Substrate processing method and plasma processing device

Abstract

The present invention provides a technique for improving the selectivity of etching a silicon-containing film relative to etching a mask during plasma etching. A substrate processing method according to an exemplary embodiment includes providing a substrate into a chamber of a plasma processing apparatus. The substrate includes a silicon-containing film and a mask disposed on the silicon-containing film. The substrate processing method also includes generating plasma in the chamber from a first processing gas containing hydrogen fluoride gas. In the plasma generating step, the film is etched by chemical species from the plasma. The flow rate of the hydrogen fluoride gas is 25% by volume or more relative to the total flow rate of the first processing gas excluding the inert gas.

Description

Technical Field

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

[0002] Patent Document 1 discloses a method for etching a film within a substrate. The film comprises silicon, and the substrate further includes a mask disposed on the film. The mask comprises amorphous carbon or an organic polymer. Etching in this method utilizes plasma generated from a process gas comprising hydrocarbon gas and hydrofluorocarbon gas.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2016-39310

[0004] The present invention provides a technique for improving the selectivity between etching of a silicon-containing film and etching of a mask during plasma etching. Summary of the Invention

[0005] In one exemplary embodiment, a substrate processing method is provided. The substrate processing method includes providing a substrate into a chamber of a plasma processing apparatus. The substrate includes a silicon-containing film and a mask disposed on the silicon-containing film. The substrate processing method also includes generating plasma in the chamber from a first processing gas including hydrogen fluoride gas. During the plasma generation step, the silicon-containing film is etched by chemical species from the plasma. The flow rate of the hydrogen fluoride gas is 25% by volume or greater relative to the total flow rate of the first processing gas excluding the inert gas.

[0006] Effects of the Invention

[0007] According to the present invention, it is possible to provide a technique for improving the selectivity between etching of a silicon-containing film and etching of a mask during plasma etching. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a flowchart showing an example of the substrate processing method according to the first embodiment.

[0009] Figure 2 This is a diagram schematically showing an example of a plasma processing apparatus.

[0010] Figure 3 This is a partially enlarged cross-sectional view of an example of a substrate provided in step ST11.

[0011] Figure 4 Is executing Figure 1 A partially enlarged cross-sectional view of an example substrate after the substrate processing method is shown.

[0012] Figure 5 It means for evaluation Figure 1A graph showing the experimental results of the substrate processing method shown.

[0013] Figure 6 This is a flowchart showing an example of a substrate processing method according to the second embodiment.

[0014] Figure 7 This is a flowchart showing an example of a substrate processing method according to the third embodiment.

[0015] Figure 8 This is a flowchart showing another example of the substrate processing method according to the third embodiment.

[0016] Explanation of symbols

[0017] 1 Plasma treatment device

[0018] 10 chambers

[0019] W substrate

[0020] SF membrane

[0021] MSK Mask DETAILED DESCRIPTION

[0022] Various exemplary embodiments are described below.

[0023] In an exemplary embodiment, a substrate processing method is provided. The substrate processing method includes a process 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 also includes a process of generating plasma from a first processing gas containing hydrogen fluoride gas in the chamber. In the process of generating plasma, the silicon-containing film is etched by chemical species from the plasma. The flow rate of the hydrogen fluoride gas is 25% by volume or more relative to the total flow rate of the first processing gas excluding the inert gas. According to this embodiment, the selectivity of etching the silicon-containing film to etching the mask is improved by using a plasma generated by a first processing gas having a flow rate of the hydrogen fluoride gas of 25% by volume or more relative to the total flow rate excluding the inert gas.

[0024] In an exemplary embodiment, the flow rate of the hydrogen fluoride gas may be less than 80 volume % relative to the total flow rate of the first process gas excluding the inert gas.

[0025] In an exemplary embodiment, the first process gas includes at least one selected from a carbon-containing gas, an oxygen-containing gas, and a halogen-containing gas.

[0026] In an exemplary embodiment, the carbon-containing gas may include at least one selected from the group consisting of fluorocarbon gas, hydrofluorocarbon gas, and hydrocarbon gas.

[0027] In one exemplary embodiment, the silicon-containing film may be at least one selected from a stacked film including a silicon oxide film and a silicon nitride film, a polysilicon film, a low dielectric constant film, and a stacked film including a silicon oxide film and a polysilicon film.

[0028] In an exemplary embodiment, the mask may be a carbon-containing mask or a metal-containing mask.

