Plasma processing method and plasma processing apparatus

Abstract

The invention provides a plasma processing method and a plasma processing apparatus. A plasma processing method according to an exemplary embodiment includes a step of applying a first DC voltage to a lower electrode of a substrate support provided in a chamber of a plasma processing apparatus during a first period in a plasma generation process in the chamber. The plasma processing method further includes a step of applying a second DC voltage to the lower electrode during a second period different from the first period in the plasma generation process in the chamber. The second DC voltage has a level different from that of the first DC voltage. The second DC voltage has the same polarity as that of the first DC voltage.

Description

[0001] This application is a divisional application of an application with a filing date of May 19, 2020, application number 202010423589.1, and invention name “Plasma processing method and plasma processing device”. Technical Field

[0002] Exemplary embodiments of the present invention relate to a plasma processing method and a plasma processing apparatus. Background Art

[0003] The plasma processing device is used to process plasma on a substrate. The plasma processing device includes a chamber and a substrate holding electrode. The substrate holding electrode is disposed in the chamber. The substrate holding electrode holds the substrate placed on the main surface. One of such plasma processing devices is described in Patent Document 1, JP-A-2009-187975.

[0004] The plasma processing device described in Patent Document 1 also includes a high-frequency generator and a DC negative pulse generator. The high-frequency generator applies a high-frequency voltage to the substrate holding electrode. In the plasma processing device described in Patent Document 1, the high-frequency voltage is switched on and off alternately. In addition, in the plasma processing device described in Patent Document 1, a DC negative pulse voltage is applied from the DC negative pulse generator to the substrate holding electrode according to the time of the high-frequency voltage being turned on and off. In the plasma processing device described in Patent Document 1, when a DC negative pulse voltage, i.e., a negative polarity pulse-shaped DC voltage, is applied to the substrate holding electrode, the energy of the ions supplied to the substrate becomes maximum. When the DC negative pulse voltage is not applied to the substrate, the energy of the ions supplied to the substrate becomes minimum. Summary of the invention

[0005] The present invention provides a technology capable of supplying ions having energy between the energy of the ions when a DC voltage of a unipolar level is applied to a lower electrode of a substrate support and the energy of the ions that can be obtained when the potential of the lower electrode is a ground potential to a substrate.

[0006] In an exemplary embodiment, a plasma processing method is provided. The plasma processing method includes a step of applying a first DC voltage to a lower electrode of a substrate supporter disposed in a chamber during a first period of plasma generation in a chamber of a plasma processing device. The plasma processing method also includes a step of applying a second DC voltage to the lower electrode during a second period different from the first period during the plasma generation in the chamber. The second DC voltage has a level different from that of the first DC voltage. The second DC voltage has the same polarity as that of the first DC voltage.

[0007] According to an exemplary embodiment, ions having energy between the energy of ions when a DC voltage of a unipolar level is applied to a lower electrode of a substrate supporter and the energy of ions available when the potential of the lower electrode is a ground potential can be supplied to the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a flow chart of a plasma processing method according to an exemplary embodiment.

[0009] Figure 2 FIG. 1 is a diagram schematically showing a plasma processing apparatus according to an exemplary embodiment.

[0010] Figure 3 (a) and Figure 3 (b) are respectively Figure 2 FIG. 2 is a diagram showing a structure of a power supply device of a plasma processing apparatus.

[0011] Figure 4 is with Figure 1 A timing chart of an example of the plasma processing method shown.

[0012] Figure 5 is with Figure 1 A timing chart of another example of the plasma processing method shown.

[0013] Figure 6 is a flow chart of a plasma processing method according to another exemplary embodiment.

[0014] Figure 7 FIG. 1 is a diagram schematically showing a plasma processing apparatus according to another exemplary embodiment.

[0015] Figure 8 is with Figure 6 A timing chart of an example of the plasma processing method shown.

[0016] Fig. 9 It is a diagram showing an example of one or more potential measuring probes.

[0017] Fig.10 is a flow chart of a plasma processing method according to another exemplary embodiment.

[0018] Fig.11 is with Fig.10 A timing chart of an example of the plasma processing method shown. DETAILED DESCRIPTION

[0019] Various exemplary embodiments are described below.

[0020] In an exemplary embodiment, a plasma processing method is provided. The plasma processing method includes a process of applying a first DC voltage to a lower electrode of a substrate supporter disposed in the chamber during a first period of plasma generation in a chamber of a plasma processing device. The plasma processing method also includes a process of applying a second DC voltage to the lower electrode during a second period of plasma generation in the chamber. The second period is a period different from the first period. The second DC voltage has a level different from the level of the first DC voltage. The second DC voltage has the same polarity as the first DC voltage.

[0021] In the plasma processing method of the above-mentioned embodiment, the first DC voltage and the second DC voltage have the same polarity. Furthermore, the absolute value of one of the first DC voltage and the second DC voltage is smaller than the absolute value of the other DC voltage. Therefore, in one of the first period and the second period when a DC voltage is applied to the lower electrode, the energy of the ions supplied to the substrate is lower than the energy of the ions supplied to the substrate in the other period. Furthermore, the energy of the ions supplied to the substrate in one period is higher than the energy supplied to the substrate when the potential of the lower electrode is the ground potential. Therefore, it is possible to supply the substrate with ions having an energy between the energy of the ions supplied to the substrate when a DC voltage of a unipolar level is applied to the lower electrode and the energy of the ions supplied to the substrate when the potential of the lower electrode is the ground potential.

[0022] In an exemplary embodiment, a plasma processing apparatus may include a power supply device, a first switch, and a second switch. In this embodiment, the power supply device has a first output for a first DC voltage and a second output for a second DC voltage. The first switch is connected between the first output and the lower electrode. The second switch is connected between the second output and the lower electrode. During a first period, the first switch is set to a conducting state in order to connect the first output and the lower electrode to each other, and the second switch is set to a non-conducting state in order to cut off the connection between the second output and the lower electrode. During a second period, the second switch is set to a conducting state in order to connect the second output and the lower electrode to each other, and the first switch is set to a non-conducting state in order to cut off the connection between the first output and the lower electrode.

[0023] In an exemplary embodiment, the plasma processing method further includes a step of setting the potential of the lower electrode to a ground potential during a third period. The third period is a period between the end time of the first period and the start time of the second period. In this embodiment, the plasma processing apparatus further includes a third switch connected between the lower electrode and the ground line. During the first period and the second period, the third switch is set to a non-conducting state in order to cut off the connection between the lower electrode and the ground line. During the third period, the third switch is set to a conducting state in order to connect the lower electrode and the ground line to each other. Furthermore, during the third period, the first switch is set to a non-conducting state in order to cut off the connection between the first output and the lower electrode, and the second switch is set to a non-conducting state in order to cut off the connection between the second output and the lower electrode.

[0024] In an exemplary embodiment, the plasma processing method may further include setting the first switch, the second switch, and the third switch to a non-conductive state during a period between an end time of the third period and a start time of the second period.

[0025] In one exemplary embodiment, the step of applying the first DC voltage and the step of applying the second DC voltage may be repeated alternately. In one exemplary embodiment, the plasma processing method may further include a step of setting the potential of the lower electrode to a ground potential during a period between the end time of the second period and the start time of the next first period.

[0026] In other exemplary embodiments, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a substrate support, a power supply device, and a control unit. The substrate support includes a lower electrode and is disposed in the chamber. The control unit is configured to control the application of a voltage from the power supply device to the lower electrode. The control unit is configured to perform a first control of applying a first DC voltage from the power supply device to the lower electrode during a first period of a plasma generation process in the chamber. The control unit is configured to also perform a second control of applying a second DC voltage from the power supply device to the lower electrode during a second period of a plasma generation process in the chamber. The second period is a period different from the first period. The second DC voltage has a level different from that of the first DC voltage and has the same polarity as that of the first DC voltage.

[0027] In an exemplary embodiment, the power supply device may have a first output for a first DC voltage and a second output for a second DC voltage. In this embodiment, the plasma processing device may also have a first switch and a second switch. The first switch is connected between the first output and the lower electrode. The second switch is connected between the second output and the lower electrode. The control unit is configured to set the first switch to a conductive state in order to connect the first output and the lower electrode to each other, and to set the second switch to a non-conductive state in order to cut off the connection between the second output and the lower electrode. The control unit is configured to set the second switch to a conductive state in order to connect the second output and the lower electrode to each other, and to set the first switch to a non-conductive state in order to cut off the connection between the first output and the lower electrode in the second control.

