Etching method and plasma processing apparatus

Abstract

To provide a technique for protecting a surface in a chamber from reactive species.SOLUTION: A disclosed etching method includes a step (a) of forming a protective film containing carbon on a surface in a chamber of a plasma processing apparatus. The etching method further includes a step (b) of etching an etch film of a substrate with plasma generated from an etching gas that includes a hydrogen fluoride gas and a hydrofluorocarbon gas within the chamber. The substrate includes the etch film, which is a silicon-containing film, and a mask containing carbon and provided on the etch film.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] A plasma processing apparatus is used in plasma processing such as etching. The plasma processing apparatus includes a chamber. A surface in the chamber is exposed to reactive species used in the plasma processing and is removed by the reactive species. In order to protect the surface in the chamber from the reactive species, a technique is used in which a protective film is formed on the surface in the chamber before performing plasma processing on a substrate. The following Patent Documents 1 to 3 disclose such techniques. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-76625 A [Patent Document 2] JP 2009-188257 A [Patent Document 3] U.S. Patent No. 6,071,573 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides techniques for protecting surfaces within a chamber from reactive species. [Means for solving the problem]

[0005] In one exemplary embodiment, an etching method is provided. The etching method includes a step (a) of forming a protective film containing carbon on a surface in a chamber of a plasma processing apparatus. The etching method further includes a step (b) of etching the etching film of the substrate with plasma generated in the chamber from an etching gas containing hydrogen fluoride gas and a hydrofluorocarbon gas. The substrate includes an etching film that is a silicon-containing film and a mask containing carbon and provided on the etching film. Effect of the Invention

[0006] According to one exemplary embodiment, surfaces within the chamber may be protected from reactive species. [Brief description of the drawings]

[0007] [Figure 1] 1 is a flow diagram of an etching method according to an exemplary embodiment. [Diagram 2] FIG. 2 is an enlarged cross-sectional view of a portion of an example substrate. [Diagram 3] 1 is a schematic diagram illustrating a plasma processing apparatus according to an exemplary embodiment; [Figure 4] FIG. 2 illustrates a state in which a protective film is formed on a surface within a chamber of a plasma processing apparatus according to an exemplary embodiment. [Diagram 5] FIG. 2 is a partial enlarged cross-sectional view of an example substrate after etching has been performed. [Figure 6] FIG. 2 illustrates the state of a chamber after etching has been performed in a plasma processing apparatus according to an exemplary embodiment. [Figure 7] FIG. 2 illustrates the state of a chamber after dry cleaning in a plasma processing apparatus according to an exemplary embodiment. [Figure 8] FIG. 13 is a cross-sectional view illustrating a protective film according to another exemplary embodiment. [Figure 9]FIG. 9(a) is a diagram showing an example of the distribution of carbon content in the thickness direction of a protective film according to yet another exemplary embodiment, and FIG. 9(b) is a diagram showing an example of the ratio of the flow rate of a carbon-containing gas to the total flow rate of a film-forming gas for forming a protective film. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Various exemplary embodiments are described below.

[0009] In one exemplary embodiment, an etching method is provided. The etching method includes a step (a) of forming a protective film containing carbon on a surface in a chamber of a plasma processing apparatus. The etching method further includes a step (b) of etching the etching film of the substrate with plasma generated in the chamber from an etching gas containing hydrogen fluoride gas and a hydrofluorocarbon gas. The substrate includes an etching film that is a silicon-containing film and a mask containing carbon and provided on the etching film.

[0010] In the above embodiment, a protective film is formed on the surface inside the chamber before etching the etching film. The protective film is made of the same material as the mask, i.e., a material containing carbon, and is therefore difficult to etch. Therefore, according to the above embodiment, it is possible to more effectively protect the surface inside the chamber from reactive species.

[0011] In one exemplary embodiment, the protective film may be formed by chemical vapor deposition, molecular layer deposition, or sputter deposition using a carbon-containing gas.

[0012] In one exemplary embodiment, the protective film may be a laminate film including two or more different films. In one exemplary embodiment, the protective film may include a first film containing silicon and a second film containing carbon formed on the first film.

