Plasma processing apparatus and substrate processing method

Abstract

To provide a technique to improve the selection ratio of etching of a film containing silicon to etching of a mask in plasma etching.SOLUTION: A substrate processing method according to an illustrative embodiment includes a step of providing a substrate into 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 controlling the temperature of a substrate support on which the substrate is mounted to 0°C or less. The substrate processing method further includes a step of etching the silicon-containing film by plasma generated from a first processing gas including a hydrofluoric gas and at least one carbon-containing gas selected from the group consisting of a fluorocarbon gas and a hydrofluorocarbon gas. In the step of etching, the film is etched by a chemical species from the plasma. In the first processing gas from which an inert gas is removed, the hydrofluoric gas has the largest flow rate.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Patent Document 1 discloses a method for etching a film in a substrate. The film contains silicon, and the substrate further includes a mask disposed on the film. The mask includes amorphous carbon or an organic polymer. The etching in this method uses a plasma generated from a process gas including a hydrocarbon gas and a fluorohydrocarbon gas. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-39310 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides techniques for improving the selectivity of etching a silicon-containing film relative to etching a mask in plasma etching. [Means for solving the problem]

[0005] In one exemplary embodiment, a substrate processing method is provided. The substrate processing method includes 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 controlling a temperature of a substrate support on which the substrate is placed to 0° C. or less. The substrate processing method further includes 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 a fluorocarbon gas and a hydrofluorocarbon gas. In the etching step, the silicon-containing film is etched by chemical species from the plasma. The hydrogen fluoride gas has the largest flow rate among the first processing gases excluding an inert gas. Effect of the Invention

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

[0007] [Figure 1] 4 is a flowchart showing an example of a substrate processing method according to the first embodiment. [Diagram 2] FIG. 1 is a diagram illustrating an example of a plasma processing apparatus. [Diagram 3] 1 is a partially enlarged cross-sectional view of an example of a substrate provided in step ST11. FIG. [Figure 4] 2 is a partially enlarged cross-sectional view of the example substrate after the substrate processing method shown in FIG. 1 is performed. [Diagram 5] 10 is a timing chart relating to an example substrate processing method. [Figure 6] 2 is a graph showing the results of experiment 1 conducted to evaluate the substrate processing method shown in FIG. [Figure 7] 2 is a graph showing the results of experiment 2 conducted to evaluate the substrate processing method shown in FIG. [Figure 8]FIG. 8(a) is a graph showing the results of Experiment 3, and FIG. 8(b) is a graph showing the results of Experiment 4. [Figure 9] 10 is a flowchart showing an example of a substrate processing method according to a second embodiment. [Figure 10] 13 is a flowchart showing an example of a substrate processing method according to a third embodiment. [Figure 11] 13 is a flowchart showing another example of the substrate processing method according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Various exemplary embodiments are described below.

[0009] In one exemplary embodiment, a substrate processing method is provided. The substrate processing method includes 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 controlling a temperature of a substrate support on which the substrate is placed to 0° C. or less. The substrate processing method further includes 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 a fluorocarbon gas and a hydrofluorocarbon gas. In the etching step, the silicon-containing film is etched by chemical species from the plasma. Among the first processing gases excluding the inert gas, the flow rate of hydrogen fluoride gas is the highest. According to this embodiment, the selectivity of etching the silicon-containing film relative to etching the mask is improved by using plasma generated from a first processing gas having a flow rate of hydrogen fluoride gas the highest among all flow rates excluding the inert gas.

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

[0011] In one exemplary embodiment, the fluorocarbon gas is CF4 , C 2 F 2 , C 2 F 4 , C 3 F 8 , C 4 F 6 , C 4 F 8 and C 5 F 8 It may be at least one selected from the group consisting of:

[0012] In one exemplary embodiment, the fluorocarbon gas is 4 F 8 It may be a gas.

[0013] In one exemplary embodiment, the hydrofluorocarbon gas is CHF 3 , C.H. 2 F 2 , C.H. 3 F, C 2 HF 5 , C 2 H 2 F 4 , C 2 H 3 F 3 , C 2 H 4 F 2 , C 3 HF 7 , C 3 H 2 F 2 , C 3 H 2 F 6 , C 3 H 2 F 4 , C 3 H 3 F 5 , C 4 H 5 F 5 , C 4 H 2 F 6 , C 5 H 2 F 10 , cC 5 H 3 F 7 and C 3 H2 F 4 It may be at least one selected from the group consisting of:

[0014] In one exemplary embodiment, the hydrofluorocarbon gas is 3 H 2 F 4 Gas and C 4 H 2 F 6 The gas may be at least one selected from the group consisting of gases.

[0015] In one exemplary embodiment, the first process 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 process 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 the hydrogen fluoride gas relative to the total flow rate of the first process gas excluding the inert gas may be 96 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 stacked film including a silicon oxide film and a silicon nitride film, and a stacked 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 from 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 method for processing the substrate further includes generating a plasma from the second process gas in the chamber, wherein the plasma is generated to clean the interior of the chamber with chemical species from the plasma.

[0022] In one exemplary embodiment, the second process 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 method for processing a substrate further includes generating a plasma from a third process gas in the chamber prior to providing the substrate, wherein the plasma is generated from the third process gas to form a pre-coat on an inner wall of the chamber.

