Plasma processing method and plasma processing apparatus

Abstract

The present invention provides a plasma processing method and a plasma processing apparatus. The method is used to process a substrate by plasma in a plasma processing apparatus, and the plasma processing apparatus includes: a chamber; an upper electrode structure that forms the upper part of the chamber, the upper electrode structure having a plate whose temperature is controlled, an electrode plate disposed below the plate, and an electrostatic adsorption part sandwiched between the electrode plate and the plate, the electrostatic adsorption part including a contact surface in contact with the lower surface of the plate, an adsorption surface that adsorbs the upper surface of the electrode plate, a first electrode, and a second electrode; a power supply that applies voltages to the first electrode and the second electrode; and a temperature acquisition part that acquires the temperature distribution of the electrode plate. The method includes: an acquisition step of acquiring the temperature distribution of the electrode plate; an application step of applying a first voltage to the first electrode and a second voltage to the second electrode according to the temperature distribution; and a processing step of processing the substrate by plasma.

Description

Technical Field

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

[0002] Patent Document 1 discloses an upper electrode of a plasma processing apparatus. The upper electrode has an electrode plate and a plate in contact with the electrode plate. The upper surface of the electrode plate is in contact with the lower surface of the plate. An electrostatic adsorption portion is provided between the electrode plate and the plate. The electrostatic adsorption portion is made of ceramic and is fixed to the lower surface of the plate via a jig.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2015-216261 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] The present disclosure provides a technique capable of flexibly adjusting the temperature distribution of an upper electrode plate when a substrate is subjected to plasma processing.

[0008] Solutions for Solving the Problems

[0009] In one exemplary embodiment, there is provided a method of processing a substrate by plasma in a plasma processing apparatus. The plasma processing apparatus includes a chamber, an upper electrode structure, a power supply, and a temperature acquisition unit. The chamber is configured to accommodate a substrate. The upper electrode structure forms an upper portion of the chamber. The upper electrode structure has a plate whose temperature is controlled, an electrode plate disposed below the plate, and an electrostatic adsorption portion interposed between the electrode plate and the plate. The electrostatic adsorption portion includes a contact surface in contact with the lower surface of the plate, an adsorption surface that adsorbs the upper surface of the electrode plate, a first electrode, and a second electrode. The power supply is configured to apply a voltage to the first electrode and the second electrode. The temperature acquisition unit is configured to acquire the temperature distribution of the electrode plate. The method includes an acquisition step, an application step, and a processing step. In the acquisition step, the temperature distribution of the electrode plate is acquired by the temperature acquisition unit. In the application step, a first voltage is applied to the first electrode and a second voltage is applied to the second electrode according to the acquired temperature distribution. In the processing step, the substrate is processed by plasma.

[0010] Effects of the Invention

[0011] According to one exemplary embodiment, the temperature distribution of the upper electrode plate can be flexibly adjusted when the substrate is subjected to plasma processing. Brief Description of the Drawings

[0012] Figure 1 is a flowchart of a plasma processing method according to an exemplary embodiment.

[0013] Figure 2 is a diagram schematically showing a plasma processing apparatus according to an exemplary embodiment.

[0014] Figure 3 is a cross-sectional view of an upper electrode according to an exemplary embodiment.

[0015] Figure 4 is a cross-sectional view of an upper electrode according to an exemplary embodiment.

[0016] Figure 5 is a cross-sectional view of an upper electrode according to an exemplary embodiment.

[0017] Figure 6 is a diagram schematically showing an example of the layout of a first electrode and a second electrode.

[0018] Figure 7 In (A) of [], is an example of the temperature distribution of the electrode plate, Figure 7 In (B) of [], is an example of the distribution of the applied voltage applied to the electrostatic chuck.

[0019] Figure 8 In (A) of [], is another example of the temperature distribution of the electrode plate, Figure 8 In (B) of [], is another example of the distribution of the applied voltage applied to the electrostatic chuck.

[0020] Figure 9 In (A) of [], is an example of the electrode configuration. Figure 9 In (B) of [], is another example of the electrode configuration. Figure 9 In (C) of [], is another example of the electrode configuration. Figure 9 In (D) of [], is an example of the separation of the main body of the electrostatic chuck.

[0021] Explanation of Reference Signs

[0022] 10: Plasma processing apparatus; 12: Chamber body; 34: Electrode plate; 35: Electrostatic chuck (an example of an electrostatic adsorption part); 36: Gas plate (an example of a plate); Cnt: Control part. Detailed implementation manners

[0023] Next, various exemplary embodiments will be described.

[0024] In the plasma processing apparatus of Patent Document 1, plasma is generated below the electrode plate. The temperature of the electrode plate rises due to heat input from the plasma. The electrode plate is pushed by the electrostatic adsorption portion to contact the upper plate and is cooled by heat conduction. However, sometimes the plasma heat input is not uniform with respect to the electrode plate. Also, the interfacial thermal resistance between the electrode plate and the plate sometimes changes as the apparatus is used. The temperature deviation of the electrode plate caused by such reasons may affect the plasma processing process. Also, depending on the process, it may sometimes be necessary to deliberately create a temperature difference between a specified region and other regions of the electrode plate. There is room for improvement in the plasma processing apparatus of Patent Document 1 in terms of adjusting the temperature distribution of the electrode plate.

