Plasma processing method and plasma processing apparatus

Abstract

A plasma processing method disclosed in the present invention includes a step of generating plasma in a chamber of a plasma processing apparatus by supplying high-frequency power from a high-frequency power source during a first period. The plasma processing method further includes a step of stopping the supply of the high-frequency power from the high-frequency power source during a second period following the first period. The plasma processing method further includes a step of applying a DC voltage having a negative polarity from the bias power source to the substrate support during a third period following the second period. In the third period, the high-frequency power is not supplied. In the third period, the negative-polarity direct-current voltage is set so that ions are generated in the chamber by means of secondary electrons that are released by causing the ions in the chamber to collide with the substrate.

Description

[0001] This application is a divisional application of the application filed on November 25, 2020, with application number 202011335819.5 and title "Plasma Processing Method and Plasma Processing Apparatus". Technical Field

[0002] The exemplary embodiments of the present invention relate to a plasma processing method and a plasma processing apparatus. Background Technology

[0003] In plasma processing of a substrate, a plasma processing apparatus is used. The plasma processing apparatus includes a chamber, a substrate support, and a high-frequency power supply. The substrate support is configured to have a lower electrode and support the substrate within the chamber. The high-frequency power supply supplies high-frequency electricity to generate plasma from gas within the chamber. Such a plasma processing apparatus is disclosed in Patent Document 1 (i.e., Japanese Patent Application Publication No. 2009-187975).

[0004] The plasma processing apparatus disclosed in Patent Document 1 further includes a DC negative pulse generating device. When the DC negative pulse generating device supplies high-frequency power from a high-frequency power source to generate plasma, it intermittently applies pulses of negative polarity DC voltage to the lower electrode. Summary of the Invention

[0005] This invention provides a technique for improving the processing efficiency of a substrate compared to using electricity.

[0006] In one exemplary embodiment, a plasma processing method is provided. The plasma processing method includes a step of generating plasma within a cavity of a plasma processing apparatus during a first period by supplying high-frequency power from a high-frequency power source. During the first period, a negative DC voltage is not applied from a bias power source to a substrate support disposed within the cavity. The plasma processing method further includes a step of stopping the supply of high-frequency power from the high-frequency power source during a second period following the first period. During the second period, a negative DC voltage is not applied from the bias power source to the substrate support. The plasma processing method further includes a step of applying a negative DC voltage from the bias power source to the substrate support during a third period following the second period. During the third period, high-frequency power is not supplied. During the third period, the negative DC voltage is set to generate ions within the cavity using secondary electrons, which are released by causing the ions within the cavity to collide with a substrate on the substrate support.

[0007] According to one exemplary embodiment, the processing efficiency of the substrate can be improved relative to the use of electricity. Attached Figure Description

[0008] Figure 1This is a flowchart illustrating a plasma processing method according to an exemplary embodiment.

[0009] Figure 2 This is a diagram that schematically illustrates a plasma processing apparatus according to an exemplary embodiment.

[0010] Figure 3 This is a time series diagram of an example of high-frequency power, DC voltage, electron density, and ion density.

[0011] Figure 4 This is a timing diagram of an example of high-frequency power and DC voltage.

[0012] Figure 5 This is a diagram showing the structure of the high-frequency power supply and bias power supply of a plasma processing apparatus according to an exemplary embodiment.

[0013] Figure 6 (a) is a diagram illustrating an example of the plasma state and free radical behavior during the first period. Figure 6 (b) is a diagram illustrating an example of the behavior of ions during the third period. Figure 6 (c) is a diagram illustrating an example of the behavior of byproducts in the exhaust gas after the third period.

[0014] Figure 7 This is another example of a timing diagram for high-frequency power and DC voltage. Detailed Implementation

[0015] The following describes various exemplary embodiments.

[0016] In one exemplary embodiment, a plasma processing method is provided. The plasma processing method includes a step of generating plasma within a cavity of a plasma processing apparatus during a first period by supplying high-frequency power from a high-frequency power source. During the first period, a negative DC voltage is not applied from a bias power source to a substrate support disposed within the cavity. The plasma processing method further includes a step of stopping the supply of high-frequency power from the high-frequency power source during a second period following the first period. During the second period, a negative DC voltage is not applied from the bias power source to the substrate support. The plasma processing method further includes a step of applying a negative DC voltage from the bias power source to the substrate support during a third period following the second period. During the third period, high-frequency power is not supplied. During the third period, the negative DC voltage is set to generate ions within the cavity using secondary electrons, which are released by causing the ions within the cavity to collide with a substrate on the substrate support.

