Plasma Processing Method and Plasma Processing Apparatus

Abstract

Provided is a plasma processing method and a plasma processing apparatus for suppressing defective etching shapes of an organic film. In this plasma processing method, an organic film is etched through a mask formed of a silicon-containing film and having an opening portion on the organic film. The plasma processing method includes a step of repairing the shape of the mask, and the step of repairing the shape of the mask includes: a step of modifying the side wall of the opening portion of the mask; and a step of etching the upper surface of the mask.

Description

Technical Field

[0001] The present disclosure relates to a plasma processing method and a plasma processing apparatus. Background Art

[0002] For example, in the etching process of 3D NAND, an organic film such as an amorphous carbon film is used as a mask for etching a stacked film of a SiO x film and a SiN film. By etching the organic film using an inorganic film such as a SiON film as a mask, a pattern of the mask of the organic film is formed.

[0003] Patent Document 1 discloses a method for controlling the critical dimension (CD) of an etching structure in an etching layer by generating a plasma of an opening gas containing COS in an opening of a functional organic matter mask layer in a stack formed of a resist mask, an intermediate mask layer, a functional organic matter mask layer, and an etching layer.

[0004] <Prior Art Documents>

[0005] <Patent Documents>

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2010-109373 Summary of the Invention

[0007] <Problems to be Solved by the Invention>

[0008] In one aspect, the present disclosure provides a plasma processing method and a plasma processing apparatus for suppressing poor etching shape of an organic film.

[0009] <Means for Solving the Problems>

[0010] To solve the above problems, according to one embodiment, there is provided a plasma processing method for etching the organic film through a mask formed of a silicon-containing film on the organic film and having an opening portion, the plasma processing method including: a step of repairing the shape of the mask, wherein the step of repairing the shape of the mask includes: a step of modifying a side wall of the opening portion of the mask; and a step of etching an upper surface of the mask.

[0011] <Effects of the Invention>

[0012] According to one aspect, it is possible to provide a plasma processing method and a plasma processing apparatus for suppressing poor etching shape of an organic film. Brief Description of the Drawings

[0013] Figure 1It is a cross-sectional schematic diagram showing an example of a plasma processing apparatus according to an embodiment.

[0014] Figure 2 It is a flowchart for explaining an example of a process of etching an organic film using an inorganic film as a mask.

[0015] Figure 3 It is a flowchart for explaining the process in the mask rectangularization process.

[0016] Figure 4 It is a diagram schematically showing the structure of a substrate.

[0017] Figure 5 It is a diagram for explaining the movement of oxygen ions.

[0018] Figure 6 It is a diagram showing the relationship between the flow rate ratio of the first processing gas and the second processing gas and the shape of the silicon-containing film. Detailed Embodiments

[0019] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In each of the drawings, the same reference numerals are given to the same components, and redundant descriptions may sometimes be omitted.

[0020] Use Figure 1 The substrate processing apparatus 1 according to the present embodiment will be described. Figure 1 It is a cross-sectional schematic diagram showing an example of a substrate processing apparatus (plasma processing apparatus) 1 according to the present embodiment.

[0021] The substrate processing apparatus 1 includes a chamber 10. The chamber 10 provides an internal space 10s therein. The chamber 10 includes a chamber body 12. The chamber body 12 has a substantially cylindrical shape. The chamber body 12 is formed of, for example, aluminum. A corrosion-resistant film is provided on the inner wall surface of the chamber body 12. This film can be a ceramic such as alumina or yttrium oxide.

[0022] A passage 12p is formed in the side wall of the chamber body 12. The substrate W is transported between the internal 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.

[0023] A support portion 13 is provided on the bottom of the chamber body 12. The support portion 13 is formed of an insulating material. The support portion 13 has a substantially cylindrical shape. The support portion 13 extends upward from the bottom of the chamber body 12 in the internal space 10s. The support portion 13 has a support table (mounting table) 14 at the upper part. The support table 14 is configured to support the substrate W in the internal space 10s.