[0025] In an exemplary embodiment, a method for processing a substrate by plasma in a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, an upper electrode structure, a power source, and a temperature acquisition unit. The chamber is configured to accommodate the substrate. The upper electrode structure constitutes the upper part of the chamber. The upper electrode structure has a plate whose temperature is controlled, an electrode plate disposed below the plate, and an electrostatic adsorption portion sandwiched between the electrode plate and the plate. The electrostatic adsorption portion includes a contact surface that contacts the lower surface of the plate, an adsorption surface that adsorbs the upper surface of the electrode plate, a first electrode, and a second electrode. The power source is configured to apply voltages to the first electrode and the second electrode. The temperature acquisition unit is configured to acquire the temperature distribution of the electrode plate. The method includes an acquisition step, an application step, and a processing step. In the acquisition step, the temperature distribution of the electrode plate is acquired by the temperature acquisition unit. In the application step, a first voltage is applied to the first electrode and a second voltage is applied to the second electrode according to the acquired temperature distribution. In the processing step, the substrate is processed by plasma.

[0026] In this method, the temperature distribution of the electrode plate is acquired, and voltages are applied to the first electrode and the second electrode of the electrostatic adsorption portion according to the acquired temperature distribution. Thereby, this method can adjust the adsorption force generated by the first electrode and the adsorption force generated by the second electrode according to the temperature distribution of the electrode plate. Therefore, compared with the method of providing a uniform adsorption force to the entire electrode plate, this method can flexibly adjust the temperature distribution of the upper electrode plate.

[0027] In an exemplary embodiment, the electrode plate may be circular, the first electrode is disposed at a position corresponding to the center of the electrode plate, and the second electrode is disposed so as to surround the periphery of the first electrode. In this case, this method can independently adjust the temperature of the central region of the electrode plate and the temperature of the region outside the central region of the electrode plate according to the temperature distribution.

[0028] In an exemplary embodiment, alternatively, the temperature acquisition unit may include a first temperature sensor and a second temperature sensor. The first temperature sensor detects the temperature at the position where the first electrode is clamped by the electrode plate, and the second temperature sensor detects the temperature at the position where the second electrode is clamped by the electrode plate. In this case, the method can acquire the temperature distribution including the temperature at the position where the first electrode is clamped by the electrode plate and the temperature at the position where the second electrode is clamped by the electrode plate.

[0029] In an exemplary embodiment, alternatively, the application process may include the following process: applying a voltage to the first electrode and the second electrode such that the difference between the detected temperature of the first temperature sensor and the detected temperature of the second temperature sensor becomes equal to or less than a specified temperature threshold. In this case, the method can make the temperature of the electrode plate uniform.

[0030] In an exemplary embodiment, alternatively, the electrostatic adsorption unit has a single body formed of a dielectric, and the first electrode and the second electrode are provided inside the single body. In this case, compared with the case where the first electrode and the second electrode are respectively provided inside different bodies, the method can reduce the number of components of the device.

[0031] In an exemplary embodiment, alternatively, the single body is made of ceramic. In this case, compared with the case of using other materials, the method can improve the heat resistance of the electrostatic adsorption unit.

[0032] In an exemplary embodiment, alternatively, the single body is formed of an elastic dielectric. In this case, the method can easily and appropriately assemble the electrode plate and the plate.

[0033] In an exemplary embodiment, alternatively, the electrostatic adsorption unit has a first body formed of a dielectric and a second body separated from the first body and formed of a dielectric. The first electrode is provided inside the first body, and the second electrode is provided inside the second body. In this case, compared with the case where the first electrode and the second electrode are provided inside a single body, the method can flexibly arrange the electrostatic adsorption unit.

[0034] In an exemplary embodiment, alternatively, the first body and the second body are made of ceramic. In this case, compared with the case of using other materials, the method can improve the heat resistance of the electrostatic adsorption unit.

[0035] In an exemplary embodiment, alternatively, the first body and the second body are formed of an elastic dielectric. In this case, the method can easily and appropriately assemble the electrode plate and the plate.

[0036] In an exemplary embodiment, alternatively, the method further includes repeating the steps of the acquisition step, the application step, and the processing step. In this case, the method can repeatedly perform the adjustment of the temperature distribution of the electrode plate and the plasma treatment of the substrate.

[0037] In other exemplary embodiments, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, an RF power source, an upper electrode structure, a power supply, a temperature acquisition unit, and a control unit. The chamber is configured to accommodate a substrate. The RF power source is configured to generate plasma. The upper electrode structure forms the upper part of the chamber. The upper electrode structure has a plate whose temperature is controlled, an electrode plate disposed below the plate, and an electrostatic chuck portion interposed between the electrode plate and the plate. The electrostatic chuck portion includes a contact surface that contacts the lower surface of the plate, an adsorption surface that adsorbs the upper surface of the electrode plate, a first electrode, and a second electrode. The power supply is configured to apply voltages to the first electrode and the second electrode. The temperature acquisition unit is configured to acquire the temperature distribution of the electrode plate. The control unit executes a process including an acquisition step, an application step, and a processing step. In the acquisition step, the temperature distribution of the electrode plate is acquired by the temperature acquisition unit. In the application step, the power supply is controlled to apply a first voltage to the first electrode and a second voltage to the second electrode according to the temperature distribution acquired in the acquisition step. In the processing step, the substrate is subjected to plasma treatment.

