Substrate processing method and plasma processing apparatus

Abstract

Provided is a technique for improving the selection ratio of etching of a silicon-containing film to etching of a mask during plasma etching. A substrate processing method according to an exemplary 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 generating plasma from a first processing gas containing a hydrogen fluoride gas in the chamber. In the step of generating the plasma, the film is etched by chemical species from the plasma. The flow rate of the hydrogen fluoride gas is 25 vol% or more with respect to the total flow rate of the first processing gas other than the inert gas.

Description

[0001] This application is a divisional application of the invention patent application of Chinese National Application No. 202011285147.1, filed on November 17, 2020, with the title of “Substrate processing method and Plasma processing device”. TECHNICAL FIELD

[0002] Exemplary embodiments of the present application relate to a substrate processing method and a plasma processing device. BACKGROUND

[0003] In Patent Literature 1, a method of etching a film in a substrate is disclosed. The film contains silicon, and the substrate further has a mask provided on the film. The mask contains amorphous carbon or an organic polymer. The etching in the method uses plasma generated from a processing gas containing a hydrocarbon gas and a hydrofluorocarbon gas.

[0004] Patent Literature 1: Japanese Patent Application Publication No. 2016-39310

[0005] The present application provides a technology of improving a selectivity ratio of etching of a silicon-containing film to etching of a mask at the time of plasma etching. SUMMARY

[0006] In one exemplary embodiment, a substrate processing method is provided. The substrate processing method includes a step of providing a substrate into a chamber of a plasma processing device. 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 generating plasma from a first processing gas containing a hydrogen fluoride gas in the chamber. In the step of generating plasma, the silicon-containing film is etched by chemical species from the plasma. A flow rate of the hydrogen fluoride gas is 25% by volume or more with respect to a total flow rate of the first processing gas except for an inert gas.

[0007] EFFECT OF THE INVENTION

[0008] According to the present application, a technology of improving a selectivity ratio of etching of a silicon-containing film to etching of a mask at the time of plasma etching can be provided. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 is a flowchart showing an example of the substrate processing method of the first embodiment.

[0010] Figure 2 is a diagram schematically showing an example of a plasma processing device.

[0011] Figure 3 is a partial enlarged sectional view of an example of a substrate provided in the step ST11.

[0012] Figure 4 is a partial enlarged sectional view of an example of a substrate provided in the step ST11. Figure 1A partial enlarged sectional view of a substrate after the substrate processing method shown.

[0013] Figure 5 is a graph showing the results of experiments performed in order to evaluate Figure 1 is a graph showing the results of experiments performed in the substrate processing method shown.

[0014] Figure 6 is a flowchart showing an example of the substrate processing method of the second embodiment.

[0015] Figure 7 is a flowchart showing an example of the substrate processing method of the third embodiment.

[0016] Figure 8 is a flowchart showing another example of the substrate processing method of the third embodiment.

[0017] Explanation of symbols

[0018] 1 Plasma processing apparatus

[0019] 10 Chamber

[0020] W Substrate

[0021] SF Film

[0022] MSK Mask DETAILED DESCRIPTION

[0023] Hereinafter, various exemplary embodiments will be described.

[0024] In an exemplary embodiment, a substrate processing method is provided. The substrate processing method includes a step of supplying 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 also includes a step of generating a plasma from a first processing gas including a hydrogen fluoride gas in the chamber. In the step of generating the plasma, the silicon-containing film is etched by chemical species from the plasma. A flow rate of the hydrogen fluoride gas is 25 vol% or more with respect to a total flow rate of the first processing gas excluding an inert gas. According to this embodiment, the selectivity of etching of the silicon-containing film to etching of the mask is improved by using the plasma generated from the first processing gas having a flow rate of the hydrogen fluoride gas of 25 vol% or more with respect to the total flow rate excluding the inert gas.

[0025] In an exemplary embodiment, the flow rate of the hydrogen fluoride gas with respect to the total flow rate of the first processing gas excluding the inert gas can be less than 80 vol%.

[0026] In an exemplary embodiment, the first processing gas includes at least one selected from a carbon-containing gas, an oxygen-containing gas, and a halogen-containing gas.

[0027] In one example embodiment, the carbon-containing gas can include at least one selected from a fluorocarbon gas, a hydrofluorocarbon gas, and a hydrocarbon gas.