[0013] In one exemplary embodiment, the protective film may have a carbon content that increases with distance in its thickness direction from a surface in the chamber. In one exemplary embodiment, in step (a), the protective film may be formed using a deposition gas, and a ratio of a flow rate of a carbon-containing gas in the deposition gas to a total flow rate of the deposition gas may be increased over time.

[0014] In another exemplary embodiment, an etching method is also provided. The etching method includes a step (a) of forming a protective film on a surface in a chamber of a plasma processing apparatus. The etching method further includes a step (b) of etching the etching film of the substrate by plasma generated in the chamber from an etching gas including hydrogen fluoride gas and a hydrogen-containing gas. The substrate includes an etching film and a mask provided on the etching film. The protective film is formed of the same type of material as the material of the mask.

[0015] In the above embodiment, a protective film is formed on the surface inside the chamber before etching the etching film. The protective film is made of the same material as the mask material and is therefore difficult to etch. Therefore, according to the above embodiment, it is possible to more effectively protect the surface inside the chamber from reactive species.

[0016] In one exemplary embodiment, the hydrogen-containing gas may include at least one selected from the group consisting of H2, CH4, C2H2, C4H2F6, CH2F2, CH3F, CHF3, H2O, HCl, HBr, and HI.

[0017] In one exemplary embodiment, the plasma processing apparatus may be a capacitively coupled plasma processing apparatus, and may include a substrate support disposed in a chamber and an upper electrode disposed on the substrate support.

[0018] In one exemplary embodiment, the surface of the upper electrode facing the internal space of the chamber may be provided by a top plate made of silicon.

[0019] In one exemplary embodiment, the etching method may further include a step (c) of applying a negative DC voltage to the upper electrode during or after step (a) and before step (b). According to this embodiment, the protective film is densified.

[0020] In one exemplary embodiment, the etching method may further include a step (d) of modifying a surface in the chamber before step (a). According to this embodiment, the adhesion of the protective film to the surface in the chamber is improved. In step (d), a plasma may be generated from a noble gas in the chamber after the chamber cleaning.

[0021] In one exemplary embodiment, the etching method may further include a step (e) of performing a roughening treatment on the surface of the protective film after the step (a) and before the step (b). According to this embodiment, the adhesion of the reactive species generated in the step (b) to the surface of the protective film is enhanced. In the step (e), a plasma may be generated from hydrogen gas in the chamber.

[0022] In another exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a gas supply, a plasma generation unit, and a controller. The gas supply is configured to supply a gas into the chamber. The plasma generation unit is configured to generate a plasma from the gas in the chamber. The controller controls the gas supply to supply a deposition gas into the chamber to form a carbon-containing protective film on a surface in the chamber. The controller controls the gas supply and the plasma generation unit to generate a plasma generated from an etching gas including a hydrogen fluoride gas and a hydrofluorocarbon gas in the chamber to etch an etching film on a substrate.

[0023] Various exemplary embodiments will now be described in detail with reference to the drawings, in which the same or corresponding parts are designated by the same reference numerals.

[0024] 1 is a flow diagram of an etching method according to an exemplary embodiment. The etching method shown in FIG. 1 (hereinafter referred to as "method MT") is performed to etch an etch film of a substrate.

[0025] Fig. 2 is a partially enlarged cross-sectional view of an example substrate. The method MT may be applied to the substrate W shown in Fig. 2. The substrate W has a film EF and a mask MK. The substrate W may further have an underlayer region UR. The film EF may be provided on the underlayer region UR.

[0026] The film EF is an etching film to be etched in the method MT. The film EF is, for example, a silicon-containing film. The silicon-containing film may be a single-layer film or a multilayer film. The single-layer film is, for example, a silicon oxide film, a silicon nitride film, a polycrystalline silicon film, or a silicon-containing low dielectric constant film. The multilayer film is formed of two or more of a silicon oxide film, a silicon nitride film, and a polycrystalline silicon film. The multilayer film may be a stacked film including a silicon oxide film and a silicon nitride film. The film EF may be formed of other materials. For example, the film EF may be formed of a metal.