[0038] In this apparatus, the temperature distribution of the electrode plate is acquired, and voltages are applied to the first electrode and the second electrode of the electrostatic chuck portion according to the acquired temperature distribution. Thereby, the apparatus can adjust the adsorption force generated by the first electrode and the adsorption force generated by the second electrode according to the temperature distribution of the electrode plate. Therefore, compared with an apparatus that provides a uniform adsorption force to the entire electrode plate, the apparatus can flexibly adjust the temperature distribution of the upper electrode plate.

[0039] Hereinafter, various exemplary embodiments will be described in detail with reference to the drawings. In addition, the same or corresponding parts are denoted by the same reference numerals in the respective drawings.

[0040] [Outline of Plasma Processing Method and Apparatus]

[0041] Figure 1 is a flowchart of a plasma processing method according to an exemplary embodiment. In order to process a substrate by plasma, the Figure 1 plasma processing method shown (hereinafter referred to as "method MT") is executed. More specifically, method MT is executed in order to adjust the temperature of the upper electrode that contributes to plasma generation before or during substrate processing. In method MT, there are no particular limitations on the material, shape, gas type, etc. of the substrate as the object.

[0042] Method MT is executed in a plasma processing apparatus. Figure 2 FIG. is a diagram schematically showing a plasma processing apparatus according to an exemplary embodiment. Figure 2 The illustrated plasma processing apparatus 10 is a capacitively coupled plasma etching apparatus. The plasma processing apparatus 10 includes a chamber body 12. The chamber body 12 has a substantially cylindrical shape and provides an internal space 12s. The chamber body 12 is formed of, for example, aluminum. A process for making the inner wall surface of the chamber body 12 have plasma resistance is performed on the inner wall surface of the chamber body 12. For example, an anodic oxidation process is performed on the inner wall surface of the chamber body 12. The chamber body 12 is electrically grounded.

[0043] A passage 12p is formed in a side wall of the chamber body 12. The workpiece W (an example of a substrate) passes through the passage 12p when being carried into or out of the internal space 12s. The passage 12p can be opened and closed by a gate valve 12g.

[0044] A support portion 13 is provided on a bottom of the chamber body 12. The support portion 13 is formed of an insulating material. The support portion 13 has a substantially cylindrical shape. The support portion 13 extends in a vertical direction from the bottom of the chamber body 12 in the internal space 12s. The support portion 13 supports a mounting table 14. The mounting table 14 is provided in the internal space 12s.

[0045] The mounting table 14 has a lower electrode 18 and an electrostatic chuck 20. The mounting table 14 may further include an electrode plate 16. The electrode plate 16 is formed of a conductive material such as aluminum and has a substantially disc shape. The lower electrode 18 is provided on the electrode plate 16. The lower electrode 18 is formed of a conductive material such as aluminum and has a substantially disc shape. The lower electrode 18 is electrically connected to the electrode plate 16.

[0046] The electrostatic chuck 20 is provided on the lower electrode 18. The workpiece W is placed on an upper surface of the electrostatic chuck 20. The electrostatic chuck 20 has a main body formed of a dielectric. A film-like electrode is provided in the main body of the electrostatic chuck 20. The electrode of the electrostatic chuck 20 is connected to a DC power supply 22 via a switch. When a voltage from the DC power supply 22 is applied to the electrode of the electrostatic chuck 20, an electrostatic attraction force is generated between the electrostatic chuck 20 and the workpiece W. The workpiece W is attracted by the generated electrostatic attraction force and held by the electrostatic chuck 20.

[0047] An edge ring FR is disposed on the mounting table 14 so as to surround an edge of the workpiece W. The edge ring FR is provided to improve in-plane uniformity of etching. There is no limitation on the edge ring FR, and it can be formed of silicon, silicon carbide, or quartz.

[0048] A flow path 18f is provided inside the lower electrode 18. Refrigerant is supplied to the flow path 18f from a cooling device 26 disposed outside the chamber body 12 via a pipe 26a. The refrigerant supplied to the flow path 18f returns to the cooling device 26 via a pipe 26b. In the plasma processing apparatus 10, the temperature of the workpiece W placed on the electrostatic chuck 20 is adjusted by heat exchange between the refrigerant and the lower electrode 18.

[0049] A gas supply line 28 is provided in the plasma processing apparatus 10. The gas supply line 28 is used to supply a heat transfer gas, such as He gas, from a heat transfer gas supply mechanism between the upper surface of the electrostatic chuck 20 and the back surface of the workpiece W.

[0050] The plasma processing apparatus 10 further includes an upper electrode 30. The upper electrode 30 is disposed above the mounting table 14. The upper electrode 30 is supported by the upper part of the chamber body 12 via a member 32. The member 32 is formed of an insulating material. The upper electrode 30 includes an electrode plate 34, an electrostatic chuck 35 (an example of an electrostatic adsorption part), and a gas plate 36 (an example of a plate). The lower surface of the electrode plate 34 is the lower surface on the inner space 12s side, and divides the inner space 12s. The electrode plate 34 can be formed of a low-resistance conductor or semiconductor that generates less Joule heat. A plurality of gas ejection holes 34a are formed in the electrode plate 34. The plurality of gas ejection holes 34a penetrate the electrode plate 34 in the thickness direction of the electrode plate 34.