[0017] In the above embodiment, the electron density in the plasma generated in the first period decreases rapidly in the second period. In the third period, secondary electrons are released by ions in the plasma colliding with the surface of the substrate. In the third period, the substrate is processed by ions generated from the released secondary electrons. During the third period, no high-frequency power is supplied, and therefore no high-frequency power reflection occurs. Therefore, according to the above embodiment, the substrate processing efficiency (e.g., etching efficiency) is higher than that using electricity.

[0018] In one exemplary embodiment, a series of steps including generating plasma, stopping the supply of high-frequency power, and applying a negative DC voltage can be repeated.

[0019] In one exemplary embodiment, the plasma processing method may further include a step of venting the gas in the chamber without supplying high-frequency power from a high-frequency power source and without applying a DC voltage from a bias power source to the lower electrode. The venting step is performed after performing a series of steps including generating plasma, stopping the supply of high-frequency power, and applying a negative DC voltage. According to this embodiment, the venting step effectively removes byproducts generated during the execution of the series of steps.

[0020] In one exemplary embodiment, a series of steps can be repeated alternately with the step of venting gas.

[0021] In one exemplary embodiment, the plasma processing method may further include a step of applying a positive DC voltage to the substrate support during the second period. In this embodiment, the number of electrons in the plasma can be further reduced rapidly during the second period. Therefore, the second period can be shortened.

[0022] In one exemplary embodiment, the absolute value of the negative DC voltage applied to the substrate support during the third period can be 500V or more.

[0023] In one exemplary embodiment, during the first period, free radicals from the plasma can adhere to the substrate on the substrate support. During the third period, the free radicals and ions can etch the substrate by colliding with the substrate through ions generated by secondary electrons.

[0024] In another exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a substrate support, a high-frequency power supply, a bias power supply, and a control unit. The substrate support includes a base. The substrate support is configured to support a substrate within the chamber. The high-frequency power supply is configured to supply high-frequency power to generate plasma from gas within the chamber. The bias power supply is configured to apply a negative DC voltage to the substrate support. The control unit is configured to control the high-frequency power supply and the bias power supply. The control unit is configured to perform a first control during a first period. The first control includes controlling the high-frequency power supply to supply high-frequency power to generate plasma within the chamber when a negative DC voltage from the bias power supply is not applied to the substrate support. The control unit is configured to perform a second control during a second period following the first period. The second control includes controlling the high-frequency power supply to stop supplying high-frequency power when a negative DC voltage from the bias power supply is not applied to the substrate support. The control unit is configured to perform a third control during a third period following the second period. The third control includes controlling the bias power supply to apply a negative DC voltage to the substrate support when no high-frequency power from the high-frequency power supply is supplied. During the third period, the negative DC voltage applied to the substrate support is set to generate ions in the chamber using secondary electrons, which are released by causing the ions in the chamber to collide with the substrate on the substrate support.

[0025] In one exemplary embodiment, the control unit is configured to repeatedly execute a series of controls, including a first control, a second control, and a third control.

[0026] In one exemplary embodiment, the plasma processing apparatus may further include an exhaust device. The control unit may be configured to perform a fourth control after executing a series of controls including a first control, a second control, and a third control once or more. The fourth control includes controlling the exhaust device to exhaust the gas in the chamber when no high-frequency power from the high-frequency power source is supplied and no DC voltage is applied from the bias power source to the substrate support.

[0027] In one exemplary embodiment, the control unit may be configured to alternately execute a series of controls once or more with a fourth control.

[0028] In one exemplary embodiment, the second control may further include controlling a bias power supply or another bias power supply to apply a positive DC voltage to the substrate support during the second period.

[0029] In one exemplary embodiment, the absolute value of the negative DC voltage applied to the substrate support during the third period can be 500V or more.

[0030] Hereinafter, various exemplary embodiments will be described in detail with reference to the accompanying drawings. Furthermore, in each drawing, the same or corresponding parts are labeled with the same symbols.

[0031] Figure 1 This is a flowchart illustrating a plasma processing method according to an exemplary embodiment. Execution Figure 1 The plasma processing method shown (hereinafter referred to as "Method MT") is used to perform plasma processing on a substrate in a plasma processing apparatus. The plasma processing in Method MT is, for example, plasma etching.

[0032] Figure 2 This is a schematic diagram illustrating a plasma processing apparatus according to an exemplary embodiment. It can be used... Figure 2 The plasma processing apparatus 1 shown executes method MT. The plasma processing apparatus 1 is a capacitively coupled plasma processing apparatus. The plasma processing apparatus 1 includes a chamber 10. An internal space 10s is provided inside the chamber 10.

