Plasma processing method and plasma processing apparatus

Abstract

The present disclosure provides a plasma treatment method and a plasma treatment apparatus for suppressing etching shape defects of an organic film. The plasma treatment method is a plasma treatment method for etching the organic film through a mask formed as a silicon-containing film on the organic film and having an opening, and includes a process for restoring the shape of the mask. The process for restoring the shape of the mask includes a process for modifying the sidewall of the opening of the mask and a process for etching the upper surface of the mask.

Description

Technology Field

[0001] The present disclosure relates to a plasma treatment method and a plasma treatment apparatus. Background Technology

[0002] For example, in the etching process of 3D NAND, an organic film such as an amorphous carbon film is used as a mask to etch a stack of SiO2 and SiN films. With this organic film mask, a pattern is formed by etching the organic film using an inorganic film such as a SiON film as a mask.

[0003] Patent Document 1 discloses a method for controlling the limit dimension (CD) of an etching configuration within an etching layer by generating a plasma of an opening gas containing COS in an opening of a functional organic mask layer, in a laminate formed by a resist mask, an intermediate mask layer, a functional organic mask layer, and an etching layer. Prior art literature

[0004] Japanese Patent Publication No. JP2010-109373 The problem to be solved

[0005] In one aspect, the present disclosure provides a plasma treatment method and a plasma treatment apparatus for suppressing etching shape defects of an organic film. means of solving the problem

[0006] In order to solve the above problem, according to one embodiment, a plasma treatment method is provided for etching an organic film through a mask formed as a silicon-containing film on an organic film and having an opening, the method comprising a process for restoring the shape of the mask, wherein the process for restoring the shape of the mask comprises a process for modifying the sidewall of the opening of the mask and a process for etching the upper surface of the mask. Effects of the invention

[0007] According to one aspect, a plasma treatment method and a plasma treatment apparatus for suppressing etching shape defects of an organic film can be provided. Brief explanation of the drawing

[0008] FIG. 1 is a schematic cross-sectional view showing an example of a plasma processing apparatus according to one embodiment. Figure 2 is a flowchart illustrating an example of a process for etching an organic film using an inorganic film as a mask. Figure 3 is a flowchart illustrating the processing in the squared mask process. Figure 4 is a diagram schematically showing the structure of a substrate. Figures 5a and 5b are schematic diagrams illustrating the behavior of oxygen ions. Figure 6 is a diagram showing the relationship between the flow rate ratio of the first and second treatment gases and the shape of the silicon-containing film. Specific details for implementing the invention

[0009] Hereinafter, embodiments for implementing the present disclosure are described with reference to the drawings. In each drawing, the same reference numerals are used for identical components, and redundant descriptions may be omitted.

[0010] A substrate processing device (1) (plasma processing device) according to the present embodiment will be explained using FIG. 1. FIG. 1 is a schematic cross-sectional view showing an example of a substrate processing device (1) according to the present embodiment.

[0011] A substrate processing device (1) comprises a chamber (10). An internal space (10s) is formed within the chamber (10). The chamber (10) includes a chamber body (12). The chamber body (12) has a roughly cylindrical shape. The chamber body (12) is formed, for example, of aluminum. A corrosion-resistant film is formed on the inner wall surface of the chamber body (12). The film may be a ceramic such as aluminum oxide or yttrium oxide.

[0012] A passage (12p) is formed in the side wall of the chamber body (12). A 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) formed in the side wall of the chamber body (12).

[0013] A support member (13) is provided on the bottom portion of the chamber body (12). The support member (13) is formed of an insulating material. The support member (13) has a roughly cylindrical shape. The support member (13) extends upward from the bottom portion of the chamber body (12) within the internal space (10s). The support member (13) is provided with a support table (14) on its upper side. The support table (14) (mount) is configured to support a substrate (W) within the internal space (10s).

[0014] The support table (14) is equipped with a lower electrode (18) and an electrostatic chuck (20). The support table (14) may further be equipped with an electrode plate (16). The electrode plate (16) is formed of a conductor such as aluminum and is approximately disc-shaped. The lower electrode (18) is provided on the electrode plate (16). The lower electrode (18) is formed of a conductor such as aluminum and is approximately disc-shaped. The lower electrode (18) is electrically connected to the electrode plate (16).

