Methods for processing workpieces

Abstract

The present invention provides a method for processing a workpiece, comprising: an etching step including a main etching step of etching a target film of the workpiece placed on a stage at a low temperature by generating a plasma of a processing gas containing a fluorocarbon gas and / or a hydrofluorocarbon gas; a step of increasing the temperature of an electrostatic chuck immediately after the etching step or the main etching; and a step of removing the workpiece from a chamber while the electrostatic chuck is set to a high temperature. This method allows for the removal or reduction of deposits on the workpiece between the completion of the plasma etching and the removal of the workpiece from the chamber.

Description

Technical Field

[0001] An embodiment of the present invention relates to a method for processing a workpiece. Background Art

[0002] In the manufacture of semiconductor devices and other devices, plasma etching is often used to etch the target film of the workpiece. During plasma etching, the workpiece is placed on an electrostatic chuck on a mounting table within the main chamber of a plasma processing apparatus. A processing gas is then supplied into the chamber and excited, generating plasma.

[0003] Examples of films to be etched in plasma etching include silicon oxide films, silicon nitride films, or multilayer films thereof. In plasma etching of films such as silicon oxide films, silicon nitride films, or multilayer films thereof, a fluorocarbon gas, a hydrofluorocarbon gas, or a combination thereof is used as a process gas. For example, Patent Document 1 describes a technique for etching a silicon oxide film using plasma containing a fluorocarbon gas.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 10-116822.

[0007] Problems to be solved by the invention

[0008] During plasma etching of films to be etched, such as silicon oxide films, silicon nitride films, or multilayer films thereof, the etching rate of the etched film increases when the temperature of the workpiece is low. Therefore, plasma etching is performed with the temperatures of the electrostatic chuck and the workpiece set to low temperatures. When plasma etching is performed using fluorocarbon gas, hydrofluorocarbon gas, or a process gas containing these gases, plasma products containing carbon, or carbon and fluorine, are generated. These plasma products condense or solidify in low-temperature areas, forming deposits. Consequently, unwanted deposits form on the workpiece between the completion of plasma etching and the removal of the workpiece from the chamber. Summary of the Invention

[0009] Technical solutions to solve problems

[0010] In one embodiment, a method for processing a workpiece using a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber body, a mounting platform, and a temperature control mechanism. The chamber body provides an interior space thereof as a chamber. The mounting platform is disposed within the chamber. The mounting platform includes an electrostatic chuck. The electrostatic chuck is configured to hold the workpiece mounted thereon. The temperature control mechanism regulates the temperature of the electrostatic chuck.

[0011] One embodiment of the method includes: (i) a step of etching an etching target film of a workpiece placed on an electrostatic chuck by generating plasma of a processing gas containing a fluorocarbon gas and / or a hydrofluorocarbon gas in a chamber (hereinafter referred to as an "etching step"), wherein the step includes a main etching of the etching target film in a state where the temperature of the electrostatic chuck is set to a temperature of -30°C or lower by a temperature control mechanism; (ii) a step of increasing the temperature of the electrostatic chuck to a temperature of 0°C or higher by a temperature control mechanism with the workpiece placed on the electrostatic chuck immediately after the etching step or immediately after the main etching (hereinafter referred to as a "temperature increasing step"); and (iii) a step of unloading the workpiece placed on the electrostatic chuck from the chamber in a state where the temperature of the electrostatic chuck is set to a temperature of 0°C or higher by executing the temperature increasing step (hereinafter referred to as a "unloading step").

[0012] During the etching process, a plasma product containing carbon, or carbon and fluorine, is generated. During the etching process, the plasma product adheres to the inner wall surface of the chamber body and forms a deposit. The plasma product immediately condenses or solidifies in a low-temperature portion, especially below -30°C, to form a thick deposit. Therefore, if the temperature of the electrostatic chuck and the workpiece is maintained at a temperature below -30°C after the etching is completed, the gas generated from the deposit adhered to the inner wall surface of the chamber body condenses or solidifies on the workpiece to form a thick deposit. In one embodiment of the method, the temperature of the electrostatic chuck and then the temperature of the workpiece is raised to a temperature above 0°C immediately after the etching step or the main etching is performed. Therefore, when the workpiece is moved out of the chamber after the etching is completed, the deposit on the workpiece can be removed or its amount can be reduced.

[0013] In one embodiment, the etching step may further include over-etching the etching target film after performing the main etching.

[0014] In one embodiment, the temperature of the electrostatic chuck is set to a temperature higher than -30°C and lower than 0°C during overetching. When the temperature of the workpiece during overetching is higher than that during main etching, the etching rate of the target film during overetching decreases. This improves controllability of the etching amount of the target film. Furthermore, damage to the base of the target film is suppressed.

[0015] In one embodiment, the temperature increase step is performed while the overetching step is in progress. By increasing the temperature of the electrostatic chuck in parallel with the overetching step, a separate period for increasing the temperature of the electrostatic chuck is not required. Consequently, the time from the end of the etching step to the start of the unloading step is shortened.

[0016] In one embodiment, the method further includes performing a de-electrostatic chuck step after the etching step and before the unloading step. The temperature increase step may be performed while performing the de-electrostatic chuck step. According to this embodiment, the temperature increase step is performed in parallel with the de-electrostatic chuck step performed between the etching step and the unloading step. Therefore, the time from the end of the etching step to the start of the unloading step can be shortened.

[0017] In one embodiment, the mounting table has a lower electrode having a flow path formed therein. The electrostatic chuck is provided on the lower electrode. The temperature regulating mechanism includes a first temperature regulator for supplying a first heat exchange medium and a second temperature regulator for supplying a second heat exchange medium having a temperature higher than that of the first heat exchange medium. In this embodiment, when the main etching is performed, the first heat exchange medium is supplied from the first temperature regulator to the flow path of the lower electrode. When the temperature rising step is performed, the second heat exchange medium is supplied from the second temperature regulator to the flow path of the lower electrode. According to this embodiment, at the start of the temperature rising step, the heat exchange medium supplied to the flow path of the lower electrode can be switched to a high-temperature heat exchange medium at a high speed.

[0018] In one embodiment, a mounting table includes a cooling stage with a flow path formed therein and a heater disposed within an electrostatic chuck. The electrostatic chuck is disposed on the cooling stage. A sealed space is provided between the electrostatic chuck and the cooling stage. The temperature control mechanism includes: a heater for the electrostatic chuck; a cooling unit configured to supply refrigerant to the flow path; and a piping system configured to selectively connect the space to one of the cooling unit, an exhaust device, and a heat transfer gas supply source. In this embodiment, during the main etching process, refrigerant is supplied from the cooling unit to the flow path of the cooling stage, and refrigerant is supplied from the cooling unit to the space. During the temperature increase step, the electrostatic chuck is heated by the heater, and the space is depressurized by the exhaust device. In this embodiment, since the thermal resistance of the space between the electrostatic chuck and the cooling stage increases during the temperature increase step, heat exchange between the cooling stage and the electrostatic chuck can be suppressed. Furthermore, during the temperature increase step, the electrostatic chuck is heated by the heater. Consequently, the time required to heat the electrostatic chuck, and therefore the workpiece, can be shortened.

[0019] Effects of the Invention

[0020] As described above, when the workpiece is carried out of the chamber after the plasma etching is completed, the deposits on the workpiece can be removed or their amount can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a flowchart showing a method for processing a workpiece according to one embodiment.

[0022] Figure 2 This is a cross-sectional view showing a portion of a workpiece as an example.

[0023] Figure 3 It means being able to Figure 1 A schematic diagram of a plasma processing apparatus used in the method shown.

[0024] Figure 4 This is a diagram showing an example of a temperature adjustment mechanism.

[0025] Figure 5 yes Figure 1 A timing diagram of the method is shown.

[0026] Figure 6 yes Figure 1 A timing diagram of the method is shown.

[0027] Figure 7 This is a diagram showing a state where a sediment is formed.

[0028] Figure 8 This is a graph showing the relationship between the time a silicon wafer is placed on the electrostatic chuck and the thickness of a deposit formed on the silicon wafer.

[0029] Figure 9 This is a graph showing the relationship between the temperature of the electrostatic chuck and the thickness of the deposit.

[0030] Figure 10 It is a diagram showing the state after step ST5 is executed.

[0031] Figure 11 It is a diagram showing the state after step ST7 is executed.

[0032] Figure 12 It means being able to Figure 1 A schematic diagram of another example of a plasma processing apparatus used in performing the method shown.

[0033] Figure 13 It will Figure 12 The figure is a cross-sectional view showing an enlarged portion of a mounting table of a plasma processing apparatus.

[0034] Figure 14 It will Figure 12FIG2 is a cross-sectional view showing an enlarged view of another portion of the mounting table of the plasma processing apparatus.

[0035] Figure 15 This is a diagram showing the configuration of an example of a piping system.