[0028] In one example embodiment, the silicon-containing film can be at least one selected from a laminated film including a silicon oxide film and a silicon nitride film, a polysilicon film, a low dielectric constant film, and a laminated film including a silicon oxide film and a polysilicon film.

[0029] In one example embodiment, the mask can be a carbon-containing mask or a metal-containing mask.

[0030] In one example embodiment, the carbon-containing mask can be formed of at least one selected from spin-on carbon, tungsten carbide, amorphous carbon, and boron carbide.

[0031] In one example embodiment, the substrate processing method further includes a process of generating a plasma from a second processing gas in the chamber. In the process of generating the plasma from the second processing gas, the chamber is cleaned by chemical species from the plasma.

[0032] In one example embodiment, the second processing gas can include at least one selected from a fluorine-containing gas, an oxygen-containing gas, a hydrogen-containing gas, and a nitrogen-containing gas.

[0033] In one example embodiment, the substrate processing method further includes, before the process of providing the substrate, a process of generating a plasma from a third processing gas in the chamber. In the process of generating the plasma from the third processing gas, a pre-coating film is formed on the inner wall of the chamber.

[0034] In one example embodiment, the third processing gas can include a silicon-containing gas and an oxygen-containing gas.

[0035] In another example embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a plasma generation section, and a control section. The chamber has a gas supply port and a gas exhaust port. The control section is configured to execute a process including a disposition process and an etching process. In the disposition process, a substrate having a silicon-containing film and a mask provided on the silicon-containing film is disposed in the chamber. In the etching process, a plasma is generated from a first processing gas including a hydrogen fluoride gas in the chamber and the silicon-containing film is etched. The control section is configured to control the flow rate of the hydrogen fluoride gas to be 25% or more of the total flow rate of the first processing gas excluding an inert gas in the etching process.

[0036] Various example embodiments will be described in detail below with reference to the accompanying drawings. In the drawings, like reference numerals refer to like elements throughout.

[0037] [First Embodiment]

[0038] Figure 1 is a flowchart showing an example of a substrate processing method according to the first embodiment. The method MT1 shown in Figure 1 is executed to etch a silicon-containing film. With regard to the method MT1, for example, it can be used in the manufacture of a NAND flash memory having a three-dimensional structure. With regard to the method MT1, a plasma processing apparatus is used to perform the method. Figure 2 is a diagram schematically showing an example of a plasma processing apparatus. With regard to the method MT1 shown in Figure 1 , the plasma processing apparatus 1 shown in Figure 2 can be used to perform the method.

[0039] The plasma processing apparatus 1 is provided with a chamber 10. The chamber 10 provides an internal space 10s inside thereof. The chamber 10 includes a chamber main body 12. The chamber main body 12 has a substantially cylindrical shape. The chamber main body 12 is formed of, for example, aluminum. A film having corrosion resistance is provided on the inner wall surface of the chamber main body 12. The film can be a ceramic such as aluminum oxide or yttrium oxide.

[0040] A passage 12p is formed on the side wall of the chamber main 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 side wall of the chamber main body 12.

[0041] A support portion 13 is provided on the bottom of the chamber main body 12. The support portion 13 is formed of an insulating material. The support portion 13 has a substantially cylindrical shape. The support portion 13 extends upward from the bottom of the chamber main body 12 in the internal space 10s. The support portion 13 has a support table 14 at the upper portion. The support table 14 is configured to support the substrate W in the internal space 10s.

[0042] The support table 14 has a lower electrode 18 and an electrostatic chuck 20. The support table 14 can also have an electrode plate 16. The electrode plate 16 is formed of a conductor such as aluminum and has a substantially disc shape. The lower electrode 18 is provided on the electrode plate 16. The lower electrode 18 is formed of a conductor such as aluminum and has a substantially disc shape. The lower electrode 18 is electrically connected to the electrode plate 16.

[0043] An electrostatic chuck 20 is provided on the lower electrode 18. A substrate W is placed on an upper surface of the electrostatic chuck 20. The electrostatic chuck 20 has a main body and an electrode. The main body of the electrostatic chuck 20 has a substantially disc shape and is formed of a dielectric. The electrode of the electrostatic chuck 20 is a film-shaped electrode and is provided in the main body of the electrostatic chuck 20. The electrode of the electrostatic chuck 20 is connected to a direct current power source 20p via a switch 20s. If a voltage from the direct current power source 20p is applied to the electrode of the electrostatic chuck 20, electrostatic attraction is generated between the electrostatic chuck 20 and the substrate W. The substrate W is held to the electrostatic chuck 20 by the electrostatic attraction thereof.

