Method for etching silicon oxide film and plasma processing device

Abstract

In the disclosed method, a silicon oxide film on a substrate having a mask disposed thereover is etched. The method includes performing a first plasma treatment on the substrate using a first plasma formed from a first process gas containing a fluorocarbon gas, a gas containing carbon but not fluorine, and an oxygen-containing gas. The method also includes performing a second plasma treatment on the substrate using a second plasma formed from a second process gas containing a fluorocarbon gas. The temperature of the substrate during the first plasma treatment is lower than the temperature of the substrate during the second plasma treatment.

Description

Technical Field

[0001] Exemplary embodiments of the present invention relate to a method of etching a silicon oxide film and a plasma processing apparatus. Background Art

[0002] Plasma etching of a silicon oxide film is used to transfer a mask pattern to the silicon oxide film. Japanese Patent Application Publication No. 2011-204999 (hereinafter referred to as "Patent Document 1") discloses plasma etching of a silicon oxide film. In the plasma etching described in Patent Document 1, a plasma formed from a fluorocarbon gas is used to etch the silicon oxide film. Summary of the Invention

[0003] The present invention provides a technology for suppressing a reduction in mask film thickness caused by etching of a silicon oxide film.

[0004] In one exemplary embodiment, a method for etching a silicon oxide film of a substrate is provided. The substrate has a silicon oxide film and a mask. The mask is disposed on the silicon oxide film. The method includes (a) a process of performing a first plasma treatment on the substrate using a first plasma formed from a first process gas. The first process gas includes a fluorocarbon gas, a gas containing carbon but not fluorine, and an oxygen-containing gas. During the first plasma treatment, the temperature of the substrate is set to a first temperature. The first plasma treatment deposits a carbon-containing substance on the mask and etches the silicon oxide film. The method also includes (b), after the above (a), a process of performing a second plasma treatment on the substrate using a second plasma formed from a second process gas containing a fluorocarbon gas. During the second plasma treatment, the temperature of the substrate is set to a second temperature. The second plasma treatment etches the silicon oxide film. The first temperature is lower than the second temperature.

[0005] According to one exemplary embodiment, it is possible to suppress a reduction in the film thickness of the mask due to etching of the silicon oxide film. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 FIG. 1 is a flow chart of a method for etching a silicon oxide film according to an exemplary embodiment.

[0007] Figure 2 This is a partially enlarged cross-sectional view of an example of a substrate.

[0008] Figure 3 This is a partially enlarged cross-sectional view of an example of a substrate.

[0009] Figure 4 FIG. 1 is a diagram schematically showing a plasma processing apparatus according to an exemplary embodiment.

[0010] Figure 5 middle, Figure 5 (a) is execution Figure 1 A partially enlarged cross-sectional view of an example of a substrate in a state after step STa of the method shown, Figure 5 (b) is executed Figure 1 A partially enlarged cross-sectional view of an example of a substrate in a state after step STb of the method shown.

[0011] Figure 6 It is executed Figure 1 A partially enlarged cross-sectional view of an example of a substrate in a state after step STc of the method shown.

[0012] Figure 7 middle, Figure 7 (a) is execution Figure 1 A partially enlarged cross-sectional view of an example of a substrate in a state after step ST1 of the method shown, Figure 7 (b) is executed Figure 1 A partially enlarged cross-sectional view of an example of a substrate in a state after step ST2 of the method shown. DETAILED DESCRIPTION

[0013] Various exemplary embodiments are described below.

[0014] In one exemplary embodiment, a method for etching a silicon oxide film of a substrate is provided. The substrate has a silicon oxide film and a mask. The mask is disposed on the silicon oxide film. The method includes (a) a process of performing a first plasma treatment on the substrate using a first plasma formed from a first process gas. The first process gas includes a fluorocarbon gas, a gas containing carbon but not fluorine, and an oxygen-containing gas. During the first plasma treatment, the temperature of the substrate is set to a first temperature. The first plasma treatment deposits a carbon-containing substance on the mask and etches the silicon oxide film. The method also includes (b), after the above (a), a process of performing a second plasma treatment on the substrate using a second plasma formed from a second process gas containing a fluorocarbon gas. During the second plasma treatment, the temperature of the substrate is set to a second temperature. The second plasma treatment etches the silicon oxide film. The first temperature is lower than the second temperature.