[0036] Description of Reference Numerals

[0037] 10…Plasma processing apparatus, 12…Chamber body, 16…Placement table, 18…Lower electrode, 18f…Flow path, 20…Electrostatic chuck, 24…Temperature adjustment mechanism, 24a…First temperature adjustment device, 24b…Second temperature adjustment device, 40…Gas source group, 50…Exhaust device, 62…First high-frequency power supply, 64…Second high-frequency power supply, 100…Plasma processing apparatus, 112…Chamber body, 112c…Chamber, 116…Placement table, 117…Cooling table, 117f…Flow path, 120…Electrostatic chuck, 150…Exhaust device, HN, 156, 157, 158…Heater, 161…Heater power supply, DSN, DS1, DS2, DS3…Heat transfer space, GS…Gas source, TU…Cooling unit, VU…Exhaust device, W…Workpiece, EF…Etching target film DETAILED DESCRIPTION

[0038] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, wherein the same or corresponding parts are denoted by the same reference numerals in each of the drawings.

[0039] Figure 1 This is a flowchart showing a method for processing a workpiece according to one embodiment. Figure 1 The method MT shown includes the step of etching an etching target film of a workpiece in a plasma processing apparatus. Figure 2 This is a cross-sectional view showing a portion of a workpiece. Figure 2 The workpiece W is shown.

[0040] like Figure 2 As shown, the workpiece W has a base layer UL, an etching target film EF, and a mask MK. The base layer UL is a layer that serves as the base of the etching target film EF and is formed of, for example, silicon or tungsten. The etching target film EF is provided on the base layer UL. The etching target film EF is a multilayer film in which one or more silicon oxide films and one or more silicon nitride films are alternately stacked. The mask MK is provided on the etching target film EF. The mask MK is formed of, for example, a metal such as tungsten, or an organic material such as polycrystalline silicon or amorphous carbon. The mask MK has an opening. In the method MT, the etching target film EF is etched in the portion exposed from the opening of the mask MK. The mask MK may provide a plurality of openings on the etching target film EF.

[0041] Figure 3 It means it can be used for Figure 1 A schematic diagram of a plasma processing apparatus showing the method. Figure 3 The illustrated plasma processing apparatus 10 is a capacitively coupled plasma processing apparatus. The plasma processing apparatus 10 includes a chamber body 12. The chamber body 12 has a generally cylindrical shape. The interior space of the chamber body 12 defines a chamber 12c. The chamber body 12 is formed of a metal such as aluminum. A plasma-resistant coating, such as an yttrium oxide film, is formed on the inner wall surface of the chamber body 12. The chamber body 12 is grounded.

[0042] A support portion 14 is provided within chamber 12c and on the bottom of chamber body 12. Support portion 14 is made of an insulating material and has a generally cylindrical shape. Support portion 14 extends upward from the bottom of chamber body 12 within chamber 12c. Support portion 14 supports a support table 16 on its upper side.

[0043] The mounting table 16 includes a lower electrode 18 and an electrostatic chuck 20. The lower electrode 18 comprises a first member 18a and a second member 18b. The first and second members 18a, 18b are formed of a conductor such as aluminum and are generally disc-shaped. The second member 18b is disposed on the first member 18a and is electrically connected to the first member 18a. The electrostatic chuck 20 is disposed on the lower electrode 18.

[0044] The electrostatic chuck 20 is configured to hold a workpiece W placed thereon. The electrostatic chuck 20 includes a generally disc-shaped insulating layer and a film-shaped electrode disposed within the insulating layer. The electrode of the electrostatic chuck 20 is electrically connected to a DC power supply 22 via a switch 23. The electrostatic chuck 20 attracts and holds the workpiece W onto the electrostatic chuck 20 using the electrostatic force generated by the DC voltage from the DC power supply 22. A heater may be provided within the electrostatic chuck 20.

[0045] A focus ring FR is disposed around the periphery of the lower electrode 18 to surround the edge of the workpiece W and the edge of the electrostatic chuck 20. The focus ring FR is provided to improve etching uniformity. The focus ring FR is made of a material appropriately selected according to the material being etched.

[0046] A refrigerant flow path 18f is formed in the second member 18b of the lower electrode 18. A heat exchange medium is supplied to the flow path 18f via a pipe 25a from a temperature control mechanism 24 located outside the chamber body 12. The heat exchange medium supplied to the flow path 18f returns to the temperature control mechanism 24 via a pipe 25b. In other words, the heat exchange medium circulates between the temperature control mechanism 24 and the flow path 18f. The circulation of this temperature-controlled heat exchange medium between the temperature control mechanism 24 and the flow path 18f regulates the temperature of the electrostatic chuck 20, and thereby the temperature of the workpiece W.

[0047] Figure 4 FIG is a diagram showing an example of a temperature control mechanism. Figure 4 As shown, an example of the temperature control mechanism 24 includes a first temperature controller 24a and a second temperature controller 24b. The first temperature controller 24a controls the temperature of a first heat exchange medium (e.g., salt water) and outputs the first heat exchange medium. The second temperature controller 24b controls the temperature of a second heat exchange medium (e.g., salt water) and outputs the second heat exchange medium. The temperature of the second heat exchange medium is higher than that of the first heat exchange medium. The first temperature controller 24a sets the temperature of the first heat exchange medium to, for example, -70°C. The second temperature controller 24b sets the temperature of the second heat exchange medium to, for example, a temperature within the range of 0°C to 100°C.

[0048] The temperature control mechanism 24 includes valves 24c, 24d, 24e, and 24f. The output port of the first temperature regulator 24a is connected to the pipe 25a via valve 24c. The output port of the first temperature regulator 24a is a port for outputting the first heat exchange medium. The return port of the first temperature regulator 24a is connected to the pipe 25b via valve 24d. The return port of the first temperature regulator 24a is a port for receiving the heat exchange medium that returns to the first temperature regulator 24a from the flow path 18f via the pipe 25b. The output port of the second temperature regulator 24b is connected to the pipe 25a via valve 24e. The output port of the second temperature regulator 24b is a port for outputting the second heat exchange medium. The return port of the second temperature regulator 24b is connected to the pipe 25b via valve 24f. The return port of the second temperature regulator 24b is a port for receiving the heat exchange medium that returns to the second temperature regulator 24b from the flow path 18f via the pipe 25b.

[0049] When the heat exchange medium is circulated between the first temperature regulator 24a and the flow path 18f, valves 24c and 24d are opened, and valves 24e and 24f are closed. On the other hand, when the heat exchange medium is circulated between the second temperature regulator 24b and the flow path 18f, valves 24c and 24d are closed, and valves 24e and 24f are opened.

[0050] The first and second temperature regulators 24a and 24b are temperature regulators that regulate the temperature of the heat exchange medium. However, the first and second temperature regulators 24a and 24b may also be direct expansion temperature regulators. If the first and second temperature regulators 24a and 24b are direct expansion temperature regulators, they each include a compressor, a condenser, and an expansion valve, and the mounting table 16 serves as an evaporator.

[0051] The plasma processing apparatus 10 is provided with a gas supply line 28. The gas supply line 28 supplies 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.

[0052] The plasma processing apparatus 10 further includes an upper electrode 30. The upper electrode 30 is disposed above the mounting table 16 so as to face the mounting table 16. The upper electrode 30 is supported on the upper portion of the chamber body 12 via an insulating member 32. The upper electrode 30 may include a top plate 34 and a support 36. The top plate 34 faces the chamber 12c. A plurality of gas exhaust holes 34a are formed in the top plate 34. The top plate 34 may be formed of a low-resistance conductor or semiconductor that generates little Joule heat.

[0053] The support body 36 supports the top plate 34 so that it can be attached and detached. For example, it can be formed from a conductor such as aluminum. A gas diffusion chamber 36a is provided within the support body 36. Multiple gas holes 36b extend downward from the gas diffusion chamber 36a, each connected to the multiple gas discharge holes 34a. Furthermore, a port 36c is formed in the support body 36 for guiding gas into the gas diffusion chamber 36a. The port 36c is connected to the pipe 38.

[0054] The piping 38 is connected to the gas source group 40 via the valve group 42 and the flow controller group 44. The gas source group 40 includes a plurality of gas sources for supplying process gas to the chamber 12c. The process gas includes a fluorocarbon gas and / or a hydrofluorocarbon gas. In one example, the gas source group 40 includes: a source of a fluorocarbon gas, a source of a hydrofluorocarbon gas, and a source of an oxygen-containing gas. Fluorocarbon gas is, for example, C4F8 gas. Hydrofluorocarbon gas is, for example, CH2F2 gas. Oxygen-containing gas is, for example, oxygen (O2 gas). The gas source group 40 includes: a source of hydrogen (H2 gas), a source of one or more halogen gases, and a source of hydrocarbon gas. For example, the gas source group 40 may include a source of NF3 as a source of halogen-containing gas. In addition, the gas source group 40 may include a source of CH4 gas as a source of hydrocarbon gas.