[0033] The chamber 10 includes a chamber body 12. The chamber body 12 has a generally cylindrical shape. An internal space 10s is disposed inside the chamber body 12. The chamber body 12 is formed, for example, of aluminum. A corrosion-resistant film is provided on the inner wall surface of the chamber body 12. The corrosion-resistant film can be a film formed of ceramics such as alumina or yttrium oxide.

[0034] A passage 12p is formed on the side wall of the chamber body 12. When the substrate W is transported between the internal space 10s and the outside of the chamber 10, it passes through the passage 12p. The passage 12p can be opened and closed by a gate valve 12g. The gate valve 12g is provided along the side wall of the chamber body 12.

[0035] A support portion 13 is provided on the bottom of the chamber body 12. The support portion 13 is formed of an insulating material. The support portion 13 has a generally cylindrical shape. In the internal space 10s, the support portion 13 extends upward from the bottom of the chamber body 12. The support portion 13 supports the substrate support 14. The substrate support 14 is configured to support the substrate W in the internal space 10s.

[0036] The substrate support 14 has a base 18 and an electrostatic chuck 20. The substrate support 14 may further include an electrode plate 16. The electrode plate 16, the base 18, and the electrostatic chuck 20 are disposed within the chamber 10. The electrode plate 16 is formed, for example, of a conductor such as aluminum, and has a generally disc shape. The base 18 is disposed on the electrode plate 16. The base 18 is formed, for example, of a conductor such as aluminum, and has a generally disc shape. The base 18 is electrically coupled to the electrode plate 16.

[0037] An electrostatic chuck 20 is disposed on a base 18. A substrate W is mounted on the upper surface of the electrostatic chuck 20. The electrostatic chuck 20 has a main body and electrodes. The main body of the electrostatic chuck 20 has a generally disk-shaped shape and is formed of a dielectric material. The electrodes of the electrostatic chuck 20 are film electrodes and are disposed within the main body of the electrostatic chuck 20. The electrodes of the electrostatic chuck 20 are connected to a DC power supply 20p via a switch 20s. When a voltage from the DC power supply 20p is applied to the electrodes of the electrostatic chuck 20, an electrostatic attraction is generated between the electrostatic chuck 20 and the substrate W. Through the generated electrostatic attraction, the substrate W is attracted to the electrostatic chuck 20 and held by the electrostatic chuck 20.

[0038] An edge ring ER is mounted on the periphery of the substrate support 14. The edge ring ER is provided to improve the in-plane uniformity of plasma processing of the substrate W. The edge ring ER is generally plate-shaped and annular. 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 and within the area surrounded by the edge ring ER.

[0039] A flow path 18f is provided inside the base 18. A heat exchange medium (e.g., refrigerant) is supplied to the flow path 18f via a cooling unit 22 located outside the chamber 10 through a pipe 22a. The heat exchange medium supplied to the flow path 18f returns 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.

[0040] The plasma processing apparatus 1 is provided with a gas supply line 24. The gas supply line 24 supplies heat transfer gas (e.g., He gas) from the heat transfer gas supply mechanism to the gap between the upper surface of the electrostatic chuck 20 and the back surface of the substrate W.

[0041] The plasma processing apparatus 1 further includes an upper electrode 30. The upper electrode 30 is disposed above the substrate support 14. The upper electrode 30 is supported on the upper part of the chamber body 12 via a component 32. The component 32 is formed of an insulating material. The upper electrode 30 and the component 32 close the upper opening of the chamber body 12.

[0042] The upper electrode 30 may include a top plate 34 and a support 36. The lower surface of the top plate 34 is the lower surface of the internal space 10s side and defines the internal space 10s. The top plate 34 may be formed of a low-resistance conductor or semiconductor with low Joule heating. A plurality of gas vent holes 34a are formed on the top plate 34. The plurality of gas vent holes 34a penetrate the top plate 34 along its thickness direction.

[0043] The support body 36 detachably supports the top plate 34. The support body 36 is made of a conductive material such as aluminum. A gas diffusion chamber 36a is provided inside the support body 36. Multiple gas holes 36b are formed on the support body 36. The multiple gas holes 36b extend downwards from the gas diffusion chamber 36a. The multiple gas holes 36b are respectively connected to multiple gas discharge holes 34a. A gas inlet 36c is formed on 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.

