Plasma processing method and plasma processing apparatus

Abstract

The plasma processing method disclosed in the present invention includes a process of generating plasma in a chamber of a plasma processing apparatus by supplying high-frequency electric power from a high-frequency power source during a first period. The plasma processing method further includes a process of stopping the supply of high-frequency electric power from the high-frequency power source during a second period that is consecutive to the first period. The plasma processing method further includes a process of applying a direct-current voltage of a negative polarity from a bias power source to a substrate support during a third period that is consecutive to the second period. During the third period, no high-frequency electric power is supplied. During the third period, the direct-current voltage of the negative polarity is set to generate ions in the chamber using secondary electrons that are released by causing ions in the chamber to collide with a substrate.

Description

TECHNICAL FIELD

[0001] An exemplary embodiment of the present application relates to a plasma processing method and a plasma processing apparatus. BACKGROUND

[0002] In plasma processing of a substrate, a plasma processing apparatus is used. The plasma processing apparatus is provided with a chamber, a substrate support, and a high-frequency power source. The substrate support is configured to have a lower electrode and support a substrate in the chamber. The high-frequency power source supplies high-frequency electric power to generate plasma from a gas in the chamber. Such a plasma processing apparatus is disclosed in Patent Literature 1 (i.e., Japanese Patent Application Publication No. 2009-187975).

[0003] The plasma processing apparatus disclosed in Patent Literature 1 is further provided with a DC negative pulse generating device. The DC negative pulse generating device intermittently applies a pulse of a direct current voltage of a negative polarity to the lower electrode when the high-frequency power source supplies the high-frequency electric power to generate the plasma. SUMMARY

[0004] The present application provides a technology for improving processing efficiency of a substrate with respect to electric power used.

[0005] In one exemplary embodiment, a plasma processing method is provided. The plasma processing method includes a step of generating plasma in a chamber of a plasma processing apparatus by supplying high-frequency electric power from a high-frequency power source during a first period. During the first period, a direct current voltage of a negative polarity is not applied from a bias power source to a substrate support provided in the chamber. The plasma processing method further includes a step of stopping the supply of the high-frequency electric power from the high-frequency power source during a second period that is subsequent to the first period. During the second period, the direct current voltage of the negative polarity is not applied from the bias power source to the substrate support. The plasma processing method further includes a step of applying the direct current voltage of the negative polarity from the bias power source to the substrate support during a third period that is subsequent to the second period. During the third period, the high-frequency electric power is not supplied. During the third period, the direct current voltage of the negative polarity is set to generate ions in the chamber by secondary electrons that are released by causing ions in the chamber to collide with a substrate on the substrate support.

[0006] According to one exemplary embodiment, it is possible to improve processing efficiency of a substrate with respect to electric power used. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 is a flowchart of a plasma processing method according to one exemplary embodiment.

[0008] Figure 2 is a diagram that schematically shows a plasma processing apparatus according to one exemplary embodiment.

[0009] Figure 3 is a timing chart of one example of high-frequency power, DC voltage, electron density, and ion density.

[0010] Figure 4 is a timing chart of one example of high-frequency power and DC voltage.

[0011] Figure 5 is a diagram showing a structure of a high-frequency power supply and a bias power supply of a plasma processing apparatus according to one illustrative embodiment.

[0012] Figure 6 (a) is a diagram showing one example of a state of plasma and behavior of radicals during a first period, Figure 6 (b) is a diagram showing one example of behavior of ions during a third period, Figure 6 (c) is a diagram showing one example of behavior of byproducts in exhaust gas after the third period.

[0013] Figure 7 is a timing chart of another example of high-frequency power and DC voltage. DETAILED DESCRIPTION

[0014] Hereinafter, various illustrative embodiments will be described.

[0015] In one illustrative embodiment, a plasma processing method is provided. The plasma processing method includes a process of generating plasma in a chamber of a plasma processing apparatus by supplying high-frequency power from a high-frequency power supply during a first period. During the first period, a negative DC voltage is not applied from a bias power supply to a substrate support provided in the chamber. The plasma processing method further includes a process of stopping the supply of the high-frequency power from the high-frequency power supply during a second period succeeding the first period. During the second period, the negative DC voltage is not applied from the bias power supply to the substrate support. The plasma processing method further includes a process of applying the negative DC voltage from the bias power supply to the substrate support during a third period succeeding the second period. During the third period, the high-frequency power is not supplied. During the third period, the negative DC voltage is set to generate ions in the chamber by secondary electrons released by ions in the chamber colliding with a substrate on the substrate support.

[0016] In the above-described embodiment, electron density in the plasma generated during the first period rapidly decreases during the second period. During the third period, secondary electrons are released by ions in the plasma colliding with a surface of the substrate. During the third period, the substrate is processed by ions generated from the released secondary electrons. During the third period, the high-frequency power is not supplied, and thus reflection of the high-frequency power does not occur. Therefore, according to the above-described embodiment, the processing efficiency (e.g., etching efficiency) of the substrate relative to the use power becomes high.