[0015] The electrostatic chuck (20) is provided on the lower electrode (18). A substrate (W) is mounted 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) is roughly disc-shaped and is formed of a dielectric material. The electrode of the electrostatic chuck (20) is a film-shaped electrode and is provided within the main body of the electrostatic chuck (20). The electrode of the electrostatic chuck (20) is connected to a DC power source (20p) through a switch (20s). When a voltage from the DC power source (20p) is applied to the electrode of the electrostatic chuck (20), an electrostatic attraction is generated between the electrostatic chuck (20) and the substrate (W). The substrate (W) is held in the electrostatic chuck (20) by this electrostatic attraction.

[0016] An edge ring (25) is disposed on the perimeter edge portion of the lower electrode (18) to surround the edge of the substrate (W). The edge ring (25) improves the in-plane uniformity of the plasma treatment on the substrate (W). The edge ring (25) may be formed of silicon, silicon carbide, or quartz, etc.

[0017] 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) through a pipe (22a) from a chiller unit (not shown) provided outside the chamber (10). The heat exchange medium supplied to the flow path (18f) returns to the chiller unit through a pipe (22b). In the substrate processing device (1), the temperature of the substrate (W) mounted on the electrostatic chuck (20) is adjusted by heat exchange between the heat exchange medium and the lower electrode (18).

[0018] The substrate processing device (1) is equipped with a gas supply line (24). The gas supply line (24) supplies a heating gas (e.g., He gas) from a heating gas supply device between the upper surface of the electrostatic chuck (20) and the back surface of the substrate (W).

[0019] The substrate processing device (1) also has an upper electrode (30). The upper electrode (30) is provided above the support table (14). The upper electrode (30) is supported on the upper part of the chamber body (12) with a member (32) in between. The member (32) is formed of an insulating material. The upper electrode (30) and the member (32) block the upper opening of the chamber body (12).

[0020] The upper electrode (30) may include a ceiling plate (34) and a support (36). The lower surface of the ceiling plate (34) is the lower surface facing the internal space (10s) and partitions the internal space (10s). The ceiling plate (34) may be formed of a low-resistance conductor or semiconductor that generates less Joule heat. The ceiling plate (34) has a plurality of gas discharge holes (34a) that penetrate the ceiling plate (34) in the thickness direction.

[0021] The support body (36) detachably supports the ceiling plate (34). The support body (36) is formed of a conductive material such as aluminum. A gas diffusion chamber (36a) is provided inside the support body (36). The support body (36) has a plurality of gas holes (36b) extending downward from the gas diffusion chamber (36a). Each of the plurality of gas holes (36b) is connected to a plurality of gas discharge holes (34a). A gas inlet port (36c) is formed in the support body (36). The gas inlet port (36c) is connected to the gas diffusion chamber (36a). A gas supply pipe (38) is connected to the gas inlet port (36c).

[0022] 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 shut-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) through the corresponding shut-off valve of the valve group (42) and the corresponding flow controller of the flow controller group (44).

[0023] In the substrate processing device (1), a shield (46) is detachably provided along the inner wall surface of the chamber body (12) and the outer circumference of the support member (13). The shield (46) prevents reaction by-products from adhering to the chamber body (12). The shield (46) is formed by forming a corrosion-resistant film on the surface of a base material, for example, formed of aluminum. The corrosion-resistant film may be formed of a ceramic such as yttrium oxide.

[0024] A baffle plate (48) is provided between the support member (17) and the side wall of the chamber body (12). The baffle plate (48) is formed by forming a corrosion-resistant film (such as a film of yttrium oxide) on the surface of a base material formed, for example, of aluminum. A plurality of through holes are formed in the baffle plate (48). An exhaust port (12e) is provided below the baffle plate (48) and at the bottom of the chamber body (12). An exhaust device (50) is connected to the exhaust port (12e) through an exhaust pipe (52). The exhaust device (50) includes a pressure regulating valve and a vacuum pump such as a turbo molecular pump.

[0025] The plasma processing device (1) is equipped with a first high-frequency power source (62) and a second high-frequency power source (64). The first high-frequency power source (62) is a power source that generates the first high-frequency power. The first high-frequency power has a frequency suitable for plasma generation. For example, the frequency of the first high-frequency power is a frequency within the range of 27 MHz to 100 MHz. The first high-frequency power source (62) is connected to the lower electrode (18) with the matching unit (66) and the electrode plate (16) in between. The matching unit (66) has a circuit for matching the output impedance of the first high-frequency power source (62) with the impedance of the load side (lower electrode (18) side). Meanwhile, the first high-frequency power source (62) may also be connected to the upper electrode (30) with the matching unit (66) in between. The first high-frequency power source (62) constitutes an example plasma generation unit.