[0024] The support stage 14 has a lower electrode 18 and an electrostatic chuck 20. The support stage 14 may further have an electrode plate 16. The electrode plate 16 is formed of a conductor such as aluminum and has a substantially disc-shaped form. The lower electrode 18 is provided on the electrode plate 16. The lower electrode 18 is formed of a conductor such as aluminum and has a substantially disc-shaped form. The lower electrode 18 is electrically connected to the electrode plate 16.

[0025] The electrostatic chuck 20 is provided on the lower electrode 18. A substrate W is placed on the upper surface of the electrostatic chuck 20. The electrostatic chuck 20 has a main body and an electrode. The main body of the electrostatic chuck 20 has a substantially disc-shaped form and is formed of a dielectric. The electrode of the electrostatic chuck 20 is a film-shaped electrode and is provided inside the main body of the electrostatic chuck 20. The electrode of the electrostatic chuck 20 is connected to a DC power supply 20p via a switch 20s. When a voltage from the DC power supply 20p is applied to the electrode of the electrostatic chuck 20, an electrostatic attraction force is generated between the electrostatic chuck 20 and the substrate W. By this electrostatic attraction force, the substrate W is held on the electrostatic chuck 20.

[0026] On the peripheral portion of the lower electrode 18, an edge ring 25 is arranged so as to surround the edge of the substrate W. The edge ring 25 is used to improve the in-plane uniformity of plasma processing for the substrate W. The edge ring 25 may be formed of silicon, silicon carbide, quartz, or the like.

[0027] A flow path 18f is provided inside the lower electrode 18. A heat exchange medium (e.g., refrigerant) is supplied to the flow path 18f via a pipe 22a from a cooler unit (not shown) provided outside the chamber 10. The heat exchange medium supplied to the flow path 18f returns to the cooler unit via a pipe 22b. In the substrate 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.

[0028] A gas supply line 24 is provided in the substrate processing apparatus 1. The gas supply line 24 supplies a heat transfer gas (e.g., He gas) from a heat transfer gas supply mechanism between the upper surface of the electrostatic chuck 20 and the back surface of the substrate W.

[0029] The substrate processing apparatus 1 further includes an upper electrode 30. The upper electrode 30 is provided above the support stage 14. The upper electrode 30 is supported by a member 32 at the upper part of the chamber main body 12. The member 32 is formed of a material having insulating properties. The upper electrode 30 and the member 32 close the upper opening of the chamber main body 12.

[0030] 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 on the inner space 10s side and defines the inner space 10s. The top plate 34 may be formed of a low-resistance conductor or semiconductor that generates less Joule heat. The top plate 34 has a plurality of gas discharge holes 34a penetrating through the top plate 34 in the thickness direction of the top plate 34.

[0031] The support 36 supports the top plate 34 in a detachable manner. The support 36 is formed of a conductive material such as aluminum. A gas diffusion chamber 36a is provided inside the support 36. The support 36 has a plurality of gas holes 36b extending downward from the gas diffusion chamber 36a. The plurality of gas holes 36b communicate with the plurality of gas discharge holes 34a respectively. A gas inlet 36c is formed on the support 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.

[0032] A valve group 42, a flow controller group 44, and a gas source group 40 are connected to the gas supply pipe 38. The gas source group 40, the valve group 42, and the flow controller group 44 constitute a gas supply unit. The gas source group 40 includes a plurality of gas sources. The valve group 42 includes a plurality of on-off valves. The flow controller group 44 includes a plurality of flow controllers. Each of the plurality of flow controllers in the flow controller group 44 is a mass flow controller or a pressure-controlled flow controller. Each of the plurality of gas sources in the gas source group 40 is connected to the gas supply pipe 38 via a corresponding on-off valve of the valve group 42 and a corresponding flow controller of the flow controller group 44.

[0033] In the substrate processing apparatus 1, a shielding member 46 is detachably provided along the inner wall surface of the chamber body 12 and the outer periphery of the support portion 13. The shielding member 46 is used to prevent reaction by-products from adhering to the chamber body 12. The shielding member 46 is constituted, for example, by forming a corrosion-resistant film on the surface of a base material formed of aluminum. The corrosion-resistant film may be formed of a ceramic such as yttrium oxide.

