Plasma processing device

Abstract

To provide a technique for improving a selection ratio of etching of a film containing silicon relative to etching of a mask in plasma etching.SOLUTION: A plasma processing device includes: a chamber having a gas supply port and a gas discharge port; a plasma generation unit; and a control unit. The control unit executes processing including the steps of: disposing a substrate having a silicon-containing film including a silicon oxide film and a mask on the silicon-containing film in the chamber; supplying a first processing gas including a hydrogen fluoride gas and a halogen-containing gas; and etching the silicon-containing film by plasma generated from the first processing gas.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a method for etching a film in a substrate. The film contains silicon, and the substrate further has a mask provided on the film. The mask includes amorphous carbon or an organic polymer. In the method, etching is performed using plasma generated from a processing gas containing a hydrocarbon gas and a fluorohydrocarbon gas.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a technique for improving the selectivity of etching a silicon-containing film with respect to etching of a mask in plasma etching.

Means for Solving the Problems

[0005] A plasma processing apparatus according to one exemplary embodiment includes a chamber having a gas supply port and a gas discharge port, a plasma generation unit, and a control unit. The control unit executes a process including a step of disposing a substrate having a silicon-containing film including a silicon oxide film and a mask on the silicon-containing film in the chamber, a step of supplying a first processing gas including hydrogen fluoride gas and a halogen-containing gas, and a step of etching the silicon-containing film with plasma generated from the first processing gas.

Effects of the Invention

[0006] According to the present disclosure, a technique can be provided for improving the selectivity of etching of a silicon-containing film with respect to etching of a mask in plasma etching.

Brief Description of the Drawings

[0007]

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Embodiments for Carrying Out the Invention

[0008] Hereinafter, various exemplary embodiments will be described.

[0009] In one exemplary embodiment, a substrate processing method is provided. The substrate processing method includes a step of providing a substrate in a chamber of a plasma processing apparatus. The substrate has a silicon-containing film including a silicon oxide film and a mask provided on the silicon-containing film. The substrate processing method includes a step of controlling the temperature of a substrate support on which the substrate is placed to 0° C. or lower. The substrate processing method further includes a step of etching the silicon-containing film with plasma generated from a first processing gas including hydrogen fluoride gas and at least one carbon-containing gas selected from the group consisting of fluorocarbon gas and hydrofluorocarbon gas. In the etching step, the silicon-containing film is etched by chemical species from the plasma. The flow rate of hydrogen fluoride gas is the highest among the first processing gases excluding the inert gas. According to this embodiment, by using plasma generated from the first processing gas in which the flow rate of hydrogen fluoride gas is the highest among the total flow rates excluding the inert gas, the etching selectivity of the silicon-containing film with respect to the etching of the mask is improved.

[0010] In one exemplary embodiment, the flow rate of hydrogen fluoride gas with respect to the total flow rate of the first processing gas excluding the inert gas may be 70% by volume or more.

[0011] In one exemplary embodiment, the fluorocarbon gas may be at least one selected from the group consisting of CF4, C2F2, C2F4, C3F8, C4F6, C4F8, and C5F8.

[0012] In one exemplary embodiment, the fluorocarbon gas may be C4F8 gas.

[0013] In one exemplary embodiment, the hydrofluorocarbon gas is CHF3, CH2F2, CH3F, C2HF5, C2H2F4, C2H3F3, C2H4F2, C3HF7, C3H2F2, C3H2F6, C3H2F4, C3H3F5, C4H5F5, C4H2F6, C5H2F 10 , c-C5H3F7, and at least one selected from the group consisting of C3H2F4 may be used.

[0014] In one exemplary embodiment, the hydrofluorocarbon gas may be at least one selected from the group consisting of C3H2F4 gas and C4H2F6 gas.

[0015] In one exemplary embodiment, the first processing gas may further include at least one selected from the group consisting of an oxygen-containing gas and a halogen-containing gas.

[0016] In one exemplary embodiment, the first processing gas may further include at least one selected from the group consisting of a phosphorus-containing gas, a sulfur-containing gas, and a boron-containing gas.

[0017] In one exemplary embodiment, the flow rate of hydrogen fluoride gas relative to the total flow rate of the first processing gas excluding the inert gas may be 96% by volume or less.

[0018] In one exemplary embodiment, the silicon-containing film may be at least one selected from the group consisting of a silicon oxide film, a laminated film including a silicon oxide film and a silicon nitride film, and a laminated film including a silicon oxide film and a polysilicon film.

[0019] In one exemplary embodiment, the mask may be a carbon-containing mask or a metal-containing mask.

[0020] In one exemplary embodiment, the carbon-containing mask may be formed of at least one selected from the group consisting of spin-on carbon, tungsten carbide, amorphous carbon, and boron carbide.

[0021] In one exemplary embodiment, the substrate processing method further includes a step of generating plasma from a second processing gas in the chamber. In the step of generating plasma from the second processing gas, the inside of the chamber is cleaned by chemical species from the plasma.

[0022] In one exemplary embodiment, the second processing gas may include at least one selected from the group consisting of a fluorine-containing gas, an oxygen-containing gas, a hydrogen-containing gas, and a nitrogen-containing gas.

[0023] In one exemplary embodiment, the substrate processing method further includes a step of generating plasma from a third processing gas in a chamber before the step of providing the substrate. In the step of generating plasma from the third processing gas, a precoat is formed on the inner wall of the chamber.

[0024] In one exemplary embodiment, the third processing gas may include a carbon-containing gas.

[0025] In another exemplary embodiment, a substrate processing method is provided. The substrate processing method includes a step of providing a substrate in a chamber of a plasma processing apparatus. The substrate has a silicon-containing film including a silicon oxide film and a mask provided on the silicon-containing film. The substrate processing method further includes a step of etching the silicon-containing film with plasma generated from a first processing gas including hydrogen fluoride gas and at least one carbon-containing gas selected from the group consisting of C4F8 gas, C3H2F4 gas, and C4H2F6 gas in the chamber. In the etching step, the silicon-containing film is etched by chemical species from the plasma. The flow rate of the hydrogen fluoride gas with respect to the total flow rate of the first processing gas excluding the inert gas is 70% by volume or more and 96% by volume or less. According to this embodiment, by using plasma generated from the first processing gas in which the flow rate of the hydrogen fluoride gas is 70% by volume or more and 96% by volume or less with respect to the total flow rate excluding the inert gas, the etching selectivity of the silicon-containing film with respect to the etching of the mask is improved.

[0026] In one exemplary embodiment, the first processing gas may further include at least one selected from the group consisting of an oxygen-containing gas and a halogen-containing gas.

[0027] In one exemplary embodiment, the first processing gas may further include a phosphorus-containing gas.