[0026] The second high-frequency power source (64) is a power source that generates the 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 to attract ions to the substrate (W). The frequency of the second high-frequency power is, for example, a frequency within the range of 400 kHz to 13.56 MHz. The second high-frequency power source (64) is connected to the lower electrode (18) with the matching device (68) and the electrode plate (16) in between. The matching device (68) has a circuit for matching the output impedance of the second high-frequency power source (64) with the load side (lower electrode (18) side) impedance.

[0027] Meanwhile, plasma may be generated using a second high-frequency power without using a first high-frequency power, that is, using only a single high-frequency power. In this case, the frequency of the second high-frequency power may be a frequency greater than 13.56 MHz, for example, 40 MHz. The substrate processing device (1) may not be equipped with a first high-frequency power supply (62) and a matching unit (66). The second high-frequency power supply (64) constitutes an example plasma generation unit.

[0028] In the substrate processing device (1), gas is supplied from the gas supply unit into the internal space (10s) to generate plasma. Additionally, a first high-frequency power and / or a second high-frequency power is 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.

[0029] The substrate processing device (1) is equipped with a power source (70). The power source (70) is connected to an upper electrode (30). The electrode (70) applies a voltage to the upper electrode (30) to attract cations present in the internal space (10s) to the ceiling plate (34).

[0030] The substrate processing device (1) may additionally be equipped with a control unit (80). The control unit (80) may be a computer equipped with a processor, a memory unit such as memory, an input device, a display device, and an input / output interface for signals. The control unit (80) controls each part of the substrate processing device (1). In the control unit (80), an operator may perform input operations of commands to manage the substrate processing device (1) using an input device. In addition, the control unit (80) may visualize and display the operating status of the substrate processing device (1) by means of a display device. Furthermore, a control program and recipe data are stored in the memory unit. The control program is executed by a processor to perform various processes in the substrate processing device (1). The processor executes the control program and controls each part of the substrate processing device (1) according to the recipe data.

[0031] Next, a substrate processing method (plasma processing method) performed by the substrate processing device (1) will be explained using FIGS. 2 to 4. FIGS. 2 and 3 are flowcharts illustrating an example of a process for etching an organic film (110) using a silicon-containing film (120) as a mask. FIG. 4 is a diagram schematically showing the structure of a substrate (W).

[0032] FIG. 4(a) shows the structure of a 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).

[0033] The silicon-containing film (120) has a pattern of openings (121), such as holes and trenches, formed therein and is used 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 silicon-containing film (120) is described as a SiON film. Meanwhile, the silicon-containing film (120) is not limited to a SiON film and may be a SiO2 film, a Si-ARC film, etc.

[0034] An organic film (110) is provided below a silicon-containing film (120). The organic film (110) is a film in which a pattern of openings (111) is formed by etching the silicon-containing film (120), which has an opening (121) pattern formed thereon, through an etching process shown in FIG. 2 described later, using the silicon-containing film (120) with the opening (121) pattern formed thereon as a mask. The organic film (110) with the opening (111) pattern formed thereon (see FIG. 4 (e) described later) is used as a mask when etching the lower film (100). In the following description, the organic film (110) is described as being an amorphous carbon film. Meanwhile, the organic film (110) is not limited to an amorphous carbon film and may be an SOC (spin-on carbon) film in which carbon (C) atoms are the main components, doped carbon, a CF film (fluorine-doped carbon film), a low dielectric constant organic film, etc., or may be a laminated film in which several types of organic films are stacked.

[0035] The lower layer (100) is provided below the organic film (110). The lower layer (100) is a film that is etched using the organic film (110), which has an opening (111) pattern formed by the etching treatment of the organic film (110) shown in FIG. 2, as a mask. The lower layer (100) is, for example, SiO x It may be a stacked film of a film and a SiN film. However, the lower film (100) is not limited to this.

[0036] Before the etching process shown in FIG. 2 begins, the substrate (W) is transported through the passage (12p) to the internal space (10s) of the chamber (10) 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). Additionally, the control unit (80) closes the gate valve (12g). Additionally, the control unit (80) controls the exhaust device (50) to bring the internal space (10s) to a desired pressure. Furthermore, heat transfer gas is supplied from the gas supply line (24), and a heat exchange medium is supplied from the chiller unit (not shown) into the flow path (18f), thereby adjusting the temperature of the substrate (W) to a desired temperature.