[0044] Gas source assembly 40 is connected to gas supply pipe 38 via valve assembly 41, flow controller assembly 42, and valve assembly 43. Gas source assembly 40 includes multiple gas sources. Each of valve assembly 41 and valve assembly 43 includes multiple on / off valves. Flow controller assembly 42 includes multiple flow controllers. Each of the multiple flow controllers in flow controller assembly 42 is a mass flow controller or a pressure-controlled flow controller. Each of the multiple gas sources in gas source assembly 40 is connected to gas supply pipe 38 via a corresponding on / off valve of valve assembly 41, a corresponding flow controller of flow controller assembly 42, and a corresponding on / off valve of valve assembly 43.

[0045] In the plasma processing apparatus 1, a shielding member 46 is detachably mounted along the inner wall of the chamber body 12. The shielding member 46 is also disposed on the outer periphery of the support portion 13. The shielding member 46 prevents etching byproducts from adhering to the chamber body 12. The shielding member 46 is constructed, for example, by forming a corrosion-resistant film on the surface of a component made of aluminum. The corrosion-resistant film can be a film formed of ceramics such as yttrium oxide.

[0046] A partition 48 is provided between the support portion 13 and the side wall of the chamber body 12. The partition 48 is constructed, for example, by forming a corrosion-resistant film on the surface of a component made of aluminum. The corrosion-resistant film can be a film formed of ceramics such as yttrium oxide. Multiple through holes are formed on the partition 48. An exhaust port 12e is provided below the partition 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 includes a pressure regulating valve and a vacuum pump such as a turbomolecular pump.

[0047] The plasma processing apparatus 1 further includes a high-frequency power supply 61. The high-frequency power supply 61 is configured to generate high-frequency electrical energy HF. The frequency of the high-frequency electrical energy HF is, for example, a frequency in the range of 13 MHz to 200 MHz. The high-frequency power supply 61 supplies high-frequency electrical energy HF to generate plasma from the gas within the chamber 10.

[0048] In one embodiment, the high-frequency power supply 61 is electrically connected to the base station 18 via a matching adapter 61m, the base station 18 functioning as a lower electrode. The matching adapter 61m has a matching circuit. The matching circuit of the matching adapter 61m is configured to match the impedance on the load side (base station side) of the high-frequency power supply 61 with the output impedance of the high-frequency power supply 61. In another embodiment, the high-frequency power supply 61 may be electrically connected to the upper electrode 30 via the matching adapter 61m.

[0049] A circulator 61c and a directional coupler 61d can be combined between the high-frequency power supply 61 and the matching unit 61m. The circulator 61c has ports 1 to 3. The circulator 61c receives high-frequency power HF from the high-frequency power supply 61 at port 1 and outputs high-frequency power HF from port 2 towards the load of the high-frequency power supply 61 (i.e., the base 18 or the upper electrode 30). The circulator 61c outputs the reflected wave received at port 2 from port 3 to prevent the reflected wave from returning to the high-frequency power supply 61. The directional coupler 61d outputs a portion of the proceeding wave of the high-frequency power HF and a portion of the reflected wave from the load of the high-frequency power supply 61. A portion of the power of the proceeding wave and a portion of the power of the reflected wave are used for load power control in the control unit 80 described later.

[0050] The plasma processing apparatus 1 further includes a bias power supply 62. The bias power supply 62 is electrically connected to a substrate support. In one embodiment, the bias power supply 62 is electrically connected to a base station 18. In another embodiment, the bias power supply 62 is connected to the base station 18 via a filter 62f. The filter 62f is a low-pass filter configured to suppress high-frequency inflow into the bias power supply 62. The bias power supply 62 is configured to generate a negative DC voltage V. B This allows ions to be introduced into the substrate support 14. A negative DC voltage V is applied. B Apply to base 18.

[0051] The plasma processing apparatus 1 further includes a control unit 80. The control unit 80 may be a computer equipped with a processor, a memory, an input device, a display device, and a signal input / output interface. The control unit 80 controls each part of the plasma processing apparatus 1. In the control unit 80, the operator can use the input device to input commands and manage the plasma processing apparatus 1. Furthermore, the display device in the control unit 80 can display a visual view of the operating status of the plasma processing apparatus 1. Moreover, the control unit 80 stores control programs and recipe data in its storage unit. The processor of the control unit 80 executes the control program to perform various processes in the plasma processing apparatus 1. By executing the control program and controlling each part of the plasma processing apparatus 1 according to the recipe data, method MT can be executed in the plasma processing apparatus 1.