[0027] The mask MK is provided on the film EF. The mask MK can be made of any material as long as the film EF is selectively etched with respect to the mask MK. The mask MK may be made of a carbon-containing film, for example, an organic film such as a photoresist film, an amorphous carbon film, or a spin-on carbon film. Alternatively, the mask MK may be made of a silicon-containing film or a metal-containing film. The silicon-containing film is a polycrystalline silicon film or a silicon oxide film. The metal-containing film is made of titanium, titanium nitride, titanium carbide, titanium oxide, tungsten, tungsten carbide, ruthenium, ruthenium oxide, molybdenum, molybdenum carbide, or the like. The mask MK has a pattern to be transferred to the film EF. That is, the mask MK provides an opening OP.

[0028] In the method MT, a plasma processing apparatus is used. Fig. 3 is a schematic diagram of a plasma processing apparatus according to an exemplary embodiment. The plasma processing apparatus 1 shown in Fig. 3 is a capacitively coupled plasma processing apparatus.

[0029] The plasma processing apparatus 1 includes a chamber 10. The chamber 10 provides an internal space 10s therein. The central axis of the chamber 10 is an axis AX extending in the vertical direction. In one embodiment, the chamber 10 includes a chamber body 12. The chamber body 12 has a substantially cylindrical shape. The internal space 10s is provided in the chamber body 12. The chamber body 12 is made of, for example, aluminum. The chamber body 12 is electrically grounded. A corrosion-resistant film is provided on the inner wall surface of the chamber body 12. The corrosion-resistant film may be a film made of a ceramic such as aluminum oxide or yttrium oxide.

[0030] The chamber body 12 provides a passage 12p in its sidewall. The substrate W passes through the passage 12p when being transferred between the internal space 10s and the outside of the chamber 10. The passage 12p can be opened and closed by a gate valve 12g. The gate valve 12g is provided along the sidewall of the chamber body 12.

[0031] The plasma processing apparatus 1 further includes a substrate support 16. The substrate support 16 is configured to support a substrate W in the chamber 10. The substrate W may have a substantially disk-like shape. The substrate support 16 may be supported by a support 15. The support 15 extends upward from the bottom of the chamber body 12. The support 15 has a substantially cylindrical shape. The support 15 is made of an insulating material such as quartz.

[0032] The substrate support 16 may include a lower electrode 18 and an electrostatic chuck 20. The substrate support 16 may further include an electrode plate 19. The electrode plate 19 is made of a conductive material such as aluminum. The electrode plate 19 has a substantially disk-like shape, and its central axis is an axis line AX. The lower electrode 18 is provided on the electrode plate 19. The lower electrode 18 is made of a conductive material such as aluminum. The lower electrode 18 has a substantially disk-like shape, and its central axis is an axis line AX. The lower electrode 18 is electrically connected to the electrode plate 19.

[0033] The lower electrode 18 provides a flow path 18f therein. The flow path 18f is a flow path for a heat exchange medium (e.g., a coolant). The flow path 18f receives the heat exchange medium from a supply device (e.g., a chiller unit) via a pipe 23a. This supply device is provided outside the chamber 10. The heat exchange medium supplied to the flow path 18f flows through the flow path 18f and is returned to the supply device via a pipe 23b. The supply device for the heat exchange medium constitutes a temperature adjustment mechanism of the plasma processing device 1.

[0034] The electrostatic chuck 20 is provided on the lower electrode 18. The substrate W is placed on the upper surface of the electrostatic chuck 20. The electrostatic chuck 20 has a body and an electrode. The body of the electrostatic chuck 20 is formed from a dielectric material. The electrostatic chuck 20 and its body each have a substantially disk shape, and the central axis is an axis line AX. The electrode of the electrostatic chuck 20 is a film-like electrode and is provided in the body of the electrostatic chuck 20. The electrode of the electrostatic chuck 20 is connected to a DC power supply via a switch. When a voltage from the DC power supply is applied to the electrode of the electrostatic chuck 20, an electrostatic attractive force is generated between the electrostatic chuck 20 and the substrate W. Due to the generated electrostatic attractive force, the substrate W is attracted to the electrostatic chuck 20 and held by the electrostatic chuck 20.

[0035] The substrate support 16 may further support an edge ring ER disposed thereon. The edge ring ER may be made of silicon, silicon carbide, or quartz. The substrate W is disposed on the electrostatic chuck 20 and within a region surrounded by the edge ring ER.

[0036] The plasma processing apparatus 1 may further include a gas supply line 25. The gas supply line 25 supplies a heat transfer gas (e.g., He gas) from a gas supply mechanism to the gap between the upper surface of the electrostatic chuck 20 and the rear surface (lower surface) of the substrate W.