[0028] In another exemplary embodiment, a substrate processing method is provided. The substrate processing method includes a step of providing a substrate in a chamber of a plasma processing apparatus. The substrate has a silicon-containing film and a mask provided on the silicon-containing film. The substrate processing method further includes a step of etching the silicon-containing film with plasma generated from a first processing gas containing hydrogen fluoride gas. In the etching step, the silicon-containing film is etched by chemical species from the plasma. The flow rate of the hydrogen fluoride gas with respect to the total flow rate of the first processing gas excluding the inert gas is 70% by volume or more and 96% by volume or less. According to this embodiment, by using plasma generated from the first processing gas in which the flow rate of the hydrogen fluoride gas is 70% by volume or more and 96% by volume or less with respect to the total flow rate excluding the inert gas, the etching selectivity of the silicon-containing film with respect to the etching of the mask is improved.

[0029] In one exemplary embodiment, the first processing gas may include a carbon-containing gas and at least one selected from the group consisting of an oxygen-containing gas, a halogen-containing gas, and a phosphorus-containing gas.

[0030] In one exemplary embodiment, the carbon-containing gas may include at least one selected from the group consisting of a fluorocarbon gas, a hydrofluorocarbon gas, and a hydrocarbon gas.

[0031] In one exemplary embodiment, the fluorocarbon gas may be at least one selected from the group consisting of CF4, C2F2, C2F4, C3F8, C4F6, C4F8, and C5F8.

[0032] In one exemplary embodiment, the fluorocarbon gas may be C4F8 gas.

[0033] In one exemplary embodiment, the hydrofluorocarbon gas may be at least one selected from the group consisting of CHF3, CH2F2, CH3F, C2HF5, C2H2F4, C2H3F3, C2H4F2, C3HF7, C3H2F2, C3H2F6, C3H2F4, C3H3F5, C4H5F5, C4H2F6, C5H2F 10 , and may be at least one selected from the group consisting of c-C5H3F7 and C3H2F4.

[0034] In one exemplary embodiment, the hydrofluorocarbon gas may be at least one selected from the group consisting of C3H2F4 gas and C4H2F6 gas.

[0035] In one exemplary embodiment, the hydrocarbon gas may be at least one selected from the group consisting of CH4, C2H6, C3H6, C3H8, and C4H 10 and may be at least one selected from the group consisting of.

[0036] In one exemplary embodiment, the carbon-containing gas may be a hydrofluorocarbon gas having 3 or more carbon atoms.

[0037] In one exemplary embodiment, the silicon-containing film may be at least one selected from the group consisting of a laminated film including a silicon oxide film and a silicon nitride film, a polysilicon film, a low dielectric constant film, and a laminated film including a silicon oxide film and a polysilicon film.

[0038] In one exemplary embodiment, the mask may be a carbon-containing mask or a metal-containing mask.

[0039] In one exemplary embodiment, before the step of etching, the step of adjusting the temperature of the substrate support on which the substrate is placed to 0°C or lower may further be included.

[0040] In another exemplary embodiment, a substrate processing method is provided. The substrate processing method includes a step of generating plasma from a precoat gas in a chamber of a plasma processing apparatus to form a precoat on an inner wall of the chamber. The plasma processing method further includes a step of providing a substrate in the chamber. The substrate has a silicon-containing film including a silicon oxide film and a mask provided on the silicon-containing film. The substrate processing method further includes a step of controlling the temperature of a substrate support on which the substrate is placed to 0°C or less. The substrate processing method includes a step of etching the silicon-containing film with plasma generated from a processing gas including hydrogen fluoride gas and at least one carbon-containing gas selected from the group consisting of fluorocarbon gas and hydrofluorocarbon gas. In the etching step, the silicon-containing film is etched by chemical species from the plasma. The flow rate of the hydrogen fluoride gas with respect to the total flow rate of the first processing gas excluding the inert gas is 70% by volume or more. The substrate processing method further includes a step of generating plasma from a cleaning gas in the chamber to clean the chamber. According to this embodiment, by using plasma generated from the first processing gas in which the flow rate of the hydrogen fluoride gas is 70% by volume or more with respect to the total flow rate excluding the inert gas, the etching selectivity of the silicon-containing film with respect to the etching of the mask is improved.

[0041] In another exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a plasma generation unit, and a control unit. The chamber has a gas supply port and a gas discharge port. The control unit is configured to execute a process including a step of disposing a substrate in the chamber, a step of controlling the temperature of the substrate support, and a step of etching. In the step of disposing a substrate in the chamber, a substrate having a silicon-containing film including a silicon oxide film and a mask provided on the silicon-containing film is disposed on the substrate support. In the step of controlling the temperature of the substrate support, the temperature of the substrate support is controlled to 0°C or lower. In the step of etching, in the chamber, the silicon-containing film is etched by plasma generated from a first processing gas including hydrogen fluoride gas and at least one carbon-containing gas selected from the group consisting of fluorocarbon gas and hydrofluorocarbon gas. The control unit controls such that the flow rate of hydrogen fluoride gas is the highest among the first processing gases excluding the inert gas in the step of etching.

[0042] Hereinafter, various exemplary embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts will be denoted by the same reference numerals.

[0043] [First Embodiment] FIG. 1 is a flowchart showing an example of a substrate processing method according to the first embodiment. The method MT1 shown in FIG. 1 is executed to etch a film containing silicon. The method MT1 can be used, for example, in the manufacture of a 3D-structured NAND flash memory. The method MT1 is executed using a plasma processing apparatus. FIG. 2 is a diagram schematically showing an example of a plasma processing apparatus. The method MT1 shown in FIG. 1 can be executed using the plasma processing apparatus 1 shown in FIG. 2.

[0044] The plasma 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. The film may be a ceramic such as aluminum oxide or yttrium oxide.

[0045] 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.

[0046] 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 within the internal space 10s. The support portion 13 has a support base 14 at the upper portion. The support base 14 is configured to support the substrate W within the internal space 10s.

[0047] The support base 14 has a lower electrode 18 and an electrostatic chuck 20. The support base 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 shape. 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 shape. The lower electrode 18 is electrically connected to the electrode plate 16. Note that the support base 14 is an example of a substrate support.

[0048] The electrostatic chuck 20 is provided 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 an electrode (chuck electrode). The main body of the electrostatic chuck 20 has a substantially disk shape and is formed of a dielectric. The chuck electrode of the electrostatic chuck 20 is a film-like electrode and is provided inside the main body of the electrostatic chuck 20. The chuck 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 chuck electrode of the electrostatic chuck 20, an electrostatic attraction force is generated between the electrostatic chuck 20 and the substrate W. Due to the electrostatic attraction force, the substrate W is held by the electrostatic chuck 20. In addition to the chuck electrode described above, the electrostatic chuck 20 may have a bias electrode for drawing ions into the substrate W inside the main body. The bias electrode may be a film-like electrode similar to the chuck electrode.

