Plasma processing apparatus, etching method, manufacturing method of a NAND flash memory with a three-dimensional structure, and etching gas composition

Abstract

An exemplary embodiment of the substrate processing method of the present invention includes the step of providing a substrate into 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 the step of controlling the temperature of a substrate support on which the substrate is placed to be below 0°C. The substrate processing method further includes the step of etching the silicon-containing film using a plasma generated from a first processing gas comprising 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 film is etched by chemical species from the plasma. Among the first processing gas excluding inert gases, hydrogen fluoride gas has the highest flow rate.

Description

Technical Field

[0001] The exemplary embodiments of the present invention relate to a substrate processing method and a plasma processing apparatus. Prior Technology

[0002] Japanese Patent Application Publication No. 2016-39310 discloses a method for etching a film within a substrate. The film contains silicon, and the substrate further has a mask disposed on the film. The mask comprises amorphous carbon or an organic polymer. The etching in this method uses a plasma generated from a processing gas containing hydrocarbon gas and hydrofluorocarbon gas. Summary of the Invention

[0003] This invention provides a technique for improving the selectivity of etching of silicon-containing films relative to etching of masks during plasma etching.

[0004] In one exemplary embodiment, a substrate processing method is provided. The substrate processing method includes the step of providing a substrate into 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 the step of controlling the temperature of a substrate support on which the substrate is placed to below 0°C. The substrate processing method further includes the step of etching the silicon-containing film using a plasma generated from a first processing gas comprising 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. Of the first processing gas excluding inert gases, the hydrogen fluoride gas has the highest flow rate.

[0005] According to the present invention, a technique can be provided to improve the selectivity ratio of etching of silicon-containing films relative to etching of masks during plasma etching. Simple Explanation of the Diagram

[0006] Figure 1 is a flowchart illustrating one example of the substrate processing method according to the first embodiment. Figure 2 is a schematic diagram of an example plasma processing apparatus. Figure 3 is a partially enlarged cross-sectional view of an example substrate provided in step ST11. Figure 4 is a partial enlarged cross-sectional view of an example substrate after the substrate processing method shown in Figure 1 has been performed. Figure 5 is a timing diagram of an example of a substrate processing method. Figure 6 is a graph showing the results of Experiment 1, which was conducted to evaluate the substrate processing method shown in Figure 1. Figure 7 is a graph showing the results of Experiment 2, which was conducted to evaluate the substrate processing method shown in Figure 1. Figure 8(a) is a graph showing the results of Experiment 3, and Figure 8(b) is a graph showing the results of Experiment 4. Figure 9 is a flowchart illustrating one example of the substrate processing method according to the second embodiment. Figure 10 is a flowchart illustrating one example of the substrate processing method according to the third embodiment. Figure 11 is a flowchart illustrating another example of the substrate processing method according to the third embodiment. Implementation

[0007] The following describes various exemplary implementation methods.

[0008] In one exemplary embodiment, a substrate processing method is provided. The substrate processing method includes the step of providing a substrate into a chamber of a plasma processing apparatus. The substrate has a silicon-containing film comprising a silicon oxide film and a mask disposed on the silicon-containing film. The substrate processing method includes the step of controlling the temperature of a substrate support on which the substrate is placed to be below 0°C. The substrate processing method further includes the step of etching the silicon-containing film using a plasma generated from a first processing gas comprising 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. Among the first processing gas excluding inert gases, hydrogen fluoride gas has the highest flow rate. According to this embodiment, by using plasma generated from a first processing gas with the highest flow rate of hydrogen fluoride gas among the total flow rates excluding inert gases, the selectivity ratio of etching of the silicon-containing film relative to etching of the mask is improved.

[0009] In one exemplary embodiment, the flow rate of hydrogen fluoride gas may be 70% by volume or more relative to the total flow rate of the first processing gas excluding the inert gas.

[0010] 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.

[0011] In one exemplary embodiment, the fluorocarbon gas may be C4F8 gas.

[0012] 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, C5H2F10, c-C5H3F7, and C3H2F4.

[0013] In one exemplary embodiment, the hydrofluorocarbon gas may be at least one selected from the group consisting of C3H2F4 gas and C4H2F6 gas.

[0014] In one exemplary embodiment, the first processing gas may further comprise at least one gas selected from the group consisting of oxygen-containing gases and halogen-containing gases.

[0015] In one exemplary embodiment, the first processing gas may further comprise at least one gas selected from the group consisting of phosphorus-containing gases, sulfur-containing gases, and boron-containing gases.

[0016] In one exemplary embodiment, the flow rate of hydrogen fluoride gas may be 96% by volume or less relative to the total flow rate of the first processing gas excluding the inert gas.

[0017] In one exemplary embodiment, the silicon-containing film may be at least one selected from the group consisting of silicon oxide film, a laminated film comprising silicon oxide film and silicon nitride film, and a laminated film comprising silicon oxide film and polycrystalline silicon film.

[0018] In one exemplary embodiment, the mask may be a carbon mask or a metal mask.

[0019] In one exemplary embodiment, the carbon mask may be formed from at least one selected from the group consisting of spin-coated carbon, tungsten carbide, amorphous carbon, and boron carbide.

[0020] In one exemplary embodiment, the substrate processing method further includes the step of generating plasma from a second processing gas within a cavity. In the step of generating plasma from the second processing gas, the cavity is cleaned using chemical species derived from the plasma.

[0021] In one exemplary embodiment, the second processing gas may comprise at least one gas selected from the group consisting of fluorine-containing gas, oxygen-containing gas, hydrogen-containing gas, and nitrogen-containing gas.

[0022] In one exemplary embodiment, the substrate processing method further includes, prior to the step of providing the substrate, a step of generating plasma from a third processing gas within a chamber. During the step of generating plasma from the third processing gas, a pre-coating is formed on the inner wall of the chamber.

[0023] In one exemplary embodiment, the third processing gas may contain a carbon-containing gas.

[0024] In another exemplary embodiment, a substrate processing method is provided. The substrate processing method includes the step of providing a substrate into a chamber of a plasma processing apparatus. The substrate has a silicon-containing film comprising a silicon oxide film and a mask disposed on the silicon-containing film. The substrate processing method further includes the step of etching the silicon-containing film within the chamber using a plasma generated from a first processing gas comprising 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 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 relative to the total flow rate of the first processing gas excluding inert gases. According to this embodiment, by using plasma generated from a first processing gas in which the flow rate of hydrogen fluoride gas is 70% to 96% by volume relative to the total flow rate excluding inert gases, the selectivity of etching of silicon-containing films relative to etching of masks is improved.

[0025] In one exemplary embodiment, the first processing gas may further comprise at least one gas selected from the group consisting of oxygen-containing gases and halogen-containing gases.

[0026] In one exemplary embodiment, the first processing gas may further contain phosphorus-containing gas.