[0052] The following, with Figure 2For reference Figure 3 and Figure 4 . Figure 3 This is a time series diagram of an example of high-frequency power, DC voltage, electron density, and ion density. Figure 4 This is a timing diagram for an example of high-frequency power and DC voltage. In Figure 3 and Figure 4 In the middle, V OUT This indicates the output voltage of bias power supply 62. Figure 3 In this context, Ne represents the electron density in chamber 10, and Ni represents the ion density in chamber 10.

[0053] like Figure 3 As shown, the high-frequency power supply 61 supplies high-frequency power HF during the first period P1. The high-frequency power supply 61 stops supplying high-frequency power HF during the second period P2 following the first period P1 and the third period P3 following the second period P2. That is, the high-frequency power supply 61 supplies pulses of high-frequency power HF. During the first to third periods, the pulses of high-frequency power HF are maintained in the first period P1.

[0054] During periods 1 to 3, bias power supply 62, in period 3 P3, applies a negative DC voltage V. B The bias power supply 62 stops applying a negative DC voltage V to the base 18 during periods P1 and P2. B .

[0055] The high-frequency power supply 61 and the bias power supply 62 are controlled by the control unit 80. The control unit 80 performs a first control during the first period P1. The first control includes controlling the high-frequency power supply 61 to supply high-frequency power HF, so as to prevent the negative polarity DC voltage V from the bias power supply 62 from being applied. B Plasma is generated within chamber 10 under conditions applied to the base 18. The first control may further include controlling the bias power supply 62 to stop the negative polarity DC voltage V. B Application to the base 18. The first 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. During the first period P1, plasma is generated from the gas in the chamber 10 by a high-frequency electric field based on high-frequency electricity HF.

[0056] During the second period P2, the control unit 80 performs a second control. The second control includes controlling the high-frequency power supply 61 to prevent the negative polarity DC voltage V from the bias power supply 62 from being applied. B The supply of high-frequency power HF is stopped when applied to base station 18. The second control may further include controlling the bias power supply 62 to maintain a negative DC voltage V. BThe application to the base 18 is stopped. The 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. In addition, the duration of the second period P2 is preset such that although ions in the plasma generated in the first period P1 remain in the chamber 10, the electrons in the plasma are substantially eliminated.

[0057] During the third period P3, the control unit 80 performs the third control. The third control includes controlling the bias power supply 62 to reduce the negative DC voltage V when no high-frequency power HF from the high-frequency power supply 61 is supplied. B The bias power supply 62 applies a negative DC voltage V to the base 18. B A pulse is applied to base 18. During periods 1 to 3, P3 maintains a negative DC voltage V during period 3. B The pulse. The third control may further include controlling the high-frequency power supply 61 to maintain the state where the supply of 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, i.e., during the third period P3, a negative DC voltage V is preset. B This is to generate ions within the chamber 10 by utilizing secondary electrons released through collisions between ions within the chamber 10 and the substrate W on the substrate support 14. A negative polarity DC voltage V B The absolute value is, for example, above 500V. During period P3, ions generated by secondary electrons pass through a negatively polarized DC voltage V. B The generated bias accelerates the material toward the substrate W.

[0058] In one embodiment, the control unit 80 can repeatedly execute a series of controls, including the first control, the second control, and the third control. That is, as... Figure 3 and Figure 4 As shown, the high-frequency power supply 61 can repeatedly (i.e., periodically) supply pulses of high-frequency power HF with a first cycle T1. In this embodiment, the bias power supply 62 is also capable of supplying negative polarity DC voltage V. B The first period T1 is applied repeatedly (i.e. periodically) to the base 18. The first period T1 can be a period defined at a frequency of more than 100 kHz and less than 800 kHz.

[0059] In one embodiment, the control unit 80 can perform a fourth control after executing the above-described series of controls once or more. The fourth control includes controlling the exhaust device 50 to exhaust gas from the chamber 10 when no high-frequency power HF from the high-frequency power supply 61 is supplied and no DC voltage is applied from the bias power supply 62 to the base station 18. That is, as... Figure 4 As shown, during period T, the control unit 80 ON Execute the above series of controls once or more, during the T period ON During the period T OFF Execute the fourth control. During period T ON The control unit 80 can periodically execute the aforementioned series of controls in a first cycle T1. Furthermore, the control unit 80 can alternately execute the aforementioned series of controls (more than once) with the fourth control. That is, the control unit 80 can periodically execute another series of controls, including executing the aforementioned series of controls (more than once) and executing the fourth control, in a second cycle T2. The second cycle T2 can be a period defined at a frequency of 1 kHz or higher and 40 kHz or lower.