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

[0025] In another exemplary embodiment, a method for processing a substrate is provided. The method for processing a substrate includes 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 disposed on the silicon-containing film. The method for processing the substrate includes providing a hydrogen fluoride gas and a C 4 F 8 Gas, C. 3 H 2 F 4 Gas and C 4 H 2 F 6The method further includes a step of etching the silicon-containing film with plasma generated from a first process gas containing at least one carbon-containing gas selected from the group consisting of carbon-containing gases. In the etching step, the silicon-containing film is etched by chemical species from the plasma. The flow rate of hydrogen fluoride gas is 70% by volume or more and 96% by volume or less with respect to the total flow rate of the first process gas excluding the inert gas. According to this embodiment, the selectivity of the etching of the silicon-containing film to the etching of the mask is improved by using plasma generated from the first process gas in which the flow rate of 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.

[0026] In one exemplary embodiment, the first process 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 process gas may further include a phosphorus-containing gas.

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

[0029] In one exemplary embodiment, the first process 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 is CF 4 , C 2 F 2 , C 2 F 4 , C 3 F 8 , C 4 F 6 , C 4 F 8 and C 5 F 8 It may be at least one selected from the group consisting of:

[0032] In one exemplary embodiment, the fluorocarbon gas is 4 F 8 It may be a gas.

[0033] In one exemplary embodiment, the hydrofluorocarbon gas is CHF 3 , C.H. 2 F 2 , C.H. 3 F, C 2 HF 5 , C 2 H 2 F 4 , C 2 H 3 F 3 , C 2 H 4 F 2 , C 3 HF 7 , C 3 H 2 F 2 , C 3 H 2 F6 , C 3 H 2 F 4 , C 3 H 3 F 5 , C 4 H 5 F 5 , C 4 H 2 F 6 , C 5 H 2 F 10 , cC 5 H 3 F 7 and C 3 H 2 F 4 It may be at least one selected from the group consisting of:

[0034] In one exemplary embodiment, the hydrofluorocarbon gas is 3 H 2 F 4 Gas and C 4 H 2 F 6 The gas may be at least one selected from the group consisting of gases.

[0035] In one exemplary embodiment, the hydrocarbon gas is CH 4 , C 2 H 6 , C 3 H 6 , C 3 H 8 and C 4 H 10 It 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 a carbon number of 3 or more.

[0037] In one exemplary embodiment, the silicon-containing film may be at least one selected from the group consisting of a laminate film including a silicon oxide film and a silicon nitride film, a polysilicon film, a low dielectric constant film, and a laminate 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, the method may further include adjusting the temperature of a substrate support on which the substrate is placed to 0° C. or less prior to the etching step.

[0040] In another exemplary embodiment, a substrate processing method is provided. The substrate processing method includes 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 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 controlling a temperature of a substrate support on which the substrate is placed to 0° C. or less. The substrate processing method includes 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 a fluorocarbon gas and a 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 relative 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 generating plasma from a cleaning gas in the chamber to clean the inside of the chamber. According to this embodiment, by using plasma generated from a first process gas in which the flow rate of hydrogen fluoride gas is 70 volume % or more relative to the total flow rate excluding the inert gas, the selectivity of etching the silicon-containing film relative to etching the mask is improved.

[0041] In another exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a plasma generating unit, and a control unit. The chamber has a gas supply port and a gas exhaust port. The control unit is configured to execute a process including a step of placing a substrate in the chamber, a step of controlling a temperature of a substrate support, and a step of etching. In the step of placing 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 placed 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 less. In the step of etching, the silicon-containing film is etched in the chamber by plasma generated from a first process gas including hydrogen fluoride gas and at least one carbon-containing gas selected from the group consisting of a fluorocarbon gas and a hydrofluorocarbon gas. In the step of etching, the control unit controls the flow rate of hydrogen fluoride gas to be the largest among the first process gases excluding the inert gas.

[0042] Various exemplary embodiments will now be described in detail with reference to the drawings, in which the same or corresponding parts are designated 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 performed to etch a film containing silicon. The method MT1 can be used, for example, in manufacturing a NAND flash memory having a three-dimensional structure. The method MT1 is performed using a plasma processing apparatus. FIG. 2 is a diagram showing a schematic diagram of an example of a plasma processing apparatus. The method MT1 shown in FIG. 1 can be performed 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 made 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 a sidewall of the chamber body 12. The substrate W is transferred 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 sidewall of the chamber body 12.

[0046] A support 13 is provided on the bottom of the chamber body 12. The support 13 is made of an insulating material. The support 13 has a generally cylindrical shape. The support 13 extends upward from the bottom of the chamber body 12 within the internal space 10s. The support 13 has a support base 14 on its upper portion. The support base 14 is configured to support the substrate W within the internal space 10s.