[0034] A baffle 48 is provided between the support portion 13 and the side wall of the chamber body 12. The baffle 48 is constituted, for example, by forming a corrosion-resistant film (a film such as yttrium oxide) on the surface of a base material formed of aluminum. A plurality of through holes are formed in the baffle 48. An exhaust port 12e is provided below the baffle 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 turbo molecular pump.

[0035] The substrate 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 that generates first high-frequency power. The first high-frequency power has a frequency suitable for plasma generation. 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 matcher 66 and an electrode plate 16. The matcher 66 has a circuit for matching the output impedance of the first high-frequency power supply 62 with the impedance on the load side (the lower electrode 18 side). It should be noted that the first high-frequency power supply 62 can be connected to the upper electrode 30 via the matcher 66.

[0036] The second high-frequency power supply 64 is a power supply that generates second high-frequency power. The frequency of the second high-frequency power is 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 high-frequency power for attracting ions to 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 a matcher 68 and an electrode plate 16. The matcher 68 has a circuit for matching the output impedance of the second high-frequency power supply 64 with the impedance on the load side (the lower electrode 18 side).

[0037] It should be noted that the second high-frequency power can be used without using the first high-frequency power, that is, plasma can be generated using only a single high-frequency power. In this case, the frequency of the second high-frequency power can be a frequency greater than 13.56 MHz, for example, it can be 40 MHz. The substrate processing apparatus 1 may not include the first high-frequency power supply 62 and the matcher 66. The first high-frequency power supply 62, the second high-frequency power supply 64, the upper electrode 30, and the lower electrode 18 constitute an example of a plasma generation unit.

[0038] In the substrate processing apparatus 1, gas is supplied from the gas supply unit to the internal space 10s to generate plasma. In addition, by supplying the first high-frequency power and / or the second high-frequency power, a high-frequency electric field is generated between the upper electrode 30 and the lower electrode 18. The plasma is generated by the generated high-frequency electric field.

[0039] The substrate processing apparatus 1 includes a power supply 70. The power supply 70 is connected to the upper electrode 30. The power supply 70 applies a voltage for attracting positive ions existing in the internal space 10s to the top plate 34 to the upper electrode 30.

[0040] The substrate processing apparatus 1 may further include a control unit 80. The control unit 80 may be a computer having a processor, a storage unit such as a memory, an input device, a display device, an input / output interface for signals, etc. The control unit 80 controls each unit of the substrate processing apparatus 1. In the control unit 80, an operator can use the input device to perform operations such as inputting commands to manage the substrate processing apparatus 1. In addition, in the control unit 80, the operating state of the substrate processing apparatus 1 can be visually displayed through the display device. Furthermore, a control program and recipe data are stored in the storage unit. The control program is executed by the processor to perform various processes in the substrate processing apparatus 1. The processor executes the control program and controls each unit of the substrate processing apparatus 1 according to the recipe data.

[0041] Next, Figures 2 to 4 A substrate processing method (plasma processing method) performed by the substrate processing apparatus 1 will be described. Figure 2 and Figure 3 is a flowchart illustrating an example of a process of etching the organic film 110 using the silicon-containing film 120 as a mask. Figure 4 is a diagram schematically showing the structure of the substrate W.

[0042] Figure 4 (a) shows the structure of the substrate W before the start of the etching process. The substrate W has a lower layer film 100, an organic film 110, and a silicon-containing film 120.

[0043] The silicon-containing film 120 is patterned with openings 121 such as holes and trenches, and serves as a mask when etching the organic film 110. In the following description, the silicon-containing film 120 is a silicon-containing film having at least silicon oxide (Si-O). In the following description, the case where the silicon-containing film 120 is a SiON film will be described. It should be noted that the silicon-containing film 120 is not limited to the SiON film, and may also be a SiO2 film, Si-ARC, etc.

[0044] The organic film 110 is provided below the silicon-containing film 120. The organic film 110 is etched by the etching process shown below using the silicon-containing film 120 patterned with the openings 121 as a mask, and forms a film with a pattern of openings 111. The openings 111 are formed (see Figure 2 shown below) Figure 4(e)) is used as a mask when etching the underlying film 100. In the following description, the case where the organic film 110 is an amorphous carbon film will be described. It should be noted that the organic film 110 is not limited to an amorphous carbon film, and may also be an SOC (spin-on carbon) film mainly composed of carbon (C) atoms, doped carbon, a CF film (carbon film added with fluorine), a low dielectric constant organic film, etc., or may be a laminated film in which multiple organic films are laminated.