[0028] In an exemplary embodiment, the plasma processing apparatus may further include a third switch connected between the lower electrode and the ground line. The control unit is configured to set the third switch to a non-conductive state in order to cut off the connection between the lower electrode and the ground line in the first control and the second control. The control unit is configured to further perform control to set the third switch to a conductive state in order to connect the lower electrode and the ground line to each other during the third period. The third period is a period between the end time of the first period and the start time of the second period. The control unit is configured to set the first switch to a non-conductive state in order to cut off the connection between the first output and the lower electrode, and to set the second switch to a non-conductive state in order to cut off the connection between the second output and the lower electrode in the control during the third period.

[0029] In an exemplary embodiment, the control unit may be configured to further perform control to set the first switch, the second switch, and the third switch to a non-conductive state during a period between an end time of the third period and a start time of the second period.

[0030] In an exemplary embodiment, the control unit may be configured to alternately repeat the first control and the second control. In an exemplary embodiment, the control unit may also perform other control during a period between the end time of the second period and the start time of the next first period. The control unit is configured to set the third switch to a conductive state in order to connect the lower electrode and the ground line to each other in the other control. The control unit is configured to set the first switch to a non-conductive state in order to cut off the connection between the first output and the lower electrode, and to set the second switch to a non-conductive state in order to cut off the connection between the second output and the lower electrode in the other control.

[0031] In another exemplary embodiment, a plasma processing method is provided. The plasma processing method includes a process of applying a DC voltage from a power supply device to a lower electrode of a substrate support disposed in the chamber during a first period of a plasma generation process in a chamber of a plasma processing device. The plasma processing method also includes a process of connecting the lower electrode to a ground line during a second period of a plasma generation process in the chamber. The second period is a period different from the first period. During the second period, the lower electrode is electrically isolated from the power supply device. The plasma processing method also includes a process of connecting the power supply device to the lower electrode during a third period of a plasma generation process in the chamber. The third period is a period after the second period and starts before the potential of the lower electrode reaches the ground potential. During the third period, the lower electrode is electrically isolated from the ground line. The end time of the third period is the time before the potential of the lower electrode becomes a stable state. At the end time of the third period, the lower electrode is electrically isolated from the power supply device.

[0032] In the plasma processing method of the above embodiment, in the second period, the absolute value of the potential of the lower electrode decreases from the absolute value of the potential of the lower electrode in the first period, but does not reach zero. And, in the third period, the absolute value of the potential of the lower electrode increases from the absolute value of the potential of the lower electrode in the second period, but does not reach the same potential as the potential of the lower electrode in the first period. Therefore, the energy of the ions supplied to the substrate in the second period and the energy of the ions supplied to the substrate in the third period are lower than the energy of the ions supplied to the substrate in the first period. And, the energy of the ions supplied to the substrate in the second period and the energy of the ions supplied to the substrate in the third period are higher than the energy supplied to the substrate when the potential of the lower electrode is the ground potential. Therefore, it is possible to supply the substrate with ions having an energy between the energy of the ions supplied to the substrate when a DC voltage of a unipolar level is applied to the lower electrode and the energy of the ions supplied to the substrate when the potential of the lower electrode is the ground potential.

[0033] In an exemplary embodiment, the plasma processing method may further include a step of electrically isolating the lower electrode from both the power supply device and the ground line during a period between the end time of the second period and the start time of the third period.

[0034] In one exemplary embodiment, the process of connecting the lower electrode to the ground line and the process of connecting the power supply device to the lower electrode may be repeated alternately. In this embodiment, after the process of connecting the power supply device to the lower electrode is performed and before the potential of the lower electrode reaches a stable state, the process of connecting the lower electrode to the ground line is started again.

[0035] In another exemplary embodiment, a plasma processing device is provided. The plasma processing device includes a chamber, a substrate support, a power supply device, a first switch, a second switch, and a control unit. The substrate support includes a lower electrode and is disposed in the chamber. The first switch is connected between the power supply device and the lower electrode. The second switch is connected between the lower electrode and the ground line. The control unit is configured to control the application of a voltage from the power supply device to the lower electrode. The control unit is configured to perform a first control during a first period of a plasma generation process in the chamber. The control unit is configured to set the first switch to a conducting state in order to connect the power supply device to the lower electrode and apply a DC voltage from the power supply device to the lower electrode in the first control. The control unit is configured to set the second switch to a non-conducting state in order to electrically isolate the lower electrode from the ground line in the first control. The control unit is configured to also perform a second control during a second period of a plasma generation process in the chamber. The second period is a period different from the first period. The control unit is configured to set the second switch to a conducting state in order to connect the lower electrode to the ground line in the second control, and to set the first switch to a non-conducting state in order to electrically isolate the lower electrode from the power supply device. The control unit is configured to further perform a third control during a third period in the plasma generation process in the chamber. The third period is a period after the second period and starts before the potential of the lower electrode reaches the ground potential. The control unit is configured to set the first switch to a conducting state in order to connect the power supply device to the lower electrode in the third control, and to set the second switch to a non-conducting state in order to electrically isolate the lower electrode from the ground line. The end time of the third period is the time before the potential of the lower electrode becomes a stable state. The control unit is configured to set the first switch to a non-conducting state in order to electrically isolate the lower electrode from the power supply device at the end time of the third period.

[0036] In one exemplary embodiment, the control unit may be configured to perform another control during a period between the end time of the second period and the start time of the third period. In the another control, the control unit is configured to set both the first switch and the second switch to a non-conductive state in order to electrically isolate the lower electrode from both the power supply device and the ground line.

[0037] In an exemplary embodiment, the control unit may be configured to alternately repeat the second control and the third control, and to restart the second control after executing the third control and before the potential of the lower electrode reaches a stable state.

[0038] In another exemplary embodiment, a plasma processing method is provided. The plasma processing method includes a process of applying a first DC voltage from a first output of a power supply device to a lower electrode of a substrate support disposed in the chamber during a first period of plasma generation in a chamber of a plasma processing device. The power supply device has a first output and a second output. The second output is a second DC voltage output having a level lower than that of the first DC voltage. The plasma processing method also includes a process of connecting the lower electrode to a ground line during a second period of plasma generation in the chamber. The second period is a period different from the first period. During the second period, the lower electrode is electrically isolated from the first output and the second output. The plasma processing method also includes a process of connecting the second output to the lower electrode during a third period of plasma generation in the chamber. The third period is a period after the second period and starts before the potential of the lower electrode reaches the ground potential. During the third period, the lower electrode is electrically isolated from the first output and the ground line. The end time of the third period is the time before the potential of the lower electrode becomes a stable state. At the end time of the third period, the lower electrode is electrically isolated from the first output and the second output.

[0039] In the plasma processing method of the above embodiment, in the second period, the absolute value of the potential of the lower electrode decreases from the absolute value of the potential of the lower electrode in the first period, but does not reach zero. And, in the third period, the absolute value of the potential of the lower electrode increases from the absolute value of the potential of the lower electrode in the second period, but does not reach the same potential as the potential of the lower electrode in the first period. Therefore, the energy of the ions supplied to the substrate in the second period and the energy of the ions supplied to the substrate in the third period are lower than the energy of the ions supplied to the substrate in the first period. And, the energy of the ions supplied to the substrate in the second period and the energy of the ions supplied to the substrate in the third period are higher than the energy supplied to the substrate when the potential of the lower electrode is the ground potential. Therefore, it is possible to supply the substrate with ions having an energy between the energy of the ions supplied to the substrate when a DC voltage of a unipolar level is applied to the lower electrode and the energy of the ions supplied to the substrate when the potential of the lower electrode is the ground potential.

[0040] In an exemplary embodiment, the plasma processing method may further include a step of electrically isolating the lower electrode from the first output, the second output, and the ground line during a period between an end time of the second period and a start time of the third period.