[0037] The plasma processing apparatus 1 may further include a cylindrical portion 28 and an insulating portion 29. The cylindrical portion 28 extends upward from the bottom of the chamber body 12. The cylindrical portion 28 extends along the outer periphery of the support 15. The cylindrical portion 28 is formed of a conductive material and has a substantially cylindrical shape. The cylindrical portion 28 is electrically grounded. The insulating portion 29 is provided on the cylindrical portion 28. The insulating portion 29 is formed of a material having insulating properties. The insulating portion 29 is formed of a ceramic such as quartz. The insulating portion 29 has a substantially cylindrical shape. The insulating portion 29 extends along the outer periphery of the electrode plate 19, the outer periphery of the lower electrode 18, and the outer periphery of the electrostatic chuck 20.

[0038] The plasma processing apparatus 1 further includes an upper electrode 30. The upper electrode 30 is provided above the substrate support 16. The upper electrode 30 is supported on the upper part of the chamber body 12 via a member 32. The member 32 is made of an insulating material. The upper electrode 30 and the member 32 close the upper opening of the chamber body 12.

[0039] The upper electrode 30 may include a top plate 34 and a support 36. The bottom surface of the top plate 34 is the bottom surface on the side of the internal space 10s and defines the internal space 10s. The top plate 34 may be made of a low-resistance conductor or semiconductor with little Joule heat. In one embodiment, the top plate 34 is made of silicon. The top plate 34 provides a plurality of gas holes 34a. The plurality of gas holes 34a penetrate the top plate 34 in the plate thickness direction.

[0040] The support 36 detachably supports the top plate 34. The support 36 is made of a conductive material such as aluminum. The support 36 provides a gas diffusion chamber 36a therein. The support 36 further provides a plurality of gas holes 36b. The plurality of gas holes 36b extend downward from the gas diffusion chamber 36a. The plurality of gas holes 36b communicate with the plurality of gas holes 34a, respectively. The support 36 further provides a gas inlet 36c. The gas inlet 36c is connected to the gas diffusion chamber 36a. A gas supply pipe 38 is connected to the gas inlet 36c.

[0041] A gas source group 40 is connected to the gas supply pipe 38 via a valve group 41, a flow rate controller group 42, and a valve group 43. The gas source group 40, the valve group 41, the flow rate controller group 42, and the valve group 43 constitute a gas supply unit GS. The gas source group 40 includes a plurality of gas sources. The gas sources of the gas source group 40 include a plurality of gas sources used in the method MT. Each of the valve group 41 and the valve group 43 includes a plurality of opening and closing valves. The flow rate controller group 42 includes a plurality of flow rate controllers. Each of the plurality of flow rate controllers of the flow rate controller group 42 is a mass flow controller or a pressure control type flow rate controller. Each of the plurality of gas sources of the gas source group 40 is connected to the gas supply pipe 38 via a corresponding opening and closing valve of the valve group 41, a corresponding flow rate controller of the flow rate controller group 42, and a corresponding opening and closing valve of the valve group 43.

[0042] The plasma processing apparatus 1 may further include a shield 46. The shield 46 is detachably provided along the inner wall surface of the chamber body 12. The shield 46 prevents by-products of the plasma processing from adhering to the chamber body 12. The shield 46 is configured by forming a corrosion-resistant film on the surface of a member made of, for example, aluminum. The corrosion-resistant film may be a film made of a ceramic such as yttrium oxide.

[0043] The plasma processing apparatus 1 may further include a baffle member 48. The baffle member 48 is provided between a member (e.g., the cylindrical portion 28) surrounding the substrate support 16 and the shield 46. The baffle member 48 is formed by forming a corrosion-resistant film on the surface of a member made of, for example, aluminum. The corrosion-resistant film may be a film made of ceramic such as yttrium oxide. The baffle member 48 has a plurality of through holes. An exhaust port is provided below the baffle member 48 and at the bottom of the chamber body 12. An exhaust device 50 is connected to the exhaust port via an exhaust pipe 52. The exhaust device 50 has a pressure adjustment valve and a vacuum pump such as a turbo molecular pump.