[0045] The underlying film 100 is disposed below the organic film 110. The underlying film 100 is a film that is etched using the organic film 110 having a pattern with an opening 111 formed by the etching process of the organic film 110 shown below as a mask. The underlying film 100 may be, for example, a laminated film of a SiO film and a SiN film. It should be noted that the underlying film 100 is not limited to this. Figure 2 film and a SiN film. It should be noted that the underlying film 100 is not limited to this. x film and a SiN film. It should be noted that the underlying film 100 is not limited to this.

[0046] Before the start of the etching process shown below, the substrate W is transported into the internal space 10s of the chamber 10 via the passage 12p and placed on the support table 14. The control unit 80 controls the switch 20s to adsorb the substrate W to the electrostatic chuck 20. In addition, the control unit 80 closes the gate valve 12g. In addition, the control unit 80 controls the exhaust device 50 to set the internal space 10s to a desired pressure. In addition, by supplying a heat transfer gas from the gas supply line 24 and supplying a heat exchange medium into the flow path 18f from a cooler unit (not shown), the temperature of the substrate W is adjusted to a desired temperature. Figure 2 Before the start of the etching process shown below, the substrate W is transported into the internal space 10s of the chamber 10 via the passage 12p and placed on the support table 14. The control unit 80 controls the switch 20s to adsorb the substrate W to the electrostatic chuck 20. In addition, the control unit 80 closes the gate valve 12g. In addition, the control unit 80 controls the exhaust device 50 to set the internal space 10s to a desired pressure. In addition, by supplying a heat transfer gas from the gas supply line 24 and supplying a heat exchange medium into the flow path 18f from a cooler unit (not shown), the temperature of the substrate W is adjusted to a desired temperature.

[0047] In step S1, the organic film 110 is etched using the silicon-containing film 120 as a mask (organic film etching). Specifically, the control unit 80 controls the gas source group 40, the valve group 42, and the flow rate controller group 44 to supply an etching gas (fourth processing gas) from the gas hole 36b to the internal space 10s. It should be noted that, as the etching gas, O2 gas can be used. It should be noted that the etching gas is not limited to O2 gas, and may also be CO gas, CO2 gas, O3 gas, or may be a mixed gas. In addition, at least one gas among COS gas, Cl2 gas, HBr gas, etc. can be added. In addition, the control unit 80 controls the first high-frequency power supply 62 to apply a first high-frequency power for generating plasma to the lower electrode 18. In addition, the control unit 80 controls the second high-frequency power supply 64 to apply a second high-frequency power for attracting ions to the substrate W to the lower electrode 18.

[0048] It should be noted that an example of the preferred parameters in step S1 is shown below.

[0049] Pressure: 10 to 50 mTorr

[0050] First high-frequency power: 1000 to 5000 W

[0051] Second high-frequency power: 50 to 500 W

[0052] Substrate temperature: -10 to 20 °C

[0053] Thus, as Figure 4 (b) shows, using the oxygen ions (O + ) or oxygen radicals (O * ) generated by the plasma, the organic film 110 is plasma-etched with the silicon-containing film 120 as a mask, thereby forming an opening 111 in the organic film 110. It should be noted that CO, which is a reaction product during the plasma etching of the organic film 110, is discharged from the internal space 10s by the exhaust device 50.

[0054] In addition, the silicon-containing film 120 is also etched and consumed by the oxygen ions (O + ) or oxygen radicals (O * ) generated by the plasma. Here, it is known that the etching yield of the silicon-containing film 120 has an angular dependence on the incident angle of the ions, and is maximum when the incident angle is near a predetermined angle (although it also varies depending on the type of film or the applied voltage, but for example, it is around 60° to 75°). Therefore, in the silicon-containing film 120 having a concavo-convex pattern, a difference in etching rate is generated between the shoulder (the corner of the convex portion, the edge of the opening 121) and the flat portion (the upper surface of the convex portion). Therefore, as Figure 4 (b) shows, the shoulder of the silicon-containing film 120 is consumed first to form an inclined portion 122. In addition, due to the difference in etching rate between the inclined portion 122 and the flat portion, the inclined portion 122 expands.