[0060] The following is for reference. Figure 5 . Figure 5 This diagram illustrates the structure of a high-frequency power supply and a bias power supply of 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 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 originating from the high-frequency signal generator 61g and outputs high-frequency power (HF).

[0061] 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 points of the first period P1. The high-frequency signal generator 61g starts generating a high-frequency signal at the start point of the first period P1 based on the first synchronization signal and stops generating the high-frequency signal at the end point of the first period P1. Through this control of the high-frequency power supply 61 based on the control unit 80, high-frequency power HF is supplied during the first period P1.

[0062] In one embodiment, the bias power supply 62 may include a DC power supply 62p, switching elements 62s1 and 62s2, and a dummy load 62d. The DC power supply 62p is a negative DC voltage V. B A DC power supply. The 62pV DC power supply can be a variable DC power supply.

[0063] The DC power supply 62p is electrically connected to the base 18 via a switching element 62s1. When the switching element 62s1 is in the ON state, a voltage from the DC power supply 62p is applied to the base 18. On the other hand, when the switching element 62s1 is in the OFF state, a voltage from the DC power supply 62p is not applied to the base 18.

[0064] The switching element 62s2 is connected to the dummy load 62d at a node in the electrical path (between the DC power supply 62p and the base station 18). When the switching element 62s2 is in the ON state, it rapidly sets the potential of the base station 18 to ground potential.

[0065] The control unit 80 controls the synchronization signal generator 64 to generate a second synchronization signal that is synchronized with the start and end points of the third period P3. The second synchronization signal is provided to switching elements 62s1 and 62s2. Switching element 62s1 becomes active at the start of the third period P3 and deactive at the end of the third period P3, based on the second synchronization signal. Switching element 62s2 also becomes deactive at the start of the third period P3 and active at the end of the third period P3, based on the second synchronization signal.

[0066] Refer again Figure 1 And, besides Figure 1 In addition, also refer to Figure 6 (a) Figure 6 (b) and Figure 6 (c) Figure 6 (a) is a diagram illustrating an example of the plasma state and free radical changes during the first period. Figure 6 (b) is a diagram showing an example of the changes in ions during the third period. Figure 6 (c) is a graph illustrating an example of the variation in byproducts in the exhaust gas after the third period. Figure 6 (a) Figure 6 (b) and Figure 6 (c) also shows a portion of a substrate W. The substrate W has a bottom surface region UR, a film EF, and a mask MK. The film EF is disposed on the bottom surface region UR. The mask MK is disposed on the film EF and has a pattern that exposes a portion of the surface of the film EF. Hereinafter, the method MT will be described in detail using the plasma processing apparatus 1 as an example.

[0067] Method MT begins in step ST1. Step ST1 is executed during period P1. Through the execution of step ST1, during period P1, high-frequency power HF is supplied from high-frequency power supply 61. During period P1, the negative polarity DC voltage V is not applied. B A bias power supply 62 is applied to the base 18. For example... Figure 6As shown in (a), plasma PL is generated in chamber 10 during the first period P1 by executing step ST1. Plasma PL is generated by the dissociation of the gas by a high-frequency electric field produced by the supply of high-frequency power HF, whereby the resulting electrons collide with molecules and / or atoms in the gas. That is, plasma PL is generated in α mode during the first period P1. During the first period P1, free radicals CR originating from plasma PL adhere to the surface of membrane EF. Furthermore, control unit 80 performs the aforementioned first control to execute step ST1.

[0068] During period 2, P2 executes the next step, ST2. By executing ST2, during period 2, P2 stops supplying high-frequency power HF from high-frequency power supply 61. During period 2, P2 does not transfer the negative polarity DC voltage V. B A bias power supply 62 is applied to the base 18. For example... Figure 3 As shown, ions in the plasma PL generated during the first period P1 remain in the chamber 10 even after the second period P2 ends, but electrons in the plasma PL decrease rapidly during the second period P2 and essentially disappear. Furthermore, the control unit 80 performs the aforementioned second control to execute process ST2.

[0069] During period 3, P3 executes the next step, ST3. By executing ST3, during period 3, P3 will convert the negative DC voltage V... B A bias power supply 62 is applied to the base 18. During period 3, P3 is not supplied with high-frequency power HF. During period 3, P3 is supplied with a negative DC voltage V. B When applied to the abutment 18, ions CI are accelerated 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. During the third period P3, ions are generated within the chamber 10 through collisions of the released secondary electrons with molecules and / or atoms in the gas. As a result, Figure 3 As shown, during period 3 (P3), the ion density within chamber 10 increases. That is, during period 3 (P3), plasma is generated in γ mode. Additionally, the negative polarity DC voltage V that generates the γ mode... B The absolute value is, for example, above 500V.