[0027] In another exemplary embodiment, a substrate processing method is provided. The substrate processing method includes the step of providing a substrate into 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 the step of etching the silicon-containing film using a 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 is 70% to 96% by volume relative to the total flow rate of the first processing gas excluding inert gases. According to this embodiment, by using plasma generated from a first processing gas in which the flow rate of hydrogen fluoride gas is 70% to 96% by volume relative to the total flow rate excluding inert gases, the selectivity ratio of etching the silicon-containing film to etching the mask is improved.

[0028] In one exemplary embodiment, the first processing gas may contain a carbon-containing gas and at least one gas selected from the group consisting of oxygen-containing gas, halogen-containing gas and phosphorus-containing gas.

[0029] In one exemplary embodiment, the carbon-containing gas may include at least one selected from the group consisting of fluorocarbon gas, hydrofluorocarbon gas, and hydrocarbon gas.

[0030] 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.

[0031] In one exemplary embodiment, the fluorocarbon gas may be C4F8 gas.

[0032] 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, C5H2F10, c-C5H3F7, and C3H2F4.

[0033] In one exemplary embodiment, the hydrofluorocarbon gas may be at least one selected from the group consisting of C3H2F4 gas and C4H2F6 gas.

[0034] In one exemplary embodiment, the hydrocarbon gas may be at least one selected from the group consisting of CH4, C2H6, C3H6, C3H8 and C4H10.

[0035] In one exemplary embodiment, the carbon-containing gas may be a hydrofluorocarbon gas with 3 or more carbon atoms.

[0036] In one exemplary embodiment, the silicon-containing film may be at least one selected from the group consisting of a laminated film comprising a silicon oxide film and a silicon nitride film, a polycrystalline silicon film, a low dielectric constant film, and a laminated film comprising a silicon oxide film and a polycrystalline silicon film.

[0037] In one exemplary embodiment, the mask may be a carbon mask or a metal mask.

[0038] In one exemplary embodiment, the step may further include adjusting the temperature of the substrate support on which the substrate is placed to below 0°C before performing the etching step.

[0039] In another exemplary embodiment, a substrate processing method is provided. The substrate processing method includes the following steps: generating plasma from a pre-coating gas within a chamber of a plasma processing apparatus to form a pre-coating layer on the inner wall of the chamber. The plasma processing method further includes the step of providing a substrate into the chamber. The substrate has a silicon-containing film comprising a silicon oxide film and a mask disposed on the silicon-containing film. The substrate processing method further includes the step of controlling the temperature of a substrate support on which the substrate is placed to be below 0°C. The substrate processing method includes the following step: etching the silicon-containing film using plasma generated from a processing gas comprising 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 70% by volume or more relative to the total flow rate of the first processing gas excluding inert gases. The substrate processing method further includes the following step: generating plasma from a cleaning gas within a cavity to clean the cavity. According to this embodiment, by using plasma generated from a first processing gas in which the flow rate of hydrogen fluoride gas is 70% or more by volume relative to the total flow rate excluding inert gases, the selectivity of etching the silicon-containing film relative to etching the mask is improved.

[0040] 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 an air supply port and an exhaust port. The control unit is configured to perform a process including a step of placing a substrate in the chamber, a step of controlling the temperature of a substrate support, and a step of etching. In the step of placing the substrate in the chamber, a substrate having a silicon-containing film including a silicon oxide film and a mask disposed on the silicon-containing film is placed on a substrate support. In the step of controlling the temperature of the substrate support, the temperature of the substrate support is controlled to be below 0°C. In the etching step, within the chamber, the silicon-containing film is etched using plasma generated from a first processing gas comprising 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 the process such that, in the etching step, the flow rate of hydrogen fluoride gas, excluding inert gases, is the highest.

[0041] Hereinafter, various exemplary embodiments will be described in detail with reference to the drawings. Furthermore, in each drawing, the same or equivalent parts are labeled with the same symbols.

[0042] [First Implementation] Figure 1 is a flowchart illustrating an example of the substrate processing method according to the first embodiment. The method MT1 shown in Figure 1 is performed for etching a silicon-containing film. Method MT1 can be used, for example, to manufacture NAND flash memory with a three-dimensional structure. Method MT1 is performed using a plasma processing apparatus. Figure 2 is a schematic diagram illustrating an example of a plasma processing apparatus. The method MT1 shown in Figure 1 can be performed using the plasma processing apparatus 1 shown in Figure 2.

[0043] 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 generally cylindrical shape. The chamber body 12 is formed, for example, of aluminum. A corrosion-resistant film is provided on the inner wall surface of the chamber body 12. This film can be a ceramic such as alumina or yttrium oxide.

[0044] A passage 12p is formed on 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.

[0045] 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 generally cylindrical shape. The support portion 13 extends upward from the bottom of the chamber body 12 within the internal space 10s. The support portion 13 has a support platform 14 at its upper part. The support platform 14 is configured to support the substrate W within the internal space 10s.

[0046] The support stage 14 has a lower electrode 18 and an electrostatic chuck 20. The support stage 14 may further have an electrode plate 16. The electrode plate 16 is formed of a conductor such as aluminum and has a generally disc-shaped form. The lower electrode 18 is disposed on the electrode plate 16. The lower electrode 18 is formed of a conductor such as aluminum and has a generally disc-shaped form. The lower electrode 18 is electrically connected to the electrode plate 16. Furthermore, the support stage 14 is an example of a substrate support.

[0047] An electrostatic chuck 20 is disposed on the lower electrode 18. A substrate W is placed on the upper surface of the electrostatic chuck 20. The electrostatic chuck 20 has a body and electrodes (chuck electrodes). The body of the electrostatic chuck 20 has a generally disc-shaped form and is formed of a dielectric material. The chuck electrodes of the electrostatic chuck 20 are film electrodes disposed within the body of the electrostatic chuck 20. The chuck electrodes of the electrostatic chuck 20 are connected to a DC power supply 20p via a switch 20s. When a voltage from the DC power supply 20p is applied to the chuck electrodes of the electrostatic chuck 20, an electrostatic attraction is generated between the electrostatic chuck 20 and the substrate W. This electrostatic attraction holds the substrate W on the electrostatic chuck 20. Furthermore, in addition to the aforementioned chuck electrodes, the electrostatic chuck 20 may also have a bias electrode within its body for introducing ions to the substrate W. The bias electrode may also be a film electrode, similar to the chuck electrodes.

[0048] An edge ring 25 is disposed on the periphery of the lower electrode 18 in a manner that surrounds the edge of the substrate W. The edge ring 25 improves the in-plane uniformity of the plasma treatment of the substrate W. The edge ring 25 may be formed of silicon, silicon carbide, or quartz, etc.