[0029] In an exemplary embodiment, the carbon-containing mask may be formed of at least one selected from spin-on carbon, tungsten carbide, amorphous carbon, and boron carbide.

[0030] In one exemplary embodiment, the substrate processing method further includes generating plasma from the second process gas in the chamber. In the generating plasma from the second process gas, chemical species from the plasma are used to clean the interior of the chamber.

[0031] In an exemplary embodiment, the second process gas may include at least one selected from the group consisting of a fluorine-containing gas, an oxygen-containing gas, a hydrogen-containing gas, and a nitrogen-containing gas.

[0032] In one exemplary embodiment, the substrate processing method further includes generating plasma from a third process gas in the chamber before providing the substrate. In the step of generating plasma from the third process gas, a pre-coating film is formed on the inner wall of the chamber.

[0033] In an exemplary embodiment, the third process gas may include a silicon-containing gas and an oxygen-containing gas.

[0034] In another exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a plasma generating unit, and a control unit. The chamber includes a gas supply port and a gas exhaust port. The control unit is configured to perform a process including a configuration step and an etching step. In the configuration step, a substrate including a silicon-containing film and a mask disposed on the silicon-containing film is configured in the chamber. In the etching step, plasma is generated in the chamber from a first processing gas including hydrogen fluoride gas, and the silicon-containing film is etched. The control unit is configured to control the etching step so that the flow rate of the hydrogen fluoride gas is 25% by volume or more relative to the total flow rate of the first processing gas excluding the inert gas.

[0035] Hereinafter, various exemplary embodiments will be described in detail with reference to the accompanying drawings. In addition, in each of the drawings, the same or equivalent parts are marked with the same symbols.

[0036] [First embodiment]

[0037] Figure 1 1 is a flowchart showing an example of a substrate processing method according to the first embodiment. Figure 1The method MT1 shown is used to etch a silicon-containing film. The method MT1 can be used, for example, in the manufacture of a NAND flash memory having a three-dimensional structure. The method MT1 is performed using a plasma processing apparatus. Figure 2 This is a diagram schematically showing an example of a plasma processing apparatus. Figure 1 The method shown in MT1 can be used Figure 2 The plasma processing device 1 shown is used to perform the process.

[0038] The plasma processing apparatus 1 includes a chamber 10. The chamber 10 defines an internal space 10s. 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, from aluminum. A corrosion-resistant film is provided on the inner wall surface of the chamber body 12. The film may be made of a ceramic such as aluminum oxide or yttrium oxide.

[0039] A passage 12p is formed on a side wall of the chamber body 12. The substrate W is transferred between the internal space 10s and the outside of the chamber 10 through the passage 12p. The passage 12p is opened and closed by a gate valve 12g provided along the side wall of the chamber body 12.

[0040] A support portion 13 is provided at 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 top. The support platform 14 is configured to support the substrate W within the internal space 10s.

[0041] The support platform 14 includes a lower electrode 18 and an electrostatic chuck 20. The support platform 14 may also include an electrode plate 16. Electrode plate 16 is formed of a conductor such as aluminum and has a generally disc-shaped shape. Lower electrode 18 is disposed on electrode plate 16. Lower electrode 18 is formed of a conductor such as aluminum and has a generally disc-shaped shape. Lower electrode 18 is electrically connected to electrode plate 16.

[0042] The 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 main body and electrodes. The main body of the electrostatic chuck 20 has a roughly disc-shaped structure and is formed of a dielectric. The electrodes of the electrostatic chuck 20 are film-shaped electrodes and are disposed within the main body of the electrostatic chuck 20. The 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 electrodes of the electrostatic chuck 20, an electrostatic attraction is generated between the electrostatic chuck 20 and the substrate W. The substrate W is held on the electrostatic chuck 20 by this electrostatic attraction.

[0043] An edge ring 25 is disposed on the periphery of the lower electrode 18 so as to surround the edge of the substrate W. The edge ring 25 improves the in-plane uniformity of plasma processing on the substrate W. The edge ring 25 can be formed of silicon, silicon carbide, quartz, or the like.

[0044] A flow path 18f is provided within the lower electrode 18. A heat exchange medium (e.g., refrigerant) is supplied to the flow path 18f via a pipe 22a from a cooler unit (not shown) located outside the chamber 10. 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 between the heat exchange medium and the lower electrode 18.