[0041] In one exemplary embodiment, the process of connecting the lower electrode to the ground line and the process of connecting the second output to the lower electrode may be repeated alternately. In this embodiment, after the process of connecting the second output to the lower electrode is performed and before the potential of the lower electrode reaches a stable state, the process of connecting the lower electrode to the ground line is started again.

[0042] In another exemplary embodiment, a plasma processing device is provided. The plasma processing device includes a chamber, a substrate support, a power supply device, a first switch, a second switch, a third switch, and a control unit. The substrate support includes a lower electrode and is disposed in the chamber. The power supply device has a first output for a first DC voltage and a second output for a second DC voltage. The second DC voltage has a level lower than the level of the first DC voltage. The first switch is connected between the first output and the lower electrode. The second switch is connected between the second output and the lower electrode. The third switch is connected between the lower electrode and the ground line. The control unit is configured to control the application of a voltage from the power supply device to the lower electrode. The control unit is configured to perform a first control during a first period of a plasma generation process in the chamber. The control unit is configured to set the first switch to a conducting state in order to connect the first output to the lower electrode and apply the first DC voltage from the first output to the lower electrode in the first control. The control unit is configured to set the second switch and the third switch to a non-conducting state in order to electrically isolate the lower electrode from the second output and the ground line in the first control. The control unit is configured to further perform a second control during a second period in the plasma generation process in the chamber. The second period is a period different from the first period. The control unit is configured to set the third switch to a conducting state in order to connect the lower electrode to the ground line in the second control, and to set the first switch and the second switch to a non-conducting state in order to electrically isolate the lower electrode from the first output and the second output. The control unit is configured to further perform a third control during a third period in the plasma generation process in the chamber. The third period is a period after the second period and starts before the potential of the lower electrode reaches the ground potential. The control unit is configured to set the second switch to a conducting state in order to connect the second output to the lower electrode in the third control, and to set the first switch and the third switch to a non-conducting state in order to electrically isolate the lower electrode from the first output and the ground line. The end time of the third period is the time before the potential of the lower electrode becomes a stable state. The control unit is configured to set the first switch and the second switch to a non-conducting state in order to electrically isolate the lower electrode from the first output and the second output at the end time of the third period.

[0043] In an exemplary embodiment, the control unit may be configured to further perform control to set the first to third switches to a non-conductive state during a period between an end time of the second period and a start time of the third period.

[0044] In one exemplary embodiment, the control unit may alternately repeat the second control and the third control. The control unit may be configured to restart the second control after executing the third control and before the potential of the lower electrode reaches a stable state.

[0045] Hereinafter, various exemplary embodiments will be described in detail with reference to the accompanying drawings. In addition, in each of the drawings, the same or corresponding parts are marked with the same symbols.

[0046] Figure 1 FIG. 1 is a flow chart of a plasma processing method according to an exemplary embodiment. Figure 1 The plasma treatment method shown (hereinafter referred to as "method MT1"). Figure 2 FIG. 1 is a diagram schematically showing a plasma processing apparatus according to an exemplary embodiment. Figure 2 The plasma processing apparatus 1 shown executes method MT1.

[0047] The plasma processing device 1 is a capacitively coupled plasma processing device. The plasma processing device 1 includes a chamber 10. The chamber 10 provides an internal space 10s therein. In one embodiment, the chamber 10 includes a chamber body 12. The chamber body 12 has a substantially cylindrical shape. The internal space 10s is disposed in the chamber body 12. The chamber body 12 is made of, for example, aluminum. The chamber body 12 is electrically grounded. A plasma-resistant film is formed on the inner wall surface of the chamber body 12, i.e., the wall surface defining the internal space 10s. The film may be a ceramic film such as a film formed by anodizing or a film formed of yttrium oxide.

[0048] A passage 12p is formed in the side wall of the chamber body 12. The substrate W passes through the passage 12p when being transferred between the internal space 10s and the outside of the chamber 10. A gate valve 12g is provided along the side wall of the chamber body 12 to open / close the passage 12p.

[0049] The plasma processing apparatus 1 further includes a substrate support 16. The substrate support 16 is disposed in the chamber 10, that is, in the internal space 10s. The substrate support 16 is configured to support a substrate W placed thereon. The substrate W may have a substantially disc shape. The substrate support 16 is supported by a support body 15. The support body 15 extends upward from the bottom of the chamber body 12. The support body 15 has a substantially cylindrical shape. The support body 15 is formed of an insulating material such as quartz.

[0050] The substrate support 16 includes a lower electrode 18. The substrate support 16 may further include an electrostatic chuck 20. The substrate support 16 may further include an electrode plate 19. The electrode plate 19 is formed of a conductive material such as aluminum and has a substantially disk shape. The lower electrode 18 is disposed on the electrode plate 19. The lower electrode 18 is formed of a conductive material such as aluminum and has a substantially disk shape. The lower electrode 18 is electrically connected to the electrode plate 19.

[0051] A flow path 18f is formed in the lower electrode 18. The flow path 18f is a flow path for a heat exchange medium. As the heat exchange medium, a liquid refrigerant or a refrigerant (e.g., Freon) that cools the lower electrode 18 by gasification is used. A heat exchange medium supply device (e.g., a cooling unit) is connected to the flow path 18f. The supply device is provided outside the chamber 10. The heat exchange medium is supplied from the supply device to the flow path 18f via the pipe 23a. The heat exchange medium supplied to the flow path 18f is returned to the supply device via the pipe 23b.

[0052] The electrostatic chuck 20 is arranged on the lower electrode 18. The substrate W is placed on the electrostatic chuck 20 when being processed in the internal space 10s, and is held by the electrostatic chuck 20. The electrostatic chuck 20 has a main body and an electrode. The main body of the electrostatic chuck 20 is formed of a dielectric such as aluminum oxide or aluminum nitride. The main body of the electrostatic chuck 20 has a roughly disc shape. The electrostatic chuck 20 includes a substrate mounting area and an edge ring mounting area. The substrate mounting area is an area having a roughly disc shape. The upper surface of the substrate mounting area extends along a horizontal plane. The axis AX extending in the vertical direction including the center of the substrate mounting area is substantially consistent with the central axis of the chamber 10. The substrate W is placed on the upper surface of the substrate mounting area when being processed in the chamber 10.

[0053] The edge ring mounting area extends in the circumferential direction so as to surround the substrate mounting area. An edge ring ER is mounted on the upper surface of the edge ring mounting area. The edge ring ER has a ring shape. The substrate W is arranged in the area surrounded by the edge ring ER. That is, the edge ring ER surrounds the edge of the substrate W mounted on the substrate mounting area of ​​the electrostatic chuck 20. The edge ring ER is formed of, for example, silicon or silicon carbide.

[0054] The electrodes of the electrostatic chuck 20 are disposed in the main body of the electrostatic chuck 20. The electrodes of the electrostatic chuck 20 are films formed of a conductor. A DC power source is electrically connected to the electrodes of the electrostatic chuck 20. When a DC voltage is applied from the DC power source to the electrodes of the electrostatic chuck 20, an electrostatic attraction is generated between the electrostatic chuck 20 and the substrate W. The substrate W is attracted to the electrostatic chuck 20 and held by the electrostatic chuck 20 by the generated electrostatic attraction.

[0055] The plasma processing apparatus 1 may further include a gas supply line 25. The gas supply line 25 supplies a heat transfer gas, such as He gas, from a gas supply mechanism to a gap between the upper surface of the electrostatic chuck 20 and the back surface (lower surface) of the substrate W.

[0056] The plasma processing apparatus 1 may further include a cylindrical portion 28 and an insulating portion 29. The cylindrical portion 28 extends upward from the bottom of the chamber body 12. The cylindrical portion 28 extends along the outer periphery of the support body 15. The cylindrical portion 28 is formed of a conductive material and has a substantially cylindrical shape. The cylindrical portion 28 is electrically grounded. The insulating portion 29 is disposed on the cylindrical portion 28. The insulating portion 29 is formed of a material having insulating properties. The insulating portion 29 is formed, for example, of ceramics such as quartz. The insulating portion 29 has a substantially cylindrical shape. The insulating portion 29 extends along the outer periphery of the electrode plate 19, the outer periphery of the lower electrode 18, and the outer periphery of the electrostatic chuck 20.