[0015] When the substrate temperature is set to a relatively low temperature, a relatively large amount of carbon-containing material is deposited from the plasma onto the substrate surface. Therefore, as a result of the first plasma treatment, a relatively large amount of carbon-containing material is deposited on the mask. Furthermore, during the first plasma treatment, the silicon oxide film is etched by the fluorine chemical species from the first plasma. During the second plasma treatment, the silicon oxide film is further etched by the fluorine chemical species from the second plasma. Meanwhile, during the second plasma treatment, the mask is protected by the carbon-containing material deposited on the mask as a result of the first plasma treatment. Therefore, according to the method according to the above embodiment, it is possible to suppress the reduction in mask thickness caused by etching of the silicon oxide film.

[0016] In one exemplary embodiment, the first process gas and the second process gas may be the same process gas.

[0017] In one exemplary embodiment, (a) and (b) can be performed using a plasma processing apparatus. The high-frequency power used in the plasma processing apparatus to generate the first plasma in (a) can be lower than the high-frequency power used in the plasma processing apparatus to generate the second plasma in (b). Using a lower high-frequency power reduces the density of the plasma, and reduces the amount of heat imparted to the substrate from the plasma. According to this embodiment, at least by adjusting the high-frequency power, the substrate temperature is set to a first temperature during the first plasma treatment and to a second temperature during the second plasma treatment.

[0018] In one exemplary embodiment, the power of a heater within a substrate support supporting the substrate may be adjusted in (a) and (b) such that the first temperature becomes lower than the second temperature. According to this embodiment, by adjusting at least the power of the heater, the temperature of the substrate is set to the first temperature during the first plasma treatment and to the second temperature during the second plasma treatment.

[0019] In an exemplary embodiment, in the first process gas, the gas containing carbon but not fluorine may be CO gas, and the oxygen-containing gas may be O 2 gas.

[0020] In one exemplary embodiment, the mask may be a mask formed of an organic material.

[0021] In another exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a substrate support, a gas supply unit, a high-frequency power supply, and a control unit. The substrate support is disposed in the chamber. The gas supply unit is configured to supply a first processing gas and a second processing gas into the chamber. The first processing gas includes a fluorocarbon gas, a gas containing carbon but not fluorine, and an oxygen-containing gas. The second processing gas includes a fluorocarbon gas. The high-frequency power supply is configured to generate high-frequency power in order to generate plasma from the gas in the chamber. The control unit performs the following first control: controls the gas supply unit so as to supply the first processing gas into the chamber, and controls the high-frequency power supply so as to generate a first plasma from the first processing gas in the chamber. The first control is performed to etch a silicon oxide film on a substrate and form a carbon-containing deposit on a mask of the substrate disposed on the silicon oxide film. The control unit further performs the following second control: controls the gas supply unit so as to supply a second processing gas into the chamber, and controls the high-frequency power supply so as to generate a second plasma from the second processing gas in the chamber, in order to further etch the silicon oxide film. The control unit sets the temperature of the substrate in the first control to be lower than the temperature of the substrate set in the second control.

[0022] Hereinafter, various exemplary embodiments will be described in detail with reference to the accompanying drawings. In addition, in each of the drawings, the same or corresponding parts are marked with the same symbols.

[0023] Figure 1 Flowchart of a method for etching a silicon oxide film according to an exemplary embodiment. Figure 1 The method shown (hereinafter referred to as "method MT") includes step ST1 and step ST2.