[0045] The plasma processing apparatus 1 is provided with a gas supply line 24. The gas supply line 24 supplies a heat transfer gas (for example, He gas) from a heat transfer gas supply mechanism to a position between the upper surface of the electrostatic chuck 20 and the back surface of the substrate W.

[0046] The plasma processing apparatus 1 further includes an upper electrode 30 . The upper electrode 30 is disposed above the support table 14 . The upper electrode 30 is supported on the upper portion 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 .

[0047] The upper electrode 30 may include a top plate 34 and a support 36. The lower surface of the top plate 34 forms the lower surface of one side of the internal space 10s and defines the internal space 10s. The top plate 34 may be formed of a low-resistance conductor or semiconductor that generates little Joule heat. The top plate 34 has a plurality of gas exhaust holes 34a extending through the top plate 34 along its thickness.

[0048] The support body 36 is detachably supported on the top plate 34. The support body 36 is formed of a conductive material such as aluminum. A gas diffusion chamber 36a is provided within 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 are each connected to the plurality of gas exhaust 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.

[0049] A valve assembly 42, a flow controller assembly 44, and a gas source assembly 40 are connected to the gas supply pipe 38. The gas source assembly 40, the valve assembly 42, and the flow controller assembly 44 constitute a gas supply unit. The gas source assembly 40 includes multiple gas sources. The valve assembly 42 includes multiple on-off valves. The flow controller assembly 44 includes multiple flow controllers. The multiple flow controllers in the flow controller assembly 44 are either mass flow controllers or pressure-controlled flow controllers. The multiple gas sources in the gas source assembly 40 are connected to the gas supply pipe 38 via corresponding on-off valves in the valve assembly 42 and corresponding flow controllers in the flow controller assembly 44.

[0050] In the plasma processing apparatus 1, a shield 46 is detachably provided along the inner wall surface of the chamber body 12 and the outer periphery of the support portion 13. The shield 46 prevents reaction byproducts from adhering to the chamber body 12. The shield 46 is formed, 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 a ceramic such as yttrium oxide.

[0051] A baffle 48 is provided between the support portion 13 and the sidewall of the chamber body 12. The baffle 48 is formed, for example, by forming a corrosion-resistant film (e.g., a film of yttrium oxide) on the surface of a base material formed of aluminum. Multiple through-holes are formed in the baffle 48. A gas 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 gas exhaust port 12e via an exhaust pipe 52. The exhaust device 50 includes a pressure regulating valve and a vacuum pump such as a turbomolecular pump.

[0052] The plasma processing apparatus 1 includes a first high-frequency power supply 62 and a second high-frequency power supply 64. The first high-frequency power supply 62 is a power supply for generating 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 matching box 66 and an electrode plate 16. The matching box 66 has a circuit for matching the output impedance of the first high-frequency power supply 62 with the impedance of 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 matching box 66. The first high-frequency power supply 62 constitutes an example of a plasma generating unit.

[0053] The second high-frequency power supply 64 is a power supply for generating a second high-frequency power. The second high-frequency power has a frequency lower than that of the first high-frequency power. When the second high-frequency power is used together with the first high-frequency power, the second high-frequency power is used as a bias high-frequency power for introducing ions into the substrate W. The frequency of the second high-frequency power is, for example, a frequency 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 the matching unit 68 and the electrode plate 16. The matching unit 68 has a circuit for matching the output impedance of the second high-frequency power supply 64 with the impedance of the load side (the lower electrode 18 side).

[0054] Alternatively, plasma can be generated using the second high-frequency power source instead of the first high-frequency power source, that is, 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 does not need to include the first high-frequency power source 62 and the matching unit 66. The second high-frequency power source 64 constitutes an example of a plasma generating unit.

[0055] In the plasma processing apparatus 1 , gas is supplied from a gas supply unit into the internal space 10s to generate plasma. Furthermore, by supplying first and / or 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.

[0056] The plasma processing apparatus 1 may further include a control unit 80. The control unit 80 may be a computer including a processor, a storage unit such as a memory, an input device, a display device, a signal input / output interface, and the like. The control unit 80 controls the various components of the plasma processing apparatus 1. In the control unit 80, the input device can be used to input instructions to manage the plasma processing apparatus 1. Furthermore, in the control unit 80, the operating status of the plasma processing apparatus 1 can be visualized and displayed using a display device. Furthermore, a control program and recipe data are stored in the storage unit. 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 the various components of the plasma processing apparatus 1 according to the recipe data.