[0017] In one illustrative embodiment, a series of processes including the process of generating plasma, the process of stopping supply of high-frequency power, and the process of applying a direct-current voltage of a negative polarity can be repeatedly performed.

[0018] In one illustrative embodiment, the plasma processing method can further include a process of exhausting gas in the chamber in a state where high-frequency power from the high-frequency power source is not supplied and a direct-current voltage from the bias power source is not applied to the lower electrode. The exhaust process is performed after the series of processes including the process of generating plasma, the process of stopping supply of high-frequency power, and the process of applying a direct-current voltage of a negative polarity are performed one or more times. According to this embodiment, byproducts generated when the series of processes are performed are effectively exhausted by the exhaust process.

[0019] In one illustrative embodiment, the series of processes and the process of exhausting gas can be alternately repeatedly performed one or more times.

[0020] In one illustrative embodiment, the plasma processing method can further include a process of applying a direct-current voltage of a positive polarity to the substrate support during the second period. In this embodiment, electrons in the plasma can be further rapidly reduced during the second period. Therefore, the second period can be shortened.

[0021] In one illustrative embodiment, the absolute value of the direct-current voltage of a negative polarity applied to the substrate support during the third period can be 500 V or more.

[0022] In one illustrative embodiment, during the first period, radicals from the plasma can be attached to a substrate on the substrate support. During the third period, the radicals and ions generated by secondary electrons can etch the substrate by colliding with the substrate.

[0023] In another illustrative embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a substrate support, a high-frequency power source, a bias power source, and a control portion. The substrate support includes a base. The substrate support is configured to support a substrate in the chamber. The high-frequency power source is configured to supply high-frequency power to generate a plasma from a gas in the chamber. The bias power source is configured to apply a negative direct-current voltage to the substrate support. The control portion is configured to control the high-frequency power source and the bias power source. The control portion is configured to perform first control during a first period. The first control includes controlling the high-frequency power source to supply the high-frequency power to generate the plasma in the chamber in a state where the negative direct-current voltage from the bias power source is not applied to the substrate support. The control portion is configured to perform second control during a second period that follows the first period. The second control includes controlling the high-frequency power source to stop the supply of the high-frequency power in the state where the negative direct-current voltage from the bias power source is not applied to the substrate support. The control portion is configured to perform third control during a third period that follows the second period. The third control includes controlling the bias power source to apply the negative direct-current voltage to the substrate support in a state where the high-frequency power from the high-frequency power source is not supplied. During the third period, the negative direct-current voltage applied to the substrate support is set to generate ions in the chamber using secondary electrons that are released by causing ions in the chamber to collide with a substrate on the substrate support.

[0024] In one illustrative embodiment, the control portion is configured to repeatedly perform a series of controls including the first control, the second control, and the third control.

[0025] In one illustrative embodiment, the plasma processing apparatus can further include an exhaust apparatus. The control portion can be configured to perform fourth control after performing the series of controls including the first control, the second control, and the third control one or more times. The fourth control includes controlling the exhaust apparatus to exhaust the gas in the chamber in a state where the high-frequency power from the high-frequency power source is not supplied and the direct-current voltage from the bias power source is not applied to the substrate support.

[0026] In one illustrative embodiment, the control portion can be configured to repeatedly perform the series of controls one or more times and the fourth control alternately.

[0027] In one illustrative embodiment, the second control can further include controlling the bias power source or another bias power source to apply a positive direct-current voltage to the substrate support during the second period.

[0028] In one illustrative embodiment, an absolute value of the negative direct-current voltage applied to the substrate support during the third period can be 500 V or more.

[0029] Hereinafter, various exemplary embodiments will be described in detail with reference to the accompanying drawings. In addition, in each drawing, the same or corresponding portions are denoted by the same symbol.

[0030] Figure 1 is a flowchart of a plasma processing method according to an exemplary embodiment. The plasma processing method shown in Figure 1 is executed in a plasma processing apparatus. The plasma processing in the method MT is, for example, plasma etching.

[0031] Figure 2 is a diagram schematically showing a plasma processing apparatus according to an exemplary embodiment. The plasma processing apparatus shown in Figure 2 The plasma processing apparatus 1 shown in is capable of executing the method MT. The plasma processing apparatus 1 is a capacitively coupled plasma processing apparatus. The plasma processing apparatus 1 is provided with a chamber 10. The chamber 10 is provided with an internal space 10s inside thereof.

[0032] 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, for example, aluminum. A film having corrosion resistance is provided on an inner wall surface of the chamber body 12. The film having corrosion resistance can be a film formed of a ceramic such as aluminum oxide or yttrium oxide.