[0049] A flow path 18f is provided inside the lower electrode 18. A heat exchange medium (e.g., refrigerant) is supplied to the flow path 18f via a cooler unit (not shown) located outside the chamber 10 through a pipe 22a. The heat exchange medium supplied to the flow path 18f returns to the cooler 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.

[0050] The plasma processing apparatus 1 is provided with a gas supply line 24. The gas supply line 24 supplies heat transfer gas (e.g., helium) from the heat transfer gas supply mechanism to the space between the upper surface of the electrostatic chuck 20 and the back surface of the substrate W.

[0051] The plasma processing apparatus 1 further includes an upper electrode 30. The upper electrode 30 is disposed above the support platform 14. The upper electrode 30 is supported by 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.

[0052] 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 of the internal space 10s side, dividing and forming the internal space 10s. The top plate 34 may be formed of a low-resistance conductor or semiconductor that generates less Joule heat. The top plate 34 has a plurality of jet holes 34a extending through the top plate 34 in its thickness direction.

[0053] The support body 36 freely supports the top plate 34. The support body 36 is formed of a conductive material such as aluminum. A gas diffusion chamber 36a is provided inside the support body 36. The support body 36 has a plurality of vents 36b extending downward from the gas diffusion chamber 36a. The plurality of vents 36b are respectively connected to a plurality of air jet holes 34a. An air supply port 36c is formed in the support body 36. The air supply port 36c is connected to the gas diffusion chamber 36a. An air supply pipe 38 is connected to the air supply port 36c.

[0054] A valve group 42, a flow controller group 44, and a gas source group 40 are connected to the gas supply pipe 38. The gas source group 40, valve group 42, and flow controller group 44 constitute the gas supply section. The gas source group 40 includes a plurality of gas sources. The valve group 42 includes a plurality of on / off valves. The flow controller group 44 includes a plurality of flow controllers. Each of the plurality of flow controllers in the flow controller group 44 is a mass flow controller or a pressure-controlled flow controller. Each of the plurality of gas sources in the gas source group 40 is connected to the gas supply pipe 38 via a corresponding on / off valve in the valve group 42 and a corresponding flow controller in the flow controller group 44.

[0055] In the plasma treatment apparatus 1, a protective cover 46 is detachably mounted and detachably installed along the inner wall of the chamber body 12 and the outer periphery of the support portion 13. The protective cover 46 prevents reaction byproducts from adhering to the chamber body 12. The protective cover 46 is constructed, for example, by forming a corrosion-resistant film on the surface of a base material formed of aluminum. The corrosion-resistant film can be formed of ceramics such as yttrium oxide.

[0056] A baffle 48 is provided between the support section 13 and the side wall of the chamber body 12. The baffle 48 is constructed, for example, by forming a corrosion-resistant film (such as yttrium oxide) on the surface of a base material made of aluminum. A plurality of through holes are formed in the baffle 48. An exhaust port 12e is provided below the baffle 48 and at the bottom of the chamber body 12. An exhaust device 50 is connected to the exhaust port 12e via an exhaust pipe 52. The exhaust device 50 includes a pressure regulating valve and a vacuum pump such as a turbomolecular pump.

[0057] 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 source for generating first high-frequency electricity. The first high-frequency electricity has a frequency suitable for plasma generation. The frequency of the first high-frequency electricity is, for example, in the range of 27 MHz to 100 MHz. The first high-frequency electricity can 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 an 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 of the load side (lower electrode 18 side). Furthermore, the first high-frequency power supply 62 can 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 generation unit.

[0058] The second high-frequency power supply 64 is a power source for generating a second high-frequency power. This second high-frequency power has a lower frequency than the first high-frequency power. When the first and second high-frequency powers are used together, the second high-frequency power is used as a bias power source to guide ions to the substrate W. The frequency of the second high-frequency power is, for example, in the range of 400 kHz to 13.56 MHz. The second high-frequency power can be a continuous wave or a pulsed wave. The second high-frequency power supply 64 is connected to the support platform 14 via a matching adapter 68. In one example, the second high-frequency power supply 64 is connected to the lower electrode 18 via the matching adapter 68 and the electrode plate 16. The matching adapter 68 has circuitry for matching the output impedance of the second high-frequency power supply 64 with the impedance of the load side (lower electrode 18 side). Furthermore, the second high-frequency power supply 64 can be connected to the bias electrode disposed within the electrostatic chuck 20 via the matching adapter 68 and the electrode plate 16, similar to the bias power supply described later.

[0059] Furthermore, a second high-frequency power source can be used instead of the first high-frequency power source, i.e., plasma can be generated using only a single high-frequency power source. In this case, the frequency of the second high-frequency power source can be greater than 13.56 MHz, for example, 40 MHz. The plasma processing apparatus 1 may not include the first high-frequency power source 62 and the matching device 66. The second high-frequency power source 64 constitutes an example of a plasma generation unit.

[0060] Furthermore, in this invention, the plasma processing apparatus 1 can be configured to apply a DC voltage to the upper electrode 30 during plasma processing. For example, the plasma processing apparatus 1 can apply a pulsed negative DC voltage to the upper electrode 30.

[0061] In the plasma processing apparatus 1, gas is supplied to the internal space from the gas supply unit for 10 seconds, thereby generating plasma. Furthermore, by supplying a first high-frequency power and / or a 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.

[0062] The plasma processing apparatus 1 may further include a control unit 80. The control unit 80 may be a computer equipped with a processor, memory, an input device, a display device, and a signal input / output interface. The control unit 80 controls each component of the plasma processing apparatus 1. In the control unit 80, the operator uses the input device to input commands for management of the plasma processing apparatus 1. Furthermore, the display device in the control unit 80 can visually display the operating status of the plasma processing apparatus 1. Furthermore, the memory unit stores control programs and process recipe data. The processor executes the control program to perform various processes using the plasma processing apparatus 1. The processor executes the control program and controls each component of the plasma processing apparatus 1 according to the process recipe data.

[0063] Referring again to Figure 1. Hereinafter, method MT1 will be described using the plasma processing apparatus 1 as an example during this execution. As shown in Figure 1, method MT1 includes step ST11. In step ST11, a substrate W is provided into the chamber 10 of the plasma processing apparatus. The substrate W is placed on an electrostatic chuck 20 and held by the electrostatic chuck 20.