[0055] In addition, the surface of the silicon-containing film 120, which is a SiON film, is oxidized by oxygen ions (O + ) or oxygen radicals (O * ). As a result, an oxide film 123, which is a SiO2 film, is formed on the surface of the silicon-containing film 120.

[0056] In step S2, the shape of the silicon-containing film 120 serving as a mask is repaired. That is, the silicon-containing film 120 with shoulders consumed to form the inclined portions 122 is rectangularized (mask rectangularization process). Specifically, the control unit 80 controls the gas source group 40, the valve group 42, and the flow controller group 44 to supply a first processing gas and a second processing gas into the internal space 10s from the gas holes 36b. In addition, the control unit 80 controls the first high-frequency power supply 62 to apply a first high-frequency power for generating plasma to the lower electrode 18. In addition, the control unit 80 controls the second high-frequency power supply 64 to apply a second high-frequency power for attracting ions to the substrate W to the lower electrode 18.

[0057] The first processing gas is a hydrogen-containing gas having at least hydrogen (H). In the following description, the case where the first processing gas is H2 will be described. It should be noted that the first processing gas is not limited to H2, and may be CH4, CH3F, CH2F2, H2O, etc., or may be a mixed gas.

[0058] The second processing gas is a halogen-containing gas having at least a halogen. In addition, the second processing gas may be a halogen-containing gas having at least a halogen and hydrogen. In the following description, the case where the second processing gas is CF4 will be described. It should be noted that the second processing gas is not limited to CF4, and may be CHF3, C4F8, C4F6, NF3, HBr, Cl2, etc., or may be a mixed gas.

[0059] It should be noted that an example of preferable parameters in step S2 is as follows.

[0060] Pressure: 10 to 50 mTorr

[0061] First high-frequency power: 1000 to 2000 W

[0062] Second high-frequency power: 50 to 500 W

[0063] Gas flow ratio (second processing gas / first processing gas): 0.11 to 2

[0064] Substrate temperature: -10 to 20 °C

[0065] Use Figure 3 The mask rectangularization process of step S2 will be further described. Figure 3 It is a flowchart for explaining the process in the mask rectangularization process.

[0066] In step S21, the side walls of the opening 121 of the mask (silicon-containing film 120) are modified using the first processing gas. As Figure 4 (c) shows, hydrogen ions (H+ ) or a hydrogen radical (H * ), using the silicon-containing film 120 as a mask, the bottom surface of the opening 111 of the organic film 110 is plasma-etched. At this time, reaction products (CH4, intermediate CH with dangling bonds) during plasma etching of the organic film 110 with hydrogen x ) are generated inside the opening 111 of the organic film 110 and adsorbed onto the sidewalls of the opening 121 of the silicon-containing film 120.

[0067] Then, on the sidewalls of the opening 121, hydrogen for promoting the reduction reaction is supplied from the plasma generated in the internal space 10s, and energy is provided by irradiation with ions or UV from the plasma, so that the adsorbed reaction products (CH4, CH x ) react with SiO2 as the oxide film 123 on the surface of the silicon-containing film 120, or the reaction products (CH4, CH x ) adsorbed on the oxide film 123 on the surface of the silicon-containing film 120 are thermally decomposed and then react with SiO2. Thus, the reduction carbonization rate from SiO2 to SiC shown by the following chemical formula (1) increases, and the sidewalls of the silicon-containing film 120 (oxide film 123) as SiO2 are modified to form a modified film 124 as SiC. It should be noted that CO and H2O as reaction products in the modification to SiC are exhausted from the internal space 10s by the exhaust device 50.

[0068] SiO2 + 3C → SiC + 2CO (1)

[0069] Here, the reaction products (CH4, CH x ) are supplied from the opening 111 of the organic film 110 to the sidewalls of the opening 121 of the silicon-containing film 120. Therefore, in the modification from SiO2 to SiC, mainly the sidewalls of the opening 121 of the silicon-containing film 120 are modified, and the modification is suppressed on the inclined portion 122 and the upper surface of the silicon-containing film 120.