[0057] The plasma processing apparatus 1 further includes an upper electrode 30 . The upper electrode 30 is provided above the substrate support 16 . The upper electrode 30 closes the upper opening of the chamber body 12 together with a member 32 . The member 32 has insulating properties. The upper electrode 30 is supported on the upper portion of the chamber body 12 via the member 32 .

[0058] The upper electrode 30 includes a top plate 34 and a support body 36. The lower surface of the top plate 34 defines an internal space 10s. A plurality of gas ejection holes 34a are formed in the top plate 34. The plurality of gas ejection holes 34a penetrate the top plate 34 in the plate thickness direction (vertical direction). The top plate 34 is not defined and is formed, for example, of silicon. Alternatively, the top plate 34 may have a structure in which a plasma-resistant film is provided on the surface of an aluminum component. The film may be a ceramic film such as a film formed by anodizing or a film formed of yttrium oxide.

[0059] 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, for example. A gas diffusion chamber 36a is provided inside the support body 36. A plurality of gas holes 36b extend downward from the gas diffusion chamber 36a. The plurality of gas holes 36b are respectively connected to the plurality of gas discharge 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.

[0060] 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 a gas supply unit. The gas source group 40 includes a plurality of gas sources. The valve group 41 and the valve group 43 each include a plurality of valves (e.g., an on-off valve). The flow controller group 42 includes a plurality of flow controllers. The plurality of flow controllers of the flow controller group 42 are respectively mass flow controllers or pressure-controlled flow controllers. The plurality of gas sources of the gas source group 40 are connected to the gas supply pipe 38 via the corresponding valve of the valve group 41, the corresponding flow controller of the flow controller group 42 and the corresponding valve of the valve group 43. The plasma processing device 1 can supply gas from one or more gas sources selected from the plurality of gas sources of the gas source group 40 to the internal space 10s at an independently adjusted flow rate.

[0061] A partition 48 is provided between the cylindrical portion 28 and the side wall of the chamber body 12. The partition 48 may be a plate-shaped member. The partition 48 may be formed, for example, by covering a ceramic such as yttrium oxide on an aluminum plate. A plurality of through holes are formed in the partition 48. Below the partition 48, an exhaust pipe 52 is connected to the bottom of the chamber body 12. An exhaust device 50 is connected to the exhaust pipe 52. The exhaust device 50 has a pressure regulating valve such as an automatic pressure control valve and a vacuum pump such as a turbomolecular pump, so that the pressure in the internal space 10s can be reduced.

[0062] The plasma processing apparatus 1 further includes a high-frequency power supply 61. The high-frequency power supply 61 is a power supply for generating high-frequency power RF for plasma generation. The frequency of the high-frequency power RF is not limited, but is a frequency in the range of 27 to 100 MHz, for example, 40 MHz or 60 MHz. In order to supply high-frequency power RF to the lower electrode 18, the high-frequency power supply 61 is connected to the lower electrode 18 via a matcher 63 and an electrode plate 19. The matcher 63 has a matching circuit for matching the output impedance of the high-frequency power supply 61 with the impedance of the load side (lower electrode 18 side). In addition, the high-frequency power supply 61 may be connected to the upper electrode 30 via the matcher 63, and may not be electrically connected to the lower electrode 18.

[0063] The plasma processing apparatus 1 further includes a power supply device 70. The power supply device 70 has a first output 70a and a second output 70b. The first output 70a is an output for a first DC voltage generated by the power supply device 70. The second output 70b is an output for a second DC voltage generated by the power supply device 70. The second DC voltage has a polarity that is the same as that of the first DC voltage. The polarity of the first DC voltage and the polarity of the second DC voltage are, for example, negative polarity. The polarity of the first DC voltage and the polarity of the second DC voltage may be positive polarity. The second DC voltage has a level different from that of the first DC voltage. In one embodiment, the level (absolute value) of the second DC voltage is lower than the level (absolute value) of the first DC voltage. In addition, the level (absolute value) of the second DC voltage may be higher than the level (absolute value) of the first DC voltage.

[0064] Figure 3 (a) and Figure 3 (b) are respectively Figure 2 FIG. 1 is a diagram showing the structure of a power supply device for a plasma processing device. Figure 3 As shown in (a), the power supply device 70 may include a DC power supply 71a and a DC power supply 71b. Figure 3 In the power supply device 70 shown in (a), a DC power supply 71a is connected to the first output 70a, and a DC power supply 71b is connected to the second output 70b.

[0065] like Figure 3 As shown in (b), the power supply device 70 may include a plurality of DC power supplies 71 connected in series. Figure 3 In the power supply device 70 shown in (b), the first output 70a is connected to the end on the opposite side of the end on the ground side of the series connection of the plurality of DC power supplies 71. Figure 3 In the power supply device 70 shown in (b) of FIG. 1 , the second output 70 b is connected to a node between two consecutive DC power supplies in the series connection of the plurality of DC power supplies 71 .

[0066] like Figure 2 As shown, the plasma processing apparatus 1 further includes a first switch SW1, a second switch SW2, and a third switch SW3. The first switch SW1 is electrically connected between the first output 70a and the lower electrode 18. The second switch SW2 is electrically connected between the second output 70b and the lower electrode 18. Figure 2 In the example shown, the first switch SW1 and the second switch SW2 share a common electric path 74. The electric path 74 is connected to the electric path 64 that connects the high-frequency power source 61 and the lower electrode 18 to each other. The electric path 74 includes a filter 76. The filter 76 is a low-pass filter, and cuts off or reduces the high-frequency power from the electric path 64 toward the power supply device 70. The third switch SW3 is connected between the ground line and the lower electrode 18. In one example, the third switch SW3 is connected between the ground line and the electric path 74.

[0067] When performing plasma processing using the plasma processing apparatus 1, gas is supplied to the internal space 10s. Then, by supplying high-frequency power RF, the gas is excited in the internal space 10s. As a result, plasma is generated in the internal space 10s. The substrate W is processed by chemical species such as ions and / or radicals from the generated plasma.

[0068] The plasma processing apparatus 1 further includes a control unit MC. The control unit MC is a computer including a processor, a storage device, an input device, a display device, etc., and controls each unit of the plasma processing apparatus 1. Specifically, the control unit MC executes a control program stored in the storage device, and controls each unit of the plasma processing apparatus 1 according to the recipe data stored in the storage device. Through the control based on the control unit MC, the process specified by the recipe data is executed in the plasma processing apparatus 1. Through the control of each unit of the plasma processing apparatus 1 by the control unit MC, the method MT1 can be executed in the plasma processing apparatus 1.

[0069] Below, reference Figure 1 and Figure 4 The method MT1 will be described in detail. In addition, the application of the voltage from the power supply device 70 to the lower electrode 18 by the control unit MC will be described below. Figure 4 is with Figure 1 A timing diagram of an example of a plasma processing method. Figure 4 The horizontal axis represents time. Figure 4 In the figure, the vertical axis represents the states of the first switch SW1, the second switch SW2, and the third switch SW3, the potential of the lower electrode 18, and the state of the high-frequency power RF. The "ON" of each state of the first switch SW1, the second switch SW2, and the third switch SW3 represents the conductive state. The "OFF" of each state of the first switch SW1, the second switch SW2, and the third switch SW3 represents the non-conductive state. The "ON" of the state of the high-frequency power RF indicates that the high-frequency power RF is supplied, and the "OFF" of the state of the high-frequency power RF indicates that the supply of the high-frequency power RF is stopped.

[0070] The method MT1 is performed in a state where the substrate W is placed on the substrate support 16. The method MT1 includes a step STP. In the step STP, plasma is generated in the chamber 10. In the step STP, gas is supplied from the gas supply unit to the internal space 10s. In the step STP, the pressure in the chamber 10 is set to a specified pressure by the exhaust device 50. In the step STP, high-frequency power RF is supplied from the high-frequency power supply 61 to excite the gas in the chamber 10. In order to perform the step STP, the gas supply unit, the exhaust device 50 and the high-frequency power supply 61 are controlled by the control unit MC. The steps ST1 and ST2 of the method MT1 described below are performed during the plasma generation process of the step STP.