[0064] Figure 3 is a partially enlarged cross-sectional view of an example substrate provided in step ST11 of method MT1. The substrate W shown in Figure 3 has a substrate layer UL, a film SF, and a mask MSK. The substrate layer UL can be a layer made of polycrystalline silicon. The film SF is disposed on the substrate layer UL. The film SF contains silicon. The film SF can be a laminated film comprising one or more layers of silicon oxide film and one or more layers of silicon nitride film. In the example shown in Figure 3, the film SF is a multilayer film comprising multiple layers of silicon oxide film IL1 and multiple layers of silicon nitride film IL2. Multiple layers of silicon oxide film IL1 and multiple layers of silicon nitride film IL2 are alternately laminated. Furthermore, the film SF can be other monolayer films containing silicon or other multilayer films containing silicon. When the film SF is a monolayer film, the film SF can be, for example, a low dielectric constant film or a polycrystalline silicon film formed from SiOC, SiOF, or SiCOH. Alternatively, when the SF membrane is a multilayer membrane, the SF membrane may be, for example, a laminated membrane comprising one or more layers of silicon oxide film and one or more layers of polycrystalline silicon film.

[0065] A masking mask (MSK) is disposed on the SF membrane. The masking mask (MSK) has a pattern for forming spaces such as holes on the SF membrane. The masking mask (MSK) may be, for example, a rigid mask. The masking mask (MSK) may be, for example, a carbon-containing mask and / or a metal-containing mask. The carbon-containing mask is formed, for example, from at least one selected from the group consisting of spin-coated 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 masking mask (MSK) may be, for example, a boron-containing mask formed from silicon boride, boron nitride, or boron carbide.

[0066] As shown in Figure 1, method MT1 further includes step ST12. Step ST12 is performed after step ST11. In step ST12, a plasma is generated from the first processing gas within chamber 10. In step ST12, the SF film is etched using chemical species from the plasma.

[0067] The first processing gas used in step ST12 contains hydrogen fluoride gas. The flow rate of the hydrogen fluoride gas is greater than the flow rate of other gases included in the first processing gas excluding inert gases. Specifically, the flow rate of the hydrogen fluoride gas in step ST12 can be set to 70% or more, 80% or more, 85% or more, 90% or more, or 95% or more, relative to the total flow rate of the first processing gas excluding inert gases. Furthermore, from the viewpoint of suppressing shape abnormalities such as bending in the SF membrane, when adding carbon-containing gases, the flow rate of the hydrogen fluoride gas can be set to less than 100% by volume, less than 99.5% by volume, less than 98% by volume, or less than 96% by volume, relative to the total flow rate of the first processing gas excluding inert gases. In one example, the flow rate of the hydrogen fluoride gas was adjusted to 70% or more and less than 96% by volume relative to the total flow rate of the first processing gas excluding inert gases. By controlling the flow rate of hydrogen fluoride gas in the first processing gas (excluding inert gases) to this range, etching of the mask MSK can be suppressed, and the film SF can be etched at a higher etching rate. As a result, the selectivity ratio of silicon film etching to mask etching can be set to 5 or higher. Therefore, even in processes requiring high aspect ratios, such as NAND flash memory with three-dimensional structures, the film SF can be etched at an effective speed. Furthermore, with this high selectivity ratio, the amount of deposition gases such as carbon-containing gases can be suppressed, thus reducing the risk of mask MSK clogging and, as described later, shortening the cleaning time in chamber 10 to less than 50%. As a result, the throughput of substrate processing can be significantly improved. On the other hand, when the flow rate of hydrogen fluoride gas is lower than the flow rate of other gases included in the first processing gas (excluding inert gases), the selectivity ratio cannot be sufficiently improved. Furthermore, the total flow rate of the first processing gas, excluding the inert gas, can be adjusted appropriately according to the chamber volume. In one example, it can be set to 100 sccm or more.

[0068] The first processing gas may contain carbon-containing gases in addition to hydrogen fluoride gas. Furthermore, in addition to hydrogen fluoride gas and carbon-containing gases, it may also contain at least one gas selected from the group consisting of oxygen-containing gases and halogen-containing gases.

[0069] When the first processing gas contains a carbon-containing gas, a carbon-containing deposit will form on the mask surface, thus further improving the selectivity of etching the silicon-containing film relative to etching the mask. The carbon-containing gas includes, for example, at least one selected from the group consisting of fluorocarbon gases, hydrofluorocarbon gases, and hydrocarbon gases. For example, CF4, C2F2, C2F4, C3F8, C4F6, C4F8, or C5F8 can be used as fluorocarbon gases. For example, CHF3, CH2F2, CH3F, C2HF5, C2H2F4, C2H3F3, C2H4F2, C3HF7, C3H2F2, C3H2F6, C3H2F4, C3H3F5, C4H5F5, C4H2F6, C5H2F10, C5H3F7, or C3H2F4 can be used as hydrofluorocarbon gases. As hydrocarbon gases, CH4, C2H6, C3H6, C3H8, or C4H10 can be used, for example. In addition to the above, carbon-containing gases may also include CO and / or CO2. In one example, fluorocarbon gases and / or hydrofluorocarbon gases with two or more carbon atoms can be used as carbon-containing gases. When using fluorocarbon gases and / or hydrofluorocarbon gases with two or more carbon atoms, shape abnormalities such as bending can be effectively suppressed. Furthermore, by using fluorocarbon gases and / or hydrofluorocarbon gases with three or more carbon atoms, shape abnormalities can be further suppressed. For example, C4F8 can be used as a fluorocarbon gas with three or more carbon atoms. Hydrofluorocarbon gases with three or more carbon atoms may contain unsaturated bonds and may also contain one or more CF3 groups. For example, C3H2F4 or C4H2F6 can be used as a hydrofluorocarbon gas with three or more carbon atoms.

[0070] When the first processing gas contains an oxygen-containing gas, mask clogging during etching can be suppressed. The oxygen-containing gas can be, for example, at least one selected from the group consisting of O2, CO, CO2, H2O, or H2O2.

[0071] When the first processing gas contains a halogen-containing gas, the etching shape can be controlled. The halogen-containing gas can be, for example, at least one gas selected from the group consisting of carbon-free fluorine-containing gases such as SF6, NF3, XeF2, SiF4, IF7, ClF5, BrF5, AsF5, NF5, PF3, PF5, POF3, BF3, HPF6, and WF6; chlorine-containing gases such as Cl2, SiCl2, SiCl4, CCl4, BCl3, PCl3, PCl5, and POCl3; bromine-containing gases such as HBr, CBr2F2, C2F5Br, PBr3, PBr5, and POBr3; and iodine-containing gases such as HI, CF3I, C2F5I, C3F7I, IF5, IF7, I2, and PI3.

[0072] In addition to the above, the first processing gas may also include gases that provide sidewall protection, such as sulfur-containing gases like COS, phosphorus-containing gases like P4O10, P4O8, P4O6, PH3, Ca3P2, H3PO4, and Na3PO4, and boron-containing gases like B2H6. Furthermore, phosphorus-containing gases that provide sidewall protection also include phosphorus halide gases containing phosphorus fluorides such as PF3 and PF5, and phosphorus chloride gases such as PCl3 and PCl5.

