the protective films formed on the first to third wafers, respectively. As shown in FIG5 , as the absolute value of the effective value of the output voltage of the DC power supply device 70 increases, the first film thickness ratio decreases. Based on this, it is confirmed that the increase in the film thickness of the protective film formed on the surface of the upper electrode 30 can be suppressed by periodically applying a pulsed negative-polarity DC voltage from the DC power supply device 70 to the upper electrode 30 during the process of generating plasma from the film-forming gas. In addition, it is confirmed that as the absolute value of the effective value of the output voltage of the DC power supply device 70 increases, the film thickness of the protective film formed on the surface of the upper electrode 30 decreases.

[0064] On the other hand, as shown in FIG5 , as the absolute value of the effective value of the output voltage of the DC power supply device 70 increases, the second film thickness ratio and the third film thickness ratio increase. This confirms that the thickness of the protective film formed on the inner wall surface 10w of the side wall of the chamber 10 can be adjusted according to the effective value of the voltage applied from the DC power supply device 70 to the upper electrode when forming the protective film.

[0065] According to the above description, it can be understood that the various embodiments of the present invention are described in this specification for the purpose of explanation, and various changes can be made without departing from the scope and gist of the present invention. Therefore, the various embodiments disclosed in this specification are not intended to be limiting, and the true scope and gist of the present invention are indicated by the attached patent scope.

[0066] 1: Plasma treatment device 10: Chamber 10a: Area 1 10b: Area 2 10s: Interior Space 10w: Inner wall surface 12: Chamber body 12e: Exhaust port 12g: Gate valve 12p: Access 13: Support Department 14: Substrate support 16: Electrode plate 18: Lower electrode 18f:Flow path 20: Electrostatic chuck 20p: DC power supply 20s: Switch 22: Cooler unit 22a:Piping 22b:Piping 24: Gas supply line 30: Upper electrode 32: Component 34: Top plate 34a: Fumarole 36: Support 36a: Gas diffusion chamber 36b: pores 36c: Gas inlet 38: Gas supply pipe 40: Gas source group 41: Valve Group 42: Traffic controller group 43: Valve Group 46:Mask 48: Baffle 50: Exhaust 52: Exhaust pipe 62: No. 1 high frequency power supply 64: Second high frequency power supply 66: Integrator 68: Integrator 70: DC power supply device 70a: Variable DC power supply 70b: Switching element 72: Grounding electrode 80: Control Department ER:Edge Ring GS: Gas Supply Department W: substrate

Claims

1. A plasma processing apparatus comprising: a chamber including a sidewall having an inner wall surface; a substrate support including a lower electrode disposed within the chamber; an upper electrode disposed above the substrate support; a gas supply unit configured to supply gas into the chamber; a high-frequency power supply for generating plasma within the chamber; a DC power supply electrically connected to the upper electrode; and a control unit configured to control the gas supply unit, the high-frequency power supply, and the DC power supply; wherein the DC power supply is configured to periodically generate a pulsed negative DC voltage during a period including a first period and a second period, the second period being all periods remaining in the period excluding the first period; and the control unit is configured to control the gas supply unit to supply gas into the chamber, and to control the high-frequency power supply to supply high-frequency power for generating plasma from the gas within the chamber. In order to control the DC power supply device by depositing chemical species from the plasma onto the inner wall surface to form a protective film on the inner wall surface, the DC power supply device is controlled by periodically applying a pulsed DC voltage with a first level in the first period and a second level lower than the first level in the second period to the upper electrode, wherein the second level is zero volts.

2. The plasma processing apparatus of claim 1, wherein the DC power supply device comprises: a variable DC power supply configured to generate a negative DC voltage; and a switching element that switches the connection and disconnection between the variable DC power supply and the upper electrode.

3. The plasma processing apparatus as claimed in claim 1 or 2, wherein the gas supply unit includes a gas source group.

4. The plasma processing apparatus of claim 3, wherein the aforementioned gas source group includes a first gas source for supplying silicon-containing gas.

5. The plasma processing apparatus of claim 4, wherein the silicon-containing gas comprises silicon halide gas.

6. The plasma processing apparatus of claim 5, wherein the aforementioned silicon halide gas comprises silicon tetrachloride gas.

7. The plasma processing apparatus of claim 3, wherein the aforementioned gas source group includes a second gas source for supplying carbon-containing gas.

8. The plasma processing apparatus of claim 7, wherein the carbon-containing gas comprises hydrocarbon gas or fluorocarbon gas.

9. The plasma processing apparatus of claim 1 or 2, wherein the effective value of the output voltage of the DC power supply device during the formation of the protective film is less than 0 V and greater than -848 V, wherein the effective value is the product of the square root of the duty cycle and the value of the pulsed negative DC voltage during the first period, wherein the duty cycle is the ratio of the duration of the first period to the duration of the cycle.

10. The plasma processing apparatus of claim 9, wherein the value of the pulsed negative DC voltage during the first period is less than 0 V and is more than -1200 V.

11. The plasma processing apparatus of claim 9, wherein the control unit is configured such that, after the formation of the protective film, in order to perform plasma processing of the substrate by processing the substrate with chemical species of plasma generated from the processing gas in the chamber, the plasma is generated from the processing gas in the chamber by supplying the high-frequency power, the gas supply unit and the high-frequency power supply are controlled such that the effective value of the output voltage of the DC power supply device is set to a value less than the effective value during the formation of the protective film, and the DC power supply device is controlled in such a way that the effective value of the output voltage of the DC power supply device is set to a value less than the effective value during the formation of the protective film.

12. The plasma processing apparatus of claim 9, wherein the control unit is configured to: control the gas supply unit and the high-frequency power supply in such a way that the protective film is removed by means of chemical species of plasma generated from the cleaning gas, and the plasma is generated in the chamber by means of supplying the high-frequency power, and control the DC power supply device in such a way that the effective value of the output voltage is set to a value greater than the effective value during the formation of the protective film.

13. A plasma processing apparatus comprising: a chamber including a sidewall having an inner wall surface; a substrate support including a lower electrode disposed within the chamber; an upper electrode disposed above the substrate support; a gas supply unit configured to supply gas into the chamber; a high-frequency power supply for generating plasma from the gas within the chamber; a DC power supply device electrically connected to the upper electrode and configured to periodically generate a pulsed negative DC voltage during a period including a first period and a second period excluding the first period; and a control unit configured to control the gas supply unit, the DC power supply device, and the high-frequency power supply, wherein the control unit is configured to set the output voltage of the DC voltage from the DC power supply device to a first level during the first period and to a second level lower than the first level during the second period; wherein the second level is zero volts.

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