[0055] Valve assembly 42 includes multiple valves, and flow controller assembly 44 includes multiple flow controllers. Each of the multiple flow controllers is a mass flow controller or a pressure-controlled flow controller. The multiple gas sources of gas source assembly 40 are connected to piping 38 via corresponding flow controllers of flow controller assembly 44 and corresponding valves of valve assembly 42.

[0056] An annular exhaust path is formed between the mounting table 16 and the side wall of the chamber body 12 when viewed from above. A baffle 48 is provided in the middle of the exhaust path in the vertical direction. The baffle 48 can be formed by coating a ceramic called Y2O3 on an aluminum material, for example. An exhaust port 12e is provided at the chamber body 12 below the baffle 48. The exhaust port 12e is connected to the exhaust device 50 via an exhaust pipe 52. The exhaust device 50 has a vacuum pump such as a pressure regulator and a turbomolecular pump. The exhaust device 50 can reduce the pressure of the chamber 12c to a specified pressure. In addition, an opening 12p for carrying in or out the workpiece W is provided on the side wall of the chamber body 12. The opening 12p can be opened and closed by a gate valve GV.

[0057] The plasma processing apparatus 10 further includes a first high-frequency power supply 62 and a second high-frequency power supply 64. The first high-frequency power supply 62 is a power supply for generating a first high-frequency power for plasma generation. The frequency of the first high-frequency power is between 27 and 100 MHz, and in one example, is 100 MHz. The first high-frequency power supply 62 is connected to the lower electrode 18 via a matching device 66. The matching device 66 includes a circuit for matching the output impedance of the first high-frequency power supply 62 with the input impedance of the load side (the lower electrode 18 side). The first high-frequency power supply 62 can be connected to the upper electrode 30 via the matching device 66.

[0058] The second high-frequency power source 64 generates a second high-frequency power source for attracting ions into the workpiece W. The second high-frequency power source has a frequency within the range of 400 kHz to 13.56 MHz, and in one example, is 3 MHz. The second high-frequency power source 64 is connected to the lower electrode 18 via a matching device 68. The matching device 68 includes a circuit for matching the output impedance of the second high-frequency power source 64 with the input impedance on the load side (the lower electrode 18 side).

[0059] The plasma processing apparatus 10 also includes a control unit CU. The control unit CU is a computer including a processor, a storage unit, an input device, a display device, and the like. The control unit CU controls the various components of the plasma processing apparatus 10. In the control unit CU, an operator can use the input device to input commands for managing the plasma processing apparatus 10. Furthermore, the display device can display the operating status of the plasma processing apparatus 10. Furthermore, the storage unit of the control unit CU stores control programs and process data for the processor to control various processes performed by the plasma processing apparatus 10. For example, the storage unit of the control unit CU stores control programs and process data for the plasma processing apparatus 10 to perform method MT.

[0060] Reference again Figure 1 , using the plasma processing device 10 Figure 2 The method MT will be described by taking the case where the workpiece W shown in FIG. Figure 1 In FIG. 1 , two parallel double lines indicate that two or more steps among the multiple steps drawn between them are executed in parallel. Figure 1 、 Figure 5 and Figure 6 . Figure 5 and Figure 6 It is a timing diagram associated with method MT.

[0061] like Figure 1 As shown, method MT starts at step ST1. In step ST1, the temperature of electrostatic chuck 20 is set to a temperature of -30°C or less for main etching described later. In step ST1, for example, a refrigerant circulates between first temperature regulator 24a and flow path 18f.

[0062] Next, in step ST2, the workpiece W is carried into the chamber 12c. In step ST2, the workpiece W is placed on the electrostatic chuck 20 and held by the electrostatic chuck 20. Step ST1 may be performed after step ST2.

[0063] Next, step ST3 is performed. In step ST3, the etching target film EF of the workpiece W is etched. In step ST3, a plasma of a processing gas containing a fluorocarbon gas and / or a hydrofluorocarbon gas is generated in the chamber 12c. The processing gas may include: hydrogen gas (H2 gas), a source containing one or more halogen gases, and a hydrocarbon gas. Specifically, in step ST3, the processing gas is supplied to the chamber 12c from the gas source group 40. The processing gas, for example, includes CH2F2 gas, C4F8 gas, H2 gas, CH4 gas, and NF3 gas. In addition, the pressure of the chamber 12c is set to a specified pressure by the exhaust device 50. In addition, the first high-frequency power for generating plasma is output from the first high-frequency power supply 62. Thus, a plasma of the processing gas is generated in the chamber 12c. In addition, as needed, the second high-frequency power is supplied from the second high-frequency power supply 64 to the lower electrode 18. In step ST3, the etching target film EF is etched using ions and / or radicals from the plasma.

[0064] Step ST3 includes main etching ST31 and over etching ST32. In the main etching ST31, the temperature of the electrostatic chuck 20 is set to -30°C or less by the temperature adjustment mechanism 24 (see Figure 5 ), the etching target film EF is etched by the ions and / or radicals from the plasma of the processing gas. When the temperature of the electrostatic chuck 20, i.e., the temperature of the workpiece W, is set to -30°C or lower, as described above, the etching rate of the etching target film EF is increased when the ions and / or radicals from the plasma of the processing gas are etched.

[0065] Overetching ST32 is performed after the main etching ST31. If the mask MK has multiple openings, the etching target film EF may not be uniformly etched below the multiple openings during the main etching ST31. That is, when the etching target film EF is etched below the openings of one portion of the mask MK until it reaches the base layer UL by the main etching ST31, only a small amount of the etching target film EF remains on the base layer UL below the openings of another portion of the mask MK. Overetching ST32 is performed to etch the etching target film EF remaining below the openings of the other portion of the mask MK in this manner, in order to uniformly remove the etching target film EF below all the openings of the mask MK.

[0066] In the overetching step ST32, the etching target film EF is etched using the ions and / or radicals from the plasma of the processing gas. In one embodiment, the overetching step ST32 is performed while the temperature of the electrostatic chuck 20, i.e., the temperature of the workpiece W, is set to a temperature higher than -30°C and lower than 0°C by the temperature control mechanism 24. Figure 5The temperature of the electrostatic chuck during overetch ST32 is shown by the dashed line. When the temperature of the workpiece W during overetch ST32 is higher than that during main etch ST31, the etching rate of the target film EF during overetch ST32 decreases. This improves the controllability of the etching amount of the target film EF. Furthermore, damage to the underlying layer UL is suppressed. The temperature of the electrostatic chuck 20 during overetch ST32 is not limited to a temperature above -30°C and below 0°C.

[0067] Next, in method MT, step ST4 is executed. In step ST4, static electricity is removed from electrostatic chuck 20. To remove static electricity from electrostatic chuck 20, a voltage having a polarity opposite to that of the voltage applied to the electrode of electrostatic chuck 20 when electrostatic chuck 20 holds workpiece W is applied to the electrode of electrostatic chuck 20.

[0068] Figure 7 : is a diagram showing a state in which a deposit is formed. When the plasma of the above-mentioned processing gas is generated, a plasma product containing carbon or carbon and fluorine is generated. The plasma product adheres to the inner wall surface of the chamber body 12 during the execution of the etching in step ST3 to form a deposit. The plasma product immediately condenses or solidifies, especially in low-temperature areas, to form a thick deposit. Therefore, if the temperature of the electrostatic chuck 20 and the workpiece W is maintained at a temperature below -30°C after the etching in step ST3 is completed, the gas generated from the deposit adhered to the inner wall surface of the chamber body 12 condenses or solidifies on the workpiece W to form a thick deposit. As a result, as Figure 7 As shown, a deposit DP is formed on the inner wall surface of the chamber body 12 , the surface of the mounting table 16 , and the surface of the workpiece W.

[0069] Here, a first experiment and a second experiment conducted to investigate the formation of deposits are described. In the first experiment, immediately after the main etching step ST31 was performed using the plasma processing apparatus 10, a silicon wafer was loaded into the chamber 12c and placed on the electrostatic chuck 20. The temperature of the electrostatic chuck 20 while the silicon wafer was placed on the chuck was maintained at the same temperature as that during the main etching step ST31. The thickness of the deposits formed on the silicon wafer was then measured. In the first experiment, the time the silicon wafer was placed on the electrostatic chuck 20 was set to various times. The relationship between the time the silicon wafer was placed on the electrostatic chuck 20 and the thickness of the deposits formed on the silicon wafer was determined. During the main etching step ST31 of the first experiment, the pressure in chamber 12c was 25 mTorr (3.333 Pa), the frequency and power of the first high-frequency power were 40 MHz and 1 kW, respectively, and the frequency and power of the second high-frequency power were 3 MHz and 5 kW, respectively. The process gas was a mixture of H2, CH2F2, CH4, C4F8, and NF3. The temperature of the electrostatic chuck 20 was -60°C, and the processing time was 600 seconds. The thickness of the deposit on the silicon wafer was not dependent on the duration of the main etching step ST31, provided that the main etching step ST31 was performed for a sufficient period of time to allow the deposit to adhere to all components within the chamber and the inner wall surface of the chamber body.