[0073] In an exemplary embodiment of the present invention, the first processing gas comprises hydrogen fluoride and at least one carbon-containing gas selected from the group consisting of fluorocarbon gases and hydrofluorocarbon gases. The carbon-containing gas may be either the aforementioned fluorocarbon gas or the aforementioned hydrofluorocarbon gas. The fluorocarbon gas may be C4F8. Furthermore, the hydrofluorocarbon gas may be at least one selected from the group consisting of C3H2F4 and C4H2F6.

[0074] In an exemplary embodiment, the first processing gas may further comprise at least one gas selected from the group consisting of oxygen-containing gases and halogen-containing gases. In this case, the halogen-containing gas may be at least one gas selected from the group consisting of halogen-containing gases containing halogen elements other than fluorine and fluorine-containing gases that do not contain carbon.

[0075] In an exemplary embodiment, the added gas may further include at least one gas selected from the group consisting of sulfur-containing gases, phosphorus-containing gases, and boron-containing gases that have a sidewall protection effect.

[0076] In addition to the aforementioned gas types, the first processing gas may also include an inert gas. Besides nitrogen, rare gases such as Ar, Kr, and Xe may also be used as inert gases. The first processing gas is controlled such that the flow rate of hydrogen fluoride gas is at the ratio described above relative to the total flow rate of the first processing gas excluding the inert gases.

[0077] To execute step ST12, the control unit 80 controls the gas supply unit to supply the aforementioned processing gas into the chamber 10. To execute step ST12, the control unit 80 controls the gas supply unit to ensure that the flow rate of hydrogen fluoride gas in the processing gas supplied to the chamber 10 is at least 70% by volume of the total flow rate of the processing gas. To execute step ST12, the control unit 80 controls the exhaust device 50 to ensure that the pressure within the chamber 10 is a specified pressure. To execute 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 first high-frequency power and / or second high-frequency power to generate plasma from the processing gas within the chamber 10.

[0078] In step ST12, in order to introduce ions from the plasma to the substrate W, the second high-frequency power supply 64 can supply a second high-frequency power of 5 W / cm2 or more (i.e., high-frequency power for bias) to the support stage 14. With the second high-frequency power of 5 W / cm2 or more, ions from the plasma can fully reach the bottom of the space of the film SF formed by etching (e.g., the space SP shown in FIG4).

[0079] Furthermore, a pulse voltage other than high frequency can be used instead of the bias voltage to supply high-frequency power to the support stage 14. Here, pulse voltage refers to a pulsed voltage supplied from a pulse power source. The pulse power source can be configured to supply pulses directly from the power source itself, or a device for pulsed voltage can be provided downstream of the pulse power source. In one example, the pulse voltage is supplied to the support stage 14 in a way that generates a negative potential in the substrate W. The pulse voltage can be a negative polarity DC voltage pulse. Furthermore, the pulse voltage can be a rectangular wave pulse, a triangular wave pulse, a pulse, or a pulse with other voltage waveforms.

[0080] Figure 5 shows an example of a timing diagram related to the substrate processing method of an exemplary embodiment. In Figure 5, the horizontal axis represents time. In Figure 5, the vertical axis represents 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 Figure 5, the first processing gas is periodically supplied to the chamber 10. Furthermore, the pulse and pulse voltage of the first high-frequency power are periodically supplied to the support stage 14. Moreover, the period of supplying the pulse of the first high-frequency power HF, the period of supplying the pulse voltage, and the period of supplying the first processing gas are synchronized. Furthermore, the first processing gas can be continuously supplied to the chamber 10.

[0081] In Figure 5, the "L" level of the first high-frequency power HF indicates that the first high-frequency power HF is not supplied or that the power level of the first high-frequency power HF is lower than the power level represented by "H". The "L" level of the pulse voltage indicates that the pulse voltage is not supplied to the support stage 14 or that the pulse voltage level is lower than the level represented by "H". Furthermore, the "ON" state of the first processing gas supply indicates that the first processing gas is supplied to the chamber 10, and the "OFF" state of the first processing gas supply indicates that the supply of the first processing gas to the chamber 10 is stopped. Here, the period when the voltage level of the pulse voltage is L is defined as the "L period", and the period when the voltage level of the pulse voltage is H is defined as the "H period".

[0082] The frequency of the pulse voltage during period H (the first frequency) can be controlled from 100 kHz to 3.2 MHz. In one example, the first frequency is controlled at 400 kHz. Furthermore, in this case, the duty ratio (the first duty ratio), which represents the proportion of the pulse voltage level within one cycle that is the period of H, can be less than 50% or less, or less than 30%.

[0083] Furthermore, the frequency of the periodically supplied pulse voltage, which defines the period of H (the second frequency), can be set to 1 kHz to 200 kHz or 5 Hz to 100 kHz. In this case, the duty ratio (the second duty ratio), which represents the proportion of H within one period, can be 50% to 90%.

[0084] Furthermore, in the exemplary embodiment, the timing of the pulse of the first high-frequency power HF, the timing of the pulse voltage, and the timing of the first processing gas are described as being synchronized, but these may also be asynchronous.

[0085] There are no particular restrictions on the temperature of the electrostatic chuck 20 in step ST12. However, by adjusting the temperature of the electrostatic chuck 20 to a low temperature, such as below 0°C or below -50°C, before starting step ST12, the adsorption of etchant on the substrate surface can be promoted, thereby increasing the etching rate. Furthermore, when the first processing gas contains phosphorus-containing gas, the temperature of the electrostatic chuck 20 can be set to below 50°C, below 30°C, or below 20°C, depending on the proportion of phosphorus-containing gas in the first processing gas.

[0086] If step ST12 is completed, then method MT1 ends. Figure 4 is a partially enlarged cross-sectional view of an example substrate after performing the substrate processing method shown in Figure 1. By performing method MT1, as shown in Figure 4, a space SP reaching, for example, the substrate layer UL is formed in the film SF.

[0087] (Experiment 1) The results of Experiment 1, conducted to evaluate Method MT1, are described below. In Experiment 1, eight sample substrates identical to the substrate W shown in Figure 3 were prepared. In Experiment 1, the film SF on the eight sample substrates was plasma etched using a plasma processing apparatus 1. During plasma etching, a first processing gas containing fluorocarbon gas, hydrofluorocarbon gas, a carbon-free fluorinated gas, and a halogenated gas was used. The first processing gas used for plasma etching of the first sample substrate did not contain hydrogen fluoride gas. In the first processing gas used for plasma etching of the second to eighth 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. Furthermore, in Experiment 1, before the plasma etching began, the temperature of the electrostatic chuck 20 holding the sample substrate was adjusted to below -50°C.

[0088] In Experiment 1, the selectivity ratio of the etching of the SF film relative to the etching of the mask MSK was determined based on the plasma etching results of the SF film on the eight sample substrates. Specifically, the selectivity ratio was determined by dividing the etching rate of the SF film by the etching rate of the mask MSK based on the plasma etching results of the SF film on the eight sample substrates.