[0071] The step ST1 is performed in the first period T1. In the step ST1, the first DC voltage is applied to the lower electrode 18 from the power supply device 70. The first period T1 may have a predetermined time length. The first period T1 includes a period during which the potential of the lower electrode 18 becomes a stable state after the first output 70a and the lower electrode 18 are connected to each other. In the step ST1, the first switch SW1 is set to the conducting state in order to connect the first output 70a and the lower electrode 18 to each other. In the step ST1, the second switch SW2 is set to the non-conducting state in order to cut off the connection between the second output 70b and the lower electrode 18. In the step ST1, the third switch SW3 is set to the non-conducting state in order to cut off the connection between the ground line and the lower electrode 18. In order to perform the step ST1, the control unit MC performs control (first control) of setting the first switch SW1 to the conducting state and setting the second switch SW2 and the third switch SW3 to the non-conducting state.

[0072] The step ST2 is performed in the second period T2. The second period T2 is a period different from the first period T1. In the step ST2, a second DC voltage is applied to the lower electrode 18 from the power supply device 70. The second period T2 may have a predetermined time length. The second period T2 includes a period during which the potential of the lower electrode 18 becomes a stable state after the second output 70b and the lower electrode 18 are connected to each other. In the step ST2, the second switch SW2 is set to a conducting state in order to connect the second output 70b and the lower electrode 18 to each other. In the step ST2, the first switch SW1 is set to a non-conducting state in order to cut off the connection between the first output 70a and the lower electrode 18. In the step ST2, the third switch SW3 is set to a non-conducting state in order to cut off the connection between the ground line and the lower electrode 18. In order to perform the step ST2, the control unit MC performs control (second control) of setting the second switch SW2 to a conducting state and setting the first switch SW1 and the third switch SW3 to a non-conducting state.

[0073] Method MT1 may further include a process STG11 between the process ST1 and the process ST2. The process STG11 is performed during the period TG11 (third period). The period TG11 is the period between the end time of the first period T1 and the start time of the second period T2. In the process STG11, the third switch SW3 is set to the on state in order to connect the lower electrode 18 and the ground line to each other. In the process STG11, the first switch SW1 is set to the non-conducting state in order to cut off the connection between the first output 70a and the lower electrode 18. In the process STG11, the second switch SW2 is set to the non-conducting state in order to cut off the connection between the second output 70b and the lower electrode 18. In order to perform the process STG11, the control unit MC performs control (third control) to set the third switch SW3 to the on state and the first switch SW1 and the second switch SW2 to the non-conducting state.

[0074] The method MT1 may further include a step STF11 between the step STG11 and the step ST2. The step STF11 is performed during the period TF11. The period TF11 is the period between the end time of the period TG11 and the start time of the second period T2. In the step STF11, the first switch SW1, the second switch SW2, and the third switch SW3 are set to a non-conductive state. That is, in the step STF11, the potential of the lower electrode 18 is set to a floating state. In order to perform the step STF11, the control unit MC performs control to set the first switch SW1, the second switch SW2, and the third switch SW3 to a non-conductive state.

[0075] In the method MT1, the step ST1 and the step ST2 may be repeated alternately. In this case, the method MT1 may further include a step STG12 between the step ST2 and the next step ST1. The step STG12 is performed during the period TG12. The period TG12 is the period between the end time of the second period T2 and the start time of the next first period T1. In the step STG12, the third switch SW3 is set to the conducting state in order to connect the lower electrode 18 and the ground line to each other. In the step STG12, the first switch SW1 is set to the non-conducting state in order to cut off the connection between the first output 70a and the lower electrode 18. In the step STG12, the second switch SW2 is set to the non-conducting state in order to cut off the connection between the second output 70b and the lower electrode 18. In order to perform the step STG12, the control unit MC performs control to set the third switch SW3 to the conducting state and the first switch SW1 and the second switch SW2 to the non-conducting state.

[0076] The method MT1 may further include a step STF12 between the step STG12 and the next step ST1. The step STF12 is performed during the period TF12. The period TF12 is the period between the end time of the period TG12 and the start time of the next first period T1. In the step STF12, the first switch SW1, the second switch SW2, and the third switch SW3 are set to a non-conductive state. That is, in the step STF12, the potential of the lower electrode 18 is set to a floating state. In order to perform the step STF12, the control unit MC performs control to set the first switch SW1, the second switch SW2, and the third switch SW3 to a non-conductive state.

[0077] The method MT1 may further include a step STJ1. In the step STJ1, it is determined whether a stop condition is satisfied. For example, the stop condition is satisfied when the number of executions of the sequence SQ1 including the steps ST1 and ST2 reaches a predetermined number of times. If it is determined in the step STJ1 that the stop condition is not satisfied, the sequence SQ1 is executed again from the step ST1. On the other hand, if it is determined in the step STJ1 that the stop condition is satisfied, the method MT1 is terminated.

[0078] As described above, the first DC voltage and the second DC voltage have the same polarity. Furthermore, the absolute value of one of the first DC voltage and the second DC voltage is smaller than the absolute value of the other DC voltage. Therefore, in one of the first period T1 and the second period T2 when a DC voltage is applied to the lower electrode 18, the energy of the ions supplied to the substrate W is lower than the energy of the ions supplied to the substrate W in the other period. Furthermore, the energy of the ions supplied to the substrate W in one period is higher than the energy supplied to the substrate W when the potential of the lower electrode 18 is the ground potential. Therefore, it is possible to supply the substrate W with ions having an energy between the energy of the ions supplied to the substrate when a DC voltage of a unipolar level is applied to the lower electrode 18 and the energy of the ions supplied to the substrate W when the potential of the lower electrode 18 is the ground potential.

[0079] The following references Figure 5 . Figure 5 is with Figure 1 A timing chart of another example of the plasma processing method shown. Figure 4 In the example shown, the high frequency power RF is continuously supplied during the execution of the sequence SQ1 or during the repetition. Figure 5 As shown, in method MT1, the supply and stop of the high-frequency power RF can be switched alternately. Figure 5 In the example shown, the supply of the high-frequency power RF is stopped in the first period T1 and the second period T2. Figure 5 In the example shown, the high-frequency power RF is supplied in the period other than the first period T1 and the second period T2.

[0080] Below, reference Figure 6 A plasma processing method according to another embodiment will be described. Figure 6 1 is a flow chart of a plasma processing method according to another exemplary embodiment. Figure 6 The plasma treatment method shown (hereinafter referred to as "Method MT2"). Figure 7 FIG. 1 is a diagram schematically showing a plasma processing apparatus according to another exemplary embodiment. Figure 7 The differences between the plasma processing apparatus 1B shown and the plasma processing apparatus 1 will be described.

[0081] The plasma processing apparatus 1B includes a power supply device 70B instead of the power supply device 70. The power supply device 70B has an output 70Ba. The power supply device 70B includes a DC power supply that generates a DC voltage, and outputs the DC voltage from the output 70Ba. The DC voltage outputted by the power supply device 70B may have a single-level level.

[0082] The plasma processing apparatus 1B may further include a first switch SWB1 and a second switch SWB2. The first switch SWB1 is connected between the output 70Ba of the power supply device 70B and the lower electrode 18. The second switch SWB2 is connected between the lower electrode 18 and the ground. In one embodiment, the first switch SWB1 is connected to the electrical path 74. The electrical path 74 is connected to the electrical path 64. The second switch SWB2 is connected between the ground and the electrical path 74.

[0083] Below, reference Figure 6 and Figure 8 The method MT2 will be described in detail. In addition, the control of the application of the voltage from the power supply device 70B to the lower electrode 18 by the control unit MC of the plasma processing apparatus 1B will also be described below. Figure 8 is with Figure 6 A timing diagram of an example of a plasma processing method is shown. Figure 8 The horizontal axis represents time. Figure 8 In FIG. 1 , the vertical axis represents each state of the first switch SWB1 and the second switch SWB2, the potential of the lower electrode 18, and the potential of the substrate W. The "ON" state of each state of the first switch SWB1 and the second switch SWB2 represents a conductive state. The "OFF" state of each state of the first switch SWB1 and the second switch SWB2 represents a non-conductive state.