[0044] The plasma processing apparatus 1 further includes a high-frequency power supply 61 and a bias power supply 62. The high-frequency power supply 61 is configured to generate high-frequency power (hereinafter, referred to as "high-frequency power HF"). The high-frequency power HF has a frequency suitable for generating plasma. The frequency of the high-frequency power HF is, for example, 27 MHz or more and 100 MHz or less. The high-frequency power supply 61 is connected to the lower electrode 18 via a matching device 61m. The matching device 61m has a circuit for matching the impedance of the load side (lower electrode 18 side) of the high-frequency power supply 61 to the output impedance of the high-frequency power supply 61. In one embodiment, the high-frequency power supply 61 can constitute a plasma generating unit. The high-frequency power supply 61 may be connected to the upper electrode 30 via the matching device 61m.

[0045] The bias power supply 62 is configured to apply an electric bias EB to the lower electrode 18. The electric bias EB has a frequency suitable for attracting ions to the substrate W. The frequency of the electric bias EB is, for example, 100 kHz or more and 40.68 MHz or less. When the electric bias EB is used together with the high frequency power HF, the electric bias EB has a frequency lower than the frequency of the high frequency power HF.

[0046] In one embodiment, the electric bias EB may be a high frequency bias power (hereinafter referred to as "high frequency power LF"). In this embodiment, the bias power supply 62 is connected to the lower electrode 18 via a matching device 62m. The matching device 62m has a circuit for matching the impedance of the load side (lower electrode 18 side) of the bias power supply 62 to the output impedance of the bias power supply 62. The plasma processing apparatus 1 may be configured to generate plasma using only the high frequency power LF. In this case, the bias power supply 62 constitutes a plasma generating unit of one embodiment. In this case, the plasma processing apparatus 1 does not need to include the high frequency power supply 61 and the matching device 61m.

[0047] In one embodiment, the electrical bias EB may be a pulse of voltage. In this embodiment, the pulse of voltage is applied periodically to the lower electrode 18. The pulse of voltage may have any polarity, provided that the potential of the substrate W can be set such that ions from the plasma can be attracted to the substrate W. The pulse of voltage may have a negative polarity, or may be a negative DC voltage. The pulse of voltage may have any waveform, such as a square wave, a triangular wave, or other waveform.

[0048] The plasma processing apparatus 1 may further include a power supply 70. The power supply 70 is electrically connected to the upper electrode 30. The power supply 70 is configured to apply a negative voltage, for example, a negative DC voltage, to the upper electrode.

[0049] The plasma processing apparatus 1 further includes a control unit 80. The control unit 80 is a computer including a processor, a storage device, an input device, a display device, etc., and controls each part of the plasma processing apparatus 1. Specifically, the control unit 80 executes a control program stored in the storage device, and controls each part of the plasma processing apparatus 1 based on recipe data stored in the storage device. Under the control of the control unit 80, a process specified by the recipe data is executed in the plasma processing apparatus 1. The method MT can be executed in the plasma processing apparatus 1 under the control of the control unit 80 for each part of the plasma processing apparatus 1.

[0050] Method MT will be described in detail with reference to FIG. 1 again. Method MT will be described below by taking as an example a case where method MT is applied to a substrate W shown in FIG. 2 using a plasma processing apparatus 1. In the following description, reference will be made further to FIGS. 4 to 7. FIG. 4 is a diagram showing a state where a protective film is formed on a surface in a chamber of a plasma processing apparatus according to an exemplary embodiment. FIG. 5 is a partially enlarged cross-sectional view of an example of a substrate after etching has been performed. FIG. 6 is a diagram showing a state of a chamber after etching has been performed in a plasma processing apparatus according to an exemplary embodiment. FIG. 7 is a diagram showing a state of a chamber after dry cleaning has been performed in a plasma processing apparatus according to an exemplary embodiment.

[0051] As shown in Fig. 1, the method MT includes steps STa and STb. In step STa, a protective film PF is formed on a surface in a chamber 10. The surface in the chamber 10 is a surface to which reaction products generated during etching in step STb may adhere if the protective film PF is not formed thereon in step STa. In one example, the surfaces in the chamber 10 include the lower surface of the upper electrode 30 (i.e., the lower surface of the top plate 34), the surface of the shield 46, the surface of the insulating part 29, and the surface of the edge ring ER. In step STb, the film EF of the substrate W is etched.