[0033] A passage 12p is formed in a side wall of the chamber body 12. The passage 12p is passed through when the substrate W is carried between the internal space 10s and the outside of the chamber 10. The passage 12p is capable of being opened and closed by a gate valve 12g. The gate valve 12g is provided along the side wall of the chamber body 12.

[0034] A support portion 13 is provided on a bottom portion of the chamber body 12. The support portion 13 is formed of an insulating material. The support portion 13 has a substantially cylindrical shape. In the internal space 10s, the support portion 13 extends upward from the bottom portion of the chamber body 12. The support portion 13 supports a substrate support 14. The substrate support 14 is configured to support the substrate W in the internal space 10s.

[0035] The substrate support 14 has a base 18 and an electrostatic chuck 20. The substrate support 14 can further have an electrode plate 16. The electrode plate 16, the base 18, and the electrostatic chuck 20 are provided inside the chamber 10. The electrode plate 16 is formed of, for example, a conductor such as aluminum, and has a substantially disc shape. The base 18 is provided on the electrode plate 16. The base 18 is formed of, for example, a conductor such as aluminum, and has a substantially disc shape. The base 18 is electrically coupled to the electrode plate 16.

[0036] An electrostatic chuck 20 is provided on the base 18. A substrate W is placed on an upper surface of the electrostatic chuck 20. The electrostatic chuck 20 has a main body and an electrode. The main body of the electrostatic chuck 20 has a substantially disc shape and is formed of a dielectric. The electrode of the electrostatic chuck 20 is a film-like electrode and is provided in the main body of the electrostatic chuck 20. The electrode of the electrostatic chuck 20 is connected to a direct current power source 20p via a switch 20s. If a voltage from the direct current power source 20p is applied to the electrode of the electrostatic chuck 20, electrostatic attraction is generated between the electrostatic chuck 20 and the substrate W. The substrate W is attracted to the electrostatic chuck 20 by the generated electrostatic attraction and is held by the electrostatic chuck 20.

[0037] An edge ring ER is mounted on a peripheral portion of the substrate support 14. The edge ring ER is provided to improve in-plane uniformity of plasma processing of the substrate W. The edge ring ER has a substantially plate shape and a ring shape. The edge ring ER is not limited and can be formed of silicon, silicon carbide, or quartz. The substrate W is disposed on the electrostatic chuck 20 in a region surrounded by the edge ring ER.

[0038] A flow path 18f is provided inside the base 18. The flow path 18f is supplied with a heat exchange medium (e.g., refrigerant) from a cooling unit 22 provided outside the chamber 10 via a pipe 22a. The heat exchange medium supplied to the flow path 18f is returned to the cooling 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 base 18.

[0039] A gas supply line 24 is provided in the plasma processing apparatus 1. The gas supply line 24 supplies a heat transfer gas (e.g., He gas) from a heat transfer gas supply mechanism to a gap between an upper surface of the electrostatic chuck 20 and a back surface of the substrate W.

[0040] The plasma processing apparatus 1 further includes an upper electrode 30. The upper electrode 30 is provided above the substrate support 14. The upper electrode 30 is supported to an upper portion of the chamber main body 12 via a member 32. The member 32 is formed of a material having insulating properties. The upper electrode 30 and the member 32 close an upper opening of the chamber main body 12.

[0041] The upper electrode 30 can include a top plate 34 and a support body 36. A lower surface of the top plate 34 is a lower surface on the inside space 10s side and defines the inside space 10s. The top plate 34 can be formed of a conductor or a semiconductor having low resistance and less Joule heat. A plurality of gas discharge holes 34a are formed in the top plate 34. The plurality of gas discharge holes 34a penetrate the top plate 34 in a plate thickness direction thereof.

[0042] The support body 36 supports the top plate 34 removably. The support body 36 is formed of an electrically conductive material such as aluminum. The inside of the support body 36 is provided with a gas diffusion chamber 36a. A plurality of gas holes 36b are formed in the support body 36. The plurality of gas holes 36b extend downward from the gas diffusion chamber 36a. The plurality of gas holes 36b respectively communicate with the plurality of gas discharge holes 34a. A gas introduction port 36c is formed in the support body 36. The gas introduction port 36c is connected to the gas diffusion chamber 36a. A gas supply pipe 38 is connected to the gas introduction port 36c.

[0043] The gas source group 40 is connected to the gas supply pipe 38 via the valve group 41, the flow rate controller group 42, and the valve group 43. 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 rate controller group 42 includes a plurality of flow rate controllers. Each of the plurality of flow rate controllers of the flow rate controller group 42 is a mass flow controller or a pressure-controlled flow rate 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 rate controller of the flow rate controller group 42, and the corresponding on-off valve of the valve group 43.