[0084] Method MT2 is performed with the substrate W placed on the substrate support 16. Figure 6As shown, method MT2 is started in step STP. Step STP of method MT2 is the same step as step STP of method MT1. In method MT2, in order to execute step STP, the gas supply unit, exhaust device 50 and high-frequency power supply 61 are controlled by control unit MC. Step ST21, step ST22 and step ST23 of method MT2 described below are executed during the plasma generation process of step STP.

[0085] The step ST21 is performed in the first period T21. In the step ST21, a DC voltage is applied to the lower electrode 18 from the power supply device 70B. The first period T21 may have a predetermined time length. The first period T21 includes a period during which the potential of the lower electrode 18 becomes a stable state after the output 70Ba and the lower electrode 18 are connected to each other. In the step ST21, the first switch SWB1 is set to a conductive state in order to connect the output 70Ba and the lower electrode 18 to each other. In the step ST21, the second switch SWB2 is set to a non-conductive state in order to cut off the connection between the lower electrode 18 and the ground line. In order to perform the step ST21, the control unit MC performs control (first control) to set the first switch SWB1 to a conductive state and the second switch SWB2 to a non-conductive state.

[0086] The step ST22 is performed in the second period T22. The second period T22 is a period different from the first period T21. In the step ST22, the lower electrode 18 is connected to the ground line. In the step ST22, the lower electrode 18 is electrically isolated from the power supply device 70B. In the step ST22, the second switch SWB2 is set to the on state in order to connect the lower electrode 18 to the ground line. In the step ST22, the first switch SWB1 is set to the non-conducting state in order to cut off the connection between the output 70Ba and the lower electrode 18. In order to perform the step ST22, the control unit MC performs control (second control) of setting the second switch SWB2 to the on state and setting the first switch SWB1 to the non-conducting state. The second period T22 ends before the potential of the lower electrode 18 reaches the ground potential. The time length of the second period T22 can be predetermined.

[0087] The step ST23 is performed in the third period T23. The third period T23 is a period after the second period T22, and starts before the potential of the lower electrode 18 connected to the ground line in the second period T22 reaches the ground potential. In the step ST23, the power supply device 70B is connected to the lower electrode 18. In the step ST23, the lower electrode 18 is electrically isolated from the ground line. In the step ST23, the first switch SWB1 is set to the on state in order to connect the output 70Ba and the lower electrode 18 to each other. In the step ST23, the second switch SWB2 is set to the non-conducting state in order to cut off the connection between the lower electrode 18 and the ground line. In order to perform the step ST23, the control unit MC performs control (third control) to set the first switch SWB1 to the on state and the second switch SWB2 to the non-conducting state.

[0088] The end time of the step ST23, i.e., the end time of the third period T23, is the time before the potential of the lower electrode 18 becomes stable. The third period T23 may have a predetermined time length. At the end time of the third period T23, the lower electrode 18 is electrically isolated from the power supply device 70B. That is, at the end time of the third period T23, the control unit MC sets the first switch SWB1 to a non-conductive state.

[0089] In one embodiment, the method MT2 may further include a step STF21. The step STF21 is performed between the step ST22 and the step ST23. That is, the step STF21 is performed in the period TF21 between the end time of the second period T22 and the start time of the third period T23. In the step STF21, the lower electrode 18 is electrically isolated from both the power supply device 70B and the ground line. In the step STF21, both the first switch SWB1 and the second switch SWB2 are set to a non-conductive state. In order to perform the step STF21, the control unit MC performs control to set both the first switch SWB1 and the second switch SWB2 to a non-conductive state.

[0090] In one embodiment, step ST22 and step ST23 may be repeated alternately. That is, sequence SQ21 including step ST22 and step ST23 may be repeated. In this case, method MT2 further includes step STJ21. In step STJ21, it is determined whether a stop condition is satisfied. For example, the stop condition is satisfied when the number of executions of sequence SQ21 reaches a predetermined number of times. If it is determined in step STJ21 that the stop condition is not satisfied, sequence SQ21 is executed again from step ST22. On the other hand, if it is determined in step STJ21 that the stop condition is satisfied, the repetition of sequence SQ21 ends.

[0091] In one embodiment, a sequence SQ22 including the step ST21 and the sequence SQ21 may be repeatedly performed. The sequence SQ22 may further include a step ST24. The step ST24 is performed after the determination of the step ST21. That is, the step ST24 is performed in the period T24 after the third period T23.

[0092] In step ST24, the lower electrode 18 is connected to the ground line. In step ST24, the lower electrode 18 is electrically isolated from the power supply device 70B. In step ST24, the second switch SWB2 is set to the conducting state in order to connect the lower electrode 18 to the ground line. In step ST24, the first switch SWB1 is set to the non-conducting state in order to disconnect the output 70Ba from the lower electrode 18. In order to execute step ST24, the control unit MC performs control to set the second switch SWB2 to the conducting state and the first switch SWB1 to the non-conducting state.

[0093] Sequence SQ22 may further include step STF22. Step STF22 is performed after step ST24. That is, step STF22 is performed during period TF22 after period T24. In step STF22, lower electrode 18 is electrically isolated from both power supply device 70B and ground. In step STF22, both first switch SWB1 and second switch SWB2 are set to a non-conductive state. In order to perform step STF22, control unit MC performs control to set both first switch SWB1 and second switch SWB2 to a non-conductive state.

[0094] Method MT2 may further include step STJ22. In step STJ22, it is determined whether a stop condition is satisfied. For example, the stop condition is satisfied when the number of executions of sequence SQ22 reaches a predetermined number of times. If it is determined in step STJ22 that the stop condition is not satisfied, sequence SQ22 is executed again from step ST21. On the other hand, if it is determined in step STJ22 that the stop condition is satisfied, method MT2 is terminated.

[0095] In the second period T22, the absolute value of the potential of the lower electrode 18 decreases from the absolute value of the potential of the lower electrode 18 in the first period T21, but does not reach zero. Also, in the third period T23, the absolute value of the potential of the lower electrode 18 increases from the absolute value of the potential of the lower electrode 18 in the second period T22, but does not reach the same potential as the potential of the lower electrode 18 in the first period T21. Therefore, the energy of the ions supplied to the substrate W in the second period T22 and the energy of the ions supplied to the substrate W in the third period T23 are lower than the energy of the ions supplied to the substrate in the first period T21. Also, the energy of the ions supplied to the substrate W in the second period T22 and the energy of the ions supplied to the substrate W in the third period T23 are higher than the energy supplied to the substrate W when the potential of the lower electrode 18 is the ground potential. Therefore, ions having an energy between the energy of the ions supplied to the substrate when the DC voltage of the unipolar level is applied to the lower electrode 18 and the energy of the ions supplied to the substrate when the potential of the lower electrode 18 is the ground potential can be supplied to the substrate.

[0096] The following references Figure 8 and Fig. 9 . Fig. 9 1B is a diagram showing an example of one or more potential measurement probes. The plasma processing apparatus 1B may further include one or more potential measurement probes. Fig. 9 In the example shown, the plasma processing apparatus 1B includes a potential measuring probe 81. The potential measuring probe 81 is configured to measure the potential of the substrate W. The control unit MC may end the step ST22 when the potential measured by the potential measuring probe 81 reaches a predetermined potential V23. That is, the control unit MC may set the second switch SWB2 to a non-conductive state when the potential measured by the potential measuring probe 81 reaches the predetermined potential V23.

[0097] Then, the control unit MC may terminate step ST23 when the potential measured by the potential measuring probe 81 reaches the predetermined potential V22. That is, the control unit MC sets the first switch SWB1 to a non-conductive state when the potential measured by the potential measuring probe 81 reaches the predetermined potential V22.

[0098] In another example, the plasma processing apparatus 1B may further include a potential measuring probe 82 or a potential measuring probe 83 as one or more potential measuring probes. The potential measuring probe 82 is configured to measure the potential of the edge ring ER. The potential measuring probe 83 is configured to measure the potential of the lower electrode 18. The control unit MC may terminate the step ST22 when the potential measured by the potential measuring probe 82 or the potential measuring probe 83 reaches a predetermined potential. Furthermore, the control unit MC may terminate the step ST23 when the potential measured by the potential measuring probe 82 or the potential measuring probe 83 reaches another predetermined potential.