[0037] 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 etching gas (fourth processing gas) from the gas hole (36b) into the internal space (10s). Meanwhile, O2 gas may be used as the etching gas. Meanwhile, the etching gas is not limited to O2 gas and may 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. may be added. In addition, the control unit (80) controls the first high-frequency power source (62) to apply the first high-frequency power to the lower electrode (18) to generate plasma. Additionally, the control unit (80) controls the second high-frequency power supply (64) to apply the second high-frequency power to the lower electrode (18) to attract ions to the substrate (W).

[0038] Meanwhile, an example of a parameter that can be appropriately used as needed in step S1 is shown below.

[0039] - Pressure: 10~50 mTorr

[0040] - 1st High Frequency Power: 1000~5000W

[0041] - Second high-frequency power: 50~500W

[0042] - Substrate temperature: -10~20℃

[0043] Thus, as shown in FIG. 4(b), oxygen ions (O) generated by the plasma + ), oxygen radical (O * By means of a silicon-containing film (120) as a mask, the organic film (110) is plasma-etched to form an opening (111) in the organic film (110). Meanwhile, CO, which is a reaction product when the organic film (110) is plasma-etched, is discharged from the internal space (10s) by an exhaust device (50).

[0044] In addition, oxygen ions (O) generated by the plasma + ), oxygen radical (O * The silicon-containing film (120) is also etched and consumed by the ) here. It is known that the etching yield of the silicon-containing film (120) has an angle dependence with respect to the angle of incidence of the ions, and is greatest at an angle of incidence near a certain angle (depending on the type of film, applied voltage, etc., for example, around 60° to 75°). Thus, in the silicon-containing film (120) with the uneven pattern formed, a difference in etching rate occurs between the shoulder portion (the edge of the convex portion, the edge of the opening (121)) and the flat portion (the upper surface of the convex portion). Therefore, as shown in FIG. 4 (b), the shoulder portion of the silicon-containing film (120) is consumed first, and the inclined portion (122) is formed. In addition, the inclined portion (122) is expanded due to the difference in etching rate between the inclined portion (122) and the flat portion.

[0045] In addition, the surface of the silicon-containing film (120), which is a SiON film, contains oxygen ions (O + ), oxygen radical (O * It is oxidized by ). As a result, an oxide film (123), which is an SiO2 film, is formed on the surface of the silicon-containing film (120).

[0046] In step S2, the shape of the silicon-containing film (120) that serves as the mask is restored. That is, the silicon-containing film (120), in which the shoulder portion is consumed and the inclined portion (122) is formed, is squared (mask squared process). Specifically, the control unit (80) controls the gas source group (40), the valve group (42), and the flow rate controller group (44) to supply the first treatment gas and the second treatment gas from the gas hole (36b) to the internal space (10s). Additionally, the control unit (80) controls the first high-frequency power source (62) to apply the first high-frequency power to the lower electrode (18) to generate plasma. Additionally, the control unit (80) controls the second high-frequency power source (64) to apply the second high-frequency power to the lower electrode (18) to attract ions to the substrate (W).

[0047] The first treatment gas is a hydrogen-containing gas that includes at least hydrogen (H). In the following description, the first treatment gas is described as being H2 gas. Meanwhile, the first treatment gas is not limited to H2 and may be CH4, CH3F, CH2F2, H2O, etc., or may be a mixed gas.

[0048] The second treatment gas is a halogen-containing gas containing at least a halogen. Additionally, the second treatment gas may be a halogen-containing gas containing at least a halogen and hydrogen. In the following description, the second treatment gas is described as CF4. Meanwhile, the second treatment gas is not limited to CF4 and may be CHF3, C4F8, C4F6, NF3, HBr, Cl2, etc., or may be a mixed gas.

[0049] Meanwhile, an example of a parameter that can be appropriately used as needed in step S2 is shown below.

[0050] - Pressure: 10~50 mTorr

[0051] - 1st High Frequency Power: 1000~2000W

[0052] - Second high-frequency power: 50~500W

[0053] - Gas flow rate ratio (2nd treated gas / 1st treated gas): 0.11~2

[0054] - Substrate temperature: -10~20℃

[0055] The mask squared process of step S2 is further explained using FIG. 3. FIG. 3 is a flowchart illustrating the processing in the mask squared process.