[0044] In the plasma processing apparatus 1, a shield 46 is removably provided along the inner wall surface of the chamber body 12. The shield 46 is also provided to the outer periphery of the support portion 13. The shield 46 prevents etching by-products from adhering to the chamber body 12. The shield 46 is constituted, for example, by forming a film having corrosion resistance on the surface of a member formed of aluminum. The film having corrosion resistance can be a film formed of a ceramic such as yttrium oxide.

[0045] A partition plate 48 is provided between the support portion 13 and the side wall of the chamber body 12. The partition plate 48 is constituted, for example, by forming a film having corrosion resistance on the surface of a member formed of aluminum. The film having corrosion resistance can be a film formed of a ceramic such as yttrium oxide. A plurality of through holes are formed in the partition plate 48. An exhaust port 12e is provided below the partition 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 turbo molecular pump.

[0046] The plasma processing apparatus 1 further has a high-frequency power supply 61. The high-frequency power supply 61 is configured to generate high-frequency electric power HF. The frequency of the high-frequency electric power HF is, for example, a frequency in a range of 13 MHz or more and 200 MHz or less. The high-frequency power supply 61 supplies the high-frequency electric power HF to generate plasma from a gas in the chamber 10.

[0047] In one embodiment, the high-frequency power source 61 is electrically coupled to the base 18 via a matcher 61m, and the base 18 functions as a lower electrode. The matcher 61m has a matching circuit. The matching circuit of the matcher 61m is configured to match the impedance of the load side (the base side) of the high-frequency power source 61 to the output impedance of the high-frequency power source 61. In another embodiment, the high-frequency power source 61 can be electrically coupled to the upper electrode 30 via the matcher 61m.

[0048] Between the high-frequency power source 61 and the matcher 61m, a circulator 61c and a directional coupler 61d can be coupled. The circulator 61c has first to third ports. The circulator 61c receives the high-frequency power HF from the high-frequency power source 61 at the first port, and outputs the high-frequency power HF from the second port toward the load (i.e., the base 18 or the upper electrode 30) of the high-frequency power source 61. The circulator 61c outputs a reflected wave received at the second port from the third port to prevent the reflected wave from returning to the high-frequency power source 61. The directional coupler 61d outputs a portion of a forward wave of the high-frequency power HF and a portion of a reflected wave from the load of the high-frequency power source 61. The portion of the forward wave and the portion of the reflected wave are used for load power control in a control section 80 described later.

[0049] The plasma processing apparatus 1 further includes a bias power source 62. The bias power source 62 is electrically coupled to the substrate support. In one embodiment, the bias power source 62 is electrically coupled to the base 18. In one embodiment, the bias power source 62 is coupled to the base 18 via a filter 62f. The filter 62f is a low-pass filter configured to suppress the inflow of high-frequency to the bias power source 62. The bias power source 62 is configured to generate a direct-current voltage V B of a negative polarity to introduce ions into the substrate support 14. The direct-current voltage V B is applied to the base 18.

[0050] The plasma processing apparatus 1 further includes a control section 80. The control section 80 can be a computer including a processor, a storage section such as a memory, an input device, a display device, an input / output interface for signals, and the like. The control section 80 controls each section of the plasma processing apparatus 1. In the control section 80, the operator can perform an input operation of an instruction or the like using the input device to manage the plasma processing apparatus 1. Also, in the control section 80, a visualized working condition of the plasma processing apparatus 1 can be displayed using the display device. Further, a control program and recipe data are stored in the storage section of the control section 80. The processor of the control section 80 executes the control program to perform various processes in the plasma processing apparatus 1. The processor of the control section 80 executes the control program to control each section of the plasma processing apparatus 1 in accordance with the recipe data, whereby the method MT can be performed in the plasma processing apparatus 1.

[0051] Hereinafter, the Figure 2Reference Signs List Figure 3 and Figure 4 . Figure 3 is a timing chart of one example of high-frequency power, DC voltage, electron density, and ion density. Figure 4 is a timing chart of one example of high-frequency power and DC voltage. In Figure 3 and Figure 4 , V OUT represents an output voltage of the bias power supply 62. In Figure 3 , Ne represents an electron density in the chamber 10, and Ni represents an ion density in the chamber 10.

[0052] As shown in Figure 3 , the high-frequency power supply 61 supplies high-frequency power HF during a 1st period P1. The high-frequency power supply 61 stops supplying the high-frequency power HF during a 2nd period P2 succeeding the 1st period P1 and during a 3rd period P3 succeeding the 2nd period P2. That is, the high-frequency power supply 61 supplies pulses of the high-frequency power HF. In the 1st to 3rd periods, the pulses of the high-frequency power HF are maintained during the 1st period P1.

[0053] In the 1st to 3rd periods, the bias power supply 62 applies a DC voltage V B of a negative polarity to the base 18 during the 3rd period P3. The bias power supply 62 stops applying the DC voltage V B of the negative polarity to the base 18 during the 1st period P1 and the 2nd period P2.