[0052] The method MT may further include one or more steps among step STm, step STv, step STr, and step STc. Step STm is performed before step STa. In step STm, the surface in the chamber 10 is modified. According to step STm, the adhesion of the protective film PF to the surface in the chamber 10 is improved.

[0053] In step STm, after the chamber cleaning, a plasma of a noble gas may be generated in the chamber 10. The noble gas may include one or more of a plurality of noble gases, such as Ar gas, Kr gas, and Xe gas. In step STm, a bias voltage may be applied to the upper electrode 30 to attract ions from the plasma generated from the noble gas to the upper electrode 30. The bias voltage may be a voltage (e.g., a negative voltage) from the power supply 70. In step STm, chemical species such as ions from the plasma of the noble gas are supplied to a surface in the chamber 10, thereby modifying the surface of the chamber 10.

[0054] In step STm, the control unit 80 controls the gas supply unit GS to supply a noble gas into the chamber 10. The control unit 80 controls the exhaust unit 50 to set the pressure of the gas in the chamber 10 to a designated pressure. The control unit 80 controls the plasma generation unit to generate plasma of the noble gas in the chamber 10. In the plasma processing apparatus 1, the control unit 80 controls the high frequency power supply 61 and / or the bias power supply 62 to supply high frequency power HF and / or an electric bias EB. In addition, in step STm, the control unit 80 may further control the power supply 70 to apply a voltage to the upper electrode 30.

[0055] In step STa, as shown in Fig. 4, a protective film PF is formed on the surface inside the chamber 10. The protective film PF may have a thickness in the range of 50 nm to 200 nm, for example, a thickness of about 100 nm. As shown in Fig. 4, step STa may be performed in a state in which a dummy substrate DW is placed on a substrate support 16.

[0056] The protective film PF may be formed of the same material as the material of the mask MK. When the mask MK is formed of a film containing carbon, the protective film PF may be formed of a carbon-containing substance. When the mask MK is formed of a silicon-containing film, the protective film PF may be formed of a silicon-containing substance (e.g., polycrystalline silicon, silicon oxide, or a silicon-containing film containing carbon). The silicon-containing film containing carbon is, for example, silicon carbide. When the mask MK is formed of a metal-containing film, the protective film PF may be formed of a metal-containing substance. The metal-containing substance includes any of titanium, titanium nitride, titanium carbide, titanium oxide, tungsten, tungsten carbide, ruthenium, ruthenium oxide, molybdenum, molybdenum carbide, and the like.

[0057] The protective film PF may be formed in the chamber 10 using a deposition gas. The deposition gas used to form the protective film PF made of a carbon-containing material includes a carbon-containing gas. The deposition gas may be a gas that does not contain fluorine. The carbon-containing gas includes one or more of CO gas, CO2 gas, COS gas, and a hydrocarbon gas. The hydrocarbon gas is CH4 gas, C2H2 gas, C3H6 gas, etc. The protective film PF made of a carbon-containing material may be formed by a CVD (chemical vapor deposition) method or an MLD (molecular layer deposition) method. The CVD method may be a plasma-assisted CVD method or a thermal CVD method. The MLD method may be a plasma-assisted MLD method or a thermal MLD method. In the MLD method, a protective film having a urea bond may be formed by mixing two or more types of gases.

[0058] In step STa, in order to form a protective film PF made of a carbon-containing material, the control unit 80 controls the gas supply unit GS to supply a film formation gas into the chamber 10. The control unit 80 controls the exhaust unit 50 to set the pressure of the gas in the chamber 10 to a designated pressure. The control unit 80 controls the plasma generation unit to generate plasma of the film formation gas in the chamber 10. In the plasma processing apparatus 1, the control unit 80 controls the high frequency power supply 61 and / or the bias power supply 62 to supply high frequency power HF and / or an electric bias EB.

[0059] The protective film PF made of a silicon-containing material is formed using a CVD method, an ALD (atomic layer deposition) method, a molecular layer deposition method, or a sputter deposition method. The CVD method may be a plasma-assisted CVD method or a thermal CVD method. The ALD method may be a plasma-assisted ALD method or a thermal ALD method. When the protective film PF made of a silicon-containing material is formed, the deposition gas includes, for example, SiH4 gas, SiCl4 gas, Si2Cl6 gas, or SiF4 gas. The deposition gas may further include a noble gas such as argon. When the protective film PF made of silicon oxide is formed, the deposition gas may further include an oxygen-containing gas containing oxygen that reacts with the precursor. When the protective film PF made of silicon carbide is formed, the deposition gas may further include a carbon-containing gas as described above.