[0070] In step S22, using a second processing gas, the upper surface of the mask (silicon-containing film 120) is plasma-etched. As Figure 4 (d) shows, by ions (CF x + etc.) or radicals (CF x * etc.) generated from the second processing gas by plasma, using the silicon-containing film 120 as a mask, the bottom surface of the opening 111 of the organic film 110 is plasma-etched. In addition, by ions (CF x + etc.) or radicals (CF x *etc.), the upper surface of the silicon-containing film 120 is subjected to plasma etching. Here, in step S22, the recipe is set such that the etching rate of the modified film 124 (SiC) is lower than the etching rate of the silicon-containing film 120 (SiON and SiO2 which is the oxide film 123 on the upper surface). That is, the selectivity of the etching rate of SiON and SiO2 with respect to SiC is increased. That is, by performing plasma etching on the silicon-containing film 120 using the second processing gas in a state where the shoulders and sidewalls of the silicon-containing film 120 are protected by the modified film 124 (SiC), the upper surface of the silicon-containing film 120 is etched and the shoulders of the silicon-containing film 120 are rectangularized.

[0071] It should be noted that although the case where the first processing gas and the second processing gas are supplied simultaneously in step S2 to simultaneously perform the process of modifying the sidewalls of the opening 121 of the mask (silicon-containing film 120) (step S21) and the process of performing plasma etching on the upper surface of the mask (silicon-containing film 120) (step S22) has been described, it is not limited thereto. It is also possible to supply the first processing gas to perform the process of modifying the sidewalls of the opening 121 of the mask (silicon-containing film 120) (step S21) and then supply the second processing gas to perform the process of performing plasma etching on the upper surface of the mask (silicon-containing film 120) (step S22).

[0072] Return Figure 2 , in step S3, the organic film 110 is etched (organic film etching) using the silicon-containing film 120 with rectangularized shoulders as a mask. Specifically, the control unit 80 controls the gas source group 40, the valve group 42, and the flow controller group 44 to supply an etching gas (third processing gas) from the gas hole 36b to the internal space 10s. It should be noted that as the etching gas, O2 gas can be used. It should be noted that the etching gas is not limited to O2 gas, and it can also be CO gas, CO2 gas, O3 gas, or a mixed gas. In addition, at least one gas among COS gas, Cl2 gas, HBr gas, etc. can be added. In addition, the control unit 80 controls the first high-frequency power supply 62 to apply a first high-frequency power for generating plasma to the lower electrode 18. In addition, the control unit 80 controls the second high-frequency power supply 64 to apply a second high-frequency power for attracting ions to the substrate W to the lower electrode 18.

[0073] It should be noted that an example of the preferred parameters in step S3 is as follows.

[0074] Pressure: 10 - 50 mTorr

[0075] First high-frequency power: 1000 - 5000 W

[0076] Second high-frequency power: 50 - 500 W

[0077] Substrate temperature: -10 - 20 °C

[0078] It should be noted that the organic film etching in step S3 can be carried out under the same conditions as the organic film etching in step S1, or under different conditions. In addition, the etching gas (the fourth processing gas) in step S1 and the etching gas (the third processing gas) in step S3 can be the same gas or different gases.

[0079] Thus, as Figure 4 (e) shows, using the silicon-containing film 120 as a mask, the organic film 110 is subjected to plasma etching, so that the depth of the opening 111 formed in the organic film 110 is extended. In addition, the silicon-containing film 120 is also etched, and the shoulder of the silicon-containing film 120 is consumed first to form an inclined portion 125. In addition, an oxide film 126 as a SiO2 film is formed on the surface of the silicon-containing film 120.

[0080] In step S4, it is determined whether the organic film etching has been carried out a specified number of times. Here, the specified number of times can be, for example, the number of times that can be considered that the opening 111 of the organic film 110 reaches the target etching depth (for example, reaches the underlying film 100). When the organic film etching has not been carried out the specified number of times (S4 is NO), the process of the control unit 80 returns to step S2, and the rectangularization (S2) of the silicon-containing film 120 as a mask and the etching (S3) of the organic film 110 are repeated until the specified number of times is reached. If the specified number of times is reached (S4 is YES), the control unit 80 ends the process.