[0056] In step S21, the sidewall of the opening (121) of the mask (silicon-containing film (120)) is modified using a first treatment gas. As shown in FIG. 4 (c), hydrogen ions (H) generated from the first treatment gas by plasma are used. + ), hydrogen radical (H * By means of ), the bottom surface of the opening (111) of the organic film (110) is plasma etched using the silicon-containing film (120) as a mask. At this time, the reaction product (CH4, intermediate CH4 having unbonded losses) when the organic film (110) is plasma etched by hydrogen. x ) is formed within the opening (111) of the organic film (110) and adsorbed to the side wall of the opening (121) of the silicon-containing film (120).

[0057] And, at the side wall of the opening (121), energy is supplied by hydrogen and ions from the plasma, UV irradiation, etc., to promote a reduction reaction from the plasma generated in the internal space (10s), and adsorbed reaction products (CH4, CH x ) and SiO2, which is the oxide film (123) on the surface of the silicon-containing film (120), react. Or, a reaction product (CH4, CH4) adsorbed on the oxide film (123) on the surface of the silicon-containing film (120). xAfter ) is pyrolyzed, it reacts with SiO2. As a result, the reduction carbonization rate from SiO2 to SiC, as shown in the following chemical formula (1), increases, and the sidewalls of the silicon-containing film (120) (oxide film (123)) which is SiO2 are modified to form a modified film (124) which is SiC. Meanwhile, CO and H2O, which are reaction products in the modification to SiC, are discharged from the internal space (10s) by the exhaust device (50).

[0058] SiO2+3C→SiC+2CO ···· (1)

[0059] At this time, the reaction product (CH4, CH4) x ) is supplied from the inside of the opening (111) of the organic film (110) to the side wall of the opening (121) of the silicon-containing film (120). Thus, the modification from SiO2 to SiC is mainly modified at the side wall of the opening (121) of the silicon-containing film (120), and modification is suppressed at the inclined portion (122) or upper surface of the silicon-containing film (120).

[0060] In step S22, the upper surface of the mask (silicon-containing film (120)) is plasma etched using a second treatment gas. As shown in FIG. 4 (d), ions (CF₀) generated from the second treatment gas by the plasma are formed. x + (etc.), radical (CF x * By means of, etc., the bottom surface of the opening (111) of the organic film (110) is plasma etched using the silicon-containing film (120) as a mask. In addition, ions (CF x + (etc.), radical (CF x *The upper surface of the silicon-containing film (120) is plasma-etched by means of the etc. At this time, in step S22, the recipe is set so 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 etching rate selectivity ratio of SiON and SiO2 relative to SiC is increased. That is, while the shoulder portion and side wall of the silicon-containing film (120) are protected by the modified film (124, SiC), the silicon-containing film (120) is plasma-etched using a second treatment gas, thereby etching the upper surface of the silicon-containing film (120) and making the shoulder portion of the silicon-containing film (120) square.

[0061] Meanwhile, in step S2, the first treatment gas and the second treatment gas are supplied simultaneously to perform a treatment (S21) for modifying the sidewall of the opening (121) of the mask (silicon-containing film (120)) and a treatment (step S22) for plasma etching the upper surface of the mask (silicon-containing film (120)), but this is not limited thereto. After performing the treatment (step S21) for modifying the sidewall of the opening (121) of the mask (silicon-containing film (120)) by supplying the first treatment gas, the second treatment gas may be supplied to perform the treatment (step S22) for plasma etching the upper surface of the mask (silicon-containing film (120)).

[0062] Returning to FIG. 2, in step S3, the organic film (110) is etched using the silicon-containing film (120), which has a squared shoulder portion, 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 etching gas (third treatment gas) from the gas hole (36b) into the internal space (10s). Meanwhile, O2 gas may be used as the etching gas. Meanwhile, the etching gas is not limited to O2 gas and may 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. may be added. In addition, the control unit (80) controls the first high-frequency power source (62) to apply the first high-frequency power to the lower electrode (18) to generate plasma. Additionally, the control unit (80) controls the second high-frequency power supply (64) to apply the second high-frequency power to the lower electrode (18) to attract ions to the substrate (W).

[0063] Meanwhile, an example of a parameter that can be appropriately used as needed in step S3 is shown below.