[0024] Figure 2 This is a partial enlarged cross-sectional view of an example of a substrate. Figure 2 Onto the substrate W shown, steps ST1 and ST2 of the method MT are applied. Figure 2 The illustrated substrate W includes a silicon oxide film OX and a mask MK. The substrate W may further include a base region UR. The silicon oxide film OX may be disposed on the base region UR. The mask MK is disposed on the silicon oxide film OX. The mask MK has a pattern that is transferred to the silicon oxide film OX by etching. In other words, the mask MK provides an opening that partially exposes the surface of the silicon oxide film. The mask MK is formed, for example, of an organic material. However, the mask MK may be formed of any material as long as the etching rate of the silicon oxide film OX is faster than that of the mask MK.

[0025] Figure 3 FIG. 1 is a partially enlarged cross-sectional view of an example substrate. In one embodiment, before applying steps ST1 and ST2, the substrate W may have Figure 3 The structure shown. Figure 3 The substrate W shown also has an organic film OF, a SiON film SF, an anti-reflection film AF and a resist mask RM. The organic film OF is provided on the silicon oxide film OX. The organic film OF is formed of an organic material. The organic film OF is, for example, an amorphous carbon film. The SiON film SF is provided on the silicon oxide film OX. The anti-reflection film AF is formed of an organic material and provided on the silicon oxide film OX. The resist mask RM is a photoresist mask and provided on the anti-reflection film AF. The resist mask RM has a pattern for forming a mask MK from the organic film OF. The resist mask RM is patterned, for example, using a photoresist material technique. In order to Figure 3 The substrate W is obtained in the state shown Figure 2 Regarding the substrate W in the state shown, the method MT may further include steps STa to STd.

[0026] In one embodiment, method MT is performed using a plasma processing apparatus. Figure 4 FIG. 1 is a diagram schematically showing a plasma processing apparatus according to an exemplary embodiment. Figure 4 The plasma processing apparatus 1 shown includes a chamber 10. Chamber 10 defines an internal space 10s. Chamber 10 includes a chamber body 12. Chamber body 12 has a generally cylindrical shape. Chamber body 12 is formed, for example, from aluminum. A corrosion-resistant film is provided on the inner wall surface of chamber body 12. This film may be made of ceramic, such as aluminum oxide or yttrium oxide.

[0027] A passage 12p is formed in a side wall of the chamber body 12 . The substrate W is transferred between the interior space 10s and the outside of the chamber 10 through the passage 12p. The passage 12p is opened and closed by a gate valve 12g provided along the side wall of the chamber body 12 .

[0028] A support portion 13 is provided at the bottom of the chamber body 12. The support portion 13 is formed of an insulating material. The support portion 13 has a generally cylindrical shape. The support portion 13 extends upward from the bottom of the chamber body 12 within the internal space 10s. The support portion 13 supports a substrate support 14. The substrate support 14 is provided within the chamber 10. The substrate support 14 is configured to support a substrate W within the internal space 10s.

[0029] The substrate support 14 includes a lower electrode 18 and an electrostatic chuck 20. The substrate support 14 may further include an electrode plate 16. The electrode plate 16 is formed of a conductor such as aluminum and has a generally disk-shaped shape. The lower electrode 18 is disposed on the electrode plate 16. The lower electrode 18 is formed of a conductor such as aluminum and has a generally disk-shaped shape. The lower electrode 18 is electrically connected to the electrode plate 16.

[0030] The electrostatic chuck 20 is disposed on the lower electrode 18. The substrate W is placed on the upper surface of the electrostatic chuck 20. The electrostatic chuck 20 has a main body and electrodes. The main body of the electrostatic chuck 20 has a roughly disc-shaped structure and is formed of a dielectric. The electrodes of the electrostatic chuck 20 are film-shaped electrodes and are disposed within the main body of the electrostatic chuck 20. The electrodes of the electrostatic chuck 20 are connected to a DC power supply 20p via a switch 20s. When a voltage from the DC power supply 20p is applied to the electrodes of the electrostatic chuck 20, an electrostatic attraction is generated between the electrostatic chuck 20 and the substrate W. This electrostatic attraction holds the substrate W on the electrostatic chuck 20.