[0057] Reference again Figure 1 Hereinafter, the method MT1 will be described by taking the case where the plasma processing apparatus 1 is used in the execution as an example. Figure 1 As shown, method MT1 includes step ST11 . In step ST11 , a substrate W is provided into chamber 10 of a plasma processing apparatus. The substrate W is placed on electrostatic chuck 20 and held by electrostatic chuck 20 .

[0058] Figure 3This is a partially enlarged cross-sectional view of an example of a substrate provided in step ST11 of method MT1. Figure 3 The substrate W shown includes a base layer UL, a film SF, and a mask MSK. The base layer UL may be a layer made of polycrystalline silicon. The film SF is provided on the base layer UL. The film SF contains silicon. The film SF may be a laminated film including one or more silicon oxide films and one or more silicon nitride films. Figure 3 In the example shown, film SF is a multilayer film including multiple silicon oxide films IL1 and multiple silicon nitride films IL2. Multiple silicon oxide films IL1 and multiple silicon nitride films IL2 are alternately stacked. Alternatively, film SF may be another single-layer film including silicon or another multilayer film including silicon. If film SF is a single-layer film, it may be, for example, a low-dielectric-constant film made of SiOC, SiOF, SiCOH, or the like, or a polycrystalline silicon film. Alternatively, if film SF is a multilayer film, it may be, for example, a stacked film including one or more silicon oxide films and one or more polycrystalline silicon films.

[0059] Mask MSK is disposed on film SF. Mask MSK has a pattern for forming spaces such as holes in film SF. Mask MSK may be, for example, a hard mask. Mask MSK may also be, for example, a carbon-containing mask and / or a metal-containing mask. Carbon-containing masks are, for example, formed from at least one selected from spin-on carbon, tungsten carbide, amorphous carbon, and boron carbide. Metal-containing masks are formed from at least one selected from titanium nitride, titanium oxide, and tungsten. Alternatively, mask MSK may be a boron-containing mask, for example, formed from silicon boride, boron nitride, or boron carbide.

[0060] 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 in chamber 10. In step ST12, film SF is etched by chemical species from the plasma.

[0061] The first processing gas used in step ST12 includes hydrogen fluoride gas. The flow rate of the hydrogen fluoride gas in step ST12 can be set to 25% by volume or more, 30% by volume or more, or 34% by volume or more relative to the total flow rate of the first processing gas excluding the inert gas. Furthermore, hydrogen fluoride gas is highly corrosive, so from the perspective of suppressing corrosion of the inner wall of chamber 10, the flow rate of the hydrogen fluoride gas can be set to less than 80% by volume, less than 78% by volume, or less than 75% by volume relative to the total flow rate of the first processing gas excluding the inert gas. In one example, the flow rate of the hydrogen fluoride gas is adjusted to be greater than 25% by volume and less than 80% by volume relative to the total flow rate of the first processing gas excluding the inert gas. By controlling the flow rate of the hydrogen fluoride gas in the first processing gas excluding the inert gas within 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 between the etching of the silicon-containing film and the etching of the mask can be improved. On the other hand, if the flow rate of hydrogen fluoride gas in the first process gas excluding the inert gas is less than 25% by volume, the selectivity may not be sufficiently improved. Furthermore, the total flow rate of the first process gas excluding the inert gas can be appropriately adjusted according to the chamber volume. For example, it can be set to 100 sccm or higher.

[0062] In addition to the hydrogen fluoride gas, the first process gas may include at least one selected from the group consisting of a carbon-containing gas, an oxygen-containing gas, and a halogen-containing gas.

[0063] When the first processing gas includes a carbon-containing gas, a deposit containing carbon is formed on the mask surface, thereby further improving the selectivity between the etching of the silicon-containing film and the etching of the mask. The carbon-containing gas includes, for example, at least one selected from a fluorocarbon gas, a hydrofluorocarbon gas, and a hydrocarbon gas. As the fluorocarbon gas, for example, CF4, C2F2, C2F4, C3F8, C4F6, C4F8, or C5F8 can be used. As the hydrofluorocarbon gas, for example, CHF3, CH2F2, CH3F, C2HF5, C2H2F4, C2H3F3, C2H4F2, C3HF7, C3H2F6, C3H2F4, C3H3F5, C4H5F5, C5H2F 10 , c-C5H3F7 or C3H2F4. As the hydrocarbide gas, for example, CH4, C2H6, C3H6, C3H8 or C4H 10 In addition to the above, the carbon-containing gas may also contain CO and / or CO2. In one example, a hydrofluorocarbon gas having a carbon number of 2 or more can be used as the carbon-containing gas. When a hydrofluorocarbon gas having a carbon number of 2 or more is used, shape abnormalities such as warping can be effectively suppressed.