[0064] - Pressure: 10~50 mTorr

[0065] - 1st High Frequency Power: 1000~5000W

[0066] - Second high-frequency power: 50~500W

[0067] - Substrate temperature: -10~20℃

[0068] Meanwhile, the organic film etching in step S3 may be performed under the same conditions as the organic film etching in step S1 or under different conditions. Additionally, the etching gas in step S1 (the fourth treatment gas) and the etching gas in step S3 (the third treatment gas) may be the same gas or different gases.

[0069] Thus, as shown in FIG. 4(e), the organic film (110) is plasma-etched using the silicon-containing film (120) as a mask, and the depth of the opening (111) formed in the organic film (110) is increased. Additionally, the silicon-containing film (120) is also etched, and the shoulder portion of the silicon-containing film (120) is consumed first to form an inclined portion (125). Furthermore, an oxide film (126), which is an SiO2 film, is formed on the surface of the silicon-containing film (120).

[0070] In step S4, it is determined whether the organic film etching has been performed a specified number of times. Here, the specified number of times may be, for example, the number of times when the opening (111) of the organic film (110) is considered to have reached a target etching depth (for example, reached the lower film (100)). If the organic film etching has not been performed a specified number of times (S4, No), the processing of the control unit (80) returns to step S2 and repeats the square formation (S2) of the silicon-containing film (120) which is the mask and the etching (S3) of the organic film (110) until the specified number of times is reached. When the specified number of times is reached (S4, Yes), the control unit (80) terminates the processing.

[0071] By the above process, an opening (111) pattern is formed in the organic film (110). Then, the lower film (100) is etched using this organic film (110) as a mask.

[0072] Next, the process of etching the organic film (110) in the present embodiment will be further explained using FIG. 5a and FIG. 5b.

[0073] FIG. 5a is a schematic diagram illustrating the behavior of oxygen ions when an inclined portion (122) is formed on the shoulder portion of a silicon-containing film (120). By applying a second high-frequency power to the lower electrode (18), oxygen ions are incident perpendicularly to the substrate (W). At this time, some of the oxygen ions incident on the inclined portion (122) bounce off the inclined portion (122), pass through the opening (121, 111), and collide with the side wall of the organic film (110), thereby etching the side wall of the organic film (110). Thus, a bowing-shaped opening (111) is formed in the organic film (110).

[0074] FIG. 5b is a schematic diagram illustrating the behavior of oxygen ions when the shoulder portion of the silicon-containing film (120) is squared. By applying a second high-frequency power to the lower electrode (18), oxygen ions are attracted to the substrate (W). At this time, since the silicon-containing film (120) is squared, oxygen ions that jump out of the silicon-containing film (120) can be suppressed from colliding with the side wall of the organic film (110). This suppresses the bowing shape of the organic film (110).

[0075] According to the above embodiment, the process of etching the organic film (110) involves making the shoulder portion of the silicon-containing film (120) square and then etching the organic film (110), thereby suppressing the collision of splashed ions with the sidewall of the organic film (110) and suppressing the bowing shape of the opening (111) of the organic film (110). By doing so, defects in the etching shape of the organic film (110) can be suppressed.

[0076] In addition, since the etching shape defect of the opening (111) of the organic film (110) can be suppressed, the etching shape defect of the lower film (100) can be suppressed when the lower film (100) is etched using the organic film (110) as a mask.

[0077] FIG. 6 is a diagram showing the relationship between the flow rate ratio of the first and second treatment gases and the shape of the silicon-containing film (120). Meanwhile, in the example of FIG. 6, (a) shows the shape before square processing (Initial), (b) shows the case where only CF4 gas is supplied as a first reference example, and (c) shows the case where the flow rate ratio of CF4 gas and H2 gas is supplied at 2:1. In addition, (d) shows the case where the flow rate ratio of CF4 gas and H2 gas is supplied at 0.5:1, (e) shows the case where the flow rate ratio of CF4 gas and H2 gas is supplied at 0.11:1, and (f) shows the case where only H2 gas is supplied as a second reference example.

[0078] As shown in FIG. 6 (a), in the initial shape before square processing, a slope is formed on the shoulder portion of the silicon-containing film (120).

[0079] As shown in FIG. 6(b), when only CF4 gas is supplied, the thickness of the silicon-containing film (120) is reduced by plasma etching. In addition, the upper surface of the silicon-containing film (120) is not flattened; in other words, the silicon-containing film (120) is not squared, that is, a slope is formed on the shoulder portion of the silicon-containing film (120).