[0051] The gas plate 36 can be formed of a conductive material such as aluminum. The electrostatic chuck 35 is disposed between the gas plate 36 and the electrode plate 34. The structure and voltage supply system of the electrostatic chuck 35 will be described later. The gas plate 36 and the electrode plate 34 are tightly joined by the adsorption force of the electrostatic chuck 35.

[0052] A cooling plate 37 is disposed above the gas plate 36. The cooling plate 37 can be formed of a conductive material such as aluminum. A flow path 37c is provided inside the cooling plate 37. Refrigerant is supplied to the flow path 37c from a cooling device (not shown) disposed outside the chamber body 12. The refrigerant supplied to the flow path 37c returns to the cooling device. Thus, the temperature of the cooling plate 37 is adjusted. In the plasma processing apparatus 10, the temperature of the electrode plate 34 is adjusted by heat exchange between the refrigerant and the gas plate 36 and the cooling plate 37.

[0053] A plurality of gas introduction passages 37a are provided inside the cooling plate 37 so as to extend downward. Between the upper surface of the gas plate 36 and the lower surface of the cooling plate 37, a plurality of gas diffusion chambers 37b are provided corresponding to the plurality of gas introduction passages 37a. A plurality of gas flow passages 36a are provided inside the gas plate 36. The gas flow passages 36a are formed at positions facing the gas ejection holes 34a so as to extend in the thickness direction. The gas flow passages 36a extend downward from the gas diffusion chambers 37b so as to communicate with the corresponding gas ejection holes 34a. A plurality of gas inlets 37d for guiding a processing gas to the plurality of gas diffusion chambers 37b are formed in the cooling plate 37. The gas inlets 37d are connected to a gas supply pipe 38.

[0054] The gas supply pipe 38 is connected to a gas supply unit GS. In one embodiment, the gas supply unit GS includes a gas source group 40, a valve group 42, and a flow controller group 44. The gas source group 40 is connected to the gas supply pipe 38 via the flow controller group 44 and the valve group 42. The gas source group 40 includes a plurality of gas sources. The plurality of gas sources include sources of a plurality of gases constituting the processing gas used in the method MT. The valve group 42 includes a plurality of on-off valves. The flow controller group 44 includes a plurality of flow controllers. Each of the plurality of flow controllers of the flow controller group 44 is a mass flow controller or a pressure-controlled flow controller. The plurality of gas sources of the gas source group 40 are connected to the gas supply pipe 38 via the corresponding valves of the valve group 42 and the corresponding flow controllers of the flow controller group 44.

[0055] In the plasma processing apparatus 10, a shield 46 is provided along the inner wall of the chamber body 12 in a detachable manner. A shield 46 is also provided on the outer periphery of the support portion 13. The shield 46 is used to prevent etching by-products from adhering to the chamber body 12. The shield 46 is formed, for example, by covering an aluminum member with a ceramic such as Y2O3.

[0056] 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 formed, for example, by covering an aluminum member with a ceramic such as Y2O3. 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. The exhaust port 12e is connected to an exhaust device 50 via an exhaust pipe 52. The exhaust device 50 has a pressure control valve and a vacuum pump such as a turbo molecular pump.

[0057] The plasma processing apparatus 10 further includes a first high-frequency power supply 62 and a second high-frequency power supply 64 as high-frequency (Radio Frequency: RF) power supplies. The first high-frequency power supply 62 is a power supply that generates a first high frequency for generating plasma. The frequency of the first high frequency is, for example, a frequency in the range of 27 MHz to 100 MHz. The first high-frequency power supply 62 is connected to the lower electrode 18 via a matcher 66 and an electrode plate 16. The matcher 66 has a circuit for matching the output impedance of the first high-frequency power supply 62 with the input impedance on the load side (the lower electrode 18 side). In addition, the first high-frequency power supply 62 may also be connected to the upper electrode 30 via the matcher 66.

[0058] The second high-frequency power supply 64 is a power supply that generates a second high frequency for attracting ions to the workpiece W. The frequency of the second high frequency is lower than the frequency of the first high frequency. The frequency of the second high frequency is, for example, a frequency in the range of 400 kHz to 13.56 MHz. The second high-frequency power supply 64 is connected to the lower electrode 18 via a matcher 68 and an electrode plate 16. The matcher 68 has a circuit for matching the output impedance of the second high-frequency power supply 64 with the input impedance on the load side (the lower electrode 18 side).

[0059] The plasma processing apparatus 10 may further include a DC power supply unit 70. The DC power supply unit 70 is connected to the upper electrode 30. The DC power supply unit 70 can generate a negative DC voltage and supply this DC voltage to the upper electrode 30.