[0070] The relationship between the time the silicon wafer is placed on the electrostatic chuck 20 and the thickness of the deposit formed on the silicon wafer obtained from the first experiment is expressed as follows: Figure 8 The curve diagram shows . Figure 8 In the graph, the horizontal axis represents the time when the silicon wafer is placed on the electrostatic chuck 20, and the vertical axis represents the thickness of the deposit. Figure 8 As shown in FIG. 1 , if the temperature of electrostatic chuck 20 is maintained at the temperature during main etching ST31, the thickness of the deposit formed on the silicon wafer increases rapidly. This confirms that after etching using the plasma of the processing gas is performed while the temperature of electrostatic chuck 20 is set to a low temperature, if the temperature of electrostatic chuck 20 is maintained at a low temperature, a thick deposit rapidly forms on the workpiece on electrostatic chuck 20.

[0071] In the second experiment, immediately after the main etching ST31 was performed in plasma processing apparatus 10 , a silicon wafer was carried into chamber 12 c and placed on electrostatic chuck 20 . The silicon wafer was left on electrostatic chuck 20 for 300 seconds.

[0072] The thickness of the deposit formed on the silicon wafer was then measured. In the second experiment, various temperatures were set, using the temperature of the electrostatic chuck 20 after the main etching step ST31 as the reference temperature. The relationship between the temperature of the electrostatic chuck 20 after the main etching step ST31 and the thickness of the deposit was determined. The processing conditions for the main etching step ST31 in the second experiment were the same as those in the first experiment.

[0073] The relationship between the temperature of the electrostatic chuck and the thickness of the deposit obtained from the second experiment is expressed as Figure 9 The curve diagram shows that. Figure 9 In the graph, the horizontal axis represents the temperature of the electrostatic chuck 20 after the main etching ST31 is performed, and the vertical axis represents the thickness of the deposit. Figure 9 As shown in FIG. 3 , it was confirmed that if the temperature of electrostatic chuck 20 was maintained at a low temperature after the main etching step ST31 was performed, thick deposits were formed on the silicon wafer. On the other hand, if the temperature of electrostatic chuck 20 was set to 0° C. or higher after the main etching step ST31 was performed, it was confirmed that the deposits on the silicon wafer were substantially removed.

[0074] As can be seen from the first and second experiments described above, the temperature of the electrostatic chuck 20, that is, the temperature of the workpiece W, should be set to 0°C or higher from the time the etching using the plasma of the processing gas is completed until the workpiece W is unloaded from the chamber 12c. Furthermore, after the etching in step ST3 or the main etching ST31 is completed, the temperatures of the electrostatic chuck 20 and the workpiece W should be immediately raised.

[0075] In method MT, step ST5 is executed to reduce the amount of deposits on workpiece W. In step ST5, the temperature of electrostatic chuck 20 is raised to 0°C or higher. Consequently, the temperature of workpiece W is also raised to 0°C or higher. In step ST5, the second heat exchange medium circulates between second temperature regulator 24b and flow path 18f.

[0076] In one embodiment, step ST5 is performed immediately after step ST3 is performed. Specifically, step ST5 is performed during the period of de-electrification of the electrostatic chuck 20 in step ST4. Figure 5 The solid line indicates the temperature of the electrostatic chuck during the execution of step ST4. By executing step ST5, the temperature of the electrostatic chuck 20 and the workpiece W is increased immediately after executing step ST3.

[0077] In another embodiment, step ST5 is performed immediately after the main etching ST31 is performed. Specifically, step ST5 is performed in parallel with the over etching ST32. Figure 5The temperature of the electrostatic chuck is shown by the dotted line during the execution of the over-etching ST32 in the embodiment. By executing step ST5, the temperature of the electrostatic chuck 20 and the workpiece W is increased immediately after the main etching ST31 is executed.

[0078] Figure 10 1 is a diagram showing the state after step ST5 is executed. When step ST5 is executed, the temperature of the electrostatic chuck 20 and the temperature of the workpiece W become 0°C or higher. Figure 10 As shown, the amount of the deposit DP on the workpiece W is reduced, or the deposit DP on the workpiece W is removed.

[0079] In the method MT, step ST6 is then performed. In step ST6, the workpiece W is unloaded from the chamber 12c. During the execution of step ST6, the temperature of the electrostatic chuck 20 is as follows: Figure 5 The temperature is maintained above 0°C as shown.

[0080] In method MT, step ST7 is then performed. In step ST7, cleaning is performed. In one embodiment, as Figure 5 As shown, step ST7 includes step ST71, step ST72, step ST73, step ST74, and step ST75. In step ST71, a dummy wafer is brought into the chamber 12c and held by the electrostatic chuck 20 for cleaning.

[0081] In the subsequent step ST72, a plasma of a cleaning gas is generated within the chamber 12c. The cleaning gas contains an oxygen-containing gas. The oxygen-containing gas may be, for example, oxygen (O2 gas), carbon monoxide gas, or carbon dioxide gas. In step ST72, the cleaning gas is supplied from the gas source assembly 40 to the chamber 12c. Furthermore, first high-frequency power is supplied from the first high-frequency power supply 62 to generate the plasma.

[0082] In the subsequent step ST73, static electricity is removed from the electrostatic chuck 20. The static electricity removal of the electrostatic chuck 20 is the same as that in step ST4. Then, in step ST74, the dummy wafer is unloaded from the chamber 12c.

[0083] In the subsequent step ST75, plasma of a cleaning gas is generated within chamber 12c, with no object such as a dummy wafer placed on electrostatic chuck 20. The cleaning gas in step ST75 is the same as the cleaning gas in step ST72. The plasma generation in step ST75 is performed in the same manner as in step ST72. Figure 11 : is a diagram showing the state after step ST7 is executed. Figure 11 As shown, the deposit DP is removed from the inner wall surface of the chamber body 12 and the surface of the mounting table 16 by executing step ST7 .

[0084] The temperature of the electrostatic chuck 20 during the execution of step ST7 can be set to any temperature. Figure 5 As shown, the temperature of electrostatic chuck 20 is maintained at 0°C or higher from the start of step ST71 to the midpoint of step ST75. Then, the temperature of electrostatic chuck 20 decreases from the midpoint of step ST75. Alternatively, the temperature of electrostatic chuck 20 is maintained at 0°C or higher in step ST71. Then, the temperature of electrostatic chuck 20 decreases from the start of step ST72.

[0085] Refer again Figure 1 In method MT, step ST8 is then executed. In step ST8, it is determined whether another workpiece is to be processed. If another workpiece is to be processed, the process from step ST1 is repeated. On the other hand, if another workpiece is not to be processed, method MT ends.

[0086] In method MT, during the execution of the above-mentioned step ST3, step ST9 is executed in parallel. In step ST9, it is determined whether the interruption condition is satisfied. The interruption condition is satisfied when an abnormality occurs during the execution of step ST3. When it is determined that the interruption condition is satisfied, step ST10 is executed. In step ST10, the electrostatic chuck 20 is de-electrified. Step ST10 is the same step as step ST4. Next, step ST11 is executed. In step ST11, the temperature of the electrostatic chuck 20 rises. In step ST11, the second heat exchange medium circulates between the second temperature regulator 24b and the flow path 18f. In addition, step ST11 can also be executed in parallel with step ST10. Please refer to Figure 6 The temperature of the electrostatic chuck during the execution of step ST10 is then determined. Next, in step ST12, the workpiece W is unloaded from the chamber 12c. Then, the method MT ends.

[0087] In method MT, the temperature of the electrostatic chuck 20, and therefore the temperature of the workpiece W, rises to a temperature above 0°C immediately after step ST3 is performed or immediately after the main etching ST31 is performed, so when the workpiece W is moved out of the chamber W, the deposit DP on the workpiece W has been removed or its amount has been reduced.

[0088] In one embodiment, as described above, step ST5 is performed during step ST4. Specifically, step ST5 is performed in parallel with the static elimination of electrostatic chuck 20 between steps ST3 and ST6. Therefore, a separate period for heating electrostatic chuck 20 is not required. Consequently, the time from the completion of etching in step ST3 to the removal of workpiece W in step ST6 is shortened.

[0089] In another embodiment, as described above, step ST5 is performed while overetching ST32 is in progress. That is, the temperature increase of electrostatic chuck 20 in step ST5 is performed in parallel with overetching ST32. Therefore, a separate period for increasing the temperature of electrostatic chuck 20 is not required. Consequently, the time from the completion of etching in step ST3 to the removal of workpiece W in step ST6 is shortened.

[0090] Furthermore, according to temperature adjustment mechanism 24, when step ST5 is started, the heat exchange medium supplied to flow path 18f can be quickly switched from the low-temperature first heat exchange medium to the high-temperature second heat exchange medium.