[0031] An edge ring 25 is disposed on the periphery of the substrate support 14 to surround the edge of the substrate W. The edge ring 25 improves the in-plane uniformity of plasma processing on the substrate W. The edge ring 25 can be formed of silicon, silicon carbide, quartz, or the like.

[0032] A flow path 18f is provided within the lower electrode 18. A heat exchange medium (e.g., a refrigerant) is supplied to the flow path 18f from a condenser (not shown) located outside the chamber 10 via a pipe 22a. The heat exchange medium supplied to the flow path 18f is returned to the condenser via a pipe 22b. In the plasma processing apparatus 1, the temperature of the substrate W placed on the electrostatic chuck 20 is adjusted by heat exchange between the heat exchange medium and the lower electrode 18.

[0033] In one embodiment, the substrate support 14 may further include a heater HT. The heater HT is provided in the substrate support 14 to heat the substrate W. The heater HT may be provided in the electrostatic chuck 20. Power is supplied to the heater HT from a heater controller HC. The heater controller HC is configured to adjust the power of the heater HT.

[0034] The plasma processing apparatus 1 is provided with a gas supply line 24. The gas supply line 24 supplies a heat transfer gas (eg, He gas) from a heat transfer gas supply mechanism to a position between the upper surface of the electrostatic chuck 20 and the back surface of the substrate W.

[0035] The plasma processing apparatus 1 further includes an upper electrode 30 . The upper electrode 30 is disposed above the substrate support 14 . The upper electrode 30 is supported on the upper portion of the chamber body 12 via a member 32 . The member 32 is formed of an insulating material. The upper electrode 30 and the member 32 seal the upper opening of the chamber body 12 .

[0036] The upper electrode 30 may include a top plate 34 and a support 36. The lower surface of the top plate 34 is the lower surface facing the internal space 10s and defines the internal space 10s. The top plate 34 may be formed of a low-resistance conductor or semiconductor that generates little Joule heat. The top plate 34 has a plurality of gas ejection holes 34a extending through the top plate 34 in the thickness direction.

[0037] The support body 36 detachably supports the top plate 34. The support body 36 is formed of a conductive material such as aluminum. A gas diffusion chamber 36a is provided within the support body 36. The support body 36 has a plurality of gas holes 36b extending downward from the gas diffusion chamber 36a. The plurality of gas holes 36b are each connected to the plurality of gas discharge holes 34a. A gas inlet 36c is formed in the support body 36. The gas inlet 36c is connected to the gas diffusion chamber 36a. A gas supply pipe 38 is connected to the gas inlet 36c.

[0038] A gas source group 40 is connected to the gas supply pipe 38 via a flow controller group 41 and a valve group 42. The gas source group 40 includes a plurality of gas sources. The flow controller group 41 includes a plurality of flow controllers. The plurality of flow controllers of the flow controller group 41 are respectively mass flow controllers or pressure-controlled flow controllers. The valve group 42 includes a plurality of on-off valves. The plurality of gas sources of the gas source group 40 are connected to the gas supply pipe 38 via corresponding flow controllers of the flow controller group 41 and corresponding on-off valves of the valve group 42. The gas source group 40, the flow controller group 41, and the valve group 42 constitute a gas supply unit. The gas supply unit is configured to supply the first processing gas and the second processing gas described later into the chamber 10.

[0039] In the plasma processing apparatus 1, a shield 46 is detachably provided along the inner wall surface of the chamber body 12 and the outer periphery of the support portion 13. The shield 46 prevents reaction byproducts from adhering to the chamber body 12. The shield 46 is formed, for example, by forming a corrosion-resistant film on the surface of a base material formed of aluminum. The corrosion-resistant film can be formed of a ceramic such as yttrium oxide.

[0040] A partition 48 is provided between the support portion 13 and the sidewall of the chamber body 12. The partition 48 is formed, for example, by forming a corrosion-resistant film (such as an yttrium oxide film) on the surface of a base material formed of aluminum. Multiple through-holes are formed in the partition 48. An exhaust port 12e is provided below the partition 48 and at the bottom of the chamber body 12. An exhaust device 50 is connected to the exhaust port 12e via an exhaust pipe 52. The exhaust device 50 includes a pressure regulating valve and a vacuum pump such as a turbomolecular pump.