[0081] Through the above processing, a pattern of the opening 111 is formed on the organic film 110. Then, using this organic film 110 as a mask, the underlying film 100 is etched.

[0082] Next, use Figure 5 The processing of etching the organic film 110 in this embodiment will be further described.

[0083] Figure 5 (a) is a schematic diagram for explaining the movement of oxygen ions when an inclined portion 122 is formed at the shoulder of the silicon-containing film 120. By applying second high-frequency power to the lower electrode 18, the oxygen ions are incident perpendicularly to the substrate W. At this time, a part of the oxygen ions incident on the inclined portion 122 bounces on the inclined portion 122, passes through the opening 121 and the opening 111, collides with the side wall of the organic film 110, and etches the side wall of the organic film 110. Therefore, an opening 111 in a bowing shape is formed on the organic film 110.

[0084] Figure 5 (b) is a schematic diagram for explaining the movement of oxygen ions when the shoulder of the silicon-containing film 120 is rectangularized. By applying a second high-frequency power to the lower electrode 18, the oxygen ions are attracted to the substrate W. At this time, since the silicon-containing film 120 is rectangularized, it is possible to suppress the collision of the oxygen ions rebounding from the silicon-containing film 120 with the side wall of the organic film 110. Thereby, the bending shape of the organic film 110 can be suppressed.

[0085] As described above, according to the process of etching the organic film 110 in the present embodiment, by etching the organic film 110 after rectangularizing the shoulder of the silicon-containing film 120, it is possible to suppress the collision of the rebounding ions with the side wall of the organic film 110 and suppress the bending shape of the opening 111 of the organic film 110. Thereby, it is possible to suppress the defective etching shape of the organic film 110.

[0086] In addition, since it is possible to suppress the defective etching shape of the opening 111 of the organic film 110, when etching the lower layer film 100 using the organic film 110 as a mask, it is possible to suppress the defective etching shape of the lower layer film 100.

[0087] Figure 6 is a graph showing the relationship between the flow rate ratio of the first processing gas and the second processing gas and the shape of the silicon-containing film 120. It should be noted that in Figure 6 the example of, (a) shows the shape before the rectangularization process (Initial). As the first reference example, (b) shows the case where only CF4 gas is supplied. (c) shows the case where the flow rate ratio of CF4 gas to H2 gas is set to 2:1 for supply. (d) shows the case where the flow rate ratio of CF4 gas to H2 gas is set to 0.5:1 for supply. (e) shows the case where the flow rate ratio of CF4 gas to H2 gas is set to 0.11:1 for supply. As the second reference example, (f) shows the case where only H2 gas is supplied.

[0088] As Figure 6 shown in (a), in the shape before the rectangularization process (Initial), an inclination is formed on the shoulder of the silicon-containing film 120.

[0089] As Figure 6 shown in (b), in the case where only CF4 gas is supplied, the thickness of the silicon-containing film 120 is reduced due to plasma etching. In addition, the upper surface of the silicon-containing film 120 is not planarized. In other words, the silicon-containing film 120 is not rectangularized, and an inclination is formed on the shoulder of the silicon-containing film 120.

[0090] On the other hand, as Figure 6As shown in (f), when only H2 gas is supplied, no change in the shape of the silicon-containing film 120 is observed, and the upper surface of the silicon-containing film 120 is not planarized. In other words, the silicon-containing film 120 is not rectangularized, but an inclination is formed on the shoulder of the silicon-containing film 120.

[0091] As Figure 6 As shown in (c) to 6(e), it can be seen that by supplying the CF4 gas in the range where the flow rate ratio of the CF4 gas to the H2 gas is 0.11 to 2, the shoulder of the silicon-containing film 120 can be appropriately rectangularized.

[0092] Although the embodiments of the substrate processing apparatus 1 and the like have been described above, the present disclosure is not limited to the above embodiments and the like, and various modifications and improvements can be made within the scope of the gist of the present disclosure described in the claims.