[0091] Next, a plasma processing apparatus according to another embodiment that can be used to perform method MT will be described. Figure 12 It means it can be used for Figure 1 A schematic diagram of another example of a plasma processing apparatus for performing the method shown. Figure 12 The plasma processing apparatus 100 shown is a capacitively coupled plasma processing apparatus. The plasma processing apparatus 100 includes a chamber body 112 and a stage 116. The chamber body 112 has a substantially cylindrical shape, and its internal space provides a chamber 112c. The chamber body 112 is formed, for example, of aluminum. A plasma-resistant ceramic coating, such as an yttrium oxide film, is formed on the surface of the chamber body 112 on the chamber 12c side. The chamber body 112 is grounded. In addition, an opening 112p for carrying a workpiece W into and out of the chamber 112c is formed on the side wall of the chamber body 112. The opening 112p can be opened and closed by a gate valve GV.

[0092] The mounting table 116 is configured to support the workpiece W within the chamber 112 c. The mounting table 116 has the functions of attracting the workpiece W, regulating the temperature of the workpiece W, and transmitting high-frequency power to the base of the electrostatic chuck. Details of the mounting table 116 will be described later.

[0093] The plasma processing apparatus 100 further includes an upper electrode 130 . The upper electrode 130 is disposed in the upper opening of the chamber body 112 and is substantially parallel to the lower electrode of the mounting table 116 . An insulating support member 132 is provided between the upper electrode 130 and the chamber body 112 .

[0094] The upper electrode 130 includes a top plate 134 and a support 136. The top plate 134 has a generally disk-like shape. It can be electrically conductive. For example, the top plate 134 can be made of silicon. Alternatively, the top plate 134 can be made of aluminum with a plasma-resistant ceramic coating formed on its surface. Multiple gas exhaust holes 134a are formed in the top plate 134. The gas exhaust holes 134a extend in a generally vertical direction.

[0095] The support body 136 detachably supports the top plate 134. The support body 136 is formed, for example, of aluminum. A gas diffusion chamber 136 a is formed in the support body 136 . Multiple gas holes 136 b extend from the gas diffusion chamber 136 a, each communicating with the multiple gas exhaust holes 134 a. Furthermore, a pipe 138 is connected to the gas diffusion chamber 136 a via a port 136 c. Similar to the plasma processing apparatus 10 , the pipe 138 is connected to the gas source assembly 40 via a valve assembly 42 and a flow controller assembly 44 .

[0096] The plasma processing apparatus 100 further includes an exhaust device 150 . The exhaust device 150 includes a pressure regulator and one or more vacuum pumps such as a turbomolecular pump. The exhaust device 150 is connected to an exhaust port formed in the chamber body 112 .

[0097] The plasma processing apparatus 100 also includes a control unit MCU. The control unit MCU has the same structure as the control unit CU of the plasma processing apparatus 10. The memory unit of the control unit MCU stores control programs and process data for controlling various processes performed by the plasma processing apparatus 100 using a processor. For example, the memory unit of the control unit MCU stores control programs and process data for executing method MT in the plasma processing apparatus 100.

[0098] The following, except Figure 12 In addition, refer to Figure 13 and Figure 14 , the mounting table 116 and the components of the plasma processing apparatus 100 attached to the mounting table 116 will be described in detail. Figure 13 It will Figure 12 The figure is a cross-sectional view showing an enlarged portion of a mounting table of a plasma processing apparatus. Figure 14 It will Figure 12 FIG2 is a cross-sectional view showing an enlarged view of another portion of the mounting table of the plasma processing apparatus.

[0099] The mounting platform 116 includes a cooling stage 117 and an electrostatic chuck 120. The cooling stage 117 is supported by a support member 114 extending upward from the bottom of the chamber body 112. The support member 114 is an insulating member formed of, for example, alumina. Furthermore, the support member 114 has a generally cylindrical shape.

[0100] Cooling stage 117 is formed of a conductive metal, such as aluminum. It has a generally disc-shaped surface. It includes a central portion 117a and a peripheral portion 117b. Central portion 117a is generally disc-shaped. Central portion 117a defines a first upper surface 117c of cooling stage 117. First upper surface 117c is generally circular.

[0101] The peripheral portion 117b is connected to the central portion 117a and extends radially (in the radial direction relative to the axis Z extending in the vertical direction) outside the central portion 117a in the circumferential direction (in the circumferential direction relative to the axis Z). The peripheral portion 117b, together with the central portion 117a, provides the lower surface 117d of the cooling stage 117. In addition, the peripheral portion 117b provides the second upper surface 117e. The second upper surface 117e is a strip-shaped surface that is located radially outside the first upper surface 117c and extends circumferentially. In addition, the second upper surface 117e is located closer to the lower surface 117d than the first upper surface 117c in the vertical direction.

[0102] Cooling stage 117 is connected to power supply 119. Power supply 119, for example, a power supply rod, is connected to lower surface 117d of cooling stage 117. Power supply 119 is made of aluminum or an aluminum alloy. Power supply 119 is connected to first high-frequency power supply 62 via matching device 66. Power supply 119 is also electrically connected to second high-frequency power supply 64 via matching device 68.

[0103] A refrigerant flow path 117f is formed in the cooling stage 117. The flow path 117f extends, for example, in a spiral shape within the cooling stage 117. Refrigerant is supplied to the flow path 117f from the cooling unit TU. The cooling unit TU forms part of the temperature control mechanism in one embodiment. The refrigerant supplied to the flow path 117f returns to the cooling unit TU. The refrigerant supplied to the flow path 117f is, for example, a refrigerant that absorbs heat by vaporizing to cool the environment. Such a refrigerant may be, for example, a hydrofluorocarbon refrigerant.

[0104] Electrostatic chuck 120 is disposed on cooling stage 117. Specifically, electrostatic chuck 120 is disposed on first upper surface 117c of cooling stage 117. Electrostatic chuck 120 includes a base 121 and an adsorption portion 123. Base 121 constitutes a lower electrode and is disposed on cooling stage 117. Base 121 is conductive. For example, base 121 may be made of ceramic, such as aluminum nitride or silicon carbide, which imparts conductivity, or may be made of metal (e.g., titanium).

[0105] The base 121 has a generally disc-shaped structure. The base 121 includes a central portion 121a and a peripheral portion 121b. The central portion 121a has a generally disc-shaped structure. The central portion 121a provides a first upper surface 121c of the base 121. The first upper surface 121c is a generally circular surface.

[0106] The peripheral portion 121b is connected to the central portion 121a and extends circumferentially radially outward from the central portion 121a. Together with the central portion 121a, the peripheral portion 121b forms the lower surface 121d of the base 121. Furthermore, the peripheral portion 121b forms a second upper surface 121e. This second upper surface 121e is a strip-shaped surface that extends circumferentially radially outward from the first upper surface 121c. Furthermore, the second upper surface 121e is located vertically closer to the lower surface 121d than the first upper surface 121c.

[0107] The adsorption portion 123 is provided on the base 121. The adsorption portion 123 is bonded to the base 121 by metal bonding using a metal interposed between the adsorption portion 123 and the base 121. The adsorption portion 123 has a substantially disk shape and is formed of ceramic. The ceramic constituting the adsorption portion 123 can have a 1×10 15 A ceramic having a volume resistivity of Ω·cm or more. For example, alumina can be used as such a ceramic.

[0108] Electrostatic chuck 120 includes an axis Z and multiple regions RN concentric with the central axis of electrostatic chuck 120. In one example, electrostatic chuck 120 includes a first region R1, a second region R2, and a third region R3. First region R1 intersects axis Z, third region R3 includes the edge of electrostatic chuck 120, and second region R2 is located between first region R1 and third region R3. In one example, first region R1 is the region from the center of electrostatic chuck 120 to a radius of 120 mm, second region R2 is the region from a radius of 120 mm to a radius of 135 mm, and third region R3 is the region from a radius of 135 mm to a radius of 150 mm. The number of regions of electrostatic chuck 120 can be any number, one or more.

[0109] The adsorption portion 123 of the electrostatic chuck 120 has a built-in adsorption electrode 125. The adsorption electrode 125 is a film-shaped electrode electrically connected to the DC power supply 22 via a switch. When a DC voltage from the DC power supply 22 is applied to the adsorption electrode 125, the adsorption portion 123 generates an electrostatic force such as a Coulomb force, and this electrostatic force holds the workpiece W.

[0110] Adsorption unit 123 also includes multiple built-in heaters HN. These heaters HN form part of the temperature control mechanism in one embodiment. The heaters HN are positioned within the multiple regions RN of the electrostatic chuck. In one example, the heaters HN include a first heater 156, a second heater 157, and a third heater 158. First heater 156 is positioned within first region R1, second heater 157 is positioned within second region R2, and third heater 158 is positioned within third region R3.

[0111] Multiple heaters HN are connected to a heater power supply 161. A filter 163a is provided between the first heater 156 and the heater power supply 161 to prevent high-frequency power from entering the heater power supply 161. A filter 163b is provided between the second heater 157 and the heater power supply 161 to prevent high-frequency power from entering the heater power supply 161. A filter 163c is provided between the third heater 158 and the heater power supply 161 to prevent high-frequency power from entering the heater power supply 161.