[0041] The plasma processing apparatus 1 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. The first high-frequency power has a frequency suitable for generating plasma. The frequency of the first high-frequency power 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 matching box 66 and an electrode plate 16. The matching box 66 has a circuit for matching the impedance of the load side (lower electrode 18 side) of the first high-frequency power supply 62 with the output impedance of the first high-frequency power supply 62. In addition, the first high-frequency power supply 62 can be connected to the upper electrode 30 via the matching box 66. The first high-frequency power supply 62 constitutes an example of a plasma generating unit.

[0042] The second high-frequency power supply 64 is a power supply for generating a second high-frequency power. The second high-frequency power has a frequency lower than the frequency of the first high-frequency power. When the second high-frequency power is used together with the first high-frequency power, the second high-frequency power is used as a bias high-frequency power for introducing ions into the substrate W. The frequency of the second high-frequency power 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 the matching device 68 and the electrode plate 16. The matching device 68 has a circuit for matching the impedance of the load side (lower electrode 18 side) of the second high-frequency power supply 64 with the output impedance of the second high-frequency power supply 64.

[0043] Alternatively, the second high-frequency power source may be used instead of the first high-frequency power source, that is, plasma may be generated using only a single high-frequency power source. In this case, the frequency of the second high-frequency power source may be greater than 13.56 MHz, for example, 40 MHz. In this case, the plasma processing apparatus 1 may not include the first high-frequency power source 62 and the matching unit 66. In this case, the second high-frequency power source 64 constitutes an example of a plasma generating unit.

[0044] In the plasma processing apparatus 1 , gas is supplied from a gas supply unit into the internal space 10s to generate plasma. Furthermore, the first high-frequency power and / or the second high-frequency power are supplied to generate a high-frequency electric field between the upper electrode 30 and the lower electrode 18 . The generated high-frequency electric field generates plasma.

[0045] The plasma processing apparatus 1 may further include a control unit 80. The control unit 80 may be a computer including a processor, a storage unit such as a memory, an input device, a display device, a signal input / output interface, and the like. The control unit 80 controls the various components of the plasma processing apparatus 1. In the control unit 80, an operator can use an input device to input commands, etc., in order to manage the plasma processing apparatus 1. Furthermore, the control unit 80 can visually display the operating status of the plasma processing apparatus 1 through a display device. In addition, a control program and recipe data are stored in the storage unit. In order for the plasma processing apparatus 1 to perform various processes, the control program is executed by the processor. The processor executes the control program and controls the various components of the plasma processing apparatus 1 according to the recipe data.

[0046] Below, refer again Figure 1 The method MT is described in detail below. Figure 3 The method MT will be described as an example of applying steps STa to STd, step ST1, and step ST2 to the substrate W shown. Figure 5 (a) Figure 5 (b) Figure 6 、 Figure 7 (a) and Figure 7 (b). Figure 5 (a) Figure 5 (b) Figure 6 、 Figure 7 (a) and Figure 7 (b) Execution Figure 1 A partially enlarged cross-sectional view of an example of a substrate in a state after step STa, step STb, step STc, step ST1, and step ST2 of the method shown.

[0047] In step STa, in order to transfer the pattern of the resist mask RM to the anti-reflection film AF, the anti-reflection film is etched by plasma etching. In step STa, plasma is generated from the processing gas in the chamber 10. The processing gas used in step STa may contain an oxygen-containing gas (e.g., oxygen). Alternatively, the processing gas used in step STa may contain nitrogen and hydrogen. In step STa, the anti-reflection film AF is etched by chemical species from the generated plasma. As a result, Figure 5 As shown in (a), the pattern of the resist mask RM is transferred to the anti-reflection film AF.

[0048] To execute step STa, the control unit 80 controls the gas supply unit to supply a processing gas into the chamber 10. To execute step STa, the control unit 80 controls the exhaust device 50 to set the pressure in the chamber 10 to a predetermined pressure. To execute step STa, the control unit 80 controls the first high-frequency power source 62 and / or the second high-frequency power source 64 to supply the first high-frequency power source and / or the second high-frequency power source.