[0054] The high-frequency power supply 61 and the bias power supply 62 are controlled by a control section 80. The control section 80 performs a 1st control during the 1st period P1. The 1st control includes controlling the high-frequency power supply 61 to supply the high-frequency power HF to generate a plasma in the chamber 10 in a state where the DC voltage V B of the negative polarity from the bias power supply 62 is not applied to the base 18. The 1st control can further include controlling the bias power supply 62 to stop the application of the DC voltage V B of the negative polarity to the base 18. The 1st control can further include controlling a gas supply section to supply a selected gas into the chamber 10 and controlling the exhaust device 50 to set a gas pressure in the chamber 10 to a specified pressure. In the 1st period P1, a plasma is generated from a gas by a high-frequency electric field based on the high-frequency power HF in the chamber 10.

[0055] The control section 80 performs a 2nd control during the 2nd period P2. The 2nd control includes controlling the high-frequency power supply 61 to stop supplying the high-frequency power HF in a state where the DC voltage V B of the negative polarity from the bias power supply 62 is not applied to the base 18. The 2nd control can further include controlling the bias power supply 62 to maintain the application of the DC voltage V BThe second control may further include controlling the gas supply unit to supply the selected gas into the chamber 10, and controlling the exhaust device 50 to set the gas pressure in the chamber 10 to a specified pressure. Furthermore, the duration of the second period P2 is predetermined so that, although ions in the plasma generated during the first period P1 remain in the chamber 10, electrons in the plasma are substantially eliminated.

[0056] The control unit 80 performs the third control in the third period P3. The third control includes controlling the bias power supply 62 to increase the negative polarity DC voltage V to 0 when the high frequency power HF from the high frequency power supply 61 is not supplied. B is applied to the base 18. That is, the bias power supply 62 applies a negative polarity DC voltage V B The pulse is applied to the base 18. During the first to third periods, the negative polarity DC voltage V is maintained during the third period P3. B The third control may further include controlling the high frequency power source 61 to maintain the state where the supply of the high frequency power HF is stopped. The third control may further include controlling the gas supply unit to supply the selected gas into the chamber 10, and further include controlling the exhaust device 50 to set the gas pressure in the chamber 10 to a specified pressure. In the third control, that is, in the third period P3, a negative polarity DC voltage V is preset. B , in order to generate ions in the chamber 10 by utilizing secondary electrons released by causing ions in the chamber 10 to collide with the substrate W on the substrate support 14. The negative polarity DC voltage V B The absolute value of is, for example, 500 V or more. In the third period P3, the ions generated by the secondary electrons are ionized by the negative DC voltage V B The generated bias accelerates the substrate W toward the substrate.

[0057] In one embodiment, the control unit 80 may repeatedly execute a series of controls including the first control, the second control, and the third control. Figure 3 and Figure 4 As shown, the high frequency power supply 61 can repeatedly (ie periodically) supply pulses of high frequency power HF with a first period T1. In this embodiment, the bias power supply 62 can also provide a negative polarity DC voltage V B The power is repeatedly applied to the base 18 at a first period T1 (ie, periodically). The first period T1 may be a period defined at a frequency of 100 kHz or more and 800 kHz or less.

[0058] In one embodiment, the control unit 80 may execute the fourth control after executing the above series of controls once or more. The fourth control includes controlling the exhaust device 50 to exhaust the gas in the chamber 10 in a state where the high frequency power HF from the high frequency power source 61 is not supplied and the DC voltage from the bias power source 62 is not applied to the base 18. That is, Figure 4 As shown, the control unit 80 is in the period T ON , execute the above series of control more than once, during the continuous period T ON Period T OFF The fourth control is executed. During the period T ON The above series of controls may be periodically executed with a first period T1. Furthermore, the control unit 80 may alternately repeat the above series of controls with the fourth control. That is, the control unit 80 may periodically execute another series of controls, including the above series of controls executed once or more and the fourth control, with a second period T2. The second period T2 may be a period defined at a frequency of 1 kHz or higher and 40 kHz or lower.

[0059] Below, reference Figure 5 . Figure 5 This diagram illustrates the configuration of a high-frequency power supply and bias power supply for a plasma processing apparatus according to an exemplary embodiment. In one embodiment, the high-frequency power supply 61 may include a high-frequency signal generator 61g and an amplifier 61a. The high-frequency signal generator 61g generates a high-frequency signal. The frequency of the high-frequency signal is the same as the frequency of the high-frequency power HF. The output of the high-frequency signal generator 61g is combined with the amplifier 61a. The amplifier 61a amplifies the high-frequency signal from the high-frequency signal generator 61g and outputs the high-frequency power HF.