[0112] A plurality of first elastic members EM1 are provided between the base 121 and the cooling stage 117. The plurality of first elastic members EM1 space the electrostatic chuck 120 upward from the cooling stage 117. Each of the plurality of first elastic members EM1 is an O-ring. The plurality of first elastic members EM1 have different diameters from one another and are concentrically arranged relative to the axis Z. In addition, the plurality of first elastic members EM1 are provided below the boundary of adjacent regions of the electrostatic chuck 120 and the edge of the edge of the electrostatic chuck 120. In one example, the plurality of first elastic members EM1 include an elastic member 165, an elastic member 167, and an elastic member 169. The elastic member 165 is provided below the boundary between the first region R1 and the second region R2, the elastic member 167 is provided below the boundary between the second region R2 and the third region R3, and the elastic member 169 is provided below the edge of the electrostatic chuck 120.

[0113] Multiple first elastic members EM1 are partially disposed in grooves provided by the first upper surface 117c of the cooling stage 117, contacting the first upper surface 117c and the lower surface 121d of the base 121. Together with the cooling stage 117 and the base 121, the multiple elastic members EM1 form a plurality of sealed heat transfer spaces DSN between the first upper surface 117c of the cooling stage 117 and the lower surface 121d of the base 121. The multiple heat transfer spaces DSN extend below each of the multiple regions RN of the electrostatic chuck 120 and are separated from each other. In one example, the multiple heat transfer spaces DSN include a first heat transfer space DS1, a second heat transfer space DS2, and a third heat transfer space DS3. The first heat transfer space DS1 is located inside the elastic member 165, the second heat transfer space DS2 is located between the elastic member 165 and the elastic member 167, and the third heat transfer space DS3 is located between the elastic member 167 and the elastic member 169. As described later, a gas source GS of heat transfer gas (e.g., He gas), a cooling unit TU, and an exhaust device VU are selectively connected to the plurality of heat transfer spaces DSN via a piping system PS. The vertical length of each of the plurality of heat transfer spaces DSN is set to, for example, not less than 0.1 mm and not more than 2.0 mm.

[0114] In one example, the plurality of first elastic components EM1 are configured to have a thermal resistance higher than the thermal resistance of each of the plurality of heat transfer spaces DSN to which He gas is supplied. The thermal resistance of the plurality of heat transfer spaces DSN depends on the thermal conductivity of the heat transfer gas, its vertical length, and its area. In addition, the thermal resistance of each of the plurality of first elastic components EM1 depends on its thermal conductivity, its vertical thickness, and its area. Therefore, the material, thickness, and area of ​​each of the plurality of first elastic components EM1 are determined according to the thermal resistance of each of the plurality of heat transfer spaces DSN. In addition, the plurality of first elastic components EM1 require lower thermal conductivity and higher heat resistance. Therefore, the plurality of first elastic components EM1 are formed, for example, of a perfluoroelastomer.

[0115] The mounting table 116 further includes a fastening member 171. The fastening member 171 is formed of metal and sandwiches the base 121 and the plurality of first elastic members EM1 between the fastening member 171 and the cooling stage 117. The fastening member 171 is formed of a material with low thermal conductivity, such as titanium, to suppress heat conduction from the fastening member 171 between the base 121 and the cooling stage 117.

[0116] In one example, the fastening member 171 includes a cylindrical portion 171a and an annular portion 171b. The cylindrical portion 171a has a substantially cylindrical shape and has a first lower surface 171c at its lower end. The first lower surface 171c is a strip-shaped surface extending in the circumferential direction.

[0117] The annular portion 171b has a substantially annular plate shape, is connected to the inner edge of the upper portion of the cylindrical portion 171a, and extends radially inward from the cylindrical portion 171a. The annular portion 171b provides a second lower surface 171d. The second lower surface 171d is a band-shaped surface extending in the circumferential direction.

[0118] The fastening member 171 is positioned so that its first lower surface 171c contacts the second upper surface 117e of the cooling stage 117, and its second lower surface 171d contacts the second upper surface 121e of the base 121. Furthermore, the fastening member 171 is secured to the peripheral edge 117b of the cooling stage 117 using screws 173. Adjusting the engagement of the screws 173 with the fastening member 171 adjusts the compression of the plurality of first elastic members EM1. This adjusts the vertical length of the plurality of heat transfer spaces DSN.

[0119] In one example, a second elastic member 175 is provided between the lower inner edge surface of the annular portion 171b of the fastening member 171 and the second upper surface 121e of the base 121. The second elastic member 175 is an O-ring and prevents particles (e.g., metal powder) generated by friction between the second lower surface 171d of the fastening member 171 and the second upper surface 121e of the base 121 from moving to the adsorption portion 123.

[0120] Furthermore, the second elastic member 175 generates a reaction force that is smaller than the reaction force generated by the plurality of first elastic members EM1. In other words, the plurality of first elastic members EM1 are configured such that the reaction force generated by the plurality of first elastic members EM1 is greater than the reaction force generated by the second elastic member 175. Furthermore, the second elastic member 175 is formed of a perfluoroelastomer, a material having high heat resistance and low thermal conductivity.

[0121] A heater 176 is provided on the fastening member 171. The heater 176 extends in the circumferential direction and is connected to the heater power supply 161 via a filter 178. The filter 178 is provided to prevent high-frequency power from entering the heater power supply 161.

[0122] Heater 176 is provided between first film 180 and second film 182. First film 180 is provided on the fastening member 171 side relative to second film 182. First film 180 has a lower thermal conductivity than second film 182. For example, first film 180 can be a sprayed film made of zirconium oxide, and second film 182 can be a sprayed film made of yttrium oxide. Alternatively, heater 176 can be a sprayed film made of tungsten.

[0123] A focus ring FR is provided on the second film 182. The focus ring FR is heated by the heat from the heater 176. Furthermore, most of the heat flux from the heater 176 is directed toward the second film 182 rather than the first film 180, and then toward the focus ring FR via the second film 182. Therefore, the focus ring FR is effectively heated.

[0124] Furthermore, the outer circumference of the cooling stage 117, the fastening member 171, and the like of the mounting table 116 are covered with one or more insulating members 186. The one or more insulating members 186 are formed of, for example, alumina or quartz.

[0125] And, as Figure 14 As shown, a gas path 190 for supplying a heat transfer gas (eg, He gas) between the workpiece W and the adsorption unit 123 is provided between the cooling stage 117 of the mounting table 116 and the electrostatic chuck 120. The gas path 190 is connected to a heat transfer gas supply unit 191.

[0126] like Figure 14 As shown, the gas path 190 includes a gas path 190a, a gas path 190b, and a gas path 190c. The gas path 190a is formed in the adsorption portion 123. In addition, the gas path 190c is formed in the cooling stage 117. The gas path 190a and the gas path 190c are connected via the gas path 190b. The gas path 190b is provided by a sleeve 192. The sleeve 192 is a roughly cylindrical component having insulation properties at least on its surface, and the surface is formed of ceramic. In one example, the sleeve 192 is formed of insulating ceramic. For example, the sleeve 192 is formed of alumina. In another example, the sleeve 192 may be a metal component with an insulation treatment applied to the surface. For example, the sleeve 192 may have an aluminum body and an acid-resistant aluminum coating provided on the surface of the body.

[0127] The susceptor 121 and the cooling stage 117 provide a storage space for accommodating the sleeve 192. An insulating ceramic coating 194 is formed on a surface 121f of the susceptor 121 that forms the storage space. The coating 194 can be, for example, a sprayed film of alumina.

[0128] A third elastic member 196 is provided between the coating 194 and the cooling stage 117 to seal the space housing the sleeve 192. The third elastic member 196 is an O-ring and has insulating properties. The third elastic member 196 is formed, for example, from a perfluoroelastomer. Furthermore, a fourth elastic member 198 is provided outside the third elastic member 196. The fourth elastic member 198 is an O-ring that contacts the first upper surface 117c of the cooling stage 117 and the lower surface 121d of the base 121, thereby sealing the heat transfer space (for example, the first heat transfer space DS1). The fourth elastic member 198 is formed, for example, from a perfluoroelastomer.

[0129] As described above, in the mounting platform 116, the cooling stage 117 and the base 121 are separated from each other by a plurality of first elastic members EM1. Furthermore, in the mounting platform 116, the base 121 and the adsorption portion 123 are bonded together without the use of an adhesive. Therefore, the temperature of the electrostatic chuck 120 can be set to a high temperature. Furthermore, since heat exchange can be performed between the electrostatic chuck 120 and the cooling stage 117 via the heat transfer gas supplied to the plurality of heat transfer spaces DSN, the temperature of the electrostatic chuck 120 can also be set to a low temperature. Furthermore, in the mounting platform 116, the power supply 119, the cooling stage 117, and the fastening member 171 ensure a power supply path for supplying high-frequency power to the base 121 of the electrostatic chuck 120. Furthermore, since the power supply 119 is not directly connected to the base 121 of the electrostatic chuck 120 but is connected to the cooling stage 117, aluminum or an aluminum alloy can be used as the material constituting the power supply 119. Therefore, even when high-frequency power of a frequency of 13.56 MHz or higher is used, the loss of high-frequency power in the power supply body 119 can be suppressed.