[0049] An edge ring 25 is disposed on the peripheral edge of the lower electrode 18 so as to surround the edge of the substrate W. The edge ring 25 improves the in-plane uniformity of the plasma treatment with respect to the substrate W. The edge ring 25 can be formed of silicon, silicon carbide, quartz, or the like.

[0050] A flow path 18f is provided inside the lower electrode 18. A heat exchange medium (for example, a refrigerant) is supplied to the flow path 18f from a chiller unit (not shown) provided outside the chamber 10 via a pipe 22a. The heat exchange medium supplied to the flow path 18f is returned to the chiller unit 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.

[0051] The plasma processing apparatus 1 is provided with a gas supply line 24. The gas supply line 24 supplies a heat transfer gas (for example, 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.

[0052] The plasma processing apparatus 1 further includes an upper electrode 30. The upper electrode 30 is provided above the support base 14. The upper electrode 30 is supported on the upper part of the chamber body 12 via a member 32. The member 32 is formed of an insulating material. The upper electrode 30 and the member 32 close the upper opening of the chamber body 12.

[0053] 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 side of 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 discharge holes 34a penetrating the top plate 34 in its plate thickness direction.

[0054] The support 36 detachably supports the top plate 34. 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 supply port 36c is formed in the support 36. The gas supply port 36c is connected to the gas diffusion chamber 36a. A gas supply pipe 38 is connected to the gas supply port 36c.

[0055] A valve group 42, a flow rate 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 rate 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 rate controller group 44 includes a plurality of flow rate controllers. Each of the plurality of flow rate controllers in the flow rate controller group 44 is a mass flow controller or a pressure control type flow rate controller. Each of the plurality of gas sources in the gas source group 40 is connected to the gas supply pipe 38 via the corresponding on-off valve in the valve group 42 and the corresponding flow rate controller in the flow rate controller group 44.

[0056] 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 by-products from adhering to the chamber body 12. The shield 46 is configured, for example, by forming a corrosion-resistant film on the surface of a base material made of aluminum. The corrosion-resistant film can be formed from a ceramic such as yttrium oxide.

[0057] A baffle plate 48 is provided between the support portion 13 and the side wall of the chamber body 12. The baffle plate 48 is configured, for example, by forming a corrosion-resistant film (such as a film of yttrium oxide) on the surface of a base material made of aluminum. A plurality of through-holes are formed in the baffle plate 48. Below the baffle plate 48 and at the bottom of the chamber body 12, a gas discharge port 12e is provided. An exhaust device 50 is connected to the gas discharge port 12e via an exhaust pipe 52. The exhaust device 50 includes a vacuum pump such as a pressure regulating valve and a turbo molecular pump.

[0058] The plasma processing apparatus 1 includes 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 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 within the range of 27 MHz to 100 MHz. The first high-frequency power may be a continuous wave or a pulse wave. The first high-frequency power source 62 is connected to the lower electrode 18 via a matching unit 66 and an electrode plate 16. The matching unit 66 has a circuit for matching the output impedance of the first high-frequency power source 62 and the impedance on the load side (lower electrode 18 side). Note that the first high-frequency power source 62 may be connected to the upper electrode 30 via the matching unit 66. The first high-frequency power source 62 constitutes an example of a plasma generation unit.

[0059] The second high-frequency power supply 64 is a power supply that generates second high-frequency power. The second high-frequency power has a frequency lower than that 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 bias to draw ions into 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 may be a continuous wave or a pulse wave. The second high-frequency power supply 64 is connected to the support base 14 via a matching unit 68. In one example, the second high-frequency power supply 64 is connected to the lower electrode 18 via the matching unit 68 and the electrode plate 16. The matching unit 68 has a circuit for matching the output impedance of the second high-frequency power supply 64 and the impedance on the load side (the lower electrode 18 side). Note that the second high-frequency power supply 64 may be connected to a bias electrode provided in the electrostatic chuck 20 via the matching unit 68 and the electrode plate 16, similar to the bias power supply described later.

[0060] Note that, without using the first high-frequency power, plasma may be generated using only the second 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 plasma processing apparatus 1 may not include the first high-frequency power supply 62 and the matching unit 66. The second high-frequency power supply 64 constitutes an example of a plasma generation unit.

[0061] Further, in the present disclosure, the plasma processing apparatus 1 may be configured to apply a DC voltage to the upper electrode 30 during plasma processing. For example, the plasma processing apparatus 1 may apply a pulsed negative-polarity DC voltage to the upper electrode 30.

[0062] In the plasma processing apparatus 1, gas is supplied from the gas supply unit to the internal space 10s to generate plasma. Further, 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 generated high-frequency electric field generates plasma.

[0063] The plasma processing apparatus 1 may further include a control unit 80. The control unit 80 can be a computer including a processor, a storage unit such as a memory, an input device, a display device, a signal input / output interface, etc. The control unit 80 controls each part of the plasma processing apparatus 1. In the control unit 80, an operator can perform an input operation of a command or the like using the input device to manage the plasma processing apparatus 1. Also, in the control unit 80, the operating status of the plasma processing apparatus 1 can be visualized and displayed by 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 execute various processes in the plasma processing apparatus 1. The processor executes the control program and controls each part of the plasma processing apparatus 1 according to the recipe data.

[0064] Referring to FIG. 1 again. Hereinafter, the method MT1 will be described by taking as an example the case where the plasma processing apparatus 1 is used in its execution. As shown in FIG. 1, the method MT1 includes a step ST11. In the step ST11, a substrate W is provided in the chamber 10 of the plasma processing apparatus. The substrate W is placed on the electrostatic chuck 20 and held by the electrostatic chuck 20.

[0065] FIG. 3 is a partially enlarged cross-sectional view of an example substrate provided in step ST11 of method MT1. The substrate W shown in FIG. 3 has an underlayer UL, a film SF, and a mask MSK. The underlayer UL can be a layer made of polycrystalline silicon. The film SF is provided on the underlayer UL. The film SF contains silicon. The film SF can be a laminated film including one or more silicon oxide films and one or more silicon nitride films. In the example shown in FIG. 3, the film SF is a multilayer film including a plurality of silicon oxide films IL1 and a plurality of silicon nitride films IL2. The plurality of silicon oxide films IL1 and the plurality of silicon nitride films IL2 are alternately laminated. Note that the film SF may be another single-layer film containing silicon or another multilayer film containing silicon. When the film SF is a single-layer film, the film SF can be, for example, a low dielectric constant film formed from SiOC, SiOF, SiCOH, etc., or a polysilicon film. Alternatively, when the film SF is a multilayer film, the film SF can be, for example, a laminated film including one or more silicon oxide films and one or more polysilicon films.

[0066] The mask MSK is provided on the film SF. The mask MSK has a pattern for forming a space such as a hole in the film SF. The mask MSK can be, for example, a hard mask. The mask MSK can be, for example, a carbon-containing mask and / or a metal-containing mask. The carbon-containing mask is formed from at least one selected from the group consisting of, for example, spin-on carbon, tungsten carbide, amorphous carbon, and boron carbide. The metal-containing mask is formed from at least one selected from the group consisting of titanium nitride, titanium oxide, and tungsten. Alternatively, the mask MSK may be, for example, a boron-containing mask formed from silicon boride, boron nitride, boron carbide, etc.