[0047] The support table 14 has a lower electrode 18 and an electrostatic chuck 20. The support table 14 may further have an electrode plate 16. The electrode plate 16 is made of a conductor such as aluminum and has a substantially disk shape. The lower electrode 18 is provided on the electrode plate 16. The lower electrode 18 is made of a conductor such as aluminum and has a substantially disk shape. The lower electrode 18 is electrically connected to the electrode plate 16. The support table 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 from a dielectric material. The chuck electrode of the electrostatic chuck 20 is a film-like electrode and is provided in 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 attractive force is generated between the electrostatic chuck 20 and the substrate W. The electrostatic attractive force causes the substrate W to be held by the electrostatic chuck 20. In addition to the above-mentioned chuck electrode, the electrostatic chuck 20 may have a bias electrode for attracting ions to the substrate W in 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 portion 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 processing on the substrate W. The edge ring 25 may 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 (e.g., 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 to between the upper surface of the electrostatic chuck 20 and the rear 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 table 14. The upper electrode 30 is supported on the upper part of the chamber body 12 via a member 32. The member 32 is made 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 bottom surface of the top plate 34 is the bottom 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 made 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 are connected to 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 configure a gas supply unit. The gas source group 40 includes a plurality of gas sources. The valve group 42 includes a plurality of opening and closing 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-controlled 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 a corresponding opening and closing valve in the valve group 42 and a 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 part 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 made of, for example, aluminum. The corrosion-resistant film may be made of a ceramic such as yttrium oxide.

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

[0058] The plasma processing apparatus 1 includes a first high-frequency power supply 62 and a second high-frequency power supply 64. The first high-frequency power supply 62 is a power supply that generates a first high-frequency power. The first high-frequency power has a frequency suitable for generating plasma. The frequency of the first high-frequency power is, for example, within a 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 supply 62 is connected to the lower electrode 18 via a matching device 66 and the electrode plate 16. The matching device 66 has a circuit for matching the output impedance of the first high-frequency power supply 62 with the impedance on the load side (the lower electrode 18 side). The first high-frequency power supply 62 may be connected to the upper electrode 30 via the matching device 66. The first high-frequency power supply 62 constitutes an example of a plasma generating unit.

[0059] The second high frequency power supply 64 is a power supply that generates a 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 a bias high frequency power for attracting ions to the substrate W. The frequency of the second high frequency power is, for example, within a 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 table 14 via a matching device 68. In one example, the second high frequency power supply 64 is connected to the lower electrode 18 via the matching device 68 and the electrode plate 16. The matching device 68 has a circuit for matching the output impedance of the second high frequency power supply 64 with the impedance on the load side (the lower electrode 18 side). The second high frequency power supply 64 may be connected to a bias electrode provided in the electrostatic chuck 20 via the matching device 68 and the electrode plate 16, similar to a bias power supply described later.

[0060] It is also possible to generate plasma by using the second high frequency power without using the first high frequency power, that is, by using only a single high frequency power. In this case, the frequency of the second high frequency power may be a frequency higher than 13.56 MHz, for example, 40 MHz. The plasma processing apparatus 1 does not need to include the first high frequency power supply 62 and the matching box 66. The second high frequency power supply 64 constitutes an example of a plasma generating unit.

[0061] In addition, 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 DC voltage to the upper electrode 30.

[0062] In the plasma processing apparatus 1, a gas is supplied from a gas supply unit to the internal space 10s to generate plasma. In addition, a high-frequency electric field is generated between the upper electrode 30 and the lower electrode 18 by supplying a first high-frequency power and / or a second high-frequency power. 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 may be a computer including a processor, a storage unit such as a memory, an input device, a display device, a signal input / output interface, and the like. The control unit 80 controls each part of the plasma processing apparatus 1. In the control unit 80, an operator can use the input device to input commands and the like to manage the plasma processing apparatus 1. In addition, the control unit 80 can visualize and display the operating status of the plasma processing apparatus 1 using the display device. Furthermore, the storage unit stores a control program and recipe data. 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 again to FIG. 1, the method MT1 will be described below by taking as an example a case where a plasma processing apparatus 1 is used in carrying out the method. As shown in FIG. 1, the method MT1 includes a step ST11. In the step ST11, a substrate W is provided in a chamber 10 of the plasma processing apparatus. The substrate W is placed on an electrostatic chuck 20 and held by the electrostatic chuck 20.

[0065] FIG. 3 is a partially enlarged cross-sectional view of an example of a substrate provided in step ST11 of the method MT1. The substrate W shown in FIG. 3 has an underlayer UL, a film SF, and a mask MSK. The underlayer UL may be a layer made of polycrystalline silicon. The film SF is provided on the underlayer UL. The film SF contains silicon. The film SF may 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 including silicon or another multilayer film including silicon. When the film SF is a single layer film, the film SF may be, for example, a low dielectric constant film formed of SiOC, SiOF, SiCOH, or the like, or a polysilicon film. Alternatively, when the film SF is a multilayer film, the film SF may 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 spaces such as holes in the film SF. The mask MSK may be, for example, a hard mask. The mask MSK may be, for example, a carbon-containing mask and / or a metal-containing mask. The carbon-containing mask is, for example, made of at least one selected from the group consisting of spin-on carbon, tungsten carbide, amorphous carbon, and boron carbide. The metal-containing mask is, for example, made of 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 made of silicon boride, boron nitride, boron carbide, or the like.