[0130] As described above, a second elastic member 175 is provided between the lower inner edge of the annular portion 171b of the fastening member 171 and the second upper surface 121e of the base 121. Since the second upper surface 121e of the peripheral portion 121b of the base 121 and the second lower surface 171d of the fastening member 171 contact each other, friction occurs at the contact point, generating particles (e.g., metal powder). Even if such particles are generated, the second elastic member 175 prevents them from adhering to the adsorption portion 123 and the workpiece W placed thereon.

[0131] Furthermore, the plurality of first elastic members EM1 are configured so that the reaction force generated by the plurality of first elastic members EM1 is greater than the reaction force generated by the second elastic member 175. This ensures that the electrostatic chuck 120 can be separated from the cooling stage 117.

[0132] Furthermore, the plurality of first elastic members EM1 have a higher thermal resistance than the thermal resistance of the plurality of heat transfer spaces DSN when He gas is supplied to the plurality of heat transfer spaces DSN. Furthermore, the plurality of first elastic members EM1 are formed, for example, from a perfluoroelastomer. With such elastic members EM1, heat conduction through the plurality of heat transfer spaces DSN prevails between electrostatic chuck 120 and cooling stage 117, rather than heat conduction through the plurality of first elastic members EM1. Consequently, the temperature distribution of electrostatic chuck 120 can be made uniform.

[0133] Furthermore, the gas path 190 for supplying heat transfer gas between the workpiece W and the adsorption unit 123 is formed without the use of an adhesive. Furthermore, the surface 121f of the susceptor 121, which forms a housing space for the sleeve 192 that partially constitutes this gas path 190, is covered with a coating 194. To seal this housing space, an insulating third elastic member 196 is provided between the coating 194 and the cooling stage 117. This prevents plasma from intruding between the susceptor 121 and the cooling stage 117, and any resulting insulation breakdown in the susceptor 121.

[0134] Furthermore, according to the plasma processing apparatus 100 including the mounting table 116 , the workpiece W can be subjected to plasma processing in a wide temperature range from low temperature to high temperature.

[0135] Hereinafter, the piping system PS that can be used in the plasma processing apparatus 100 will be described. Figure 15 This is a diagram showing the configuration of an example of a piping system. Figure 15 The piping system PS shown constitutes part of a temperature control mechanism in one embodiment and includes multiple valves. The piping system PS selectively connects the gas source GS, cooling unit TU, and exhaust device VU to each of the multiple heat transfer spaces DSN, and switches between connecting and disconnecting the cooling unit TU and the flow path 117f. The following describes an example in which the multiple heat transfer spaces DSN are composed of three heat transfer spaces (a first heat transfer space DS1, a second heat transfer space DS2, and a third heat transfer space DS3). However, the number of the multiple heat transfer spaces DSN can be any number, one or more, as long as it corresponds to the number of regions RN of the electrostatic chuck 120.

[0136] The piping system PS includes piping L21, piping L22, valves V21, and V22. One end of piping L21 is connected to the cooling unit TU, while the other end is connected to the flow path 117f. A valve V21 is provided midway along piping L21. One end of piping L22 is connected to the cooling unit TU, while the other end is connected to the flow path 117f. A valve V22 is provided midway along piping L22. When valves V21 and V22 are open, refrigerant is supplied from the cooling unit TU to the flow path 117f via piping L21. The refrigerant supplied to the flow path 117f returns to the cooling unit TU via piping L22.

[0137] In addition, the piping system PS also includes: a pressure regulator 104a, a piping L11a, a piping L12a, a piping L13a, a piping L14a, a piping L15a, a piping L17a, a piping L31a, a piping L32a, a valve V11a, a valve V12a, a valve V13a, a valve V14a, a valve V15a, a valve V31a and a valve V32a.

[0138] Pressure regulator 104a is connected to gas source GS. Pressure regulator 104a is connected to one end of pipe L11a. A valve V11a is provided midway along pipe L11a. One end of pipe L15a is connected to heat transfer space DS1. The other end of pipe L15a is connected to exhaust unit VU. Furthermore, a valve V15a is provided midway along pipe L15a.

[0139] The other end of the pipe L11a is connected to one end of the pipe L12a. The other end of the pipe L12a is connected to the pipe L15a on the first heat transfer space DS1 side relative to the valve V15a. A valve V12a is provided midway in the pipe L12a. The other end of the pipe L11a is connected to one end of the pipe L13a and one end of the pipe L14a. A valve V13a is provided midway in the pipe L13a, and a valve V14a is provided midway in the pipe L14a. The other end of the pipe L13a and the other end of the pipe L14a are connected to each other. One end of the pipe L17a is connected to the connection point between the other end of the pipe L13a and the other end of the pipe L14a. The other end of the pipe L17a is connected to the pipe L15a closer to the valve V15a than the other end of the pipe L12a.

[0140] One end of the pipe L31a is connected to the pipe L21 on the cooling unit TU side facing the valve V21. The other end of the pipe L31a is connected to the heat transfer space DS1. A valve V31a is provided midway along the pipe L31a. One end of the pipe L32a is connected to the pipe L22 on the cooling unit TU side facing the valve V22. The other end of the pipe L32a is connected to the heat transfer space DS1. A valve V32a is provided midway along the pipe L32a.

[0141] In addition, the piping system PS also includes: a pressure regulator 104b, a piping L11b, a piping L12b, a piping L13b, a piping L14b, a piping L15b, a piping L17b, a piping L31b, a piping L32b, a valve V11b, a valve V12b, a valve V13b, a valve V14b, a valve V15b, a valve V31b and a valve V32b.

[0142] Pressure regulator 104b is connected to gas source GS. Pressure regulator 104b is connected to one end of pipe L11b. A valve V11b is provided midway along pipe L11b. One end of pipe L15b is connected to heat transfer space DS2. The other end of pipe L15b is connected to exhaust unit VU. A valve V15b is also provided midway along pipe L15b.

[0143] The other end of pipe L11b is connected to one end of pipe L12b. The other end of pipe L12b is connected to pipe L15b on the side of the second heat transfer space DS2 relative to valve V15b. Valve V12b is provided midway in pipe L12b. The other end of pipe L11b is connected to one end of pipe L13b and one end of pipe L14b. Valve V13b is provided midway in pipe L13b, and valve V14b is provided midway in pipe L14b. The other end of pipe L13b and the other end of pipe L14b are connected to each other. One end of pipe L17b is connected to the connection point between the other end of pipe L13b and the other end of pipe L14b. The other end of pipe L17b is connected to pipe L15b closer to valve V15b than the other end of pipe L12b.

[0144] One end of pipe L31b is connected to pipe L21 on the cooling unit TU side facing valve V21. The other end of pipe L31b is connected to heat transfer space DS2. A valve V31b is provided midway along pipe L31b. One end of pipe L32b is connected to pipe L22 on the cooling unit TU side facing valve V22. The other end of pipe L32b is connected to heat transfer space DS2. A valve V32b is provided midway along pipe L32b.

[0145] In addition, the piping system PS also has a pressure regulator 104c, piping L11c, piping L12c, piping L13c, piping L14c, piping L15c, piping L17c, piping L31c, piping L32c, valve V11c, valve V12c, valve V13c, valve V14c, valve V15c, valve V31c and valve V32c.

[0146] Pressure regulator 104c is connected to gas source GS. Pressure regulator 104c is connected to one end of pipe L11c. A valve V11c is provided midway along pipe L11c. One end of pipe L15c is connected to third heat transfer space DS3. The other end of pipe L15c is connected to exhaust unit VU. Furthermore, a valve V15c is provided midway along pipe L15c.

[0147] The other end of pipe L11c is connected to one end of pipe L12c. The other end of pipe L12c is connected to pipe L15c on the side of the third heat transfer space DS3 relative to valve V15c. Valve V12c is provided midway along pipe L12c. The other end of pipe L11c is connected to one end of pipe L13c and one end of pipe L14c. Valve V13c is provided midway along pipe L13c, and valve V14c is provided midway along pipe L14c. The other end of pipe L13c and the other end of pipe L14c are connected to each other. One end of pipe L17c is connected to the connection point between the other end of pipe L13c and the other end of pipe L14c. The other end of pipe L17c is connected to pipe L15c closer to valve V15c than the other end of pipe L12c.

[0148] One end of the pipe L31c is connected to the pipe L21 on the cooling unit TU side facing the valve V21. The other end of the pipe L31c is connected to the third heat transfer space DS3. A valve V31c is provided midway along the pipe L31c. One end of the pipe L32c is connected to the pipe L22 on the cooling unit TU side facing the valve V22. The other end of the pipe L32c is connected to the third heat transfer space DS3. A valve V32c is provided midway along the pipe L32c.