[0060] The plasma processing apparatus 10 may further include a control unit Cnt. The control unit Cnt can be a computer including a processor, a storage unit, an input device, a display device, etc. The control unit Cnt controls each part of the plasma processing apparatus 10. In the control unit Cnt, an operator can use the input device to perform input operations of commands for managing the plasma processing apparatus 10, etc. In addition, in the control unit Cnt, the operating status of the plasma processing apparatus 10 can be visually displayed through the display device. Also, in the storage unit of the control unit Cnt, a control program and process data for controlling various processes executed in the plasma processing apparatus 10 by the processor are stored. The processor of the control unit Cnt executes the control program and controls each part of the plasma processing apparatus 10 according to the process data, thereby executing the method described below by the plasma processing apparatus 10.

[0061] Figure 3 is a cross-sectional view of the upper electrode according to an exemplary embodiment. As Figure 3As shown, the upper electrode 30 has a structure in which an electrode plate 34, a gas plate 36, and a cooling plate 37 are overlapped in this order from bottom to top. The electrode plate 34, the gas plate 36, and the cooling plate 37 can be circular plate members or column members. The electrode plate 34, the gas plate 36, and the cooling plate 37 can be arranged coaxially.

[0062] The electrostatic chuck 35 is clamped between the electrode plate 34 and the gas plate 36. The upper surface of the electrostatic chuck 35 is a contact surface 35c that contacts the lower surface 36c of the gas plate 36 and is fixed to the lower surface 36c of the gas plate 36 by an adhesive or the like. The lower surface of the electrostatic chuck 35 is an adsorption surface 35d that adsorbs the upper surface 34b of the electrode plate 34.

[0063] The lower surface 36c of the gas plate 36 may have a first region 36e facing the contact surface 35c of the electrostatic chuck 35 and a second region 36f facing the gas ejection hole 34a. The second region 36f protrudes to a position lower than the first region 36e, thereby forming a receiving portion 36d. The electrostatic chuck 35 is disposed in the receiving portion 36d.

[0064] The electrostatic chuck 35 has a main body portion 35a formed of a dielectric. The main body portion 35a has elasticity. An electrode 35b is provided inside the main body portion 35a. The electrode 35b is connected to a DC power supply. The connection to the DC power supply will be described later. When a voltage from the DC power supply is applied to the electrode 35b of the electrostatic chuck 35, an electrostatic attraction force is generated between the electrostatic chuck 35 and the electrode plate 34. The electrode plate 34 is attracted by the generated electrostatic attraction force and held by the electrostatic chuck 35. In addition, Figure 3 The upper electrode 30 shown in the figure is a diagram showing a state in which no voltage is applied to the electrostatic chuck 35. The thickness of the electrostatic chuck 35 before voltage application is thicker than the protruding length of the second region 36f based on the first region 36e.

[0065] Figure 4 It is a cross-sectional view of an upper electrode according to an exemplary embodiment. Figure 4 It shows a state in which voltage is applied to the Figure 3 electrostatic chuck 35 in the figure. As shown in Figure 4As shown, when a voltage is applied to the electrostatic chuck 35, the electrode plate 34 is attracted to the gas plate 36 by the electrostatic chuck 35. At this time, the electrostatic chuck 35 is sandwiched between the electrode plate 34 and the gas plate 36 and is pressed. The main body portion 35a of the electrostatic chuck 35 is elastic, so it can be compressed and pressed into the housing portion 36d. Moreover, the upper surface 34b of the electrode plate 34 touches the lower surface 36c of the gas plate 36, whereby the upward movement of the electrode plate 34 stops. In this way, the electrostatic chuck 35 is disposed between the electrode plate and the gas plate in a state where the main body portion 35a is compressed by the action of the electrostatic chuck 35. The thickness of the electrostatic chuck 35 after the voltage is applied is the same as the protruding length of the second region 36f with respect to the first region 36e. Therefore, the upper surface 34b of the electrode plate 34 is in close contact with the lower surface 36c of the gas plate 36.

[0066] Figure 5 It is a cross-sectional view of the upper electrode according to an exemplary embodiment. As Figure 5 shown, the electrostatic chuck 35 is connected to a power supply 39 controlled by a control unit Cnt. The power supply 39 is a DC power supply whose applied voltage can be changed. The power supply 39 has a first DC power supply 39a and a second DC power supply 39b. In addition, although two DC power supplies are shown here, the number of DC power supplies is not limited. The number of DC power supplies can correspond to the number of electrodes to be controlled by the electrostatic chuck 35. That is, in Figure 4 the example of, the electrostatic chuck 35 includes a first electrode 350 and a second electrode 351. Figure 6 It is a diagram schematically showing an example of the layout of the first electrode and the second electrode. As Figure 5 and Figure 6 shown, the first electrode 350 is disposed at the central portion of the electrostatic chuck 35. The first electrode 350 is disposed at a position corresponding to the center of the electrode plate 34. The second electrode 351 is disposed outside the first electrode 350 so as to surround the periphery of the first electrode 350. That is, the second electrode 351 is disposed at a position closer to the outer periphery of the electrode plate 34 than the first electrode 350. The first electrode 350 and the second electrode 351 have a shape in which the periphery of the body ejection hole 34a is cut off. The main body portions of the first electrode 350 and the second electrode 351 can be an integral single main body portion, or can be separately provided as a single first main body portion and a second main body portion. Hereinafter, for convenience, the structure of the electrostatic chuck 35 corresponding to the first electrode 350 is also referred to as a first adsorption portion, and the structure of the electrostatic chuck 35 corresponding to the second electrode 351 is also referred to as a second adsorption portion.