[0070] like Figure 6 As shown in (b), during period 3 P3, ions CI generated by secondary electron collisions with molecules and / or atoms in the gas are subjected to a DC voltage V based on negative polarity. B The bias is directed towards the substrate W for acceleration. As a result, the substrate W is processed. In one example, the film EF on the substrate W is etched. In this example, ions CI collide with the substrate W, resulting in a reaction between the ions CI and / or free radicals CR and the material of the film EF, thereby etching the film EF. Through this reaction, the byproduct CB is generated (see reference). Figure 6(c)). In addition, the control unit 80 performs the third control described above to execute process ST3.

[0071] During period P3, no high-frequency power HF is supplied, therefore no reflection of high-frequency power HF occurs. Thus, according to method MT and plasma processing apparatus 1, the processing efficiency (e.g., etching efficiency) of substrate W is higher compared to the use of electricity.

[0072] Compared to plasma generated in α mode, plasma generated in γ mode is characterized by a large ion current. The larger the ion current, the higher the etching rate. Therefore, by using plasma generated in γ mode during period 3 (P3) to etch the film EF, a high etching rate can be obtained. Furthermore, the electron temperature of plasma generated in γ mode is lower than that of plasma generated in α mode. At a lower electron temperature, the dissociation of molecules and / or atoms in the gas is suppressed, leading to the generation of heavy ions. Heavy ions can be introduced approximately vertically to the bottom of the openings formed on the film EF. Therefore, by using plasma generated in γ mode during period 3 (P3), the film EF can be etched to form openings with a high aspect ratio approximately vertically. Furthermore, the lateral expansion of the openings formed on the film EF can be suppressed.

[0073] In one embodiment, a series of processes SQ1, including processes ST1 to ST3, can be repeatedly performed. The repetition cycle of the series of processes SQ1 is the first cycle T1 described above. In this embodiment, the method MT includes process STa. In process STa, it is determined whether a stop condition is met. The stop condition is met when the number of times the series of processes SQ1 is executed reaches a predetermined number. If it is determined that the stop condition is not met in process STa, the series of processes SQ1 is executed again. If it is determined that the stop condition is met in process STa, the repetition of the series of processes SQ1 ends. In addition, the control unit 80 repeats the above-described series of controls to repeat the series of processes SQ1.

[0074] In one embodiment, method MT may further include step ST4. Step ST4 is performed after performing one or more steps SQ1. In step ST4, gas in chamber 10 is discharged through exhaust device 50. This is done when high-frequency power HF from high-frequency power supply 61 is not supplied and negative DC voltage V is not applied. B Process ST4 is executed while the bias power supply 62 is applied to the base 18. For example... Figure 6 As shown in (c), in step ST4, the byproduct CB is discharged from chamber 10. That is, by executing step ST4, the byproduct CB generated in a series of steps SQ1 is effectively discharged from chamber 10.

[0075] In one embodiment, a series of steps SQ1 and ST4 are executed alternately and repeatedly. That is, the execution of a series of steps SQ1 and a series of steps SQ2, including step ST4, can be repeated. The repetition cycle of the series of steps SQ2 is the second cycle T2 mentioned above. In this embodiment, method MT further includes step STb. In step STb, it is determined whether a stopping condition is met. The stopping condition is met when the number of executions of the series of steps SQ2 reaches a predetermined number. If it is determined that the stopping condition is not met in step STb, the series of steps SQ2 is executed again. If it is determined that the stopping condition is met in step STb, the repetition of the series of steps SQ2 ends.

[0076] The following is for reference. Figure 7 . Figure 7 This is another example of a timing diagram for high-frequency power and DC voltage. In another embodiment, such as Figure 7 As shown, during the second period P2, a positive DC voltage can be applied to the base 18 via the bias power supply 62. During the second period P2, a positive DC voltage can also be applied to the base 18 via another bias power supply. According to this embodiment, the number of electrons in the plasma PL can be further reduced rapidly. Therefore, the second period P2 can be shortened.

[0077] In addition, Figure 3 , Figure 4 and Figure 7 In the example shown, the negative polarity DC voltage V B The voltage shown is a voltage with a certain value during period P3 (phase 3), but is not limited to these examples. Negative polarity DC voltage V B It can also contain several voltage values. Additionally, Figure 7 The positive DC voltage shown can also include several voltage values.