[0149] In the piping system PS, when valves V21 and V22 are open, refrigerant circulates between the cooling unit TU and the flow path 117f. On the other hand, when valves V21 and V22 are closed, refrigerant is not supplied from the cooling unit TU to the flow path 117f.

[0150] When valves V31a, V32a, V31b, V32b, V31c, and V32c are open, refrigerant circulates between the cooling unit TU and the plurality of heat transfer spaces DSN (DS1, DS2, DS3). When refrigerant is supplied to the plurality of heat transfer spaces DSN (DS1, DS2, DS3), valves V11a, V12a, V13a, V14a, V15a, V11b, V12b, V13b, V14b, V15b, V11c, V12c, V13c, V14c, and V15c are closed. On the other hand, when the valves V31a, V32a, V31b, V32b, V31c, and V32c are closed, the refrigerant is not supplied from the cooling unit TU to the plurality of heat transfer spaces DSN (DS1, DS2, DS3).

[0151] In addition, when valve V11a, valve V12a, valve V11b, valve V12b, valve V11c and valve V12c are opened, and valve V13a, valve V14a, valve V15a, valve V13b, valve V14b, valve V15b, valve V13c, valve V14c and valve V15c are closed, heat transfer gas is supplied from the gas source GS to multiple heat transfer spaces DSN (DS1, DS2, DS3).

[0152] In addition, when valve V15a, valve V15b, and valve V15c are opened, and valves V11a, valve V12a, valve V13a, valve V14a, valve V11b, valve V12b, valve V13b, valve V14b, valve V11c, valve V12c, valve V13c, and valve V14c are closed, multiple heat transfer spaces DSN (DS1, DS2, DS3) are depressurized by the exhaust device VU.

[0153] Next, the plasma processing apparatus 100 is used to Figure 2 The method MT will be described in relation to the case where the method MT is applied to the workpiece W shown.

[0154] In step ST1, the temperature of the electrostatic chuck 120 is set to a temperature below -30°C for the main etching process described later. In step ST1, refrigerant circulates between the cooling unit TU and the flow path 117f, and also between the plurality of heat transfer spaces DSN and the cooling unit TU. Specifically, valves V21, V22, V31a, V32a, V31b, V32b, V31c, and V32a are opened, and the other valves in the piping system PS are closed. In step ST1, the plurality of heaters HN are turned off. That is, in step ST1, power from the heater power supply 161 is not supplied to the plurality of heaters HN.

[0155] In step ST2 , the workpiece W is carried into the chamber 112 c . In step ST2 , the workpiece W is placed on the electrostatic chuck 120 and held by the electrostatic chuck 120 .

[0156] In step ST3, the processing gas is supplied from the gas source assembly 40 to the chamber 112c. The pressure of the chamber 112c is set to a predetermined pressure by the exhaust unit 150. Furthermore, the first high-frequency power source 62 outputs first high-frequency power for generating plasma. This generates plasma of the processing gas within the chamber 112c. Furthermore, as needed, the second high-frequency power source 64 supplies second high-frequency power to the lower electrode of the mounting table 116. In step ST3, the etching target film EF is etched using ions and / or radicals generated by the plasma.

[0157] In the main etching step ST31, the etching target film EF is etched using ions and / or radicals from the plasma of the process gas while the temperature of the electrostatic chuck 120 is set to -30°C or lower. The open and closed states of the multiple valves of the piping system PS during the main etching step ST31 can be the same as those of the multiple valves of the piping system PS in step ST1.

[0158] In one example, the temperature of electrostatic chuck 120 during overetching ST32 is set to a temperature higher than -30°C and lower than 0°C. However, the temperature of electrostatic chuck 120 during overetching ST32 is not limited to a temperature higher than -30°C and lower than 0°C.

[0159] In step ST4, static electricity is removed from the electrostatic chuck 120. To remove static electricity from the electrostatic chuck 120, a voltage having a polarity opposite to that applied to the electrostatic chuck 120 when holding the workpiece W is applied to the electrostatic chuck 120's attraction electrode 125.

[0160] In step ST5, the temperature of the electrostatic chuck 120 rises to a temperature above 0°C. In step ST5, valve V21, valve V22, valve V15a, valve V15b, and valve V15c are opened, and the other valves of the piping system PS are closed. In addition, power is supplied from the heater power supply 161 to the multiple heaters HN so that the multiple heaters HN generate heat. In step ST5, the multiple heat transfer spaces DSN are decompressed by the exhaust device VU. Therefore, the heat exchange between the electrostatic chuck 120 and the cooling stage 117 can be suppressed. In addition, in step ST5, the multiple heaters HN generate heat. Therefore, in step ST5, the time required for the electrostatic chuck 120 to heat up is shortened.

[0161] In step ST6, the workpiece W is unloaded from chamber 112c. During step ST6, the temperature of electrostatic chuck 120 is maintained at or above 0°C. Furthermore, when the temperature of electrostatic chuck 120 is maintained at or above 0°C after step ST5, the open / closed states of the multiple valves in piping system PS may be the same as those in step ST5. Alternatively, power is supplied from heater power supply 161 to the multiple heaters HN to generate heat, and refrigerant is supplied from cooling unit TU to at least one of the multiple heat transfer spaces DSN (DS1, DS2, DS3) and flow path 117f. Refrigerant may be supplied from cooling unit TU to flow path 117f, and heat transfer gas may be supplied from gas source GS to the multiple heat transfer spaces DSN (DS1, DS2, DS3).

[0162] In step ST71, a dummy wafer is loaded into chamber 112c and held by electrostatic chuck 20. In step ST72, a plasma of a cleaning gas is generated in chamber 112c. In step ST73, a cleaning gas is supplied from gas source assembly 40 to chamber 112c. Furthermore, first high-frequency power is supplied from first high-frequency power supply 62 to generate the plasma. In step ST74, static electricity is removed from electrostatic chuck 120. In step ST75, a plasma of a cleaning gas is generated in chamber 112c, with no object, such as the dummy wafer, placed on electrostatic chuck 120.

[0163] In step ST10, similarly to step ST4, static electricity is removed from the electrostatic chuck 120. In step ST11, similarly to step ST5, the temperature of the electrostatic chuck 120 is increased. In step ST12, the workpiece W is unloaded from the chamber 12c.

Claims

1. A method for treating a workpiece using a plasma treatment device, characterized in that: The plasma processing device comprises: providing a chamber body for the chamber; a mounting table provided in the chamber and having an electrostatic chuck for holding a workpiece mounted on the mounting table; and a temperature regulating mechanism for regulating the temperature of the electrostatic chuck, The method for processing a workpiece comprises: a step of etching a target film of a workpiece placed on the electrostatic chuck by generating plasma of a processing gas containing a fluorocarbon gas and / or a hydrofluorocarbon gas in the chamber, wherein the step includes a main etching of the target film while the temperature of the electrostatic chuck is set to -30°C or lower by the temperature control mechanism, and an over etching of the target film after the main etching; and The step of increasing the temperature of the electrostatic chuck by using the temperature control mechanism while the workpiece is placed on the electrostatic chuck to reduce deposits containing carbon and fluorine formed on the workpiece. The step of increasing the temperature of the electrostatic chuck is performed between the main etching and the over-etching so that the temperature of the electrostatic chuck is higher than -30°C and lower than 0°C, or is performed during at least one of a period during and after the over-etching so that the temperature of the electrostatic chuck is higher than 0°C.

2. The method for processing a workpiece according to claim 1, wherein: Also includes: The step of unloading the workpiece placed on the electrostatic chuck from the chamber in a state where the temperature of the electrostatic chuck is set to 0° C. or higher by executing the step of increasing the temperature of the electrostatic chuck; as well as A step of cleaning the chamber and the mounting table after unloading the workpiece.

3. The method for processing a workpiece according to claim 2, wherein: The step of cleaning the chamber and the mounting table includes: The step of transferring a dummy wafer onto the electrostatic chuck in the chamber; generating a plasma of a cleaning gas within the chamber; a step of removing static electricity from the electrostatic chuck; The step of moving the dummy wafer out of the chamber; and The step of generating plasma of the cleaning gas in the chamber in a state where the dummy wafer is not placed on the electrostatic chuck.

4. The method for processing a workpiece according to claim 2, wherein: The method also includes a step of determining whether to process another workpiece.

5. The method for processing a workpiece according to claim 1, wherein: The method further includes the step of determining whether an interruption condition is satisfied during the execution of the step of etching the etching target film. The interruption condition is satisfied when an abnormality occurs during execution of the step of etching the etching target film.

6. The method for processing a workpiece according to claim 5, wherein: When the interruption condition is met, the following steps are also included: a step of removing static electricity from the electrostatic chuck; a step of increasing the temperature of the electrostatic chuck; and The step of carrying out the workpiece placed on the electrostatic chuck from the chamber.

Images