[0067] Voltages of different polarities can be applied to the first electrode 350 and the second electrode 351. In this case, the electrostatic chuck 35 adsorbs the electrode plate 34 in a bipolar manner. Voltages of the same polarity can also be applied to the first electrode 350 and the second electrode 351. In this case, the electrostatic chuck 35 adsorbs the electrode plate 34 in a unipolar manner.

[0068] A temperature sensor 80 is provided on the electrode plate 34. The temperature sensor 80 detects the temperature distribution of the electrode plate 34. The temperature distribution is the temperature at each position. A first temperature sensor 80a and a second temperature sensor 80b can also be provided. The first temperature sensor 80a detects the temperature of the central region of the electrode plate 34. That is, the first temperature sensor 80a detects the temperature of the position of the electrode plate 34 where the first electrode 350 is sandwiched. The second temperature sensor 80b detects the temperature of the outer region (i.e., the region surrounding the central region) of the central region of the electrode plate 34. That is, the second temperature sensor detects the temperature of the position of the electrode plate 34 where the second electrode 351 is sandwiched. The temperature sensor 80 can be, for example, a thermocouple. The detection result of the temperature sensor 80 is output to the control unit Cnt. In addition, although two temperature sensors are shown here, the number and configuration of the temperature sensors are not limited. The device includes at least two temperature sensors, whereby the temperature distribution can be detected.

[0069] The control unit Cnt controls the power supply 39 based on the temperature distribution of the electrode plate 34 obtained by the temperature sensor 80. The control unit Cnt controls the power supply 39 to apply a first voltage to the first electrode 350 and a second voltage to the second electrode 351. The first voltage and the second voltage are determined based on the temperature distribution. When making the temperature of the electrode plate 34 uniform, the control unit Cnt determines the first voltage and the second voltage such that a larger voltage is applied to the electrode corresponding to the region with a higher temperature of the electrode plate 34. For example, when the central region of the electrode plate 34 is hotter than the outer region, the first voltage is set larger than the second voltage. The control unit Cnt can repeat the acquisition of the temperature distribution, the determination and application of the voltage to adjust the temperature distribution of the electrode plate 34. The control unit Cnt can repeat the above control until the difference between the detected temperature of the first temperature sensor 80a and the detected temperature of the second temperature sensor 80b becomes below a specified temperature threshold. The control unit Cnt can adjust the temperature distribution of the electrode plate 34 while performing the plasma processing of the substrate.

[0070] The control unit Cnt can not only make the temperature of the electrode plate 34 uniform, but also adjust the temperature of a local area of the electrode plate 34. When the control unit Cnt wants to further cool the central area of the electrode plate 34 based on the temperature distribution of the electrode plate 34, it can increase the second voltage. Alternatively, when the control unit Cnt wants to cool the outer area of the electrode plate 34 based on the temperature distribution of the electrode plate 34, it can also increase the second voltage.

[0071] [Details of the plasma processing method]

[0072] Next, refer again to Figure 1 to describe the method MT in detail. Here, an example of processing a substrate by plasma in the plasma processing apparatus 10 shown in Figure 2 will be described. As shown in Figure 1 , the method MT includes a step S10 of obtaining a temperature distribution, a step S12 of applying a voltage to the electrostatic chuck, and a step S14 of processing the substrate by plasma. In addition, before executing the method MT, the control unit Cnt transfers a substrate to be processed into the chamber body 12.

[0073] As the step S10, the control unit Cnt obtains the temperature distribution of the electrode plate 34 based on the detection result of the temperature sensor 80.

[0074] As the step S12, the control unit Cnt determines the first voltage and the second voltage according to the temperature distribution obtained in the step S10. The control unit Cnt applies the first voltage to the first electrode 350 and applies the second voltage to the second electrode 351. Thereby, the temperature of the electrode plate 34 is made uniform.

[0075] As the step S14, the control unit Cnt performs plasma processing on the substrate. The control unit Cnt introduces a process gas into the processing space through the gas supply unit GS. The control unit Cnt makes the first high-frequency power supply 62 and the second high-frequency power supply 64 apply high frequency to generate plasma. Thereby, the substrate is processed by plasma. When the step S14 ends, the method MT ends.

[0076] The method MT may have a step of repeatedly performing the step S10, the step S12, and the step S14. The temperature distribution of the electrode plate 34 may vary due to the plasma generated in the step S14. In the method MT, the control unit Cnt can control the power supply 39 so that the difference between the detected temperature of the first temperature sensor 80a and the detected temperature of the second temperature sensor 80b becomes below a specified temperature threshold.