[0067] As shown in FIG. 1, method MT1 further includes step ST12. Step ST12 is executed after step ST11. In step ST12, plasma is generated from a first processing gas in chamber 10. In step ST12, the film SF is etched by chemical species from this plasma.

[0068] The first processing gas used in step ST12 contains hydrogen fluoride gas. The flow rate of the hydrogen fluoride gas is higher than the flow rates of other gases contained in the first processing gas excluding the inert gas. Specifically, the flow rate of the hydrogen fluoride gas in step ST12 may be 70% by volume or more, 80% by volume or more, 85% by volume or more, 90% by volume or more, or 95% by volume or more with respect to the total flow rate of the first processing gas excluding the inert gas. When adding a carbon-containing gas or the like from the viewpoint of suppressing the occurrence of shape abnormalities such as bowing in the film SF, the flow rate of the hydrogen fluoride gas may be less than 100% by volume, 99.5% by volume or less, 98% by volume or less, or 96% by volume or less with respect to the total flow rate of the first processing gas excluding the inert gas. In one example, the flow rate of the hydrogen fluoride gas is adjusted to be 70% by volume or more and 96% by volume or less with respect to the total flow rate of the first processing gas excluding the inert gas. By controlling the flow rate of the hydrogen fluoride gas in the first processing gas excluding the inert gas within such a range, it is possible to etch the film SF at a high etching rate while suppressing the etching of the mask MSK. As a result, the selectivity of the etching of the silicon-containing film with respect to the etching of the mask can be made 5 or more. Therefore, even in a process that requires a high aspect ratio such as a 3D-structured NAND flash memory, the film SF can be etched at an effective speed. Also, due to such a high selectivity, the addition amount of a depositing gas such as a carbon-containing gas can be suppressed, so that not only the risk of clogging of the mask MSK can be reduced, but also the cleaning time in the chamber 10 can be shortened to 50% or less as described later. As a result, it is possible to significantly improve the throughput of substrate processing. On the other hand, when the flow rate of the hydrogen fluoride gas is equal to or less than the flow rates of other gases contained in the first processing gas excluding the inert gas, the selectivity may not be sufficiently improved. The total flow rate of the first processing gas excluding the inert gas may be appropriately adjusted according to the chamber volume. In one example, it may be 100 sccm or more.

[0069] In addition to hydrogen fluoride gas, the first processing gas may contain a carbon-containing gas. Further, in addition to the hydrogen fluoride gas and the carbon-containing gas, it may contain at least one selected from the group consisting of an oxygen-containing gas and a halogen-containing gas.

[0070] When the first processing gas contains a carbon-containing gas, a deposit containing carbon is formed on the mask surface, so that the etching selectivity of the silicon-containing film with respect to the etching of the mask can be further improved. The carbon-containing gas includes, for example, at least one selected from the group consisting of fluorocarbon gas, hydrofluorocarbon gas, and hydrocarbon gas. As the fluorocarbon gas, for example, CF4, C2F2, C2F4, C3F8, C4F6, C4F8, or C5F8 can be used. As the hydrofluorocarbon gas, for example, CHF3, CH2F2, CH3F, C2HF5, C2H2F4, C2H3F3, C2H4F2, C3HF7, C3H2F2, C3H2F6, C3H2F4, C3H3F5, C4H5F5, C4H2F6, C5H2F 10 , c-C5H3F7, or C3H2F4 can be used. As the hydrocarbon gas, for example, CH4, C2H6, C3H6, C3H8, or C4H 10 can be used. The carbon-containing gas may contain CO and / or CO2 in addition to the above. In one example, as the carbon-containing gas, a fluorocarbon gas and / or a hydrofluorocarbon gas having 2 or more carbon atoms can be used. When a fluorocarbon gas and / or a hydrofluorocarbon gas having 2 or more carbon atoms is used, shape abnormalities such as boiling can be effectively suppressed. Note that by using a fluorocarbon gas and / or a hydrofluorocarbon gas having 3 or more carbon atoms, shape abnormalities can be further suppressed. As the fluorocarbon gas having 3 or more carbon atoms, for example, C4F8 can be used. The hydrofluorocarbon gas having 3 or more carbon atoms may contain an unsaturated bond and may contain 1 or more CF3 groups. As the hydrofluorocarbon gas having 3 or more carbon atoms, for example, C3H2F4 or C4H2F6 can be used.

[0071] When the first processing gas contains an oxygen-containing gas, clogging of the mask during etching can be suppressed. As the oxygen-containing gas, for example, at least one selected from the group consisting of O2, CO, CO2, H2O, or H2O2 can be used.

[0072] When the first processing gas contains a halogen-containing gas, the etching shape can be controlled. As the halogen-containing gas, for example, carbon-free fluorine-containing gases such as SF6, NF3, XeF2, SiF4, IF7, ClF5, BrF5, AsF5, NF5, PF3, PF5, POF3, BF3, HPF6, WF6, chlorine-containing gases such as Cl2, SiCl2, SiCl4, CCl4, BCl3, PCl3, PCl5, POCl3, bromine-containing gases such as HBr, CBr2F2, C2F5Br, PBr3, PBr5, POBr3, and iodine-containing gases such as HI, CF3I, C2F5I, C3F7I, IF5, IF7, I2, PI3, at least one selected from the group consisting of these can be used.

[0073] In addition to the above, the first processing gas may contain a gas having a sidewall protection effect, for example, a sulfur-containing gas such as COS, P4O 10 , P4O8, P4O6, PH3, Ca3P2, H3PO4, Na3PO4, etc., a phosphorus-containing gas, and a boron-containing gas such as B2H6. The phosphorus-containing gas having a sidewall protection effect also includes a phosphorus halide gas containing a phosphorus fluoride gas such as PF3 and PF5 and a phosphorus chloride gas such as PCl3 and PCl5 described above.

[0074] In an exemplary embodiment of the present disclosure, the first processing gas contains hydrogen fluoride and at least one carbon-containing gas selected from the group consisting of fluorocarbon gas and hydrofluorocarbon gas. The carbon-containing gas may be the fluorocarbon gas described above or the hydrofluorocarbon gas described above. The fluorocarbon gas may be C4F8. Also, the hydrofluorocarbon gas may be at least one selected from the group consisting of C3H2F4 and C4H2F6.

[0075] In an exemplary embodiment, the first processing gas may further contain at least one selected from the group consisting of an oxygen-containing gas and a halogen-containing gas. In this case, the halogen-containing gas may be at least one selected from the group consisting of a halogen-containing gas containing a halogen element other than fluorine and a fluorine-containing gas containing no carbon.