[0060] In order to form the protective film PF made of a silicon-containing material in step STa, the control unit 80 controls the gas supply unit GS to supply a film formation gas into the chamber 10. The control unit 80 controls the exhaust unit 50 to set the pressure of the gas in the chamber 10 to a designated pressure. The control unit 80 may control the plasma generation unit to generate plasma of the film formation gas in the chamber 10. In the plasma processing apparatus 1, the control unit 80 may control the high frequency power supply 61 and / or the bias power supply 62 to supply high frequency power HF and / or an electric bias EB.

[0061] The protective film PF made of a metal-containing material is formed by chemical vapor deposition, metal-organic chemical vapor deposition (MOCVD), or atomic layer deposition (ALD). When using these deposition methods, a deposition gas containing a metal-containing material as a precursor is supplied into the chamber 10. The deposition gas may be, for example, WF6, TiCl4, or CH. 24 The metal-containing gas includes N4Ti, RuCl3, or MoCl5. In order to form the protective film PF made of a metal-containing substance in the step STa, the control unit 80 controls the gas supply unit GS to supply a film formation gas into the chamber 10.

[0062] When the protective film PF is formed of tungsten, the deposition gas may include WF6. The deposition gas is supplied into the chamber 10 such that the precursor WF6 is adsorbed on the surfaces in the chamber 10. The WF6 is modified by chemical species from the plasma of a hydrogen-containing gas (e.g., H2 gas) generated in the chamber 10. As a result, the protective film PF made of tungsten is formed on the surfaces in the chamber 10. Alternatively, the protective film PF made of tungsten may be formed by a plasma-assisted CVD method or a thermal CVD method using a deposition gas containing WF6.

[0063] When the protective film PF is made of titanium, the deposition gas includes, for example, TiCl4 and H2, and the protective film PF is formed by a plasma-assisted CVD method or a thermal CVD method. When the protective film PF is made of titanium nitride, the deposition gas includes, for example, TiCl4 and N2, and the protective film PF is formed by a plasma-assisted CVD method or a thermal CVD method. Alternatively, when the protective film PF is made of titanium nitride, the deposition gas includes, for example, Ti[N(CH3)C2H5]4, and the protective film PF is formed by an MOCVD method.

[0064] In one embodiment, the process STv may be performed after the process STa or after the process STa and before the process STb. In the process STv, a negative voltage (e.g., a negative DC voltage) is applied from the power source 70 to the upper electrode 30. When the process STv is performed after the process STa and before the process STb, a negative voltage (e.g., a negative DC voltage) may be applied from the power source 70 to the upper electrode 30 while the plasma of the inert gas is being generated in the chamber 10. The inert gas may include, for example, one or more of a noble gas and a hydrogen gas. In the process STv, for example, the heat input by the plasma may promote the rearrangement of crystals in the protective film PF. Alternatively or additionally, in the process STv, impurities (e.g., hydrogen or its molecules, or a halogen element or molecules containing it) may be removed from the protective film PF by ions from the plasma colliding with the protective film PF. Therefore, in this process, the protective film PF is densified. In the process STv, the power source 70 is controlled by the control unit 80.

[0065] In one embodiment, a step STr may be performed after the step STa and before the step STb. The step STr may be performed after the step STv. In the step STr, a roughening treatment is performed on the surface of the protective film PF. The step STr enhances the adhesion of the reactive species generated in the step STb to the surface of the protective film PF. In the step STr, plasma may be generated from hydrogen gas in the chamber 10.

[0066] In step STr, the control unit 80 controls the gas supply unit GS to supply hydrogen gas into the chamber 10. The control unit 80 controls the exhaust unit 50 to set the pressure of the gas in the chamber 10 to a designated pressure. The control unit 80 may control the plasma generation unit to generate plasma of the hydrogen gas in the chamber 10. In the plasma processing apparatus 1, the control unit 80 may control the high frequency power supply 61 and / or the bias power supply 62 to supply high frequency power HF and / or an electric bias EB.