[0044] An edge ring 25 is arranged on a peripheral portion of the lower electrode 18 in a manner of surrounding an edge of the substrate W. The edge ring 25 improves in-plane uniformity of plasma processing of the substrate W. The edge ring 25 can be formed of silicon, silicon carbide, or quartz, or the like.

[0045] A flow path 18f is provided inside the lower electrode 18. A heat exchange medium (for example, refrigerant) is supplied to the flow path 18f from a cooler 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 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 of the heat exchange medium and the lower electrode 18.

[0046] A gas supply line 24 is provided in the plasma processing apparatus 1. The gas supply line 24 supplies a heat transfer gas (for example, He gas) from a heat transfer gas supply mechanism to between an upper surface of the electrostatic chuck 20 and a back surface of the substrate W.

[0047] The plasma processing apparatus 1 further has an upper electrode 30. The upper electrode 30 is provided above the support table 14. The upper electrode 30 is supported to an upper portion of the chamber main body 12 via a member 32. The member 32 is formed of a material having insulating properties. The upper electrode 30 and the member 32 close an upper opening of the chamber main body 12.

[0048] The upper electrode 30 can include a top plate 34 and a support body 36. A lower surface of the top plate 34 is a lower surface of one side of the internal space 10s and divides the internal space 10s. The top plate 34 can be formed of a conductor or a semiconductor having low resistance in which Joule heat is less generated. The top plate 34 has a plurality of gas discharge holes 34a that penetrate the top plate 34 in a plate thickness direction thereof.

[0049] The support body 36 supports the top plate 34 detachably. The support body 36 is formed of an electrically conductive material such as aluminum. A gas diffusion chamber 36a is provided inside the support body 36. The support body 36 has a plurality of gas holes 36b extending downward from the gas diffusion chamber 36a. The plurality of gas holes 36b respectively communicate with the plurality of gas discharge holes 34a. A gas supply port 36c is formed in the support body 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.

[0050] The valve group 42, the flow rate controller group 44, and the gas source group 40 are connected to the gas supply pipe 38. The gas supply section is constituted by the gas source group 40, the valve group 42, and the flow rate controller group 44. The gas source group 40 includes a plurality of gas sources. The valve group 42 includes a plurality of on-off valves. The flow rate controller group 44 includes a plurality of flow rate controllers. The plurality of flow rate controllers of the flow rate controller group 44 are respectively mass flow controllers or pressure control type flow rate controllers. The plurality of gas sources of the gas source group 40 are respectively connected to the gas supply pipe 38 via the corresponding on-off valve of the valve group 42 and the corresponding flow rate controller of the flow rate controller group 44.

[0051] 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 section 13. The shield 46 prevents reaction by-products from adhering to the chamber body 12. The shield 46 is constituted, for example, by forming a film having corrosion resistance on the surface of a base material formed of aluminum. The film having corrosion resistance can be formed of a ceramic such as yttrium oxide.

[0052] A baffle 48 is provided between the support section 13 and the side wall of the chamber body 12. The baffle 48 is constituted, for example, by forming a film having corrosion resistance (a film of yttrium oxide or the like) on the surface of a base material formed of aluminum. A plurality of through holes are formed in the baffle 48. A gas discharge 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 gas discharge 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.

[0053] The plasma processing apparatus 1 is provided with 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, a frequency in the range of 27 MHz to 100 MHz. The first high-frequency power supply 62 is connected to the lower electrode 18 via a matcher 66 and the electrode plate 16. The matcher 66 has a circuit for matching the output impedance of the first high-frequency power supply 62 to the impedance on the load side (the lower electrode 18 side). In addition, the first high-frequency power supply 62 can be connected to the upper electrode 30 via the matcher 66. The first high-frequency power supply 62 constitutes an example of a plasma generation section.