[0060] The plasma processing apparatus 1 may further include a synchronization signal generator 64. The control unit 80 controls the synchronization signal generator 64 to generate a first synchronization signal synchronized with the start and end times of the first period P1. The high-frequency signal generator 61g starts generating a high-frequency signal at the start of the first period P1 and stops generating the high-frequency signal at the end of the first period P1 in response to the first synchronization signal. Through the control of the high-frequency power source 61 by the control unit 80, high-frequency power HF is supplied during the first period P1.

[0061] In one embodiment, the bias power supply 62 may include a DC power supply 62p, a switching element 62s1, a switching element 62s2, and a dummy load 62d. The DC power supply 62p generates a negative DC voltage V B The DC power supply 62p may be a variable DC power supply.

[0062] The direct-current power supply 62p is electrically coupled to the base 18 via a switching element 62s1. When the switching element 62s1 is in an on state, a voltage from the direct-current power supply 62p is applied to the base 18. On the other hand, when the switching element 62s1 is in an off state, no voltage from the direct-current power supply 62p is applied to the base 18.

[0063] The switching element 62s2 is coupled between a node on the electric path (between the direct-current power supply 62p and the base 18) and the dummy load 62d. When the switching element 62s2 is in an on state, the electric potential of the base 18 is promptly set to the ground potential.

[0064] The control section 80 controls the synchronization signal generator 64 to generate a second synchronization signal that is synchronized with the start point and the end point of the third period P3. The second synchronization signal is supplied to the switching element 62s1 and the switching element 62s2. The switching element 62s1 becomes in an on state at the start point of the third period P3 and becomes in an off state at the end point of the third period P3 in accordance with the second synchronization signal. The switching element 62s2 becomes in an off state at the start point of the third period P3 and becomes in an on state at the end point of the third period P3 in accordance with the second synchronization signal.

[0065] Reference is again made to Figure 1 . And, in addition to Figure 1 reference is made to Figure 6 (a), Figure 6 (b) and Figure 6 (c). Figure 6 (a) is a diagram showing an example of the state of the plasma and the behavior of the radicals in the first period, Figure 6 (b) is a diagram showing an example of the behavior of the ions in the third period, Figure 6 (c) is a diagram showing an example of the behavior of the byproducts in the exhaust after the third period. In Figure 6 (a), Figure 6 (b) and Figure 6 (c), a part of the substrate W is also shown. The substrate W has a bottom surface region UR, a film EF and a mask MK. The film EF is provided on the bottom surface region UR. The mask MK is provided on the film EF and has a pattern that exposes a part of the surface of the film EF. Hereinafter, the method MT will be described in detail with the case where the plasma processing apparatus 1 is used as an example.

[0066] The method MT starts in a process ST1. The process ST1 is executed in the first period P1. By executing the process ST1, the high-frequency electric power HF is supplied from the high-frequency power supply 61 in the first period P1. In the first period P1, no direct-current voltage V B is applied from the bias power supply 62 to the base 18. As Figure 6(a) As shown, by performing the process ST1, in the 1st period P1, the plasma PL is generated in the chamber 10. The plasma PL is generated by dissociating the gas by the high frequency electric field generated by the supply of the high frequency electric power HF, and the generated electrons collide with molecules and / or atoms in the gas, thereby generating the plasma PL. That is, in the 1st period P1, the plasma PL is generated in the α mode. In the 1st period P1, the radicals CR originating from the plasma PL adhere to the surface of the film EF. In addition, the control section 80 performs the above-mentioned 1st control to perform the process ST1.

[0067] The next process ST2 is performed in the 2nd period P2. By performing the process ST2, in the 2nd period P2, the supply of the high frequency electric power HF from the high frequency power source 61 is stopped. In the 2nd period P2, the direct current voltage V B is not applied to the susceptor 18. As shown, in the 1st period P1, the ions in the plasma PL remain in the chamber 10 even after the 2nd period P2 ends, but the electrons in the plasma PL are rapidly reduced in the 2nd period P2 and substantially disappear. In addition, the control section 80 performs the above-mentioned 2nd control to perform the process ST2. Figure 3

[0068] The next process ST3 is performed in the 3rd period P3. By performing the process ST3, in the 3rd period P3, the direct current voltage V B of the negative polarity is applied to the susceptor 18. In the 3rd period P3, the high frequency electric power HF is not supplied. In the 3rd period P3, if the direct current voltage V B of the negative polarity is applied to the susceptor 18, the ions CI accelerate toward the substrate W and collide with the surface of the substrate W. As a result, secondary electrons are released from the surface of the substrate W. In the 3rd period P3, ions are generated in the chamber 10 by the released secondary electrons colliding with molecules and / or atoms in the gas. As a result, as shown, in the 3rd period P3, the ion density in the chamber 10 increases. That is, in the 3rd period P3, the plasma is generated in the γ mode. In addition, the absolute value of the direct current voltage V B of the negative polarity in which the γ mode is generated is, for example, 500 V or more. Figure 3