[0067] 1, the method MT1 further includes a step ST12. The step ST12 is performed after the step ST11. In the step ST12, a plasma is generated from the first process gas in the chamber 10. In the step ST12, the film SF is etched by chemical species from the plasma.

[0068] The first process 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 process gas except the inert gas. Specifically, the flow rate of the hydrogen fluoride gas in step ST12 may be 70 vol.% or more, 80 vol.% or more, 85 vol.% or more, 90 vol.% or more, or 95 vol.% or more with respect to the total flow rate of the first process gas except the inert gas. In addition, in order to prevent the film SF from having shape abnormalities such as bowing, when a carbon-containing gas or the like is added, the flow rate of the hydrogen fluoride gas may be less than 100 vol.%, 99.5 vol.% or less, 98 vol.% or less, or 96 vol.% or less with respect to the total flow rate of the first process gas except the inert gas. In one example, the flow rate of the hydrogen fluoride gas is adjusted to 70 vol.% or more and 96 vol.% or less with respect to the total flow rate of the first process gas except the inert gas. By controlling the flow rate of the hydrogen fluoride gas in the first process gas excluding the inert gas within such a range, the film SF can be etched at a high etching rate while suppressing the etching of the mask MSK. As a result, the selectivity ratio of the etching of the silicon-containing film to the etching of the mask can be set to 5 or more. Therefore, even in a process that requires a high aspect ratio, such as a NAND flash memory having a three-dimensional structure, the film SF can be etched at an effective rate. In addition, due to such a high selectivity ratio, the amount of deposition gas such as a carbon-containing gas added can be suppressed, so that not only can the risk of the mask MSK being blocked be reduced, but also the cleaning time in the chamber 10 can be reduced to 50% or less, as described below. As a result, the throughput of the substrate processing can be significantly improved. On the other hand, if the flow rate of the hydrogen fluoride gas is equal to or less than the flow rate of other gases contained in the first process gas excluding the inert gas, the selectivity ratio may not be sufficiently improved. The total flow rate of the first process gas excluding the inert gas may be appropriately adjusted according to the chamber volume, and may be 100 sccm or more, for example.

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

[0070] When the first process gas contains a carbon-containing gas, a carbon-containing deposit is formed on the mask surface, and therefore the etching selectivity of the silicon-containing film relative to the etching of the mask can be further improved. The carbon-containing gas contains at least one gas selected from the group consisting of, for example, a fluorocarbon gas, a hydrofluorocarbon gas, and a hydrocarbon gas. The fluorocarbon gas can be, for example, CF 4 , C 2 F 2 , C 2 F 4 , C 3 F 8 , C 4 F 6 , C 4 F 8 Or C 5 F 8 Examples of hydrofluorocarbon gases that can be used include CHF 3 , C.H. 2 F 2 , C.H. 3 F, C 2 HF 5 , C 2 H 2 F 4 , C 2 H 3 F 3 , C 2 H 4 F 2 , C 3 HF 7 , C 3 H 2 F 2 , C 3 H 2 F 6 , C 3 H 2 F 4 , C 3 H 3 F 5 , C 4 H 5 F5 , C 4 H 2 F 6 , C 5 H 2 F 10 , cC 5 H 3 F 7 Or C 3 H 2 F 4 Examples of the hydrocarbon gas include CH 4 , C 2 H 6 , C 3 H 6 , C 3 H 8 Or C 4 H 10 The carbon-containing gas may be CO and / or CO 2 In one example, a fluorocarbon gas and / or a hydrofluorocarbon gas having a carbon number of 2 or more can be used as the carbon-containing gas. When a fluorocarbon gas and / or a hydrofluorocarbon gas having a carbon number of 2 or more is used, shape abnormalities such as bowing can be effectively suppressed. Note that, by using a fluorocarbon gas and / or a hydrofluorocarbon gas having a carbon number of 3 or more, shape abnormalities can be further suppressed. Examples of fluorocarbon gases having a carbon number of 3 or more include C 4 F 8 Hydrofluorocarbon gases having 3 or more carbon atoms may contain unsaturated bonds, and may have one or more CF 3 The hydrofluorocarbon gas having 3 or more carbon atoms may include, for example, 3 H 2 F 4 Or C 4 H 2 F 6 can be used.

[0071] When the first process gas contains an oxygen-containing gas, blocking of the mask during etching can be suppressed. 2 , CO, CO 2 , H2 O or H 2 O 2 At least one selected from the group consisting of:

[0072] When the first process gas contains a halogen-containing gas, the etching shape can be controlled. Examples of the halogen-containing gas include SF 6 , N.F. 3 , XeF 2 , SiF 4 , IF 7 , ClF 5 ,BrF 5 , AsF 5 , N.F. 5 , P.F. 3 , P.F. 5 , POF 3 , B.F. 3 , HPF 6 , W.F. 6 Carbon-free fluorine-containing gases such as Cl 2 , SiCl 2 , SiCl 4 , CCl 4 , BCl 3 , PCl 3 , PCl 5 , POCl 3 Chlorine-containing gases such as HBr and CBr 2 F 2 , C 2 F 5 Br, PBr 3 , PBr 5 , POBr 3 Bromine-containing gases such as HI and CF 3 I C 2 F 5 I C 3 F 7 I, IF 5 , IF 7 , I 2 , P.I. 3 At least one selected from the group consisting of iodine-containing gases such as those mentioned above can be used.