[0054] 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 frequency lower than that of the first high-frequency power. When used in conjunction with the first high-frequency power, the second high-frequency power serves as a bias high-frequency power for introducing ions into 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 supply 64 is connected to the lower electrode 18 via a matching adapter 68 and an 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 (the lower electrode 18 side).

[0055] Furthermore, by using a second high-frequency power instead of the first high-frequency power, 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 supply 62 and the matching device 66. The second high-frequency power supply 64 constitutes an example of a plasma generation unit.

[0056] In the plasma processing apparatus 1, gas is supplied from the gas supply unit into the internal space for 10 seconds to generate plasma. Furthermore, 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. Plasma is generated from the generated high-frequency electric field.

[0057] The plasma processing apparatus 1 may also include a control unit 80. The control unit 80 may be a computer equipped with a processor, memory, and other storage units, an input device, a display device, and signal input / output interfaces. The control unit 80 controls each part of the plasma processing apparatus 1. The control unit 80 can use the input device to perform command input operations to manage the plasma processing apparatus 1. Furthermore, the control unit 80 can visualize and display the operating status of the plasma processing apparatus 1 via the display device. Moreover, the storage unit stores control programs and recipe data. In order to perform various processes in the plasma processing apparatus 1, the control program is executed by the processor. The processor executes the control program and controls each part of the plasma processing apparatus 1 according to the recipe data.

[0058] Refer again Figure 1 The following description uses the plasma processing apparatus 1 as an example to illustrate method MT1. Figure 1 As shown, 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 and held by an electrostatic chuck 20.

[0059] Figure 3This is a partially enlarged cross-sectional view of an example substrate provided in process ST11 of method MT1. Figure 3 The substrate W shown 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 laminate containing one or more silicon oxide films and one or more silicon nitride films. Figure 3 In the example shown, film SF is a multilayer film comprising multiple silicon oxide films IL1 and multiple silicon nitride films IL2. The multiple silicon oxide films IL1 and multiple silicon nitride films IL2 are alternately stacked. Alternatively, film SF can be other single-layer films or other multilayer films comprising silicon. When film SF is a single-layer film, it can be, for example, a low-dielectric-constant film or a polycrystalline silicon film formed from SiOC, SiOF, or SiCOH. Alternatively, when film SF is a multilayer film, it can be, for example, a stacked film comprising one or more silicon oxide films and one or more polycrystalline silicon films.

[0060] A mask (MSK) is disposed on a film (SF). The mask (MSK) has a pattern for forming spaces such as holes on the film (SF). The mask (MSK) can be, for example, a hard mask. The mask (MSK) can also 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 spin-coated carbon, tungsten carbide, amorphous carbon, and boron carbide. The metal-containing mask is formed from at least one selected from titanium nitride, titanium oxide, and tungsten. Alternatively, the mask (MSK) can be, for example, a boron-containing mask formed from silicon boride, boron nitride, or boron carbide.

[0061] like Figure 1 As shown, method MT1 further includes step ST12. Step ST12 is performed after step ST11. In step ST12, plasma is generated from the first process gas within chamber 10. In step ST12, the SF film is etched using chemical species derived from the plasma.

[0062] The first processing gas used in process ST12 contains hydrogen fluoride gas. The flow rate of hydrogen fluoride gas in process ST12, relative to the total flow rate of the first processing gas excluding inert gases, can be set to 25% or more, 30% or more, or 34% or more by volume. Furthermore, hydrogen fluoride gas is highly corrosive; therefore, from the viewpoint of suppressing corrosion of the inner wall of chamber 10, the flow rate of hydrogen fluoride gas relative to the total flow rate of the first processing gas excluding inert gases can be set to less than 80% by volume, less than 78% by volume, or less than 75% by volume. In one example, the flow rate of hydrogen fluoride gas relative to the total flow rate of the first processing gas excluding inert gases is adjusted to 25% or more and less than 80% by volume. By controlling the flow rate of hydrogen fluoride gas in the first processing gas excluding inert gases within this range, the etching rate of the film SF relative to the etching rate of the mask MSK can be increased. As a result, the selectivity ratio of silicon film etching to mask etching can be improved. On the other hand, when the flow rate of hydrogen fluoride gas in the first processing gas (excluding the inert gas) is less than 25% by volume, the selectivity cannot always be adequately 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.