[0064] When the first processing gas contains an oxygen-containing gas, clogging of the mask during etching can be suppressed. As the oxygen-containing gas, for example, at least one selected from O2, CO, CO2, H2O, or H2O2 can be used.

[0065] When the first processing gas includes a halogen-containing gas, the etching profile can be controlled. As the halogen-containing gas, for example, at least one selected from a fluorine-containing gas, a chlorine-containing gas, a boron-containing gas, and an iodine-containing gas can be used. Fluorine-containing gases include, for example, SF6, NF3, XeF2, SiF4, IF7, ClF5, BrF5, AsF5, NF5, PF3, PF5, POF3, BF3, HPF6, and WF6. Chlorine-containing gases include, for example, SiCl2, SiCl4, CCl4, BCl3, PCl3, PCl5, and POCl3. Bromine-containing gases include, for example, CBr2F2, C2F5Br, PBr3, PBr5, and POBr3. Iodine-containing gases include, for example, HI, CF3I, C2F5I, C3F7I, IF5, IF7, I2, and PI3.

[0066] In addition to the above, the first processing gas may also contain a gas having a sidewall protection effect (for example, sulfur-containing gas such as COS, P4O 10 , P4O8, P4O6, PH3, Ca3P2, H3PO4, Na3PO4 and other phosphorus-containing gases, B2H6 and other boron-containing gases).

[0067] In addition to these gas types, the first process gas may also contain an inert gas. In addition to nitrogen-containing gases, noble gases such as Ar, Kr, and Xe can be used as inert gases. However, the first process gas is controlled so that the flow rate of hydrogen fluoride gas relative to the total flow rate of the first process gas excluding these inert gases reaches the aforementioned ratio.

[0068] To perform step ST12, the control unit 80 controls the gas supply unit to supply the aforementioned process gas into the chamber 10. To perform step ST12, the control unit 80 controls the gas supply unit so that the flow rate of hydrogen fluoride gas in the process gas supplied into the chamber 10 is at least 25% by volume of the total flow rate of the process gas. To perform step ST12, the control unit 80 controls the exhaust device 50 so that the pressure within the chamber 10 reaches a specified pressure. To perform step ST12, the control unit 80 controls the first high-frequency power supply 62 and / or the second high-frequency power supply 64 to supply the first high-frequency power and / or the second high-frequency power to generate plasma from the process gas within the chamber 10.

[0069] In step ST12, in order to draw ions from the plasma to the substrate W, the second high frequency power supply 64 may be 5 W / cm 2The second high frequency power (ie, bias high frequency power) is supplied to the lower electrode 18. 2 With the second high frequency power as described above, ions from the plasma can sufficiently reach the space (for example, Figure 4 The bottom of the space SP shown in FIG. Alternatively, a negative DC voltage may be applied to the lower electrode 18 instead of the high-frequency bias power. Furthermore, the high-frequency bias power or the negative DC voltage may be applied to the lower electrode 18 in a pulsed manner. In this case, the pulse frequency may be set to 5 Hz to 100 kHz.

[0070] The temperature of the electrostatic chuck in step ST12 is not particularly limited. However, by adjusting the temperature of the electrostatic chuck to a low temperature (e.g., below 0°C or below -50°C) before starting step ST12, the adsorption of the etchant on the substrate surface is promoted, thereby increasing the etching rate.

[0071] When the execution of step ST12 is completed, the method MT1 ends. Figure 4 Is executing Figure 1 A partial enlarged cross-sectional view of an example of a substrate after the substrate processing method shown in FIG. Figure 4 As shown, a space SP reaching the base layer UL is formed on the film SF, for example.

[0072] The following describes the experimental results for evaluating the method MT1. Figure 3 Eight sample substrates identical to the substrate W shown are shown. In the experiment, plasma etching of the films SF of the eight sample substrates was performed using the plasma processing apparatus 1. In the plasma etching, a first processing gas containing a carbon-containing gas was used. The first processing gas used in the plasma etching of the first sample substrate among the eight sample substrates did not contain hydrogen fluoride gas. In the plasma etching of the second to eighth sample substrates, the flow ratio of the flow rate of hydrogen fluoride gas to the total flow rate of the first processing gas was 34.2 volume %, 51.0 volume %, 80.0 volume %, 95.2 volume %, 98.8 volume %, 99.5 volume % and 100 volume %, respectively. In addition, in the experiment, before starting the plasma etching, the temperature of the electrostatic chuck on which the sample substrates were placed was adjusted to a temperature below -50°C.