Claims

1. A plasma processing method, which etches the organic film through a mask formed of a silicon-containing film on the organic film and having an opening, the plasma processing method having: a step of repairing the shape of the mask, Among them, the step of repairing the shape of the mask includes: a step of modifying the side wall of the opening of the mask; and a step of etching the upper surface of the mask, in the step of modifying the side wall of the opening of the mask, the side wall of the opening of the mask is modified to SiC.

2. The plasma processing method according to claim 1, further comprising: a step of etching the organic film through the mask after etching the upper surface of the mask.

3. The plasma processing method according to claim 1, wherein, in the step of modifying the side wall of the opening of the mask, a plasma process is performed using a first processing gas containing a hydrogen-containing gas.

4. The plasma processing method according to claim 3, wherein, in the step of modifying the side wall of the opening of the mask, the organic film is etched using the plasma of the first processing gas so as to modify the side wall with the reaction product of the etching.

5. The plasma processing method according to any one of claims 1 to 4, wherein, in the step of etching the upper surface of the mask, the etching rate of SiC generated by the step of modifying the side wall of the opening of the mask is lower than the etching rate of the silicon-containing film.

6. The plasma processing method according to claim 5, wherein, in the step of etching the upper surface of the mask, a plasma process is performed using a second processing gas containing a halogen-containing gas.

7. The plasma processing method according to claim 6, wherein, the second processing gas contains a hydrogen-containing gas.

8. The plasma processing method according to claim 1, wherein, in the step of etching the upper surface of the mask, a plasma process is performed using a second processing gas containing a halogen-containing gas.

9. The plasma processing method according to any one of claims 1 to 4, wherein, after the step of modifying the side wall of the opening of the mask, the step of etching the upper surface of the mask is performed.

10. A plasma processing method, which etches the organic film through a mask formed of a silicon-containing film on the organic film and having an opening, the plasma processing method having: a step of repairing the shape of the mask, Among them, the step of repairing the shape of the mask includes: a step of modifying the side wall of the opening of the mask; and a step of etching the upper surface of the mask, the step of modifying the side wall of the opening of the mask and the step of etching the upper surface of the mask are performed simultaneously.

11. A plasma processing method, which etches the organic film through a mask formed of a silicon-containing film on the organic film and having an opening, the plasma processing method having: a step of repairing the shape of the mask, Among them, The process of repairing the shape of the mask includes: The process of modifying the side walls of the opening of the mask; and The process of etching the upper surface of the mask, After the process of repairing the shape of the mask, the plasma processing method further includes: The process of etching the organic film with the plasma of a third processing gas containing oxygen.

12. The plasma processing method according to claim 11, wherein The process of repairing the shape of the mask and the process of etching the organic film with the plasma of the third processing gas are repeated at least once.

13. The plasma processing method according to claim 11 or 12, wherein Before the process of repairing the shape of the mask, it includes: The process of oxidizing the surface of the mask with the plasma of a fourth processing gas containing oxygen.

14. The plasma processing method according to claim 13, wherein The third processing gas and the fourth processing gas use the same gas.

15. The plasma processing method according to claim 13, wherein The third processing gas and the fourth processing gas use different gases.

16. The plasma processing method according to claim 13, wherein In the process of oxidizing the surface of the mask, The organic film is etched with the plasma of the fourth processing gas.

17. The plasma processing method according to claim 16, wherein In the process of oxidizing the surface of the mask, The organic film is etched with the plasma of the fourth processing gas, and at the same time, the shoulders of the opening of the mask are consumed.

18. A plasma processing apparatus includes: A stage for placing a substrate on which a mask formed of a silicon-containing film on an organic film and having an opening is arranged; A chamber for accommodating the stage; A gas supply unit for supplying a processing gas into the chamber; A plasma generation unit for generating plasma in the chamber; And A control unit, wherein the control unit is configured to be able to execute the following processes: The process of etching the organic film; and The process of repairing the shape of the mask, The process of repairing the shape of the mask includes: The process of modifying the side walls of the opening of the mask; and The process of etching the upper surface of the mask, In the process of modifying the side walls of the opening of the mask, The side walls of the opening of the mask are modified to SiC.

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