[0049] In the subsequent step STb, in order to transfer the pattern of the anti-reflection film AF to the SiON film SF, the SiON film SF is etched by plasma etching. In the step ST1b, plasma is generated from the process gas in the chamber 10. The process gas used in the step STb contains a hydrofluorocarbon gas. The process gas used in the step STb may also contain a fluorocarbon gas. The process gas used in the step STb may further contain other gases such as oxygen and / or a rare gas. In the step STb, the SiON film SF is etched by chemical species from the generated plasma. As a result, as shown in FIG. Figure 5 As shown in (b), the pattern of the anti-reflection film AF is transferred to the SiON film SF.

[0050] To perform step STb, the control unit 80 controls the gas supply unit to supply a processing gas into the chamber 10. To perform step STb, the control unit 80 controls the exhaust device 50 to set the pressure in the chamber 10 to a predetermined pressure. To perform step STb, the control unit 80 controls the first high-frequency power source 62 and / or the second high-frequency power source 64 to supply the first high-frequency power source and / or the second high-frequency power source.

[0051] In the subsequent step STc, in order to transfer the pattern of the SiON film SF to the organic film OF, the organic film OF is etched by plasma etching. In the step STc, plasma is generated by the process gas in the chamber 10. The process gas used in the step STc may include an oxygen-containing gas (e.g., oxygen). Alternatively, the process gas used in the step STc may include nitrogen and hydrogen. In the step STc, the organic film OF is etched by chemical species from the generated plasma. As a result, as shown in FIG. Figure 6 As shown, the pattern of the SiON film SF is transferred to the organic film OF, and the mask MK is formed by the organic film OF. During this step STc, the resist mask RM and the anti-reflection film AF are removed by chemical species from the plasma.

[0052] To perform step STc, the control unit 80 controls the gas supply unit to supply a processing gas into the chamber 10. To perform step STc, the control unit 80 controls the exhaust device 50 to set the pressure in the chamber 10 to a predetermined pressure. To perform step STc, the control unit 80 controls the first high-frequency power source 62 and / or the second high-frequency power source 64 to supply the first high-frequency power source and / or the second high-frequency power source.

[0053] In the subsequent step STd, the SiON film SF is removed. In the step STd, plasma is generated from the processing gas in the chamber 10. The processing gas used in the step STd includes a hydrofluorocarbon gas. The processing gas used in the step STd may also include a fluorocarbon gas. The processing gas used in the step STd may further include other gases such as oxygen and / or a rare gas. In the step STd, the SiON film SF is etched and removed by chemical species from the generated plasma. As a result, Figure 2 The substrate W is shown.

[0054] To execute step STd, the control unit 80 controls the gas supply unit to supply a processing gas into the chamber 10. To execute step STd, the control unit 80 controls the exhaust device 50 to set the pressure in the chamber 10 to a predetermined pressure. To execute step STd, the control unit 80 controls the first high-frequency power source 62 and / or the second high-frequency power source 64 to supply the first high-frequency power source and / or the second high-frequency power source.

[0055] In the subsequent step ST1, the first plasma treatment is performed. That is, in step ST1, the substrate W is treated using the first plasma formed by the first processing gas. The first processing gas includes a fluorocarbon gas, a gas containing carbon but not fluorine, and an oxygen-containing gas. The fluorocarbon gas in the first processing gas is a gas containing C X F Y A gas of any molecule represented by . The fluorocarbon gas is, for example, C4F6 gas. In the first process gas, the gas containing carbon but not fluorine is, for example, CO gas or CO2 gas. The oxygen-containing gas in the first process gas is, for example, oxygen gas. In step ST1, plasma is generated in chamber 10 from the first process gas.