[0073] In addition to the above, the first process gas may be a gas having a sidewall protection effect, such as a sulfur-containing gas such as COS, P 4 O 10 , P4 O 8 , P 4 O 6 , PH 3 , Ca 3 P 2 , H 3 PO 4 , Na 3 PO 4 Phosphorus-containing gases such as B 2 H 6 The boron-containing gas may include the above-mentioned PF. 3 , P.F. 5 Phosphorus fluoride gas, PCl 3 , PCl 5 Also included are halogenated phosphorus gases including phosphorus chloride gases such as phosphorus chloride gases.

[0074] In an exemplary embodiment of the present disclosure, the first process gas includes hydrogen fluoride and at least one carbon-containing gas selected from the group consisting of a fluorocarbon gas and a hydrofluorocarbon gas. The carbon-containing gas may be a fluorocarbon gas as described above or a hydrofluorocarbon gas as described above. The fluorocarbon gas may be a C 4 F 8 The hydrofluorocarbon gas may be C 3 H 2 F 4 and C 4 H 2 F 6 It may be at least one selected from the group consisting of:

[0075] In an exemplary embodiment, the first process gas may further include 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 not containing carbon.

[0076] In an exemplary embodiment, the additive gas may further include at least one gas 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 process gas may contain an inert gas. Examples of the inert gas include nitrogen gas and rare gases such as Ar, Kr, and Xe. However, the first process gas is controlled so that the flow rate of hydrogen fluoride gas relative to the total flow rate of the first process gas excluding these inert gases is the above-mentioned ratio.

[0078] To perform step ST12, the control unit 80 controls the gas supply unit to supply the above-mentioned process gas into the chamber 10. To perform step ST12, the control unit 80 controls the gas supply unit so that the flow rate of hydrogen fluoride gas in the process gas supplied into the chamber 10 is 70 volume % or more of the total flow rate of the process gas. To perform step ST12, the control unit 80 controls the exhaust device 50 so that the pressure in the chamber 10 becomes a designated pressure. To perform 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 a first high frequency power and / or a second high frequency power to generate plasma from the process gas in the chamber 10.

[0079] In step ST12, the second high frequency power supply 64 is set to 5 W / cm in order to attract ions from the plasma to the substrate W. 2 The second high frequency power (i.e., high frequency power for bias) may be supplied to the support table 14. 5 W / cm 2 The second high frequency power described above enables ions from the plasma to sufficiently reach the bottom of the space (eg, the space SP shown in FIG. 4) in the film SF formed by etching.

[0080] Instead of the high frequency bias power, a pulse voltage other than high frequency may be supplied to the support table 14. Here, the pulse voltage is a pulsed voltage supplied from a pulse power source. The pulse power source may be configured to supply a pulse wave by itself, or may include a device for pulsing the voltage downstream of the pulse power source. In one example, the pulse voltage is supplied to the support table 14 so that a negative potential is generated on the substrate W. The pulse voltage may be a negative polarity DC voltage pulse. The pulse voltage may also be a square wave pulse, a triangular wave pulse, an impulse, or a pulse of another voltage waveform.

[0081] FIG. 5 shows an example of a timing chart relating to 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 pulse voltage. In FIG. 5, the first processing gas is periodically supplied into the chamber 10. Also, the pulse of the first high frequency power and the pulse voltage are periodically supplied to the support table 14. Furthermore, 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. Note that the first processing gas may be continuously supplied into the chamber 10.

[0082] 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 table 14 or that the level of the pulse voltage is lower than the level indicated by "H". In addition, the "ON" supply state of the first process gas indicates that the first process gas is being supplied into the chamber 10, and the "OFF" supply state of the first process gas indicates that the supply of the first process gas into the chamber 10 is stopped. Here, the period when the voltage level of the pulse voltage is L is referred to as the "L period", and the period when the voltage level of the pulse voltage is H is referred to as the "H period".

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

[0084] The frequency of the periodically supplied pulse voltage, i.e., the frequency (second frequency) that defines the period of the H period, may be 1 kHz to 200 kHz or 5 Hz to 100 kHz. In this case, the duty ratio (second duty ratio) that indicates the proportion of the H period in one period may be 50% to 90%.

[0085] In the exemplary embodiment, the period during which the first high frequency power HF pulse is supplied, the period during which the pulse voltage is supplied, and the period during which the first processing gas is supplied are synchronized, but these do not have to be synchronized.

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

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

[0088] (Experiment 1) The results of experiment 1 performed to evaluate 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 film SF of the eight sample substrates was plasma-etched using a 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 rates of hydrogen fluoride gas relative to the total flow rate of the first processing gas were 34.2 vol%, 51.0 vol%, 80.0 vol%, 95.2 vol%, 98.8 vol%, 99.5 vol%, and 100 vol%, respectively. In experiment 1, the temperature of the electrostatic chuck 20 on which the sample substrate was placed was adjusted to a temperature of −50° C. or lower before the start of plasma etching.