[0063] In addition to hydrogen fluoride gas, the first processing gas may also contain at least one selected from carbon-containing gas, oxygen-containing gas, and halogen-containing gas.

[0064] When the first processing gas contains a carbon-containing gas, a carbon-containing deposit is formed on the mask surface, thus further improving the selectivity ratio of silicon film etching to mask etching. The carbon-containing gas includes, for example, at least one selected from fluorocarbon gases, hydrofluorocarbon gases, and hydride gases. As fluorocarbon gases, for example, CF4, C2F2, C2F4, C3F8, C4F6, C4F8, or C5F8 can be used. As hydrofluorocarbon gases, for example, CHF3, CH2F2, CH3F, C2HF5, C2H2F4, C2H3F3, C2H4F2, C3HF7, C3H2F6, C3H2F4, C3H3F5, C4H5F5, and C5H2F4 can be used. 10 c-C5H3F7 or C3H2F4. As hydrocarbon gases, for example, CH4, C2H6, C3H6, C3H8, or C4H can be used. 10 In addition to the above, carbon-containing gases may also include CO and / or CO2. For example, hydrofluorocarbon gases with two or more carbon atoms can be used as carbon-containing gases. When hydrofluorocarbon gases with two or more carbon atoms are used, shape abnormalities such as bending can be effectively suppressed.

[0065] When the first processing gas contains an oxygen-containing gas, mask clogging during etching can be suppressed. As the oxygen-containing gas, at least one selected from O2, CO, CO2, H2O, or H2O2 can be used.

[0066] 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 selected from fluorine-containing gases, chlorine-containing gases, boron-containing gases, and iodine-containing gases. Examples of fluorine-containing gases include SF6, NF3, XeF2, SiF4, IF7, ClF5, BrF5, AsF5, NF5, PF3, PF5, POF3, BF3, HPF6, and WF6. Examples of chlorine-containing gases include SiCl2, SiCl4, CCl4, BCl3, PCl3, PCl5, and POCl3. Examples of bromine-containing gases include CBr2F2, C2F5Br, PBr3, PBr5, and POBr3. Examples of iodine-containing gases include HI, CF3I, C2F5I, C3F7I, IF5, IF7, I2, and PI3.

[0067] In addition to the above, the first processing gas may also contain gases with sidewall protection effects (e.g., sulfur-containing gases such as COS, P4O). 10 Phosphorus-containing gases such as P4O8, P4O6, PH3, Ca3P2, H3PO4, and Na3PO4, and boron-containing gases such as B2H6.

[0068] In addition to these gas types, the first processing gas may also include inert gases. As inert gases, besides nitrogen-containing gases, rare gases such as Ar, Kr, and Xe can be used. However, the first processing gas is controlled in such a manner that the flow rate of hydrogen fluoride gas is in the ratio described above to the total flow rate of the first processing gas excluding these inert gases.

[0069] 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 25% 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 reaches 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 the first high-frequency power and / or the second high-frequency power to generate plasma from the processing gas within the chamber 10.

[0070] In process ST12, in order to introduce ions from plasma into the substrate W, the second high-frequency power supply 64 can deliver 5W / cm². 2The second high-frequency power (i.e., the bias high-frequency power) is supplied to the lower electrode 18. This is achieved at 5 W / cm². 2 The second high-frequency power mentioned above allows ions from the plasma to fully reach the space of the SF film formed by etching (e.g., Figure 4 The bottom of the space SP shown. Alternatively, instead of high-frequency power for bias, a negative DC voltage can be applied to the lower electrode 18. Moreover, the high-frequency power for bias or the negative DC voltage can be applied to the lower electrode 18 in a pulsed manner. In this case, the pulse frequency can be set to 5Hz to 100kHz.

[0071] There are no particular restrictions on the temperature of the electrostatic chuck in process ST12. However, by adjusting the temperature of the electrostatic chuck to a low temperature (e.g., below 0°C or below -50°C) before starting process ST12, the adsorption of etchant on the substrate surface can be promoted, thereby increasing the etching rate.

[0072] If the execution of process ST12 is completed, then method MT1 ends. Figure 4 It is being executed Figure 1 This is a partially enlarged cross-sectional view of an example substrate after the substrate processing method shown. By performing method MT1, as... Figure 4 As shown, a space SP is formed on the membrane SF, for example, extending to the substrate layer UL.