[0073] In the experiment, the selectivity between the etching rate of the film SF and the etching rate of the mask MSK was determined based on the plasma etching results of the film SF on eight sample substrates. Specifically, the selectivity was calculated by dividing the etching rate of the film SF by the etching rate of the mask MSK based on the plasma etching results of the film SF on eight sample substrates.

[0074] The experimental results are shown in Figure 5 middle. Figure 5 It means for evaluation Figure 1 The results of experiments performed using the substrate processing methods shown in FIG. Figure 5 In the graph, the horizontal axis represents the flow ratio. The flow ratio is the ratio (volume %) of the flow rate of hydrogen fluoride gas to the total flow rate of the first processing gas excluding the inert gas. Figure 5 In the graph of , the vertical axis represents the selection ratio. Figure 5 In FIG. 1 , reference symbols P1 to P8 denote selectivities obtained from the results of plasma etching of the film SF on the first to eighth sample substrates.

[0075] like Figure 5 As shown in FIG. 1 , the experimental results show that the selectivity increases with the increase in the ratio of the flow rate of the hydrogen fluoride gas to the total flow rate of the first process gas excluding the inert gas (hereinafter referred to as the “flow rate ratio”). Figure 5 It can be seen that when the flow rate of hydrogen fluoride gas accounts for 25 volume % or more of the total flow rate of the first process gas excluding the inert gas, a selectivity of 4 or more can be obtained.

[0076] [Second embodiment]

[0077] In the substrate processing method of the first embodiment, as the number of processes increases, the amount of reaction products deposited on the inner walls of the chamber 10 or the support table 14 increases. This increased amount of reaction products changes the processing environment, potentially degrading processing uniformity across substrates W. Furthermore, the increased amount of reaction products can be a major factor in the generation of particles. Therefore, the chamber interior is cleaned using plasma generated by converting a cleaning gas into plasma.

[0078] Figure 6 This is a flowchart showing an example of a substrate processing method according to the second embodiment. Figure 6 The method MT2 shown is for etching the silicon-containing film. Steps ST21 and ST22 are the same as steps ST11 and ST12 of the method MT1 described above, and therefore their description is omitted.

[0079] like Figure 6As shown, method MT2 further includes step ST23. Step ST23 is performed after step ST22. In step ST23, a plasma is generated in chamber 10 from the second process gas. In step ST23, the interior of chamber 10 is cleaned using chemical species from the plasma. The processing time of step ST23 is typically determined by monitoring the light emission state of the plasma. According to the second embodiment, the cleaning time can be shortened to less than 50% compared to conventional techniques, and the throughput of substrate processing can be improved.

[0080] The second process gas used in step ST23 may include, for example, at least one selected from a fluorine-containing gas, an oxygen-containing gas, a hydrogen-containing gas, and a nitrogen-containing gas. Fluorine-containing gases include, for example, CF4, SF6, or NF3. Oxygen-containing gases include, for example, O2, CO, CO2, H2O, or H2O2. Hydrogen-containing gases include, for example, H2 or HCl. Nitrogen-containing gases include, for example, N2. In addition to the above, the second process gas may include a noble gas such as Ar.

[0081] Step ST23 may be executed each time a substrate W is processed, or may be executed after processing a predetermined number of substrates W or a predetermined number of batches of substrates W. Alternatively, step ST23 may be executed after processing substrates for a predetermined period of time.

[0082] [Third embodiment]

[0083] In both the first and second embodiments, the first processing gas contains hydrogen fluoride gas. Hydrogen fluoride gas is a highly corrosive gas, so it is preferable to form a pre-coating film on the inner wall of the chamber 10 before the etching process. In particular, when hydrogen fluoride gas is used at a high concentration, the pre-coating film is formed on the inner wall of the chamber 10 to suppress corrosion of the inner wall of the chamber 10, thereby reducing the maintenance frequency. Among them, in addition to the side walls and ceiling of the chamber 10 (the top plate 34 of the upper electrode 30), the inner wall of the chamber 10 includes the support table 14 and the like.