[0076] In an exemplary embodiment, as the additive gas, it may further contain at least one selected from the group consisting of a sulfur-containing gas, a phosphorus-containing gas, and a boron-containing gas having a sidewall protection effect.

[0077] In addition to these gas species, the first processing gas may contain an inert gas. As the inert gas, in addition to nitrogen gas, noble gases such as Ar, Kr, and Xe can be used. However, the first processing gas is controlled such that the flow rate of hydrogen fluoride gas with respect to the total flow rate of the first processing gas excluding these inert gases is the above-described ratio.

[0078] For the execution of step ST12, the control unit 80 controls the gas supply unit to supply the above-described processing gas into the chamber 10. For the execution of step ST12, the control unit 80 controls the gas supply unit such that the flow rate of hydrogen fluoride gas in the processing gas supplied into the chamber 10 is 70% by volume or more of the total flow rate of the processing gas. For the execution of step ST12, the control unit 80 controls the exhaust device 50 such that the pressure in the chamber 10 becomes a specified pressure. For the execution of step ST12, the control unit 80 controls the first high-frequency power supply 62 and / or the second high-frequency power supply 64 to supply the first high-frequency power and / or the second high-frequency power for generating plasma from the processing gas in the chamber 10.

[0079] In step ST12, the second high-frequency power supply 64 may supply the second high-frequency power of 5 W / cm 2 or more (i.e., the high-frequency power for bias) to the susceptor 14 to draw ions from the plasma to the substrate W. 5 W / cm 2With the above-described second high-frequency power, ions from the plasma can sufficiently reach the bottom of the space of the film SF formed by etching (for example, the space SP shown in FIG. 4).

[0080] Note that instead of the high-frequency power for bias, a pulsed voltage other than high frequency may be supplied to the support base 14. Here, the pulsed voltage is a pulsed voltage supplied from a pulse power source. The pulse power source may be configured such that the power source itself supplies a pulse wave, or may be provided with a device for pulsing the voltage on the downstream side of the pulse power source. In one example, the pulsed voltage is supplied to the support base 14 so that a negative potential is generated on the substrate W. The pulsed voltage may be a pulse of a negative-polarity DC voltage. Further, the pulsed voltage may be a pulse of a rectangular wave, may be a pulse of a triangular wave, may be an impulse, or may have a pulse of other voltage waveforms.

[0081] FIG. 5 shows an example of a timing chart regarding the substrate processing method of the exemplary embodiment. In FIG. 5, the horizontal axis indicates time. In FIG. 5, the vertical axis indicates the supply state of the first processing gas, the level of the first high-frequency power HF, and the level of the pulsed voltage. In FIG. 5, the first processing gas is periodically supplied into the chamber 10. Further, the pulses of the first high-frequency power and the pulsed voltage are periodically supplied to the support base 14. Furthermore, the period during which the pulse of the first high-frequency power HF is supplied, the period during which the pulsed voltage is supplied, and the period during which the first processing gas is supplied are synchronized. Note that the first processing gas may be continuously supplied into the chamber 10.

[0082] In FIG. 5, the "L" level of the first high-frequency power HF indicates that the first high-frequency power HF is not being supplied, or that the power level of the first high-frequency power HF is lower than the power level indicated by "H". The "L" level of the pulse voltage indicates that the pulse voltage is not applied to the support 14, or that the level of the pulse voltage is lower than the level indicated by "H". Also, "ON" of the supply state of the first processing gas indicates that the first processing gas is being supplied into the chamber 10, and "OFF" of the supply state of the first processing gas indicates that the supply of the first processing gas into the chamber 10 has been stopped. Here, the period during which the voltage level of the pulse voltage is L is defined as the "L period", and the period during which the voltage level of the pulse voltage is H is defined as the "H period".

[0083] The frequency of the pulse voltage (the first frequency) during the H period may be controlled to be from 100 kHz to 3.2 MHz. In one example, the first frequency is controlled to 400 kHz. Also, in this case, the duty ratio (the first duty ratio) indicating the ratio of the period during which the level of the pulse voltage is H within one cycle may be 50% or less, or may be 30% or less.

[0084] Also, the frequency of the pulse voltage supplied periodically, that is, the frequency (the second frequency) defining the period of the H period, may be from 1 kHz to 200 kHz or from 5 Hz to 100 kHz. Also, in this case, the duty ratio (the second duty ratio) indicating the ratio of the H period within one cycle may be from 50% to 90%.

[0085] Note that in the exemplary embodiment, the case where the period during which the pulse of the first high-frequency power HF is supplied, the period during which the pulse voltage is supplied, and the period during which the first processing gas is supplied are synchronized has been described, but these do not have to be synchronized.

[0086] The temperature of the electrostatic chuck 20 in the process ST12 is not particularly limited. However, before the start of the process ST12, by adjusting the temperature of the electrostatic chuck 20 to a low temperature, for example, 0°C or lower or -50°C or lower, the adsorption of the etchant on the substrate surface is promoted, so that the etching rate can be improved. When the first processing gas contains a phosphorus-containing gas, the temperature of the electrostatic chuck 20 may be 50°C or lower, 30°C or lower, or 20°C or lower according to the ratio of the phosphorus-containing gas in the first processing gas.

[0087] When the execution of the process ST12 is completed, the method MT1 ends. FIG. 4 is a partially enlarged cross-sectional view of an example substrate after executing the substrate processing method shown in FIG. 1. By executing the method MT1, as shown in FIG. 4, a space SP reaching, for example, the underlayer UL is formed in the film SF.

[0088] (Experiment 1) The results of Experiment 1 conducted for the evaluation of the method MT1 will be described below. In Experiment 1, eight sample substrates identical to the substrate W shown in FIG. 3 were prepared. In Experiment 1, the plasma etching of the film SF of the eight sample substrates was performed using the plasma processing apparatus 1. In the plasma etching, a first processing gas containing a fluorocarbon gas, a hydrofluorocarbon gas, a fluorine-containing gas not containing carbon, and a halogen-containing gas was used. The first processing gas used for the plasma etching of the first sample substrate among the eight sample substrates did not contain hydrogen fluoride gas. In the first processing gas used for the plasma etching of the second to eighth sample substrates among the eight sample substrates, the flow rate of the hydrogen fluoride gas with respect to the total flow rate of the first processing gas was 34.2% by volume, 51.0% by volume, 80.0% by volume, 95.2% by volume, 98.8% by volume, 99.5% by volume, and 100% by volume, respectively. In Experiment 1, before the start of the plasma etching, the temperature of the electrostatic chuck 20 on which the sample substrate was placed was adjusted to a temperature of -50°C or lower.

[0089] In Experiment 1, the etching selectivity of film SF with respect to the etching of mask MSK was determined from the results of plasma etching of film SF on eight sample substrates. Specifically, the etching selectivity was determined by dividing the etching rate of film SF by the etching rate of mask MSK based on the results of plasma etching of film SF on eight sample substrates.