[0073] The following describes the experimental results conducted to evaluate method MT1. In the experiment, samples were prepared... Figure 3 Eight sample substrates identical to the substrate W shown were used. In the experiment, plasma etching of the SF film on the eight sample substrates was performed using plasma processing apparatus 1. A first processing gas containing carbon-containing gas was used in the plasma etching. The first processing gas used in the plasma etching of the first sample substrate did not contain hydrogen fluoride gas. In the plasma etching of the second to eighth sample substrates, the flow rates of hydrogen fluoride gas 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 the experiment, the temperature of the electrostatic chuck holding the sample substrates was adjusted to below -50°C before starting the plasma etching.

[0074] In the experiment, the selectivity ratio of film SF etching to mask MSK etching was determined based on the plasma etching results of the film SF on eight sample substrates. Specifically, the selectivity ratio was determined by dividing the etching rate of film SF by the etching rate of mask MSK based on the plasma etching results of the film SF on the eight sample substrates.

[0075] The experimental results are shown inFigure 5 middle. Figure 5 It means in order to evaluate Figure 1 The graph shows the experimental results obtained using the substrate processing method illustrated. Figure 5 In the chart, the horizontal axis represents the flow ratio. The flow ratio is the proportion (by volume) of hydrogen fluoride gas flow rate in the total flow rate of the first treatment gas (excluding inert gases). Figure 5 In the chart, the vertical axis represents the selection ratio. Figure 5 In the text, reference symbols P1 to P8 represent the selection ratios determined based on the plasma etching results of the SF film on the 1st to 8th sample substrates.

[0076] like Figure 5 As shown, the experimental results confirm that the selectivity increases with the ratio of the flow rate of hydrogen fluoride gas to the total flow rate of the first treatment gas (excluding inert gases) (hereinafter referred to as the "flow rate ratio"). Furthermore, according to... Figure 5 It can be seen that when the flow rate of hydrogen fluoride gas accounts for more than 25% by volume of the total flow rate of the first processing gas excluding inert gases, a selectivity of 4 or higher can be obtained.

[0077] [Second Implementation]

[0078] 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 stage 14 increases. If the amount of reaction products adhering increases, the processing environment changes, and therefore sometimes the uniformity of processing between the substrates W deteriorates. Furthermore, the increase in the amount of reaction products adhering becomes a major cause of particulate matter generation. Therefore, plasma obtained by plasmaifying a cleaning gas is used to clean the chamber.

[0079] Figure 6 This is a flowchart illustrating an example of the substrate processing method according to the second embodiment. Similar to method MT1, the following steps are performed: Figure 6 The method MT2 shown is used to etch a silicon-containing film. Steps ST21 and ST22 are the same as steps ST11 and ST12 of the method MT1 described above, so their description is omitted.

[0080] like Figure 6As shown, method MT2 also includes step ST23. Step ST23 is performed after step ST22. In step ST23, plasma is generated within chamber 10 by a second processing gas. In step ST23, 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 to conventional techniques, the cleaning time can be reduced to less than 50%, and the throughput of substrate processing can be improved.

[0081] The second processing gas used in step ST23 may include at least one selected from fluorine-containing gases, oxygen-containing gases, hydrogen-containing gases, and nitrogen-containing gases. For example, CF4, SF6, or NF3 can be used as a fluorine-containing gas. For example, O2, CO, CO2, H2O, or H2O2 can be used as an oxygen-containing gas. For example, H2 or HCl can be used as a hydrogen-containing gas. For example, N2 can be used as a nitrogen-containing gas. In addition to the above, the second processing gas may include rare gases such as Ar.

[0082] Step ST23 can be performed on each substrate W processed, or it can be performed after processing a specified number of substrates W or a specified batch number. Alternatively, it can be performed after substrate processing for a specified time.

[0083] [Third Implementation]

[0084] In both the first and second embodiments, hydrogen fluoride gas is included in the first processing gas. Hydrogen fluoride gas is highly corrosive; therefore, it is preferable to form a pre-coating film on the inner wall of the chamber 10 before the etching process. In particular, when using hydrogen fluoride gas at a high concentration, forming a pre-coating film on the inner wall of the chamber 10 suppresses corrosion of the inner wall, thereby reducing maintenance frequency. The inner wall of the chamber 10 includes a support platform 14, etc., except for the side walls and ceiling (top plate 34 of the upper electrode 30).