[0089] Figure 6 is a graph showing the results of Experiment 1 conducted to evaluate the substrate processing method shown in Figure 1. In the graph of Figure 6, the horizontal axis represents the flow rate ratio. The flow rate ratio is the percentage (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 Figure 6, the vertical axis represents the selectivity ratio. In Figure 6, reference symbols P1 to P8 represent the selectivity ratios obtained from the plasma etching results of the SF film on the substrates of samples 1 to 8.

[0090] As shown in Figure 6, the results of Experiment 1 confirmed that the selectivity increases with 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"). Furthermore, it was confirmed that the rate of increase in selectivity is particularly greater in regions with a flow rate ratio of 80% or higher compared to regions with a flow rate ratio below 80% (the slope of the curve in Figure 6 is larger). The reason for this is believed to be as follows: In regions with a flow rate ratio below 80% (volume %), the etching rate of the silicon-containing film increases with the increase in flow rate ratio, thereby increasing the selectivity. However, in these regions, the mask is also etched to a certain extent, so the increase in selectivity is relatively slow. On the other hand, in regions with a flow rate ratio of 80% or higher (volume %), 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 ratio is 80% or more, the silicon film is etched while maintaining a high etching rate, while the mask is hardly etched, so the selectivity increases.

[0091] Furthermore, as shown in Figure 6, when the flow rate of hydrogen fluoride gas accounts for 70% or more of the total flow rate of the first processing gas excluding inert gases, a selectivity of 5 or higher is obtained. It is also evident that, particularly when the flow rate of hydrogen fluoride gas accounts for 90% or more of the total flow rate of the first processing gas excluding inert gases, a selectivity of 7 or higher is obtained, and when it accounts for 95% or more of the total flow rate, a selectivity of 7.5 or higher is obtained.

[0092] (Experiment 2) In Experiment 2, three sample substrates identical to the substrate W shown in Figure 3 were prepared. In Experiment 2, plasma etching was performed on the SF film of the three sample substrates using plasma processing apparatus 1. During plasma etching, a first processing gas containing hydrogen fluoride and a carbon-containing gas was used. The first processing gas containing hydrogen fluoride and a fluorocarbon gas was used on sample substrate 9. The first processing gas containing hydrogen fluoride and a hydrofluorocarbon gas with one carbon atom was used on sample substrate 10. The first processing gas containing hydrogen fluoride and a hydrofluorocarbon gas with four carbon atoms was used on sample substrate 11. Furthermore, in Experiment 2, before the plasma etching began, the temperature of the electrostatic chuck 20 holding the sample substrates was adjusted to below -50°C.

[0093] In Experiment 2, the selectivity ratio of the etching of the SF film relative to the etching of the mask MSK was determined based on the plasma etching results of the SF film on the three sample substrates. Specifically, the selectivity ratio was determined by dividing the etching rate of the SF film by the etching rate of the mask MSK based on the plasma etching results of the SF film on the three sample substrates.

[0094] Figure 7 is a graph representing the results of Experiment 2. In the graph of Figure 7, the horizontal axis represents the sample substrate. In the graph of Figure 7, the vertical axis represents the selectivity. In Figure 7, reference symbols Sub.9~11 indicate the selectivity determined based on the plasma etching results of the SF film on the 9th to 11th sample substrates.

[0095] As shown in Figure 7, the results of Experiment 2 confirmed that the selectivity of any sample substrate was above 6. Furthermore, it was confirmed that the selectivity was highest among the three sample substrates, especially in the 11th sample substrate using hydrofluorocarbon gas with a carbon number of 4, where the selectivity was around 14.

[0096] (Experiments 3 and 4) In Experiment 3, plasma treatment apparatus 1 was used to generate plasma from a treatment gas consisting of a mixture of hydrogen fluoride and argon, which was then used to etch the silicon oxide film. In Experiment 4, plasma treatment apparatus 1 was used to generate plasma from a treatment gas consisting of a mixture of hydrogen fluoride, argon, and PF3, which was then used to etch the silicon oxide film. In both Experiments 3 and 4, the temperature of the electrostatic chuck 20 was varied while etching the silicon oxide film. In both Experiments 3 and 4, a quadrupole mass spectrometer was used to measure the amount of hydrogen fluoride (HF) and SiF3 in the gas phase during the etching of the silicon oxide film. Figures 8(a) and 8(b) show the results of Experiments 3 and 4. Figure 8(a) shows the relationship between the temperature of the electrostatic chuck 20 and the amounts of hydrogen fluoride (HF) and SiF3 during the etching of the silicon oxide film in Experiment 3. Furthermore, Figure 8(b) shows the relationship between the temperature of the electrostatic chuck 20 and the amounts of hydrogen fluoride (HF) and SiF3 during the etching of the silicon oxide film in Experiment 4.

[0097] As shown in Figure 8(a), in Experiment 3, when the temperature of the electrostatic chuck 20 was below approximately -60°C, the amount of hydrogen fluoride (HF) used as the etchant decreased, while the amount of SiF3, the reaction product generated by etching the silicon oxide film, increased. That is, in Experiment 3, when the temperature of the electrostatic chuck 20 was below approximately -60°C, the amount of etchant used for etching the silicon oxide film increased. On the other hand, as shown in Figure 8(b), in Experiment 4, when the temperature of the electrostatic chuck 20 was below 20°C, the amount of hydrogen fluoride (HF) decreased, while the amount of SiF3 increased. That is, in Experiment 4, when the temperature of the electrostatic chuck 20 was below 20°C, the amount of etchant used for etching the silicon oxide film increased. The processing gas used in Experiment 4 included PF3 gas, which differs from the processing gas used in Experiment 3. In Experiment 4, during the etching of the silicon oxide film, phosphorus chemical species were formed on the surface of the silicon oxide film. This indicates that even at a relatively high temperature (below 20°C), the electrostatic chuck 20 can still promote the adsorption of the etchant onto the silicon oxide film when phosphorus chemical species are present on the surface. This confirms that the presence of phosphorus chemical species on the substrate surface promotes the supply of etchant to the bottom of the opening (recess), thereby increasing the etching rate of the silicon-containing film.

[0098] [Second Implementation] In the substrate processing method of the first embodiment, as the number of processing cycles increases, the amount of reaction products adhering to the inner wall of the chamber 10 or the support platform 14 increases. If the amount of reaction products adheres increases, the processing environment changes, resulting in a decrease in the processing uniformity between the substrates W. Furthermore, the increased amount of reaction products leads to particle generation. Therefore, the chamber is cleaned using plasma obtained by plasmaizing a cleaning gas.