[0077] [Relationship between temperature distribution and DC voltage]

[0078] When the DC voltage applied to the electrostatic chuck 35 is fixed regardless of the position of the electrode plate 34, the following temperature distribution is obtained. Figure 7 (A) of Figure 7 is an example of the temperature distribution of the electrode plate. The horizontal axis represents the position on the electrode plate 34 with the center of the electrode plate 34 as the origin, and the vertical axis represents the temperature. Figure 7 (A) of Figure 7 is the temperature distribution when the voltage shown in Figure 7 (B) of Figure 7 is applied. Figure 7 (B) of Figure 7 is an example of the applied voltage distribution applied to the electrostatic chuck. The horizontal axis represents the position on the electrode plate 34 with the center of the electrode plate 34 as the origin, and the vertical axis represents the voltage. As shown in Figure 7 (B) of Figure 7 , the same voltage is applied across the entire surface of the electrode plate 34. Therefore, the same adsorption force is generated across the entire surface of the electrode plate 34. As shown in Figure 7 (A) of Figure 7 , in the temperature distribution, the temperature increases as it goes from the edge to the center of the electrode plate 34, and the temperature distribution has a peak shape with the maximum value at the center of the electrode plate 34. There is a temperature difference ΔT0 between the edge and the center of the electrode plate 34. To reduce the temperature difference ΔT0, it is necessary to change the applied voltage to the electrode plate 34 by region.

[0079] When the DC voltage applied to the electrostatic chuck 35 varies depending on the position (region) of the electrode plate 34, the temperature distribution is as follows. Figure 8 (A) of Figure 8 is another example of the temperature distribution of the electrode plate. The horizontal axis represents the position on the electrode plate 34 with the center of the electrode plate 34 as the origin, and the vertical axis represents the temperature. The solid line is an example of the case where the DC voltage varies by region, and the single-dot dash line is the temperature shown in Figure 7 (A) of Figure 7 , and the single-dot dash line is shown for comparison. Figure 8 (A) of Figure 8 is the temperature distribution when the voltage shown in Figure 8 (B) of Figure 8 is applied to the electrostatic chuck. Figure 8 (B) of Figure 8 is an example of the applied voltage distribution applied to the electrostatic chuck. The horizontal axis represents the position on the electrode plate 34 with the center of the electrode plate 34 as the origin, and the vertical axis represents the voltage. The solid line is an example of the case where the DC voltage varies by region, and the single-dot dash line is the voltage shown in Figure 7 (B) of Figure 7 , and the single-dot dash line is shown for comparison.

[0080] As shown in Figure 8 (B) of Figure 8 , the applied voltage in the central region of the electrode plate 34 (the voltage applied to the first electrode 350) is set higher than the applied voltage in the outer region of the electrode plate 34 (the voltage applied to the second electrode 351). Thereby, heat dissipation in the central region of the electrode plate 34 can be promoted to a greater extent compared to the outer region of the electrode plate 34. And the applied voltage in the central region of the electrode plate 34 is set higher thanFigure 7 is larger than the voltage shown in (B). Therefore, the adsorption force generated in the central region of the electrode plate 34 is larger than Figure 7 that adsorption force in the example shown in (B), and more heat is conducted to the gas plate 36. Thus, as Figure 8 shown in (A), compared with the example shown in Figure 7 the temperature of the central region of the electrode plate 34 decreases.

[0081] And, as Figure 8 shown in (B), the applied voltage (the voltage applied to the second electrode 351) of the outer region of the electrode plate 34 is set smaller than Figure 7 the voltage shown in (B). Therefore, the adsorption force generated in the outer region of the electrode plate 34 is smaller than Figure 7 that adsorption force in the example shown in (B), and less heat is conducted to the gas plate 36. Thus, as Figure 8 shown in (A), compared with the example shown in Figure 7 the temperature of the outer region of the electrode plate 34 increases.

[0082] The control unit Cnt decreases the temperature of the central region of the electrode plate 34 and increases the temperature of the outer region of the electrode plate 34, thereby enabling uniform temperature within the plane of the electrode plate 34. As Figure 8 shown in (A), the temperature difference between the edge and the center of the electrode plate 34 can be set to ΔT1 (<ΔT0).

[0083] [Modified Example of Electrostatic Chuck]

[0084] The electrostatic chuck 35 is not limited to the Figure 6 electrode configuration shown. Figure 9 (A) is an example of the electrode configuration. As Figure 9 shown, the electrostatic chuck 35 may further include a third electrode 352 in addition to the first electrode 350 and the second electrode 351. Figure 9 (B) is another example of the electrode configuration. As Figure 9 shown in (B), the second electrode 351 can be divided (divided into four parts: 351a, 351b, 351c, and 351d). Figure 9 (C) is another example of the electrode configuration. As Figure 9 shown in (C), the first electrode 350 can be divided (divided into four parts: 350a, 3510, 350c, and 350d). Figure 9 (D) is an example of the separation of the main body of the electrostatic chuck. As Figure 9As shown in (D) of , alternatively, the electrostatic chuck 35 may have a first main body 35A and a second main body 35B, and a first electrode 350 and a second electrode 351 are provided inside each main body.

[0085] The above has described various exemplary embodiments, but is not limited to the above-described exemplary embodiments, and various omissions, substitutions, and changes can be made. In addition, elements in different embodiments can be combined to form other embodiments.

[0086] For example, the plasma processing apparatus 10 is a capacitively coupled plasma processing apparatus, but the plasma processing apparatus according to other embodiments may also be a different type of plasma processing apparatus. Such a plasma processing apparatus can be any type of plasma processing apparatus. As such a plasma processing apparatus, an inductively coupled plasma processing apparatus, a plasma processing apparatus that generates plasma by a surface wave such as a microwave, etc. are exemplified.