[0056] In step ST1, the temperature of the substrate W is set to a first temperature. The first temperature is lower than the second temperature, which is the temperature of the substrate W in step ST2. The first temperature is, for example, lower than 50°C. In one embodiment, to set the temperature of the substrate W to the first temperature in step ST1, the first high-frequency power is set to a power lower than the first high-frequency power used in step ST2. When a lower high-frequency power is used, the plasma density decreases, and the amount of heat transferred from the plasma to the substrate W decreases. According to this embodiment, the temperature of the substrate W is set to the first temperature during the first plasma treatment by at least adjusting the high-frequency power.

[0057] In other embodiments, the temperature of the substrate W during the first plasma treatment can be set to the first temperature by adjusting the power of the heater HT. In still another embodiment, the temperature of the substrate W in step ST1 can be set to the first temperature by both adjusting the first high-frequency power and adjusting the power of the heater HT.

[0058] When the temperature of the substrate W is set to a relatively low temperature, a relatively large amount of carbon-containing substances is deposited from the first plasma onto the surface of the substrate W. Therefore, as a result of the first plasma treatment, Figure 7 As shown in (a), a relatively large amount of carbon-containing material DP is deposited on the mask MK. Also, during the first plasma treatment, the silicon oxide film OX is etched by fluorine chemical species from the first plasma.

[0059] To perform step ST1, the control unit 80 controls the gas supply unit to supply the first processing gas into the chamber 10. To perform step ST1, the control unit 80 controls the exhaust device 50 to set the pressure within the chamber 10 to a predetermined pressure. To perform step ST1, the control unit 80 controls the first high-frequency power source 62 and the second high-frequency power source 64 to supply the first high-frequency power and the second high-frequency power. In step ST1, either the first high-frequency power or the second high-frequency power may be supplied. Furthermore, in step ST1, the control unit 80 controls the first high-frequency power source 62 and / or the heater controller HC to set the temperature of the substrate W to the first temperature.

[0060] After step ST1, step ST2 is performed. In step ST2, a second plasma treatment is performed. That is, in step ST2, the substrate W is treated using a second plasma formed by a second process gas. The second process gas is a gas containing a fluorocarbon gas. In one embodiment, the second process gas can be the same gas as the first process gas. That is, the second process gas can contain a fluorocarbon gas, a gas containing carbon but not fluorine, and an oxygen-containing gas. The fluorocarbon gas in the second process gas is a gas containing C X F YA gas of any molecule represented by . The fluorocarbon gas is, for example, C4F6 gas. In the second process gas, the gas containing carbon but not fluorine is, for example, CO gas or CO2 gas. The oxygen-containing gas in the second process gas is, for example, oxygen gas. In step ST2, plasma is generated in chamber 10 from the second process gas.

[0061] In step ST2, the temperature of the substrate W is set to a second temperature. The second temperature is higher than the first temperature, which is the temperature of the substrate W in step ST1. The second temperature is, for example, 50°C or higher. In one embodiment, to set the temperature of the substrate W to the second temperature in step ST2, the first high-frequency power is set to a power higher than the first high-frequency power used in step ST1.

[0062] In another embodiment, the temperature of the substrate W during the second plasma treatment can be set to the second temperature by adjusting the power of the heater HT. In still another embodiment, the temperature of the substrate W in step ST2 can be set to the second temperature by adjusting both the first high-frequency power and the power of the heater HT.

[0063] During the second plasma treatment, the silicon oxide film OX is further etched by the fluorine chemical species from the second plasma. On the other hand, during the second plasma treatment, the mask MK is protected by the carbon-containing material DP deposited on the mask MK as a result of the first plasma treatment (see FIG. Figure 7 (b)) Therefore, according to the method MT, it is possible to suppress a reduction in the film thickness of the mask MK due to etching of the silicon oxide film OX.

[0064] To perform step ST2, the control unit 80 controls the gas supply unit to supply the second processing gas into the chamber 10. To perform step ST2, the control unit 80 controls the exhaust device 50 to set the pressure within the chamber 10 to a predetermined pressure. To perform step ST2, the control unit 80 controls the first high-frequency power source 62 and the second high-frequency power source 64 to supply the first high-frequency power source and the second high-frequency power source. Furthermore, to set the temperature of the substrate W to the second temperature during step ST2, the control unit 80 controls the first high-frequency power source 62 and / or the heater controller HC.