[0084] In addition to silicon-containing films such as silicon oxide films, the pre-coating film can be formed of the same material as the material of the mask MSK. In the case where the mask MSK is a carbon-containing mask, the pre-coating film can be formed of a carbon-containing substance. The carbon-containing substance, for example, includes at least one selected from spin-on carbon, tungsten carbide, amorphous carbon, and boron carbide. In the case where the mask MSK is a metal-containing mask, the pre-coating film can be formed of a metal-containing substance. The metal-containing substance, for example, includes at least one selected from titanium nitride, titanium oxide, and tungsten. Furthermore, in the case where the mask MSK is a boron-containing mask, the pre-coating film is formed of a boron-containing substance. The boron-containing substance, for example, includes at least one selected from the group consisting of silicon boride, boron nitride, and boron carbide.

[0085] Figure 7 This is a flowchart showing an example of a substrate processing method according to the third embodiment. Figure 7 The method MT3 shown is for etching the silicon-containing film. Steps ST31 and ST32 are the same as steps ST11 and ST12 of the method MT1 described above, and therefore their description is omitted.

[0086] like Figure 7 As shown, method MT3 further includes step ST30. Step ST30 is performed before step ST31. In step ST30, plasma is generated from the third process gas in chamber 10. In step ST30, a pre-coat film is formed on the inner wall of chamber 10 by chemical species from the plasma.

[0087] The pre-coat film can be formed using a third process gas by Chemical Vapor Deposition (CVD) or Atomic Layer Deposition (ALD). For example, when forming a silicon oxide film as the pre-coat film, a silicon-containing gas such as SiCl4 or an aminosilane-based gas, or an oxygen-containing gas such as O2, can be used as the third process gas.

[0088] The step ST30 may be executed each time a substrate W is processed, or may be executed after processing a predetermined number of substrates W or a predetermined number of batches of substrates W. Alternatively, the step ST30 may be executed after processing substrates for a predetermined period of time.

[0089] In addition, according to Figure 8 In another example of the substrate processing method according to the third embodiment, the step of forming the pre-coating film can be performed in combination with the cleaning step. This can simultaneously suppress the generation of particles and the corrosion of the inner wall of the chamber 10.

[0090] Although various exemplary embodiments have been described above, the present invention is not limited to the exemplary embodiments described above, and various omissions, substitutions, and changes can be made. Furthermore, elements of different exemplary embodiments can be combined to form other exemplary embodiments.

[0091] For example, the plasma processing apparatus used in methods MT1 to MT4 may be a plasma processing apparatus different from plasma processing apparatus 1. The plasma processing apparatus used in methods MT1 to MT4 may be another capacitively coupled plasma processing apparatus, an inductively coupled plasma processing apparatus, or a plasma processing apparatus that generates plasma using surface waves such as microwaves.

[0092] Furthermore, as described above, hydrogen fluoride gas is a highly corrosive gas, so the flow ratio of the hydrogen fluoride gas or the type of gas added to the first process gas can be changed according to the processing stage. In one example, the flow ratio of the hydrogen fluoride gas at the end of the etching period, when it is not necessary to maintain the thickness of the mask, can be set to be lower than the flow ratio of the hydrogen fluoride gas during the early to middle stages of the etching period, when it is necessary to maintain the thickness of the mask. In other examples, when etching low-aspect-ratio regions where shape abnormalities such as bending are prone to occur, the flow ratio of a gas with a sidewall protection effect can be increased compared to etching high-aspect-ratio regions. Furthermore, the shape after etching can be monitored using an optical observation device, and the flow ratio of the hydrogen fluoride gas, the type of gas added to the first process gas, or the flow ratio can be changed according to the shape.

[0093] As will be appreciated from the foregoing description, various exemplary embodiments of the present invention are described in this specification for illustrative purposes, and various modifications may be made without departing from the scope and spirit of the present invention. Therefore, the present 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 substrate processing method, comprising: providing a silicon-containing film and a substrate having a mask on the silicon-containing film into a chamber; as well as a step of generating plasma from a first processing gas containing hydrogen fluoride gas and phosphorus-containing gas in the chamber to etch the silicon-containing film; The flow rate of the hydrogen fluoride gas is 25 volume % or more relative to the total flow rate of the first process gas excluding the inert gas.

2. The substrate processing method according to claim 1, wherein: The flow rate of the hydrogen fluoride gas is less than 80 volume % of the total flow rate of the first process gas excluding the inert gas.