[0099] Below, reference Fig.10 A plasma processing method according to still another embodiment will be described. Fig.10 FIG. 1 is a flow chart of a plasma processing method according to another exemplary embodiment. Fig.10 The plasma processing method (hereinafter referred to as "method MT3") shown in the figure. When the method MT3 is performed, the plasma processing apparatus 1 can be used. When the plasma processing apparatus 1 is used when the method MT3 is performed, the second DC voltage output from the second output 70b of the power supply device 70 has a level (absolute value) lower than the level (absolute value) of the first DC voltage output from the first output 70a of the power supply device 70.

[0100] Below, reference Fig.10 and Fig.11 The method MT3 will be described in detail. In addition, the control of the application of the voltage from the power supply device 70 to the lower electrode 18 by the control unit MC of the plasma processing apparatus 1 will also be described below. Fig.11 is with Fig.10 A timing diagram of an example of a plasma processing method is shown. Fig.11 The horizontal axis represents time. Fig.11 , the vertical axis represents each state of the first switch SW1, the second switch SW2, and the third switch SW3, the potential of the lower electrode 18, and the potential of the substrate W. "ON" in each state of the first switch SW1, the second switch SW2, and the third switch SW3 represents a conductive state. "OFF" in each state of the first switch SW1, the second switch SW2, and the third switch SW3 represents a non-conductive state.

[0101] Method MT3 is performed with the substrate W placed on the substrate support 16. Fig.10 As shown, the method MT3 is started in the step STP. The step STP of the method MT3 is the same step as the step STP of the method MT1. In the method MT3, in order to execute the step STP, the gas supply part, the exhaust device 50 and the high-frequency power supply 61 are also controlled by the control part MC. In the plasma generation process of the step STP, the steps ST31, ST32 and ST33 of the method MT3 described below are executed.

[0102] The step ST31 is performed in the first period T31. In the step ST31, the first DC voltage is applied to the lower electrode 18 from the first output 70a of the power supply device 70. The first period T31 may have a predetermined time length. The first period T31 includes a period during which the potential of the lower electrode 18 becomes a stable state after the first output 70a and the lower electrode 18 are connected to each other. In the step ST31, the first switch SW1 is set to the conducting state in order to connect the first output 70a and the lower electrode 18 to each other. In the step ST31, the second switch SW2 is set to the non-conducting state in order to disconnect the connection between the lower electrode 18 and the second output 70b. In the step ST31, the third switch SW3 is set to the non-conducting state in order to disconnect the connection between the lower electrode 18 and the ground line. In order to perform the step ST31, the control unit MC performs control (first control) of setting the first switch SW1 to the conducting state and setting the second switch SW2 and the third switch SW3 to the non-conducting state.

[0103] The step ST32 is performed in the second period T32. The second period T32 is a period different from the first period T31. In the step ST32, the lower electrode 18 is connected to the ground line. In the step ST32, the lower electrode 18 is electrically isolated from the first output 70a and the second output 70b. In the step ST32, the third switch SW3 is set to the conducting state in order to connect the lower electrode 18 to the ground line. In the step ST32, the first switch SW1 is set to the non-conducting state in order to cut off the connection between the first output 70a and the lower electrode 18. In the step ST32, the second switch SW2 is set to the non-conducting state in order to cut off the connection between the second output 70b and the lower electrode 18. In order to perform the step ST32, the control unit MC performs control (second control) to set the third switch SW3 to the conducting state and the first switch SW1 and the second switch SW2 to the non-conducting state. The second period T32 ends before the potential of the lower electrode 18 reaches the ground potential. The time length of the second period T32 can be predetermined.

[0104] The step ST33 is performed in the third period T33. The third period T33 is a period after the second period T32, and starts before the potential of the lower electrode 18 connected to the ground line in the second period T32 reaches the ground potential. In the step ST33, the second output 70b is connected to the lower electrode 18. In the step ST33, the lower electrode 18 is electrically isolated from the first output 70a and the ground line. In the step ST33, the second switch SW2 is set to the conducting state in order to connect the second output 70b and the lower electrode 18 to each other. In the step ST33, the first switch SW1 is set to the non-conducting state in order to disconnect the connection between the lower electrode 18 and the first output 70a. In the step ST33, the third switch SW3 is set to the non-conducting state in order to disconnect the connection between the lower electrode 18 and the ground line. In order to perform the step ST32, the control unit MC performs control (third control) to set the second switch SW2 to the conducting state and the first switch SW1 and the third switch SW3 to the non-conducting state.

[0105] The end time of the step ST33, i.e., the end time of the third period T33, is the time before the potential of the lower electrode 18 becomes a stable state. The third period T33 may have a predetermined time length. At the end time of the third period T33, the lower electrode 18 is electrically isolated from the second output 70b of the power supply device 70. That is, at the end time of the third period T33, the control unit MC sets the second switch SW2 to a non-conductive state.

[0106] In one embodiment, the method MT3 may further include a step STF31. The step STF31 is performed between the step ST32 and the step ST33. That is, the step STF31 is performed in the period TF31 between the end time of the second period T32 and the start time of the third period T33. In the step STF31, the lower electrode 18 is electrically isolated from the first output 70a, the second output 70b, and the ground. In the step STF31, the first switch SW1, the second switch SW2, and the third switch SW3 are set to a non-conductive state. In order to perform the step STF31, the control unit MC performs control to set the first switch SW1, the second switch SW2, and the third switch SW3 to a non-conductive state.

[0107] In one embodiment, step ST32 and step ST33 may be repeated alternately. That is, sequence SQ31 including step ST32 and step ST33 may be repeated. In this case, method MT3 includes step STJ31. In step STJ31, it is determined whether a stop condition is satisfied. For example, the stop condition is satisfied when the number of executions of sequence SQ31 reaches a predetermined number of times. If it is determined in step STJ31 that the stop condition is not satisfied, sequence SQ31 is executed again from step ST32. On the other hand, if it is determined in step STJ31 that the stop condition is satisfied, the repetition of sequence SQ31 ends.

[0108] In one embodiment, a sequence SQ32 including the step ST31 and the sequence SQ31 may be repeatedly performed. The sequence SQ32 may further include a step ST34. The step ST34 is performed after the determination of the step ST31. That is, the step ST34 is performed in the period T34 after the third period T33.

[0109] In step ST34, the lower electrode 18 is connected to the ground line. In step ST34, the lower electrode 18 is electrically isolated from the first output 70a and the second output 70b. In step ST34, the third switch SW3 is set to the conducting state in order to connect the lower electrode 18 to the ground line. In step ST34, the first switch SW1 is set to the non-conducting state in order to cut off the connection between the first output 70a and the lower electrode 18. In step ST34, the second switch SW2 is set to the non-conducting state in order to cut off the connection between the second output 70b and the lower electrode 18. In order to execute step ST34, the control unit MC performs control to set the third switch SW3 to the conducting state and set the first switch SW1 and the second switch SW2 to the non-conducting state.

[0110] The sequence SQ32 may further include a step STF32. The step STF32 is performed after the step ST34. That is, the step STF32 is performed during the period TF32 after the period T34. In the step STF32, the lower electrode 18 is electrically isolated from the first output 70a, the second output 70b, and the ground. In the step STF32, the first switch SW1, the second switch SW2, and the third switch SW3 are set to a non-conductive state. In order to perform the step STF32, the control unit MC performs control to set the first switch SW1, the second switch SW2, and the third switch SW3 to a non-conductive state.

[0111] Method MT3 may further include step STJ32. In step STJ32, it is determined whether a stop condition is satisfied. For example, the stop condition is satisfied when the number of executions of sequence SQ32 reaches a predetermined number of times. If it is determined in step STJ32 that the stop condition is not satisfied, sequence SQ32 is executed again from step ST31. On the other hand, if it is determined in step STJ32 that the stop condition is satisfied, method MT3 is terminated.