[0065] Various exemplary embodiments have been described above, but the present invention is not limited to the exemplary embodiments described above, and various additions, omissions, substitutions, and changes can be made. Furthermore, elements of different embodiments can be combined to form other embodiments.

[0066] For example, at least one of steps STa, STb, STc, STd, ST1, and ST2 of method MT may be performed using a plasma processing apparatus different from the plasma processing apparatus used in other steps of method MT.

[0067] Furthermore, method MT may be performed using a capacitively coupled plasma processing apparatus or another type of plasma processing apparatus, which is different from plasma processing apparatus 1. Examples of other types of plasma processing apparatus include capacitively coupled plasma processing apparatuses and plasma processing apparatuses that excite gas using surface waves such as microwaves.

[0068] As can be seen from the above description, the various embodiments of the present invention are described in this specification for illustrative purposes and various modifications may be made without departing from the scope and spirit of the present invention. Therefore, the various embodiments disclosed in this specification are not intended to be limiting, and the true scope and spirit are shown by the scope of the attached technical solutions.

Claims

1. A method for etching a silicon oxide film of a substrate, wherein: The substrate has the silicon oxide film and a mask disposed on the silicon oxide film, and the method includes the following steps: (a) performing a first plasma treatment on the substrate using a first plasma formed from a first processing gas containing a fluorocarbon gas, a gas containing carbon but not containing fluorine, and an oxygen-containing gas, wherein the temperature of the substrate is set to a first temperature during the first plasma treatment, and the first plasma treatment deposits a carbon-containing substance on the mask and etches the silicon oxide film. (b) is a step of performing a second plasma treatment on the substrate using a second plasma formed from a second process gas containing a fluorocarbon gas after step (a), wherein the temperature of the substrate is set to a second temperature during the second plasma treatment. The second plasma treatment etches the silicon oxide film while the mask is protected by the carbon-containing substance formed in step (a). The first temperature is lower than the second temperature.

2. The method according to claim 1, wherein The first process gas and the second process gas are the same process gas.

3. The method according to claim 1, wherein Performing (a) and (b) using a plasma processing device, The high-frequency power used in the plasma processing apparatus to generate the first plasma in (a) is lower than the high-frequency power used in the plasma processing apparatus to generate the second plasma in (b).

4. The method according to any one of claims 1 to 3, wherein In (a) and (b), the electric energy of the heater in the substrate supporter supporting the substrate is adjusted so that the first temperature is lower than the second temperature.

5. The method according to any one of claims 1 to 3, wherein In the first processing gas, the gas containing carbon but not containing fluorine is CO gas, and the oxygen-containing gas is O 2 gas.

6. The method according to any one of claims 1 to 3, wherein The mask is formed of an organic material.

7. A plasma processing apparatus comprising: chamber; a substrate supporter, disposed in the chamber; a gas supply unit configured to supply a first process gas including a fluorocarbon gas, a gas containing carbon but not fluorine, and an oxygen-containing gas, and a second process gas including a fluorocarbon gas into the chamber; a high-frequency power supply configured to generate high-frequency power for generating plasma from the gas in the chamber; and a control unit configured to control the gas supply unit and the high-frequency power supply, The control unit performs: a first control for controlling the gas supply unit so as to supply the first process gas into the chamber, and controlling the high-frequency power supply so as to generate a first plasma from the first process gas in the chamber, in order to etch the silicon oxide film of the substrate and form a carbon-containing deposit on a mask of the substrate provided on the silicon oxide film; and The second control controls the gas supply unit to supply the second process gas into the chamber, and controls the high-frequency power supply to generate a second plasma in the chamber from the second process gas, in order to further etch the silicon oxide film while the mask is protected by the carbon-containing deposit formed by the first control. The temperature of the substrate in the first control is set to be lower than the temperature of the substrate set in the second control.

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