[0089] In experiment 1, the selectivity ratio of the etching of the film SF to the etching of the mask MSK was obtained from the results of plasma etching of the film SF of the eight sample substrates. Specifically, the selectivity ratio was obtained by dividing the etching rate of the film SF by the etching rate of the mask MSK from the results of plasma etching of the film SF of the eight sample substrates.

[0090] Fig. 6 is a graph showing the results of experiment 1 conducted to evaluate 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 ratio. In Fig. 6, reference symbols P1 to P8 represent the selectivity ratios obtained from the results of plasma etching of the film SF of the first to eighth sample substrates.

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

[0092] 6 also shows that when the flow rate of hydrogen fluoride gas accounts for 70 volume % or more of the total flow rate of the first process gas excluding the inert gas, a selectivity ratio of 5 or more can be obtained. In particular, when the flow rate of hydrogen fluoride gas accounts for 90 volume % or more of the total flow rate of the first process gas excluding the inert gas, a selectivity ratio of 7 or more can be obtained, and when the flow rate of hydrogen fluoride gas accounts for 95 volume % or more, a selectivity ratio 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 film SF of the three sample substrates was plasma etched 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 a carbon number of 1 was used. For the eleventh sample substrate, a first processing gas containing hydrogen fluoride gas and a hydrofluorocarbon gas having a carbon number of 4 was used. In addition, in experiment 2, the temperature of the electrostatic chuck 20 on which the sample substrate is placed was adjusted to a temperature of −50° C. or lower before the start of plasma etching.

[0094] In experiment 2, the selectivity ratio of the etching of the film SF to the etching of the mask MSK was obtained from the results of plasma etching of the film SF of the three sample substrates. Specifically, the selectivity ratio was obtained by dividing the etching rate of the film SF by the etching rate of the mask MSK from the results of 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 symbols Sub. 9 to 11 represent the selectivity ratios obtained from the results of plasma etching of the film SF of the ninth to eleventh sample substrates.

[0096] As shown in Figure 7, the results of Experiment 2 confirmed that the selectivity ratio was 6 or more for all sample substrates. In particular, the selectivity ratio of the 11th sample substrate, which used a hydrofluorocarbon gas with a carbon number of 4, was about 14, and it was confirmed that the selectivity ratio was the highest among the three sample substrates.

[0097] (Experiment 3 and Experiment 4) In experiment 3, the plasma processing apparatus 1 was used to generate plasma from a processing gas that was a mixture of hydrogen fluoride gas and argon gas, and to etch a silicon oxide film. In experiment 4, the plasma processing apparatus 1 was used to generate plasma from a processing gas that was a mixture of hydrogen fluoride gas, argon gas, and PF 3 A plasma was generated from a process gas, which was a mixture of gases, and a silicon oxide film was etched. In Experiments 3 and 4, the silicon oxide film was etched while changing the temperature of the electrostatic chuck 20. In Experiments 3 and 4, a quadrupole mass spectrometer was used to measure the amount of hydrogen fluoride (HF) in the gas phase during etching of the silicon oxide film and the amount of SiF 3 The amounts of hydrogen fluoride (HF) and SiF were measured. The results of Experiments 3 and 4 are shown in Fig. 8(a) and 8(b). Fig. 8(a) shows the relationship between the temperature of the electrostatic chuck 20, the amount of hydrogen fluoride (HF), and SiF 3 FIG. 8(b) shows the relationship between the temperature of the electrostatic chuck 20, the amount of hydrogen fluoride (HF), and the amount of SiF during etching of the silicon oxide film in Experiment 4. 3 The relationship between each of the quantities is shown.

[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) as the etchant decreased, and SiF 3 That is, in experiment 3, when the temperature of the electrostatic chuck 20 was about −60° C. or lower, the amount of etchant used in etching 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 SiF 3 In other words, in experiment 4, when the temperature of the electrostatic chuck 20 was 20° C. or lower, the amount of etchant used in etching the silicon oxide film increased. The processing gas used in experiment 4 was PF 3The process gas used in Experiment 4 differs from that used in Experiment 3 in that it contains a gas. In Experiment 4, a state in which phosphorus species are present on the surface of the silicon oxide film during etching of the silicon oxide film was formed. From this, it can be understood that when phosphorus species are present on the surface of the silicon oxide film, adsorption of the etchant to the silicon oxide film is promoted even when the temperature of the electrostatic chuck 20 is a relatively high temperature of 20° C. or less. From this, it was confirmed that when phosphorus 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 table 14, etc. increases. When the amount of reaction products increases, the processing environment changes, which may result in a deterioration in processing uniformity between substrates W. Furthermore, an increase in the amount of reaction products can cause particle generation. Therefore, the inside of the chamber is cleaned with plasma obtained by converting a cleaning gas into plasma.

[0100] Fig. 9 is a flowchart showing an example of a substrate processing method according to the second embodiment. Similar to the method MT1, the method MT2 shown in Fig. 9 is performed to etch a silicon-containing film. Steps ST21 and ST22 are similar to steps ST11 and ST12 of the method MT1 described above, and therefore will not be described here.