[0099] Figure 9 is a flowchart illustrating an example of the substrate processing method according to the second embodiment. The method MT2 shown in Figure 9 is performed similarly to method MT1 for etching a silicon-containing film. Steps ST21 and ST22 are the same as steps ST11 and ST12 of method MT1 described above, and therefore are omitted here.

[0100] As shown in Figure 9, method MT2 further includes step ST23. Step ST23 is performed after step ST22. In step ST23, plasma is generated in chamber 10 by a second processing gas (cleaning gas). In step ST23, the chamber 10 is cleaned by chemical species from the plasma. The processing time of step ST23 is typically determined by monitoring the luminescence state of the plasma. According to the second embodiment, compared with the prior art, the cleaning time can be reduced to less than 50%, which can improve the throughput of substrate processing.

[0101] The second processing gas used in step ST23 may include at least one gas selected from the group consisting of fluorine-containing gases, oxygen-containing gases, hydrogen-containing gases, and nitrogen-containing gases. For example, CF4, SF6, or NF3 may be used as a fluorine-containing gas. For example, O2, CO, CO2, H2O, or H2O2 may be used as an oxygen-containing gas. For example, H2 or HCl may be used as a hydrogen-containing gas. For example, N2 may be used as a nitrogen-containing gas. In addition to the above, the second processing gas may also include rare gases such as Ar.

[0102] Step ST23 can be performed once for each substrate W processed, or it can be performed after processing a specific number of substrates W or a specific batch. Alternatively, it can be performed after processing substrates at a specific time.

[0103] [Third Implementation] In both the first and second embodiments, the first processing gas contains hydrogen fluoride gas. Hydrogen fluoride gas is highly corrosive; therefore, it is preferable to form a pre-coating on the inner wall of the chamber 10 before the etching step. Especially when using hydrogen fluoride gas at high concentrations, forming a pre-coating on the inner wall of the chamber 10 suppresses corrosion and reduces maintenance frequency. Here, the inner wall of the chamber 10 includes not only the side walls and top wall (top plate 34 of the upper electrode 30) of the chamber 10, but also the support platform 14, etc.

[0104] The pre-coated film can be formed from a silicon-containing film such as a silicon oxide film, or from a material of the same type as the masking MSK. When the masking MSK is a carbon-containing mask, the pre-coated layer can be formed from a carbon-containing material. The carbon-containing material includes, for example, at least one selected from the group consisting of spin-coated carbon, tungsten carbide, amorphous carbon, and boron carbide. When the masking MSK is a boron-containing mask, the pre-coated layer can be formed from a boron-containing material. As a boron-containing material, the boron-containing material includes, for example, at least one selected from the group consisting of boron silicon hydride, boron nitride, and boron carbide.

[0105] Figure 10 is a flowchart illustrating an example of the substrate processing method according to the third embodiment. The method MT3 shown in Figure 10 is performed similarly to method MT1 for etching a silicon-containing film. Steps ST31 and ST32 are the same as steps ST11 and ST12 of method MT1 described above, and therefore are omitted here.

[0106] As shown in Figure 10, method MT2 further includes step ST30. Step ST30 is performed prior to step ST31. In step ST30, a plasma is generated within chamber 10 from a third processing gas (pre-coating gas). In step ST30, a pre-coating is formed on the inner wall of chamber 10 by chemical species from the plasma.

[0107] The pre-coating can be formed using a third processing gas via CVD (Chemical Vapor Deposition) or ALD (Atomic Layer Deposition). For example, when forming a silicon oxide film as the pre-coating, the third processing gas can be a silicon-containing gas such as SiCl4 or an aminosilane-based gas, or an oxygen-containing gas such as O2. Similarly, when forming a carbon film as the pre-coating, the third processing gas can be a carbon-containing gas such as CH4 or C2H2.

[0108] Step ST33 can be performed once for each substrate W processed, or it can be performed after processing a specific number of substrates W or a specific batch. Alternatively, it can be performed after processing substrates at a specific time.

[0109] Furthermore, the pre-coating step can also be combined with the cleaning step, as shown in another example of the substrate processing method of the third embodiment in FIG11. In this way, the generation of particles and the corrosion of the inner wall of the chamber 10 can be suppressed simultaneously.

[0110] The above descriptions of various exemplary embodiments are not limited to these exemplary embodiments, and various omissions, substitutions, and changes can be made. Furthermore, elements from different exemplary embodiments can be combined to form other exemplary embodiments.

[0111] For example, the plasma processing apparatus used in methods MT1-4 may also be a different plasma processing apparatus from plasma processing apparatus 1. The plasma processing apparatus used in methods MT1-4 may also be other capacitively coupled plasma processing apparatus, inductively coupled plasma processing apparatus, or plasma processing apparatus that uses surface waves such as microwaves to generate plasma.

[0112] Furthermore, as mentioned above, hydrogen fluoride gas is a highly corrosive gas. Therefore, the flow rate ratio of hydrogen fluoride gas or the type of gas added to the first processing gas can be changed according to the processing stage. In one example, at the end of etching when the thickness of the mask does not need to be maintained, the flow rate ratio of hydrogen fluoride gas can be lower than that in the early to middle stages of etching when the thickness of the mask needs to be maintained. In another example, the flow rate ratio of a gas that provides sidewall protection can be higher for etching low aspect ratio areas prone to bending or other shape abnormalities compared to etching high aspect ratio areas. Furthermore, the shape after etching can be monitored using optical observation devices, and the flow rate ratio of hydrogen fluoride gas, the type of gas added to the first processing gas, or the flow rate ratio can be changed according to the shape.

[0113] Furthermore, the disclosed implementation methods further include the following forms.

[0114] (Postscript 1) A substrate processing method, It includes the following steps: A substrate is provided into the cavity, the substrate having a silicon-containing film including a silicon oxide film and a mask on the silicon-containing film; The temperature of the substrate support on which the above-mentioned substrate is placed is controlled to be below 0°C; and Within the aforementioned chamber, the silicon-containing film is etched using a plasma generated from a first processing gas comprising a first processing gas and at least one carbon-containing gas selected from the group consisting of hydrogen fluoride gas, C3H2F4 gas, and C4H2F6 gas; and Of the first processing gases, excluding inert gases, the hydrogen fluoride gas has the highest flow rate.

[0115] (Postscript 2) As described in Appendix 1, the first processing gas further includes at least one additive gas selected from the group consisting of oxygen-containing gas, halogen-containing gas and phosphorus-containing gas.

[0116] (Note 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% by volume or more relative to the total flow rate excluding inert gases.

[0117] (Postscript 4) The etching gas composition described in (Appendix 3) wherein the fluorocarbon gas is selected from at least one of the group consisting of CF4, C2F2, C2F4, C3F8, C4F6, C4F8 and C5F8.

[0118] (Note 5) The etching gas composition described in (Appendix 3) is wherein the fluorocarbon gas is C4F8 gas.