[0090] FIG. 6 is a graph showing the results of Experiment 1 conducted for the evaluation of the substrate processing method shown in FIG. 1. In the graph of FIG. 6, the horizontal axis represents the flow rate ratio. The flow rate ratio is the ratio (volume %) of the flow rate of hydrogen fluoride gas to the total flow rate of the first processing gas excluding the inert gas. In the graph of FIG. 6, the vertical axis represents the selectivity. In FIG. 6, reference numerals P1 to P8 indicate the selectivities determined from the results of plasma etching of film SF on the first to eighth sample substrates.

[0091] As shown in FIG. 6, from the results of Experiment 1, it was confirmed that the selectivity increases with an increase in the ratio of the flow rate of hydrogen fluoride gas to the total flow rate of the first processing gas excluding the inert gas (hereinafter referred to as the "flow rate ratio"). In particular, in the region where the flow rate ratio is 80% by volume or more, it was confirmed that the increase rate of the selectivity is larger (the slope of the graph in FIG. 6 is larger) compared to the region where the flow rate ratio is less than 80% by volume. The reason is considered as follows. In the region where the flow rate ratio is less than 80% by volume, as the flow rate ratio increases, the etching rate of the silicon-containing film increases, thereby increasing the selectivity. However, in this region, since a certain amount of the mask is also etched, the increase in the selectivity is relatively slow. On the other hand, in the region where the flow rate ratio is 80% by volume or more, the etching rate of the silicon-containing film tends to saturate, but the etching rate of the mask decreases, thereby increasing the selectivity. That is, in the region where the flow rate ratio is 80% by volume or more, while the silicon-containing film is etched while maintaining a high etching rate, the mask is hardly etched, so the increase rate of the selectivity becomes large.

[0092] Also, as can be seen from FIG. 6, when the flow rate of hydrogen fluoride gas occupies 70% by volume or more in the total flow rate of the first processing gas excluding the inert gas, a selectivity of 5 or more can be obtained. In particular, when the flow rate of hydrogen fluoride gas occupies 90% by volume or more in the total flow rate of the first processing gas excluding the inert gas, a selectivity of 7 or more can be obtained, and when it occupies 95% by volume or more, a selectivity of 7.5 or more can be obtained.

[0093] (Experiment 2) In Experiment 2, three sample substrates identical to the substrate W shown in FIG. 3 were prepared. In Experiment 2, the plasma etching of the film SF of the three sample substrates was performed using the plasma processing apparatus 1. In the plasma etching, a first processing gas containing hydrogen fluoride gas and a carbon-containing gas was used. For the ninth sample substrate, a first processing gas containing hydrogen fluoride gas and a fluorocarbon gas was used. For the tenth sample substrate, a first processing gas containing hydrogen fluoride gas and a hydrofluorocarbon gas having 1 carbon atom was used. For the eleventh sample substrate, a first processing gas containing hydrogen fluoride gas and a hydrofluorocarbon gas having 4 carbon atoms was used. In Experiment 2, before the start of plasma etching, the temperature of the electrostatic chuck 20 on which the sample substrate was placed was adjusted to a temperature of -50°C or lower.

[0094] In Experiment 2, from the results of the plasma etching of the film SF of the three sample substrates, the selectivity of the etching of the film SF with respect to the etching of the mask MSK was determined. Specifically, the selectivity was determined by dividing the etching rate of the film SF by the etching rate of the mask MSK from the results of the plasma etching of the film SF of the three sample substrates.

[0095] FIG. 7 is a graph showing the results of Experiment 2. In the graph of FIG. 7, the horizontal axis represents the sample substrate. In the graph of FIG. 7, the vertical axis represents the selectivity. In FIG. 7, reference numerals Sub.9 to 11 indicate the selectivities obtained from the results of the plasma etching of the film SF of the ninth to eleventh sample substrates.

[0096] As shown in Fig. 7, as a result of Experiment 2, it was confirmed that the selection ratio was 6 or more for all sample substrates. In particular, in the 11th sample substrate using a hydrofluorocarbon gas having 4 carbon atoms, the selection ratio was about 14, and it was confirmed that the selection ratio was the highest among the three sample substrates.

[0097] (Experiment 3 and Experiment 4) In Experiment 3, using the plasma processing apparatus 1, plasma was generated from a processing gas which is a mixed gas of hydrogen fluoride gas and argon gas to etch the silicon oxide film. In Experiment 4, using the plasma processing apparatus 1, plasma was generated from a processing gas which is a mixed gas of hydrogen fluoride gas, argon gas, and PF3 gas to etch the silicon oxide film. In Experiment 3 and Experiment 4, while changing the temperature of the electrostatic chuck 20, the silicon oxide film was etched. In Experiment 3 and Experiment 4, a quadrupole mass spectrometer was used to measure the amount of hydrogen fluoride (HF) and the amount of SiF3 in the gas phase during the etching of the silicon oxide film. The results of Experiment 3 and Experiment 4 are shown in Figs. 8(a) and 8(b). Fig. 8(a) shows the relationship between the temperature of the electrostatic chuck 20 during the etching of the silicon oxide film in Experiment 3 and the amounts of hydrogen fluoride (HF) and SiF3 respectively. Further, Fig. 8(b) shows the relationship between the temperature of the electrostatic chuck 20 during the etching of the silicon oxide film in Experiment 4 and the amounts of hydrogen fluoride (HF) and SiF3 respectively.

[0098] As shown in FIG. 8(a), in Experiment 3, when the temperature of the electrostatic chuck 20 was about -60°C or lower, the amount of hydrogen fluoride (HF), which is an etchant, decreased, and the amount of SiF3, which is a reaction product generated by etching the silicon oxide film, increased. That is, in Experiment 3, when the temperature of the electrostatic chuck 20 was about -60°C or lower, the amount of the etchant used in the etching of the silicon oxide film increased. On the other hand, as shown in FIG. 8(b), in Experiment 4, when the temperature of the electrostatic chuck 20 was 20°C or lower, the amount of hydrogen fluoride (HF) decreased, and the amount of SiF3 increased. That is, in Experiment 4, when the temperature of the electrostatic chuck 20 was 20°C or lower, the amount of the etchant used in the etching of the silicon oxide film increased. The processing gas used in Experiment 4 was different from that used in Experiment 3 in that it contained PF3 gas. In Experiment 4, when etching the silicon oxide film, a state in which phosphorus chemical species were present on the surface of the silicon oxide film was formed. From this, it can be understood that when phosphorus chemical species are present on the surface of the silicon oxide film, even at a relatively high temperature of 20°C or lower of the electrostatic chuck 20, the adsorption of the etchant to the silicon oxide film was promoted. From this, it was confirmed that when phosphorus chemical species are present on the surface of the substrate, the supply of the etchant to the bottom of the opening (recess) is promoted, and the etching rate of the silicon-containing film is increased.