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

[0102] The second process gas used in step ST23 may include at least one gas selected from the group consisting of a fluorine-containing gas, an oxygen-containing gas, a hydrogen-containing gas, and a nitrogen-containing gas. The fluorine-containing gas may be, for example, CF 4 ,SCIENCE FICTION 6 or NF 3 The oxygen-containing gas may be, for example, O 2 , CO, CO 2 , H 2 O or H 2 O 2 The hydrogen-containing gas may be, for example, H 2 Alternatively, HCl can be used. The nitrogen-containing gas can be, for example, N 2 In addition to the above, the second process gas may contain a rare gas such as Ar.

[0103] Step ST23 may be performed after each processing of a substrate W, or after processing a predetermined number or a predetermined lot of substrates W. Alternatively, step ST23 may be performed after processing substrates for a predetermined period of time.

[0104] [Third embodiment] In both the first and second embodiments, the first process gas contains hydrogen fluoride gas. Since hydrogen fluoride gas is highly corrosive, it is preferable to form a precoat on the inner wall of the 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 the chamber 10 can suppress corrosion of the inner wall of the chamber 10, thereby reducing the frequency of maintenance. Here, the inner wall of the chamber 10 includes the side wall and ceiling of the chamber 10 (top plate 34 of the upper electrode 30), as well as the support stand 14, etc.

[0105] The precoat film may be formed of a silicon-containing film such as a silicon oxide film, or the same material as the material of the mask MSK. When the mask MSK is a carbon-containing mask, the precoat may be formed of a carbon-containing material. The carbon-containing material may include at least one material selected from the group consisting of spin-on carbon, tungsten carbide, amorphous carbon, and boron carbide. When the mask MSK is a boron-containing mask, the precoat may be formed of a boron-containing material. The boron-containing material may include at least one material selected from the group consisting of silicon boron 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 performed to etch a silicon-containing film, similar to the method MT1. Steps ST31 and ST32 are similar to steps ST11 and ST12 of the method MT1 described above, and therefore will not be described here.

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

[0108] The pre-coating can be formed by Chemical Vapor Deposition (CVD) or Atomic Layer Deposition (ALD) using a third process gas. For example, when forming a silicon oxide film as the pre-coating, the third process gas is SiCl 4 Silicon-containing gases such as aminosilane gases and O 2 In addition, when a carbon film is formed as a precoat, the third process gas may be CH 4 , C 2 H 2 Carbon-containing gases such as the above can be used.

[0109] Step ST33 may be performed after each processing of a substrate W, or after processing a predetermined number or a predetermined lot of substrates W. Alternatively, step ST33 may be performed after processing substrates for a predetermined period of time.

[0110] The step of forming the pre-coat may be combined with a cleaning step as shown in another example of the substrate processing method according to the third embodiment of FIG 11. This makes it possible to simultaneously suppress the generation of particles and the corrosion of the inner wall of the chamber 10.

[0111] Although various exemplary embodiments have been described above, the present invention is not limited to the above-described exemplary embodiments, and various omissions, substitutions, and modifications may be made. In addition, elements in different exemplary embodiments may be combined to form other exemplary embodiments.

[0112] For example, the plasma processing apparatus used in the methods MT1 to MT4 may be a plasma processing apparatus other than the plasma processing apparatus 1. The plasma processing apparatus used in the methods MT1 to MT4 may be another capacitively coupled plasma processing apparatus, an inductively coupled plasma processing apparatus, or a plasma processing apparatus that generates plasma using surface waves such as microwaves.

[0113] As described above, hydrogen fluoride gas is a highly corrosive gas. Therefore, the flow rate ratio of hydrogen fluoride gas and the type of gas added to the first processing gas may be changed depending on the processing stage. In one example, the flow rate ratio of hydrogen fluoride gas may be lower at the end of etching when the thickness of the mask does not need to be maintained than at the beginning to middle of etching when the thickness of the mask needs to be maintained. In another example, the flow rate ratio of a gas having a sidewall protection effect may be higher in etching of a low aspect ratio region where shape abnormalities such as bowing are likely to occur than in etching of a high aspect ratio region. In addition, the shape after etching may be monitored by an optical observation device or the like, and the flow rate ratio of hydrogen fluoride gas and the type or flow rate ratio of a gas added to the first processing gas may be changed depending on the shape.

[0114] Furthermore, the disclosed embodiments further include the following aspects.

[0115] (Appendix 1) Providing a substrate having a silicon-containing film, the silicon-containing film including a silicon oxide film, in a chamber and a mask on the silicon-containing film; controlling the temperature of a substrate support on which the substrate is placed to 0° C. or less; In the chamber, hydrogen fluoride gas and C 4 F 8 Gas, C. 3 H 2 F 4 Gas and C 4 H 2 F 6 etching the silicon-containing film with a plasma generated from a first process gas including at least one carbon-containing gas selected from the group consisting of gases; Including, The flow rate of the hydrogen fluoride gas is the highest among the first process gases excluding the inert gas. A method for processing a substrate.

[0116] (Appendix 2) The substrate processing method according to (Supplementary Note 1), wherein the first processing gas further contains 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 comprising hydrogen fluoride gas and at least one carbon-containing gas selected from the group consisting of fluorocarbon gases and hydrofluorocarbon gases, wherein the flow rate of the hydrogen fluoride gas is 70 volume % or more relative to a total flow rate excluding an inert gas.