[0069] As shown, in the 3rd period P3, the ions CI generated by the secondary electrons colliding with molecules and / or atoms in the gas accelerate toward the substrate W by the bias based on the direct current voltage V B of the negative polarity. As a result, the substrate W is processed. In one example, the film EF of the substrate W is etched. In this example, the ions CI collide with the substrate W to cause a reaction between the ions CI and / or the radicals CR and the material of the film EF, thereby etching the film EF. By this reaction, a byproduct CB is generated (refer to FIG. 2B). Figure 6 Figure 6 ​​​(c)). In addition, the control section 80 executes the above-described third control to execute the process ST3.

[0070] In the third period P3, the high-frequency power HF is not supplied, and thus the reflection of the high-frequency power HF does not occur. Therefore, according to the method MT and the plasma processing apparatus 1, the processing efficiency (for example, the etching efficiency) of the substrate W is made higher with respect to the used power.

[0071] The plasma generated in the γ mode has a characteristic that the ion current is large, as compared with the plasma generated in the α mode. The larger the ion current, the higher the etching rate becomes. Therefore, according to the etching of the film EF using the plasma generated in the γ mode in the third period P3, a high etching rate can be obtained. Also, the electron temperature of the plasma generated in the γ mode is lower than the electron temperature of the plasma generated in the α mode. When the electron temperature is low, heavy ions are generated by inhibiting the dissociation of molecules and / or atoms in the gas. The heavy ions can be introduced to the bottom of the opening formed in the film EF substantially perpendicularly. Therefore, by using the plasma generated in the γ mode in the third period P3, it is possible to etch the film EF to form an opening of a high aspect ratio substantially perpendicularly. Also, it is possible to inhibit the opening formed in the film EF from expanding in the lateral direction.

[0072] In one embodiment, the series of processes SQ1 including the process ST1 to the process ST3 can be repeatedly performed. The repetition cycle of the series of processes SQ1 is the above-described first period T1. In this embodiment, the method MT includes a process STa. In the process STa, it is determined whether or not a stop condition is satisfied. The stop condition is satisfied when the number of times of execution of the series of processes SQ1 reaches a prescribed number of times. If it is determined that the stop condition is not satisfied in the process STa, the series of processes SQ1 is executed again. If it is determined that the stop condition is satisfied in the process STa, the repetition of the series of processes SQ1 is ended. In addition, the control section 80 repeats the above-described series of controls to repeat the series of processes SQ1.

[0073] In one embodiment, the method MT can further include a process ST4. The process ST4 is executed after the series of processes SQ1 is executed one or more times. In the process ST4, the gas in the chamber 10 is exhausted by the exhaust apparatus 50. In the process ST4, the high-frequency power HF is not supplied from the high-frequency power source 61, and the negative direct-current voltage V B The process ST4 is executed in a state where the bias voltage Vbias is applied to the susceptor 18 from the bias power source 62. As described above, the bias voltage Vbias is applied to the susceptor 18 from the bias power source 62 in the process ST2. Therefore, the process ST4 is executed in a state where the bias voltage Vbias is applied to the susceptor 18 from the bias power source 62. Figure 6 As shown in (c), in the process ST4, the byproduct CB is exhausted from the chamber 10. That is, by executing the process ST4, the byproduct CB generated in the series of processes SQ1 is effectively exhausted from the chamber 10.

[0074] In one embodiment, the series of processes SQ1 is repeatedly performed one or more times alternately with the process ST4. That is, the series of processes SQ1 can be repeatedly performed one or more times, and the series of processes SQ2 including the process ST4. The repetition cycle of the series of processes SQ2 is the above-mentioned second cycle T2. In this embodiment, the method MT further includes a process STb. In the process STb, it is determined whether a stop condition is satisfied. The stop condition is satisfied when the number of times of execution of the series of processes SQ2 reaches a prescribed number of times. If it is determined in the process STb that the stop condition is not satisfied, the series of processes SQ2 is executed again. If it is determined in the process STb that the stop condition is satisfied, the repetition of the series of processes SQ2 is ended.

[0075] Hereinafter, the above-described embodiments will be described with reference to the drawings. Figure 7 . Figure 7 is a timing chart of another example of the high-frequency electric power and the direct-current voltage. In another embodiment, as shown in Figure 7 , during the second period P2, a direct-current voltage of a positive polarity can be applied to the base 18 by the bias power supply 62. During the second period P2, a direct-current voltage of a positive polarity can be applied to the base 18 by another bias power supply. According to this embodiment, it is possible to further rapidly reduce the electrons in the plasma PL. Therefore, it is possible to shorten the second period P2.