[0099] [Second Embodiment] In the substrate processing method according to the first embodiment, as the number of processing times increases, the amount of reaction products adhering to the inner wall of the chamber 10, the support base 14, etc. increases. When the amount of reaction products adhering increases, the processing environment changes, so the uniformity of processing between substrates W may deteriorate. In addition, the increase in the amount of reaction products adhering is a cause of particle generation. Therefore, the inside of the chamber is cleaned with plasma in which a cleaning gas is made into plasma.

[0100] FIG. 9 is a flowchart showing an example of a substrate processing method according to the second embodiment. The method MT2 shown in FIG. 9 is executed to etch a silicon-containing film, similar to the method MT1. Since steps ST21 and ST22 are the same as steps ST11 and ST12 of the method MT1 described above, the description here is omitted.

[0101] As shown in FIG. 9, the method MT2 further includes a step ST23. Step ST23 is executed after step ST22. In step ST23, plasma is generated from a second processing gas (cleaning gas) in chamber 10. In step ST23, the inside of chamber 10 is cleaned by chemical species from this plasma. The processing time of step 23 is usually determined by monitoring the light emission state of the plasma. According to the second embodiment, compared with the prior art, the cleaning time can be shortened to 50% or less, and the throughput of substrate processing can be improved.

[0102] The second processing gas used in step ST23 may include at least one selected from the group consisting of, for example, a fluorine-containing gas, an oxygen-containing gas, a hydrogen-containing gas, and a nitrogen-containing gas. As the fluorine-containing gas, for example, CF4, SF6, or NF3 can be used. As the oxygen-containing gas, for example, O2, CO, CO2, H2O, or H2O2 can be used. As the hydrogen-containing gas, for example, H2 or HCl can be used. As the nitrogen-containing gas, for example, N2 can be used. In addition to the above, the second processing gas may include a noble gas such as Ar.

[0103] Step ST23 may be executed each time one substrate W is processed, or may be executed after processing a predetermined number or a predetermined lot number of substrates W. Alternatively, it may be executed after substrate processing for a predetermined time.

[0104] [Third Embodiment] In both the first embodiment and the second embodiment, hydrogen fluoride gas is included in the first processing gas. Since hydrogen fluoride gas is a highly corrosive gas, it is preferable to form a precoat on the inner wall of chamber 10 before the etching process. In particular, when hydrogen fluoride gas is used at a high concentration, forming a precoat on the inner wall of chamber 10 and suppressing the corrosion of the inner wall of chamber 10 can reduce the maintenance frequency. Here, the inner wall of chamber 10 includes the side wall and ceiling (top plate 34 of upper electrode 30) of chamber 10, as well as support base 14 and the like.

[0105] The precoat film may be formed of a silicon-containing film such as a silicon oxide film, or a material of the same type as the material of mask MSK. When mask MSK is a carbon-containing mask, the precoat may be formed of a carbon-containing material. The carbon-containing material includes, for example, at least one selected from the group consisting of spin-on carbon, tungsten carbide, amorphous carbon, and boron carbide. When mask MSK is a boron-containing mask, the precoat may be formed of a boron-containing material. The boron-containing material includes, for example, at least one selected from the group consisting of boron-containing silicon hydride, boron nitride, and boron carbide.

[0106] FIG. 10 is a flowchart showing an example of a substrate processing method according to the third embodiment. The method MT3 shown in FIG. 10 is executed to etch a silicon-containing film, similarly to method MT1. Since steps ST31 and ST32 are the same as steps ST11 and ST12 of method MT1 described above, the description here is omitted.

[0107] As shown in FIG. 10, method MT2 further includes step ST30. Step ST30 is executed before step ST31. In step ST30, plasma is generated from a third processing gas (precoat gas) in chamber 10. In step ST30, a precoat is formed on the inner wall of chamber 10 by chemical species from this plasma.

[0108] The precoat can be formed by Chemical Vapor Deposition (CVD) or Atomic Layer Deposition (ALD) using a third processing gas. For example, when forming a silicon oxide film as the precoat, a silicon-containing gas such as SiCl4 or an aminosilane-based gas, and an oxygen-containing gas such as O2 can be used as the third processing gas. Also, when forming a carbon film as the precoat, a carbon-containing gas such as CH4 or C2H2 can be used as the third processing gas.

[0109] Step ST33 may be executed every time one substrate W is processed, or may be executed after processing a predetermined number of substrates W or a predetermined lot number of substrates W. Alternatively, it may be executed after substrate processing for a predetermined time.

[0110] Note that the step of forming the precoat may be executed in combination with the cleaning step as shown in another example of the substrate processing method according to the third embodiment of FIG. 11. Thereby, the generation of particles and the corrosion of the inner wall of the chamber 10 can be suppressed simultaneously.

[0111] As described above, various exemplary embodiments have been described, but the present invention is not limited to the above-described exemplary embodiments, and various omissions, substitutions, and changes may be made. Also, it is possible to form other exemplary embodiments by combining elements in different exemplary embodiments.

[0112] For example, the plasma processing apparatus used in methods MT1 to 4 may be a plasma processing apparatus different from the plasma processing apparatus 1. The plasma processing apparatus used in methods MT1 to 4 may be another capacitively coupled plasma processing apparatus, an inductively coupled plasma processing apparatus, or a plasma processing apparatus that generates plasma using a surface wave such as a microwave.

[0113] Also, as described above, hydrogen fluoride gas is a highly corrosive gas. Therefore, depending on the processing stage, the flow rate ratio of hydrogen fluoride gas and the type of gas added to the first processing gas may be changed. In one example, at the end stage of etching where it is not necessary to maintain the mask thickness, the flow rate ratio of hydrogen fluoride gas may be made lower than that in the initial to middle stages of etching where it is necessary to maintain the mask thickness. In another example, in the etching of a low aspect ratio region where shape abnormalities such as bowing are likely to occur, the flow rate ratio of the gas having a sidewall protection effect may be increased compared to the etching of a high aspect ratio region. Further, the shape after etching may be monitored with an optical observation device or the like, and depending on the shape, the flow rate ratio of hydrogen fluoride gas, the type or flow rate ratio of the gas added to the first processing gas may be changed.

[0114] The disclosed embodiments further include the following aspects.

[0115] (Appendix 1) A step of providing a silicon-containing film including a silicon oxide film and a substrate having a mask on the silicon-containing film in a chamber, A step of controlling the temperature of a substrate support on which the substrate is placed to 0°C or lower, A step of etching the silicon-containing film by plasma generated from a first processing gas including hydrogen fluoride gas and at least one carbon-containing gas selected from the group consisting of C4F8 gas, C3H2F4 gas, and C4H2F6 gas in the chamber, including, Among the first processing gases excluding the inert gas, the flow rate of the hydrogen fluoride gas is the highest, A substrate processing method.