[0078] The above descriptions have illustrated various exemplary embodiments, but the embodiments are not limited to these exemplary embodiments. Various additions, omissions, substitutions, and modifications can be made. Furthermore, elements of different embodiments can be combined to form another embodiment.

[0079] In another embodiment, the plasma processing apparatus can be another type of plasma processing apparatus, such as an inductively coupled plasma processing apparatus. In an inductively coupled plasma processing apparatus, high-frequency power (HF) is supplied to an antenna used to generate inductively coupled plasma.

[0080] In another embodiment, one or more bias electrodes may be disposed within the body of the electrostatic chuck 20, or may be combined with the bias power supply 62 for a negative DC voltage (in addition, they may be combined with other bias power supplies for a positive DC voltage). The bias electrodes may also be the electrodes of the electrostatic chuck described above.

[0081] As can be seen from the above description, the various embodiments of the present invention have been described in this specification for illustrative purposes, and various modifications can be made without departing from the scope and spirit of the 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 additional technical solutions.

Claims

1. A plasma processing apparatus, comprising: chamber; The substrate support within the cavity includes a lower electrode; The upper electrode is disposed above the substrate support; An RF power supply is configured to supply RF power to the lower electrode or the upper electrode, the RF power comprising multiple power levels during repetition, the multiple power levels including a first power level during a first state, a second power level during a second state, and a third power level during a third state, the second power level and the third power level being equal to a zero power level; as well as A DC power supply is configured to apply a DC voltage to the lower electrode. The DC voltage includes multiple voltage levels during the repetition period. The multiple voltage levels include a first voltage level during the first state, a second voltage level during the second state, and a third voltage level during the third state, and the first voltage level is equal to zero voltage level.

2. The plasma processing apparatus as described in claim 1, wherein, The third voltage level has a negative polarity.

3. The plasma processing apparatus as described in claim 2, wherein, The absolute value of the third voltage level is above 500V.

4. The plasma processing apparatus as described in claim 2, wherein, The second voltage level is equal to the zero voltage level.

5. The plasma processing apparatus as described in claim 2, wherein, The second voltage has a positive polarity.

6. The plasma processing apparatus as described in claim 5, wherein, The absolute value of the third voltage level is greater than the absolute value of the second voltage level.

7. The plasma processing apparatus as claimed in claim 6, wherein, The absolute value of the third voltage level is above 500V.

8. The plasma processing apparatus as claimed in claim 1, wherein, The repetition period is repeated at a repetition frequency in the range of 100kHz to 800kHz.

9. The plasma processing apparatus as claimed in claim 1, wherein, The RF power has a frequency in the range of 13MHz-200MHz.

10. A plasma processing apparatus comprising: chamber; The substrate support within the cavity; An RF power supply is configured to supply RF power for generating plasma from gas within the chamber. This RF power includes multiple power levels during repetition, including a first power level during a first state, a second power level during a second state, and a third power level during a third state, wherein the second power level and the third power level are equal to a zero power level. The DC power supply is configured to apply a DC voltage to the substrate support, the DC voltage including multiple voltage levels during the repetition period, the multiple voltage levels including a first voltage level during the first state, a second voltage level during the second state, and a third voltage level during the third state, and the first voltage level is equal to zero voltage level.

11. The plasma processing apparatus of claim 10, wherein, The third voltage level has a negative polarity.

12. The plasma processing apparatus of claim 11, wherein, The second voltage level is equal to the zero voltage level.

13. The plasma processing apparatus of claim 11, wherein, The second voltage has a positive polarity.

14. The plasma processing apparatus as claimed in claim 13, wherein, The absolute value of the third voltage level is greater than the absolute value of the second voltage level.

15. A system having: An RF generator configured to generate RF power comprising multiple power levels during repetition, the multiple power levels including a first power level during a first state, a second power level during a second state, and a third power level during a third state, wherein the second power level and the third power level are equal to a zero power level; and A DC generator is configured to generate a DC voltage, the DC voltage comprising multiple voltage levels during the repetition period, the multiple voltage levels including a first voltage level during the first state, a second voltage level during the second state, and a third voltage level during the third state, wherein the first voltage level is equal to a zero voltage level.

16. The system of claim 15, wherein, The third voltage level has a negative polarity.

17. The system of claim 16, wherein, The second voltage level is equal to the zero voltage level.

18. The system of claim 16, wherein, The second voltage has a positive polarity.

19. The system of claim 18, wherein, The absolute value of the third voltage level is greater than the absolute value of the second voltage level.

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