[0087] In addition, regarding the plasma processing apparatus 10, an example in which the lower electrode 18 is connected to two systems of high-frequency power supplies and the upper electrode 30 is connected to a DC power supply is shown, but is not limited thereto. For example, alternatively, the lower electrode 18 and the upper electrode 30 of the plasma processing apparatus 10 may be connected to high-frequency power supplies. In addition, the gas plate 36 and the cooling plate 37 may be integrally formed as a plate.

[0088] The material of the main body of the electrostatic chuck 35 is not limited to an elastic dielectric, and may also be ceramic or the like.

[0089] The gas plate 36 and the electrode plate 34 do not necessarily have to be tightly joined, and may also be connected via a member capable of transferring heat. That is, the electrode plate 34 only needs to be configured below the gas plate 36 and have a structure in which its temperature is adjusted.

[0090] It should be understood from the above description that the purpose of describing various embodiments of the present disclosure in this specification is for explanation, and various changes can be made to the various embodiments of the present disclosure without departing from the scope and gist of the present disclosure. Therefore, the various embodiments disclosed in this specification are not intended to be limiting, and the true scope and gist are shown by the appended claims.

Claims

1. A plasma processing method is a method for processing a substrate by plasma in a plasma processing apparatus, wherein, the plasma processing apparatus includes: a chamber configured to accommodate the substrate; an upper electrode structure that forms the upper part of the chamber, the upper electrode structure having a plate whose temperature is controlled, an electrode plate disposed below the plate, and an electrostatic chucking portion sandwiched between the electrode plate and the plate. The electrostatic chucking portion includes a contact surface that contacts the lower surface of the plate, an adsorption surface that adsorbs the upper surface of the electrode plate, a first electrode, and a second electrode. The first electrode and the second electrode are used for electrostatically chucking the electrode plate; a power supply configured to apply a voltage to the first electrode and the second electrode; and a temperature acquisition unit configured to acquire the temperature distribution of the electrode plate, the plasma processing method includes the following steps: an acquisition step of acquiring the temperature distribution of the electrode plate by the temperature acquisition unit; an application step of applying a first voltage to the first electrode and a second voltage to the second electrode according to the temperature distribution acquired in the acquisition step; and a processing step of processing the substrate by plasma.

2. The plasma processing method according to claim 1, wherein, the electrode plate is circular, the first electrode is disposed at a position corresponding to the center of the electrode plate, the second electrode is disposed so as to surround the periphery of the first electrode.

3. The plasma processing method according to claim 1 or 2, wherein, the temperature acquisition unit includes a first temperature sensor and a second temperature sensor. The first temperature sensor detects the temperature at the position of the electrode plate where the first electrode is sandwiched, and the second temperature sensor detects the temperature at the position of the electrode plate where the second electrode is sandwiched.

4. The plasma processing method according to claim 3, wherein, the application step includes the following step: applying a voltage to the first electrode and the second electrode such that the difference between the detected temperature of the first temperature sensor and the detected temperature of the second temperature sensor becomes below a specified temperature threshold.

5. The plasma processing method according to claim 1 or 2, wherein, the electrostatic chucking portion has a single body formed of a dielectric, the first electrode and the second electrode are provided inside the single body.

6. The plasma processing method according to claim 5, wherein, the single body is made of ceramic.

7. The plasma processing method according to claim 5, wherein, the single body is made of an elastic dielectric.

8. The plasma processing method according to claim 1 or 2, wherein, the electrostatic chucking portion has a first body made of a dielectric and a second body made of a dielectric that is separated from the first body, the first electrode is provided inside the first body, the second electrode is provided inside the second body.

9. The plasma processing method according to claim 8, wherein the first body and the second body are made of ceramic.

10. The plasma processing method according to claim 8, wherein the first body and the second body are made of an elastic dielectric.

11. The plasma processing method according to claim 1 or 2, wherein it further includes a step of repeatedly performing the obtaining step, the applying step, and the processing step.

12. A plasma processing apparatus, comprising: a chamber configured to accommodate a substrate; a radio frequency power source for generating plasma; an upper electrode structure forming an upper portion of the chamber, the upper electrode structure having a plate whose temperature is controlled, an electrode plate disposed below the plate, and an electrostatic chuck portion sandwiched between the electrode plate and the plate, the electrostatic chuck portion including a contact surface in contact with a lower surface of the plate, an adsorption surface for adsorbing an upper surface of the electrode plate, a first electrode, and a second electrode, the first electrode and the second electrode being configured to electrostatically chuck the electrode plate; a power source configured to apply a voltage to the first electrode and the second electrode; a temperature acquisition unit configured to acquire a temperature distribution of the electrode plate; and a control unit, Among them, the control unit executes a process including the following steps: an obtaining step of obtaining the temperature distribution of the electrode plate by the temperature acquisition unit; an applying step of controlling the power source to apply a first voltage to the first electrode and a second voltage to the second electrode according to the temperature distribution obtained by the obtaining step; and a processing step of performing plasma processing on the substrate.

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