[0080] Meanwhile, as shown in (f) of FIG. 6, when only H2 gas is supplied, there is no change in the shape of the silicon-containing film (120), and the upper surface of the silicon-containing film (120) is not flattened, in other words, the silicon-containing film (120) is not square, that is, a slope is formed on the shoulder portion of the silicon-containing film (120).

[0081] As shown in FIG. 6 (c) to (e), it was confirmed that the shoulder portion of the silicon-containing film (120) can be appropriately squared as needed by supplying a flow rate ratio of CF4 gas to H2 gas in the range of 0.11 to 2.

[0082] Although embodiments of the substrate processing device (1) have been described above, the present disclosure is not limited to the above embodiments, and various modifications and improvements are possible within the scope of the gist of the present disclosure as described in the claims.

[0083] The present invention claims priority based on patent application No. 2019-201668 filed with the Japan Patent Office on November 6, 2019, the entire contents of which are incorporated herein by reference.

Claims

Claim 1 A plasma treatment method for etching an organic film through a mask formed as a silicon-containing film on an organic film and having an opening, the method comprising a process of etching the organic film and a process of restoring the shape of the mask, wherein the process of restoring the shape of the mask comprises a process of modifying the sidewall of the opening of the mask and a process of etching the upper surface of the mask, and wherein the process of modifying the sidewall of the opening of the mask modifies the sidewall of the opening of the mask into SiC. Claim 2 A plasma treatment method for etching an organic film through a mask having an opening formed as a silicon-containing film on an organic film, the method comprising a process for etching the organic film and a process for restoring the shape of the mask, wherein the process for restoring the shape of the mask comprises a process for modifying the sidewalls of the openings of the mask and a process for etching the upper surface of the mask, wherein the process for modifying the sidewalls of the openings of the mask is plasma treatment with a first treatment gas comprising a hydrogen-containing gas, and wherein, in the process for etching the upper surface of the mask, the etching rate of SiC generated by the process for modifying the sidewalls of the openings of the mask is lower than the etching rate of the silicon-containing film. Claim 3 A plasma treatment method for etching an organic film through a mask having an opening formed as a silicon-containing film on an organic film, the method comprising a process for etching the organic film and a process for restoring the shape of the mask, wherein the process for restoring the shape of the mask comprises a process for modifying the sidewall of the opening of the mask and a process for etching the upper surface of the mask, wherein the process for modifying the sidewall of the opening of the mask comprises etching the organic film with a plasma of a first treatment gas and modifying the sidewall using a reaction product of said etching, and wherein, in the process for etching the upper surface of the mask, the etching rate of SiC generated by the process for modifying the sidewall of the opening of the mask is lower than the etching rate of the silicon-containing film. Claim 4 In claim 1, the process of modifying the sidewall of the opening of the mask is a plasma treatment method in which plasma treatment is performed with a first treatment gas containing a hydrogen-containing gas. Claim 5 In paragraph 2, the process of modifying the sidewall of the opening of the mask is a plasma treatment method in which the organic film is etched with the plasma of the first treatment gas and the sidewall is modified using the reaction product of the etching. Claim 6 A plasma treatment method according to claim 1, wherein in the process of etching the upper surface of the mask, the etching rate of SiC generated by the process of modifying the sidewall of the opening of the mask is lower than the etching rate of the silicon-containing film. Claim 7 A plasma treatment method according to any one of claims 1 to 3, wherein the process of etching the upper surface of the mask is plasma treatment with a second treatment gas containing a halogen-containing gas. Claim 8 A plasma treatment method according to claim 7, wherein the second treatment gas comprises a hydrogen-containing gas. Claim 9 A plasma treatment method according to claim 4 or 5, wherein the process of etching the upper surface of the mask is plasma treatment with a second treatment gas containing a halogen-containing gas. Claim 10 A plasma treatment method for etching an organic film through a mask formed as a silicon-containing film on an organic film and having an opening, the method comprising a process of etching the organic film and a process of restoring the shape of the mask, wherein the process of restoring the shape of the mask comprises a process of modifying the sidewall of the opening of the mask and a process of etching the upper surface of the mask, wherein the process of modifying the sidewall of the opening of the mask and the process of etching the upper surface of the mask are performed simultaneously. Claim 11 A plasma treatment method according to any one of claims 1 to 3, wherein the process of etching the