[0118] (Appendix 4) The fluorocarbon gas is CF 4 , C 2 F 2 , C 2 F 4 , C 3 F 8 , C 4 F 6 , C 4 F 8 and C 5 F 8 The etching gas composition according to (Appendix 3), wherein the etching gas composition is at least one selected from the group consisting of:

[0119] (Appendix 5) The fluorocarbon gas is 4 F 8 The etching gas composition according to (Appendix 3), which is a gas.

[0120] (Appendix 6) The hydrofluorocarbon gas is CHF 3 , C.H. 2 F 2 , C.H. 3 F, C 2 HF 5 , C 2 H 2 F 4 , C 2 H 3 F 3 , C 2 H 4 F 2 , C 3 HF7 , C 3 H 2 F 2 , C 3 H 2 F 6 , C 3 H 2 F 4 , C 3 H 3 F 5 , C 4 H 5 F 5 , C 4 H 2 F 6 , C 5 H 2 F 10 , cC 5 H 3 F 7 and C 3 H 2 F 4 The etching gas composition according to (Appendix 3), wherein the compound is at least one selected from the group consisting of:

[0121] (Appendix 7) The hydrofluorocarbon gas is 3 H 2 F 4 Gas and C 4 H 2 F 6 The etching gas composition according to (Appendix 3), wherein the etching gas composition is at least one selected from the group consisting of gases.

[0122] (Appendix 8) The etching gas composition according to any one of (Appendix 3) to (Appendix 7), further comprising at least one gas 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 gas 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 (Supplementary Note 3) to (Supplementary Note 9), wherein a flow rate of the hydrogen fluoride gas relative to a total flow rate excluding the inert gas is 96 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 foregoing, it will be understood that various exemplary embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may 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, with the true scope and spirit being indicated by the appended claims. [Explanation of symbols]

[0127] 1...plasma processing apparatus, 10...chamber, W...substrate, SF...film, MSK...mask.

Claims

1. a chamber having a gas inlet and a gas outlet; A plasma generating unit; A control unit; A plasma processing apparatus comprising: The control unit is disposing a substrate having a silicon-containing film, the silicon-containing film including a silicon oxide film, in the chamber and a carbon-containing mask on the silicon-containing film; controlling the temperature of a substrate support on which the substrate is placed to 0° C. or less; After the step of controlling the temperature of the substrate support to 0° C. or less, etching the silicon-containing film with a plasma generated from a first process gas including hydrogen fluoride gas and a phosphorus-containing gas; Perform a process including the control unit controls the flow rate of the hydrogen fluoride gas to be the largest among the first process gases excluding an inert gas in the etching step. Plasma processing equipment.

2. 2. The plasma processing apparatus according to claim 1, wherein a flow rate of said hydrogen fluoride gas relative to a total flow rate of said first process gas excluding an inert gas is 70 volume % or more.

3. 2. The plasma processing apparatus according to claim 1, wherein a flow rate of the hydrogen fluoride gas relative to a total flow rate of the first process gas excluding an inert gas is 70 volume % or more and 96 volume % or less.

4. 4. The plasma processing apparatus according to claim 1, wherein the first process gas further contains a carbon-containing gas.

5. The plasma processing apparatus according to claim 4 , 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.

6. The method of claim 1, wherein the first process gas further comprises a halogen-containing gas.

6. The plasma processing apparatus according to claim 4, wherein the halogen-containing gas includes at least one gas 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.

7. 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 , IF 7 , I 2 The plasma processing apparatus according to claim 6 , further comprising at least one selected from the group consisting of PI 3 .

8. 8. The plasma processing apparatus according to claim 1, wherein the first process gas includes an inert gas.

9. 9. The plasma processing apparatus according to claim 8, wherein the inert gas is at least one selected from the group consisting of nitrogen gas, Ar gas, Kr gas, and Xe gas.

10. The plasma processing apparatus according to any one of claims 1 to 9, wherein the mask is a carbon-containing mask, a boron-containing mask, or a metal-containing mask.

11. 11. The plasma processing apparatus according to claim 1, wherein the carbon-containing mask is made of at least one selected from the group consisting of spin-on carbon, tungsten carbide, amorphous carbon, and boron carbide.

12. 11. The plasma processing apparatus according to claim 1, wherein the mask is made of at least one material selected from the group consisting of titanium nitride, titanium oxide, and tungsten.

13. 11. The plasma processing apparatus according to claim 1, wherein the mask is made of silicon boride, boron nitride, or boron carbide.

14. 14. The 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.

15. 14. The 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 polysilicon films. Plasma processing equipment.

16. providing a substrate having a silicon-containing film in a chamber and a mask on the silicon-containing film; controlling the temperature of a substrate support on which the substrate is placed to 0° C. or less; After the step of controlling the temperature of the substrate support to 0° C. or less, a plasma is generated from a first process gas including hydrogen fluoride gas and a phosphorus-containing gas to etch the silicon-containing film; Including, A substrate processing method, wherein in the etching step, the hydrogen fluoride gas has a largest flow rate among the first process gases excluding an inert gas.

Images