[0085] Besides silicon-containing films such as silicon oxide films, the pre-coated film can be formed from a material of the same type as the mask MSK. When the mask MSK is a carbon-containing mask, the pre-coated film can be formed from a carbon-containing material. The carbon-containing material includes, for example, at least one selected from spin-coated carbon, tungsten carbide, amorphous carbon, and boron carbide. When the mask MSK is a metal-containing mask, the pre-coated film can be formed from a metal-containing material. The metal-containing material includes, for example, at least one selected from titanium nitride, titanium oxide, and tungsten. Furthermore, when the mask MSK is a boron-containing mask, the pre-coated film is formed from a boron-containing material. The boron-containing material includes, for example, at least one selected from the group consisting of silicon boride, boron nitride, and boron carbide.

[0086] Figure 7 This is a flowchart illustrating an example of the substrate processing method according to the third embodiment. Similar to method MT1, the following steps are performed: Figure 7 The method MT3 shown is used to etch a silicon-containing film. Steps ST31 and ST32 are the same as steps ST11 and ST12 of the method MT1 described above, so their description is omitted.

[0087] like Figure 7 As shown, method MT3 further includes step ST30. Step ST30 is performed before step ST31. In step ST30, plasma is generated within chamber 10 by a third process gas. In step ST30, a pre-coated film is formed on the inner wall of chamber 10 by chemical species from the plasma.

[0088] Regarding the pre-coated film, a third processing gas can be used, and it can be formed by Chemical Vapor Deposition (CVD) or Atomic Layer Deposition (ALD). For example, in the case of forming a silicon oxide film as the pre-coated film, silicon-containing gases such as SiCl4 or aminosilane-based gases and oxygen-containing gases such as O2 can be used as the third processing gas.

[0089] Step ST30 can be performed on each substrate W processed, or it can be performed after processing a specified number of substrates W or a specified batch number. Alternatively, it can be performed after substrate processing for a specified time.

[0090] In addition, according to Figure 8 In another example of the substrate processing method of the third embodiment, the step of forming the pre-coating film can be performed in combination with the cleaning step. This allows for the simultaneous suppression of particulate generation and corrosion of the inner wall of the chamber 10.

[0091] The above descriptions of various exemplary embodiments are not limited to these embodiments, and various omissions, substitutions, and modifications are possible. Furthermore, elements from different exemplary embodiments can be combined to form other exemplary embodiments.

[0092] For example, the plasma processing apparatus used in methods MT1 to MT4 can be a different plasma processing apparatus from plasma processing apparatus 1. The plasma processing apparatus used in methods MT1 to MT4 can 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.

[0093] 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 varied depending on the processing stage. In one example, the flow rate ratio of hydrogen fluoride gas at the end of etching when mask thickness maintenance is not required can be set lower than the flow rate ratio of hydrogen fluoride gas during the initial to middle stages of etching when mask thickness maintenance is required. In other examples, during etching of low aspect ratio regions prone to shape abnormalities such as bending, the flow rate ratio of a gas with sidewall protection effect can be increased compared to etching of high aspect ratio regions. 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 adjusted according to the shape.

[0094] As can be understood from the above description, various exemplary embodiments of the present invention have been described in this specification for illustrative purposes, and various modifications can be made without departing from the scope and spirit of the invention. Therefore, the invention is not limited to the various exemplary embodiments disclosed in this specification, and the true scope and spirit are indicated by the appended claims.

Claims

1. A plasma processing device, characterized in that, include: Chamber; A support platform that supports a substrate within the cavity; A gas supply unit is configured to supply a first processing gas containing hydrogen fluoride gas into the chamber. The plasma generation unit is configured to generate plasma from the first processed gas; and Control Department The control unit performs a process including the following steps by controlling the gas supply unit and the plasma generation unit: (a) A process of placing a substrate having a silicon-containing film and a mask disposed on the silicon-containing film on the support platform; and (b) The step of forming pores on the silicon-containing film by generating plasma from the first processing gas. In (b), the flow rate of the hydrogen fluoride gas is controlled such that it is 25% or more by volume relative to the total flow rate of the first processing gas excluding the inactive gas.