upper surface of the mask is performed after the process of modifying the sidewall of the opening of the mask. Claim 12 A plasma treatment method according to any one of claims 1 to 3, comprising a process of etching the organic film by a plasma of a third treatment gas containing oxygen after the process of restoring the shape of the mask. Claim 13 A plasma treatment method according to claim 12, wherein the process of restoring the shape of the mask and the process of etching the organic film by the plasma of the third treatment gas are repeated at least once. Claim 14 A plasma treatment method according to claim 12, comprising a process of oxidizing the surface of the mask by a plasma of a fourth treatment gas containing oxygen before a process of restoring the shape of the mask. Claim 15 A plasma treatment method according to claim 14, wherein the same gas is used as the third treatment gas and the fourth treatment gas. Claim 16 A plasma treatment method according to claim 14, wherein different gases are used as the third treatment gas and the fourth treatment gas. Claim 17 A plasma treatment method according to claim 14, wherein in the process of oxidizing the surface of the mask, the organic film is etched by the plasma of the fourth treatment gas. Claim 18 A plasma treatment method according to claim 17, wherein in the process of oxidizing the surface of the mask, the organic film is etched by the plasma of the fourth treatment gas and the shoulder portion of the opening of the mask is consumed. Claim 19 A plasma treatment method according to claim 1, wherein the process of modifying the side wall of the opening of the mask is plasma treatment with a first treatment gas, and the process of etching the upper surface of the mask is plasma treatment with a second treatment gas, wherein the first treatment gas comprises at least one hydrogen-containing gas selected from the group consisting of H2 gas, CH4 gas, CH3F gas, CH2F2 gas, and H2O gas, and the second treatment gas comprises at least one halogen-containing gas selected from the group consisting of CF4 gas, CHF3 gas, C4F8 gas, C4F6 gas, NF3 gas, HBr gas, and Cl2 gas. Claim 20 A plasma treatment method according to claim 12, wherein the third treatment gas comprises at least one gas selected from the group consisting of O2 gas, CO gas, CO2 gas, O3 gas, COS gas, Cl2 gas, and HBr gas. Claim 21 A plasma processing apparatus comprising: a mounting base for mounting a substrate having a mask formed as a silicon-containing film on an organic film and having an opening; a chamber for housing the mounting base; a gas supply unit for supplying a processing gas into the chamber; a plasma generation unit for generating plasma within the chamber; and a control unit, wherein the control unit is configured to perform a process of etching the organic film and a process of restoring the shape of the mask, wherein the process of restoring the shape of the mask includes a process of modifying the sidewall of the opening of the mask and a process of etching the upper surface of the mask, and wherein the process of modifying the sidewall of the opening of the mask modifies the sidewall of the opening of the mask into SiC. Claim 22 A plasma treatment method for etching an organic film through a mask having an opening formed as a silicon-containing film on an organic film, the method comprising a process for etching the organic film and a process for restoring the shape of the mask, wherein the process for restoring the shape of the mask comprises a process for modifying the sidewalls of the opening of the mask and a process for etching the upper surface of the mask, wherein the process for modifying the sidewalls of the opening of the mask is plasma treatment with a first treatment gas and the process for etching the upper surface of the mask is plasma treatment with a second treatment gas, wherein the first treatment gas comprises at least one hydrogen-containing gas selected from the group consisting of H2 gas, CH4 gas, CH3F gas, CH2F2 gas, and H2O gas, and the second treatment gas comprises at least one halogen-containing gas selected from the group consisting of CF4 gas, CHF3 gas, C4F8 gas, C4F6 gas, NF3 gas, HBr gas, and Cl2 gas. Claim 23 A plasma treatment method for etching an organic film through a mask formed as a silicon-containing film on an organic film and having an opening, comprising a process for etching the organic film and a process for restoring the shape of the mask, wherein the process for restoring the shape of the mask comprises a process for modifying the sidewalls of the opening of the mask and a process for etching the upper surface of the mask, wherein the process for modifying the sidewalls of the opening of the mask is plasma treatment with a first treatment gas, wherein the organic film is etched with the plasma of the first treatment gas and the sidewalls are modified using the reaction product of the etching, and the process for etching the upper surface of the mask is plasma treatment with a second treatment gas, wherein the first treatment gas comprises at least one hydrogen-containing gas selected from the group consisting of H2 gas, CH4 gas, CH3F gas, CH2F2 gas, and H2O gas, and the second treatment gas comprises CF4 gas, CHF3 gas, C4F8 gas, A plasma treatment method comprising at least one halogen-containing gas selected from the group consisting of C4F6 gas, NF3 gas, HBr gas, and Cl2 gas.

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