[0076] In addition, in the examples shown in Figure 3 , Figure 4 and Figure 7 , the direct-current voltage V B is shown as a voltage having a certain voltage value during the third period P3, but is not limited to these examples. The direct-current voltage V B may also include several voltage values. In addition, the direct-current voltage of a positive polarity shown in Figure 7 may also include several voltage values.

[0077] The above-described various exemplary embodiments have been described, but are not limited to the above-described exemplary embodiments, and various additions, omissions, substitutions, and changes can be made. Furthermore, components of different embodiments can be combined to form another embodiment.

[0078] In another embodiment, the plasma processing apparatus can be an inductively coupled plasma processing apparatus or another type of plasma processing apparatus. In an inductively coupled plasma processing apparatus, high-frequency electric power HF is supplied to an antenna for generating an inductively coupled plasma.

[0079] In another embodiment, one or more bias electrodes can be provided within the body of the electrostatic chuck 20 and can be coupled to the bias power supply 62 for a negative DC voltage (in addition, for a positive DC voltage, other bias power supplies can be coupled). The bias electrodes can also be the electrodes described above for the electrostatic chuck.

[0080] As is apparent from the above description, the various embodiments of the present application are described in the present specification for the purpose of illustration, and various changes can be made without departing from the scope and spirit of the present application. Therefore, the various embodiments disclosed in the present specification are not intended to be limiting, and the true scope and spirit of the present application are shown by the scope of the appended claims.

Claims

1. A plasma treatment method, comprising: a step of generating plasma in a chamber of a plasma processing apparatus by supplying high-frequency power from a high-frequency power supply during a first period, wherein a negative-polarity DC voltage is not applied from a bias power supply to a substrate support disposed in the chamber during the first period of the step; a step of stopping the supply of the high-frequency power from the high-frequency power source during a second period subsequent to the first period, wherein the negative-polarity DC voltage is not applied from the bias power source to the substrate support during the second period; and The negative polarity DC voltage is applied from the bias power supply to the substrate support during a third period following the second period, wherein the high-frequency power is not supplied during the third period of the process. During the third period, the negative polarity DC voltage is set so that ions are generated in the chamber using secondary electrons, and the generated ions are used to etch the substrate. The secondary electrons are released when the ions in the chamber collide with the substrate on the substrate support. During the second period, no positive polarity DC voltage is applied to the substrate support. A series of steps including the step of generating plasma, the step of stopping the supply of the high-frequency power, and the step of applying the negative-polarity DC voltage are repeated without applying the positive-polarity DC voltage to the substrate support.

2. The plasma processing method according to claim 1, wherein During the third period, an absolute value of the negative-polarity DC voltage applied to the substrate support is 500 V or greater.

3. The plasma processing method according to claim 1, wherein: The substrate is etched during the third period.

4. The plasma processing method according to claim 3, wherein: During the first period, radicals from the plasma adhere to the substrate on the substrate support. During the third period, the ions generated from the secondary electrons collide with the substrate, and the radicals and the ions etch the substrate.

5. The plasma processing method according to any one of claims 1 to 4, wherein: The plasma processing apparatus is a capacitively coupled plasma processing apparatus.

6. A plasma processing apparatus comprising: chamber; a substrate supporter including a base and configured to support the substrate in the chamber; a high-frequency power supply configured to supply high-frequency power to generate plasma from the gas in the chamber; a bias power supply configured to apply a negative-polarity DC voltage to the substrate support; and a control unit configured to control the high frequency power supply and the bias power supply, The control unit is configured to perform a first control in a first period, the first control including controlling the high-frequency power supply to supply the high-frequency power so as to generate plasma in the chamber without applying the negative-polarity DC voltage from the bias power supply to the substrate supporter. The control unit is configured to perform a second control in a second period following the first period, the second control including controlling the high-frequency power supply to stop supplying the high-frequency power in a state where the negative-polarity DC voltage from the bias power supply is not applied to the substrate support. The control unit is configured to perform a third control in a third period following the second period, the third control including controlling the bias power supply to apply the negative polarity DC voltage to the substrate support in a state where the high-frequency power from the high-frequency power supply is not supplied, the negative polarity DC voltage being set so as to generate ions in the chamber using secondary electrons released by causing ions in the chamber to collide with the substrate on the substrate support, and to etch the substrate using the generated ions. During the second period, no positive polarity DC voltage is applied to the substrate support. The control unit is configured to repeatedly execute a series of controls including the first control, the second control, and the third control without applying a positive-polarity DC voltage to the substrate support.

7. The plasma processing apparatus according to claim 6, wherein: During the third period, an absolute value of the negative-polarity DC voltage applied to the substrate support is 500 V or greater.

8. The plasma processing apparatus according to claim 6, wherein: The substrate is etched during the third period.

9. The plasma processing apparatus according to any one of claims 6 to 8, wherein: The plasma processing apparatus is a capacitively coupled plasma processing apparatus.

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