2. The plasma processing apparatus according to claim 1, characterized in that, The substrate includes a base layer. The silicon-containing film is disposed on the substrate layer. The control unit controls the gas supply unit and the plasma generation unit so that step (b) is performed after step (a) until the hole reaches the substrate layer.

3. The plasma processing apparatus according to claim 1, characterized in that, The support platform includes electrodes connected to a power supply for supplying high-frequency power for biasing. The control unit controls the power supply in (b) to supply the bias high-frequency power to the electrode, thereby supplying ions from the plasma to the bottom of the aperture.

4. The plasma processing apparatus according to claim 1, characterized in that, The support platform includes electrodes connected to a power supply for supplying a pulsed DC voltage for biasing. The control unit controls the power supply in (b) to supply the pulsed DC voltage to the electrode, thereby supplying ions from the plasma to the bottom of the hole.

5. The plasma processing apparatus according to claim 1, wherein, The first processing gas contains at least one selected from fluorocarbon gas, hydrofluorocarbon gas, and hydrocarbon gas.

6. The plasma processing apparatus according to claim 1, wherein, The first processed gas contains halogenated gas.

7. The plasma processing apparatus according to claim 6, wherein, The halogenated gas includes chlorine-containing gas.

8. The plasma processing apparatus according to claim 6, wherein, The halogen-containing gas includes bromine-containing gas.

9. The plasma processing apparatus according to claim 1, characterized in that, The mask is a hard mask.

10. The plasma processing apparatus according to claim 9, wherein, The mask is a carbon-containing mask, a metal-containing mask, or a boron-containing mask.

11. The plasma processing apparatus according to claim 1, characterized in that, The silicon-containing film is a laminated film comprising one or more silicon oxide films and one or more silicon nitride films.

12. The plasma processing apparatus according to claim 1, characterized in that, The silicon-containing film is a laminated film comprising one or more silicon oxide films and one or more polycrystalline silicon films.

13. A plasma processing apparatus, characterized in that, include: Chamber; A support stage that supports a substrate within the cavity, the substrate comprising a silicon-containing film; A gas supply unit configured to supply a first processing gas containing hydrogen fluoride gas into the chamber, wherein the gas supply unit supplies the first processing gas such that the flow rate of the hydrogen fluoride gas is 25% or more by volume relative to the total flow rate of the first processing gas excluding inert gases; and The plasma generation unit is configured to form pores on the silicon-containing film by generating plasma from the first processing gas.

14. The plasma processing apparatus according to claim 13, characterized in that, The support platform includes electrodes connected to a power supply for supplying high-frequency power or pulsed DC voltage for biasing. During the generation of the plasma, ions from the plasma are supplied to the bottom of the aperture by the high-frequency power or the pulsed DC voltage supplied to the electrode.

15. The plasma processing apparatus according to claim 13, wherein, The support platform includes a flow path connected to the cooling unit and supplied with a heat exchange medium. During the generation of the plasma, the temperature of the support platform is adjusted to below 0°C using the heat exchange medium.

16. The plasma processing apparatus according to claim 13, wherein, The gas supply unit includes a flow controller assembly. The flow rate of the hydrogen fluoride gas is controlled relative to the total flow rate of the first processing gas, excluding the inert gas, by the flow controller group.

17. The plasma processing apparatus according to claim 16, characterized in that, The flow controller group consists of either a mass flow controller or a pressure control flow controller.

18. A substrate processing method, comprising: (a) A process of providing a substrate having a silicon-containing film and a mask disposed on the silicon-containing film into a cavity; as well as (b) The step of generating plasma from a first processing gas containing hydrogen fluoride gas within the chamber to form pores on the silicon-containing film. The flow rate of the hydrogen fluoride gas is 25% or more by volume relative to the total flow rate of the first processing gas excluding the inert gas.

19. The substrate processing method according to claim 18, characterized in that, The substrate includes a base layer. The silicon-containing film is disposed on the substrate layer. Step (b) is performed after step (a) until the hole reaches the base layer.

20. The substrate processing method according to claim 18, characterized in that, In (a), the substrate is provided onto a support platform including electrodes connected to a power supply for supplying high-frequency power or pulsed DC voltage for biasing. In (b), ions from the plasma are supplied to the bottom of the aperture by the high-frequency power or the pulsed DC voltage supplied to the electrode.

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