[0112] In the second period T32, the absolute value of the potential of the lower electrode 18 decreases from the absolute value of the potential of the lower electrode 18 in the first period T31, but does not reach zero. Also, in the third period T33, the absolute value of the potential of the lower electrode 18 increases from the absolute value of the potential of the lower electrode 18 in the second period T32, but does not reach the same potential as the potential of the lower electrode 18 in the first period T31. Therefore, the energy of the ions supplied to the substrate W in the second period T32 and the energy of the ions supplied to the substrate W in the third period T33 are lower than the energy of the ions supplied to the substrate in the first period T31. Also, the energy of the ions supplied to the substrate W in the second period T32 and the energy of the ions supplied to the substrate W in the third period T33 are higher than the energy supplied to the substrate W when the potential of the lower electrode 18 is the ground potential. Therefore, ions having an energy between the energy of the ions supplied to the substrate when the DC voltage of the unipolar level is applied to the lower electrode 18 and the energy of the ions supplied to the substrate when the potential of the lower electrode 18 is the ground potential can be supplied to the substrate.

[0113] In addition, when executing method MT3, the potential measuring probe 81, the potential measuring probe 82, or the potential measuring probe 83 may be used. The control unit MC may end step ST32 when the potential of the substrate W measured by the potential measuring probe 81 reaches the predetermined potential V33. That is, the control unit MC may set the third switch SW3 to a non-conductive state when the potential measured by the potential measuring probe 81 reaches the predetermined potential V33.

[0114] Furthermore, the control unit MC may end the step ST33 when the potential of the substrate W measured by the potential measuring probe 81 reaches the predetermined potential V32. That is, the control unit MC may set the third switch SW2 to a non-conductive state when the potential of the substrate W measured by the potential measuring probe 81 reaches the predetermined potential V32.

[0115] In another example, the control unit MC may terminate the step ST32 when the potential of the edge ring ER measured by the potential measuring probe 82 or the potential of the lower electrode 18 measured by the potential measuring probe 83 reaches a predetermined potential. Furthermore, the control unit MC may terminate the step ST33 when the potential of the edge ring ER measured by the potential measuring probe 82 or the potential of the lower electrode 18 measured by the potential measuring probe 83 reaches another predetermined potential.

[0116] Various exemplary embodiments have been described above, but the present invention is not limited to the exemplary embodiments described above, and various omissions, substitutions, and changes may be made. Furthermore, elements in different embodiments may be combined to form other embodiments.

[0117] For example, the plasma processing apparatus used in the method MT1, the method MT2, and the method MT3 may be any type of plasma processing apparatus other than a capacitive coupling type. Examples of such a plasma processing apparatus include an inductively coupled plasma processing apparatus and a plasma processing apparatus that generates plasma using surface waves such as microwaves. In addition, in each of the plasma processing methods involved in the various embodiments, the number of levels of the potential set at the lower electrode 18 may be more than three.

[0118] As can be seen from the above description, various embodiments of the present invention are described in this specification for the purpose of illustration, and various changes can be made without departing from the scope and spirit of the present invention. Therefore, the various embodiments disclosed in this specification are not intended to be limiting, and the true scope and spirit are shown by the scope of the attached claims.

Claims

1. A plasma processing device comprising: a plasma processing chamber; a substrate support disposed within the plasma processing chamber, the substrate support comprising a lower electrode; a first DC power supply configured to generate a first DC voltage having a first voltage level; a second DC power supply configured to generate a second DC voltage having a second voltage level different from the first voltage level, the second DC voltage having the same polarity as the first DC voltage; a first switch configured to switch between a first conducting state and a first non-conducting state, wherein the lower electrode is connected to the first DC power source in the first conducting state and is disconnected from the first DC power source in the first non-conducting state; a second switch configured to switch between a second conducting state and a second non-conducting state, wherein the lower electrode is connected to the second DC power source in the second conducting state and is disconnected from the second DC power source in the second non-conducting state; as well as A controller configured to: causing, during a first period of a repeating sequence, the first conducting state of the first switch and the second non-conducting state of the second switch; as well as During a second period of the repeating sequence, the first non-conductive state of the first switch and the second conductive state of the second switch are induced.

2. The plasma processing apparatus according to claim 1, further comprising: a third switch configured to switch between a third conductive state and a third non-conductive state, wherein the lower electrode is connected to a reference potential in the third conductive state and disconnected from the reference potential in the third non-conductive state, in, The controller is configured to control the first switch, the second switch and the third switch so that: causing the first conducting state, the second non-conducting state and the third non-conducting state during the first period of the repeating sequence; causing the first non-conducting state, the second conducting state and the third non-conducting state during the second period of the repeating sequence; and During a third period of the repeating sequence between the first period and the second period, the first non-conducting state, the second non-conducting state and the third conducting state are induced.

3. The plasma processing apparatus according to claim 2, wherein: The controller is configured to control the first switch, the second switch, and the third switch to cause the first non-conducting state, the second non-conducting state, and the third conducting state during a fourth period of the repeating sequence after the second period.

4. The plasma processing apparatus according to claim 3, wherein: An absolute value of the reference potential is smaller than an absolute value of the first voltage level and an absolute value of the second voltage level.

5. The plasma processing apparatus according to claim 4, wherein: The reference potential is ground potential.

6. The plasma processing apparatus according to claim 5, wherein: The first DC voltage and the second DC voltage have negative polarity.

7. A plasma processing device comprising: a plasma processing chamber; a substrate support disposed within the plasma processing chamber, the substrate support comprising a lower electrode; A power supply system is configured to apply a first DC voltage to the lower electrode during a first period of a repeating sequence and to apply a second DC voltage to the lower electrode during a second period of the repeating sequence, wherein the first DC voltage has a first voltage level and the second DC voltage has a second voltage level different from the first voltage level.

8. The plasma processing apparatus according to claim 7, wherein: The power supply system is configured to connect the lower electrode to a reference potential during a third period of the repeating sequence between the first period and the second period.

9. The plasma processing apparatus according to claim 8, wherein: The power supply system is configured to connect the lower electrode to a reference potential during a fourth period of the repeating sequence following the second period.

10. The plasma processing apparatus according to claim 9, wherein: An absolute value of the reference potential is smaller than an absolute value of the first voltage level and an absolute value of the second voltage level.

11. The plasma processing apparatus according to claim 10, wherein: The reference potential is ground potential.

12. The plasma processing apparatus according to claim 11, wherein: The first DC voltage and the second DC voltage have negative polarity.

13. The plasma processing apparatus according to claim 9, wherein: The power supply system comprises: a switch configured to switch between a conducting state and a non-conducting state, wherein the lower electrode is connected to the reference potential in the conducting state and is disconnected from the reference potential in the non-conducting state; and A controller is configured to control the switch to cause the non-conducting state during the first and second periods of the repeating sequence and to cause the conducting state during the third and fourth periods of the repeating sequence.

14. A plasma processing device comprising: a plasma processing chamber; a substrate support disposed within the plasma processing chamber, the substrate support comprising a lower electrode; a DC power supply configured to generate a DC voltage; a first switch configured to switch between a first conducting state and a first non-conducting state, wherein the lower electrode is connected to the DC power source in the first conducting state and is disconnected from the DC power source in the first non-conducting state; a second switch configured to switch between a second conductive state and a second non-conductive state, wherein the lower electrode is connected to a reference potential in the second conductive state and is disconnected from the reference potential in the second non-conductive state; as well as A controller configured to: During a first period, maintaining the first conducting state of the first switch and the second non-conducting state of the second switch to increase the potential of the lower electrode; as well as During a second period, the first non-conductive state of the first switch and the second conductive state of the second switch are maintained to reduce the potential of the lower electrode. The first period and the second period are repeated in an alternating manner, so that the transition from the first period to the second period occurs before the lower electrode reaches a maximum potential.

15. The plasma processing apparatus according to claim 14, wherein: The controller is configured to: In a third period, the first conductive state of the first switch and the second non-conductive state of the second switch are maintained until the lower electrode reaches the maximum potential.

16. The plasma processing apparatus according to claim 14, wherein: The first period is less than the second period.

17. The plasma processing apparatus according to claim 16, wherein: The DC voltage has a first voltage level, and an absolute value of the reference potential is smaller than an absolute value of the first voltage level.

18. The plasma processing apparatus according to claim 17, wherein: The reference potential is ground potential.

19. The plasma processing apparatus according to claim 18, wherein: The DC voltage has a negative polarity.

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