[0116] (Appendix 2) The substrate processing method according to (Appendix 1), wherein the first processing gas further includes at least one additive gas selected from the group consisting of an oxygen-containing gas, a halogen-containing gas, and a phosphorus-containing gas.

[0117] (Appendix 3) An etching gas composition containing hydrogen fluoride gas and at least one carbon-containing gas selected from the group consisting of fluorocarbon gas and hydrofluorocarbon gas, wherein the flow rate of the hydrogen fluoride gas relative to the total flow rate excluding the inert gas is 70% by volume or more.

[0118] (Appendix 4) The fluorocarbon gas is at least one selected from the group consisting of CF4, C2F2, C2F4, C3F8, C4F6, C4F8, and C5F8, and the etching gas composition according to (Appendix 3).

[0119] (Appendix 5) The fluorocarbon gas is C4F8 gas, and the etching gas composition according to (Appendix 3).

[0120] (Appendix 6) The hydrofluorocarbon gas is at least one selected from the group consisting of CHF3, CH2F2, CH3F, C2HF5, C2H2F4, C2H3F3, C2H4F2, C3HF7, C3H2F2, C3H2F6, C3H2F4, C3H3F5, C4H5F5, C4H2F6, C5H2F 10 , c-C5H3F7, and C3H2F4, and the etching gas composition according to (Appendix 3).

[0121] (Appendix 7) The hydrofluorocarbon gas is at least one selected from the group consisting of C3H2F4 gas and C4H2F6 gas, and the etching gas composition according to (Appendix 3).

[0122] (Appendix 8) The etching gas composition according to any one of (Appendix 3) to (Appendix 7), further comprising at least one selected from the group consisting of an oxygen-containing gas and a halogen-containing gas.

[0123] (Appendix 9) The etching gas composition according to any one of (Appendix 3) to (Appendix 8), further comprising at least one selected from the group consisting of a phosphorus-containing gas, a sulfur-containing gas, and a boron-containing gas.

[0124] (Appendix 10) The etching gas composition according to any one of (Appendix 3) to (Appendix 9), wherein the flow rate of the hydrogen fluoride gas with respect to the total flow rate excluding the inert gas is 96% by volume or less.

[0125] (Appendix 11) Hydrogen fluoride gas for use in the etching gas composition according to any one of (Appendix 3) to (Appendix 10).

[0126] From the above description, it will be understood that the various exemplary embodiments of the present disclosure are described herein for purposes of illustration and that various changes can be made without departing from the scope and spirit of the present disclosure. Accordingly, the various exemplary embodiments disclosed herein are not intended to be limiting, and the true scope and spirit are indicated by the appended claims.

Description of Reference Numerals

[0127] 1... Plasma processing apparatus, 10... Chamber, W... Substrate, SF... Film, MSK... Mask.

Claims

1. A chamber, a substrate support supporting a substrate including a silicon-containing film and a mask on the silicon-containing film in the chamber; a gas supply unit that supplies a first process gas containing hydrogen fluoride gas and a halogen-containing gas into the chamber; a plasma generating unit that generates plasma from the first processing gas; A control unit; Including, The control unit controlling the gas supply unit to supply the first process gas into the chamber; generating plasma from the first process gas and controlling the plasma generating unit to etch the silicon-containing film; Plasma processing equipment.

2. The control unit controls the gas supply unit so that the flow rate of the hydrogen fluoride gas is the highest among the first process gases excluding an inert gas. The plasma processing apparatus according to claim 1 .

3. A plasma processing apparatus as described in claim 1, wherein the control unit controls the gas supply unit so that the flow rate of the hydrogen fluoride gas relative to the total flow rate of the first processing gas excluding the inert gas is 70 volume % or more.

4. A plasma processing apparatus as described in claim 1, wherein the control unit controls the gas supply unit so that the flow rate of the hydrogen fluoride gas relative to the total flow rate of the first processing gas excluding the inert gas is 70 volume % or more and 96 volume % or less.

5. A plasma processing apparatus according to claim 1, wherein the first processing gas further contains a carbon-containing gas.

6. The plasma processing apparatus described in claim 5, wherein the carbon-containing gas includes at least one gas selected from the group consisting of a fluorocarbon gas, a hydrofluorocarbon gas, and a hydrocarbon gas.

7. A plasma processing apparatus described in any one of claims 1 to 6, wherein the halogen-containing gas includes at least one selected from the group consisting of a carbon-free fluorine-containing gas, a chlorine-containing gas, a bromine-containing gas, and an iodine-containing gas.

8. The halogen-containing gas includes SF 6 , NF 3 , XeF 2 , SiF 4 , IF 7 , ClF 5 , BrF 5 , AsF 5 , NF 5 , PF 3 , PF 5 , POF 3 , BF 3 , HPF 6 , WF 6 , Cl 2 , SiCl2, SiCl4, CCl4, BCl3, PCl3, PCl5, POCl3, HBr, CBr2F2, C2F5Br, PBr3, PBr5, POBr3, HI, CF3I, C2F 5 I, C 3 F 7 I, IF 5 , I 2 , and PI 7. The plasma processing apparatus according to claim 1, further comprising at least one selected from the group consisting of:

9. A plasma processing apparatus according to claim 1, wherein the halogen-containing gas contains two different types of halogen.

10. The plasma processing apparatus of claim 9, wherein the halogen-containing gas includes at least two selected from the group consisting of fluorine, bromine, and iodine.

11. The plasma processing apparatus of claim 10, wherein the halogen-containing gas further contains carbon.

12. A plasma processing apparatus according to claim 1, wherein the halogen-containing gas contains fluorine and chlorine.

13. The plasma processing apparatus according to claim 1, wherein the halogen-containing gas includes IF 5 or IF 7 .

14. A plasma processing apparatus described in any one of claims 1 to 13, wherein the first processing gas further contains at least one gas selected from the group consisting of a phosphorus-containing gas, a sulfur-containing gas, and a boron-containing gas.

15. A plasma processing apparatus according to claim 1, wherein the mask is a carbon-containing mask, a boron-containing mask, or a metal-containing mask.

16. A plasma processing apparatus according to claim 1, wherein the silicon-containing film is a laminated film including one or more silicon oxide films and one or more silicon nitride films.

17. A plasma processing apparatus described in any one of claims 1 to 15, wherein the silicon-containing film is a laminated film including one or more silicon oxide films and one or more polysilicon films.

18. A method of manufacturing a semiconductor device, comprising: providing a substrate having a silicon-containing film in a chamber and a mask on the silicon-containing film; supplying a first process gas including hydrogen fluoride gas and a halogen-containing gas; generating a plasma from the first process gas to etch the silicon-containing film; An etching method comprising:

19. A method for manufacturing a NAND flash memory having a three-dimensional structure, comprising the etching method described in claim 18.

20. An etching gas composition for etching a silicon-containing film, comprising hydrogen fluoride gas and a halogen-containing gas.

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