3. The substrate processing method according to claim 1 or 2, wherein: The first processing gas includes at least one selected from a carbon-containing gas, an oxygen-containing gas, and a halogen-containing gas.

4. The substrate processing method according to claim 1 or 2, wherein: The first processing gas includes a halogen-containing gas.

5. The substrate processing method according to claim 3, wherein: The halogen-containing gas is at least one selected from SF6, NF3, XeF2, SiF4, IF7, ClF5, BrF5, AsF5, NF5, PF3, PF5, POF3, BF3, HPF6, WF6, SiCl2, SiCl4, CCl4, BCl3, PCl3, PCl5, POCl3, CBr2F2, C2F5Br, PBr3, PBr5, POBr3, HI, CF3I, C2F5I, C3F7I, IF5, IF7, I2 and PI3.

6. The substrate processing method according to claim 3, wherein: The halogen-containing gas is at least one selected from XeF2, PF3, PF5, WF6, BCl3, PCl3, PCl5, POCl3, CBr2F2, C2F5Br, CF3I, C2F5I and C3F7I.

7. The substrate processing method according to claim 1 or 2, wherein: The first processing gas includes at least one selected from the group consisting of fluorocarbon gas, hydrofluorocarbon gas, and hydrocarbon gas.

8. The substrate processing method according to claim 1 or 2, wherein: The first processing gas includes at least one selected from O 2 , CO, CO 2 , H 2 O, and H 2 O 2 .

9. The substrate processing method according to claim 1 or 2, wherein: The first processing gas includes a nitrogen-containing gas or a rare gas.

10. A substrate processing method, comprising: providing a silicon-containing film and a substrate having a mask on the silicon-containing film into a chamber; as well as a step of generating plasma from a first processing gas containing hydrogen fluoride gas and phosphorus-containing gas in the chamber to etch the silicon-containing film; The flow rate of the hydrogen fluoride gas is 25% by volume or more relative to the total flow rate of the first process gas excluding the inert gas. The ratio of the flow rate of the hydrogen fluoride gas to the total flow rate of the first process gas and / or the type of gas added to the first process gas are changed according to the stage in the process of etching the silicon-containing film.

11. The substrate processing method according to claim 1, 2 or 10, wherein: The silicon-containing film is at least one selected from a stacked film including a silicon oxide film and a silicon nitride film, a polysilicon film, a low dielectric constant film, and a stacked film including a silicon oxide film and a polysilicon film.

12. The substrate processing method according to claim 1, 2 or 10, wherein: The mask is a carbon-containing mask, a metal-containing mask or a boron-containing mask.

13. The substrate processing method according to claim 1, 2 or 10, wherein: The mask is a metal-containing mask including at least one selected from titanium nitride, titanium oxide, and tungsten.

14. The substrate processing method according to claim 12, wherein: The carbon-containing mask is formed of at least one selected from spin-on carbon, tungsten carbide, amorphous carbon, and boron carbide. 15 . The substrate processing method according to claim 1 , further comprising, before the etching step, a step of adjusting the temperature of an electrostatic chuck on which the substrate is placed to 0° C. or lower. 16 . The substrate processing method according to claim 1 , further comprising a step of generating plasma from a second processing gas in the chamber and cleaning the interior of the chamber.

17. The substrate processing method according to claim 16, wherein: The second processing gas includes at least one selected from fluorine-containing gas, oxygen-containing gas, hydrogen-containing gas, and nitrogen-containing gas.

18. The substrate processing method according to claim 1, 2 or 10, wherein: Before the step of providing the substrate, the method further includes generating plasma from a third process gas in the chamber to form a pre-coated film on an inner wall of the chamber.

19. The substrate processing method according to claim 18, wherein: The third processing gas includes a silicon-containing gas and an oxygen-containing gas.

20. A plasma processing apparatus comprising a chamber, a plasma generating unit, and a control unit, wherein the chamber has a gas supply port and a gas exhaust port. The control unit executes a process including the following steps: a step of arranging a substrate having a silicon-containing film and a mask provided on the silicon-containing film in the chamber; as well as a step of generating plasma from a first processing gas containing hydrogen fluoride gas and phosphorus-containing gas in the chamber to etch the silicon-containing film; In the etching step, the flow rate of the hydrogen fluoride gas is controlled to be 25 volume % or more relative to the total flow rate of the first processing gas excluding the inert gas.

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