[0119] (Note 6) The etching gas composition described in (Appendix 3) includes a hydrofluorocarbon gas selected from at least one of the group consisting of CHF3, CH2F2, CH3F, C2HF5, C2H2F4, C2H3F3, C2H4F2, C3HF7, C3H2F2, C3H2F6, C3H2F4, C3H3F5, C4H5F5, C4H2F6, C5H2F10, c-C5H3F7, and C3H2F4.

[0120] (Note 7) The etching gas composition described in (Appendix 3) includes a hydrofluorocarbon gas selected from at least one of the group consisting of C3H2F4 and C4H2F6 gases.

[0121] (Note 8) The etching gas composition described in any of (Appendix 3) to (Appendix 7) further comprises at least one gas selected from the group consisting of oxygen-containing gases and halogen-containing gases.

[0122] (Note 9) The etching gas composition described in any of (Appendix 3) to (Appendix 8) further comprises at least one gas selected from the group consisting of phosphorus-containing gases, sulfur-containing gases and boron-containing gases.

[0123] (Postscript 10) The etching gas composition described in any of (Appendix 3) to (Appendix 9) has a flow rate of hydrogen fluoride gas of 96% by volume or less relative to the total flow rate excluding the inert gas.

[0124] (Postscript 11) A hydrogen fluoride gas used in an etching gas composition as described in any one of (Appendix 3) to (Appendix 10).

[0125] As can be seen from the above description, various exemplary embodiments of the present invention have been described in this specification for the purpose of illustrating the present invention, and various changes can be made without departing from the scope and spirit of the present invention. Therefore, the various exemplary embodiments disclosed in this specification are not intended to be limiting, and the true scope and spirit are disclosed by the appended claims.

[0126] 1: Plasma treatment device 10: Chamber 10s: Interior space 12: Chamber body 12e: Exhaust port 12g: Gate valve 12p: Pathway 13: Support Department 14: Support Taiwan 16: Electrode plate 18: Lower electrode 18f:Flow path 20: Electrostatic chuck 20p: DC power supply 20s: Switch 22a:Piping 22b:Piping 24: Gas supply pipeline 25: Edge ring 30: Upper electrode 32: Components 34: Top plate 34a: Jet port 36: Support body 36a: Gas diffusion chamber 36b: Stomata 36c: Gas supply port 38: Gas supply pipe 40: Gas source group 42: Valve Group 44: Flow controller group 46: Protective shield 48: baffle 50: Exhaust device 52: Exhaust pipe 62: First High-Frequency Power Supply 64: Second High-Frequency Power Supply 66: Matcher 68: Matcher 80: Control Department IL1: Silicon oxide film IL2: Silicon nitride film MSK: Mask SF: membrane SP: Space UL: Base layer W: substrate

Claims

1. A plasma processing apparatus comprising: a chamber; a substrate support portion supporting a substrate within the chamber, the substrate comprising a silicon-containing film and a mask on the silicon-containing film; a gas supply portion supplying a first processing gas comprising hydrogen fluoride gas and a halogen-containing gas into the chamber; a plasma generation portion generating plasma from the first processing gas; and a control portion; wherein the mask is a carbon-containing mask, a boron-containing mask, or a metal-containing mask; and the control portion controlling the gas supply portion to supply the first processing gas into the chamber and controlling the plasma generation portion to generate plasma from the first processing gas to etch the silicon-containing film.

2. The plasma processing apparatus of claim 1, wherein the control unit controls the gas supply unit to maximize the flow rate of the hydrogen fluoride gas in the first processing gas other than the inert gas.

3. The plasma processing apparatus of claim 1, wherein the control unit controls the gas supply unit to make the flow rate of the hydrogen fluoride gas 70% or more of the total flow rate of the first processing gas other than the inert gas.

4. The plasma processing apparatus of claim 1, wherein the control unit controls the gas supply unit to make the flow rate of the hydrogen fluoride gas 70% or more and 96% or less of the total flow rate of the first processing gas other than the inert gas.

5. The plasma processing apparatus of any one of claims 1 to 4, wherein the first processing gas further contains a carbon-containing gas.

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

7. The plasma processing apparatus of any one of claims 1 to 4, wherein the halogen-containing gas comprises at least one gas selected from the group consisting of carbon-free fluorine-containing gases, chlorine-containing gases, bromine-containing gases and iodine-containing gases.

8. The plasma processing apparatus of any one of claims 1 to 4, wherein the halogen-containing gas comprises at least one gas selected from the group consisting of SF6, NF3, XeF2, SiF4, IF7, ClF5, BrF5, AsF5, NF5, PF3, PF5, POF3, BF3, HPF6, WF6, Cl2, SiCl2, SiCl4, CCl4, BCl3, PCl3, PCl5, POCl3, HBr, CBr2F2, C2F5Br, PBr3, PBr5, POBr3, HI, CF3I, C2F5I, C3F7I, IF5, I2, and PI3.

9. The plasma processing apparatus of any one of claims 1 to 4, wherein the halogenated gas contains two different halogens.

10. The plasma processing apparatus of claim 9, wherein the halogen-containing gas contains at least two of 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. The plasma processing apparatus of any one of claims 1 to 4, wherein the halogenated gas contains fluorine and chlorine.

13. The plasma processing apparatus of any one of claims 1 to 4, wherein the halogen-containing gas comprises IF5 or IF7.

14. The plasma processing apparatus of any one of claims 1 to 4, wherein the first processing gas further comprises at least one selected from the group consisting of phosphorus-containing gases, sulfur-containing gases and boron-containing gases.

15. The plasma processing apparatus of any one of claims 1 to 4, wherein the silicon-containing film is a laminated film comprising one or more layers of silicon oxide film and one or more layers of silicon nitride film.

16. The plasma processing apparatus of any one of claims 1 to 4, wherein the silicon-containing film is a laminated film comprising one or more layers of silicon oxide film and one or more layers of polycrystalline silicon film.

17. An etching method comprising the steps of: providing a substrate into a chamber, the substrate having a silicon-containing film and a mask on the silicon-containing film; supplying a first processing gas comprising hydrogen fluoride gas and a halogen-containing gas; generating plasma from the first processing gas to etch the silicon-containing film; wherein the mask is a carbon-containing mask, a boron-containing mask, or a metal-containing mask.

18. A method for manufacturing a NAND flash memory having a three-dimensional structure, comprising the etching method described above in claim 17.

19. An etching gas composition for etching silicon films, comprising hydrogen fluoride gas, halogen-containing gas and carbon-containing gas.

20. An etching gas composition for etching silicon films, comprising hydrogen fluoride gas and a halogen-containing gas, wherein the halogen-containing gas comprises at least one gas selected from the group consisting of carbon-free fluorine-containing gases, chlorine-containing gases, bromine-containing gases and iodine-containing gases.

Images