[0067] In the method MT, the substrate W is then placed on the substrate support 16. Then, step STb is performed. In step STb, the film EF is etched as shown in FIG. 5. The depth of the opening OP is increased by etching the film EF in step STb. In step STb, the film EF can be etched until the underlying region UR is exposed.

[0068] In step STb, the film EF is etched by using hydrogen fluoride in the chamber 10. In order to generate hydrogen fluoride, in step STb, an etching gas is supplied into the chamber 10, and plasma is generated from the etching gas in the chamber 10.

[0069] The etching gas may include hydrogen fluoride (HF) gas. In one embodiment, the etching gas may further include a hydrofluorocarbon gas in addition to the hydrogen fluoride gas. The hydrofluorocarbon gas may include one or more of C4H2F6, CH2F2, CH3F, CHF3, etc. The etching gas may further include a hydrogen-containing gas in addition to the hydrogen fluoride gas. The hydrogen-containing gas may include at least one selected from the group consisting of H2, CH4, C4H2F6, CH2F2, CH3F, CHF3, H2O, HCl, HBr, and HI.

[0070] Alternatively, the etching gas may contain a fluorine-containing gas as a fluorine source and a hydrogen-containing gas as a hydrogen source. The etching gas may contain one or more of H2, CH4, C2H2, CH2F2, CH3F, CHF3, H2O, HF, HCl, HBr, HI, etc. as a hydrogen source. The etching gas may contain one or more of CF4, C4F8, C4F6, C3F8, C5F8, SF 6、 It may contain one or more of NF3, XeF2, PF3, PF5, CF3I, C2F5I, C3F7I, IF5, IF7, WF6, HF, SiF4, etc.

[0071] The etching gas may further include one or more phosphorus-containing molecules. The one or more phosphorus-containing molecules may be tetraphosphorus decaoxide (PO 10The one or more phosphorus-containing molecules may include oxides such as phosphorus trifluoride (PF3), phosphorus pentafluoride (PF5), phosphorus trichloride (PCl3), phosphorus pentachloride (PCl5), phosphorus tribromide (PBr3), phosphorus pentabromide (PBr5), and phosphorus iodide (PI3). The one or more phosphorus-containing molecules may include phosphoryl halides such as phosphoryl fluoride (POF3), phosphoryl chloride (POCl3), and phosphoryl bromide (POBr3). The one or more phosphorus-containing molecules may include phosphine (PH3), calcium phosphide (e.g., Ca3P2), phosphoric acid (H3PO4), sodium phosphate (Na3PO4), hexafluorophosphoric acid (HPF6), and the like. The one or more phosphorus-containing molecules may include fluorophosphines (H x PF y Here, the sum of x and y is 3 or 5. Examples of fluorophosphines include HPF2 and H2PF3.

[0072] In one example, the etching gas may be a gas mixture including hydrogen fluoride gas, a fluorocarbon gas such as C4F8 gas, and a phosphorus-containing gas, the phosphorus-containing gas including one or more of the phosphorus-containing molecules described above.

[0073] In order to etch the film EF in the step STb, the control unit 80 controls the gas supply unit GS to supply an etching gas into the chamber 10. The control unit 80 controls the exhaust unit 50 to set the pressure of the gas in the chamber 10 to a designated pressure. The control unit 80 controls the plasma generation unit to generate plasma of the etching gas in the chamber 10. In the plasma processing device 1, the control unit 80 controls the high frequency power supply 61 and / or the bias power supply 62 to supply high frequency power HF and / or an electric bias EB. Note that in the step STb, the heat exchange medium supply unit may be controlled by the control unit 80 so that the temperature of the heat exchange medium supplied to the flow path 18f is −20° C. or lower.

[0074] When etching in step STb is performed, reaction products RP (reactive species) are generated. The reaction products RP may include substances containing fluorine and carbon. The reaction products RP adhere to surfaces in the chamber 10 as shown in FIG. 6.

[0075] In the method MT, after the execution of the step STb, the substrate W is unloaded from the inside of the chamber 10. Then, the step STc is executed. In the step STc, the chamber 10 is dry-cleaned. The dry-cleaning in the step STc can be executed with or without a dummy substrate placed on the substrate support 16.

[0076] In step STc, a cleaning gas is supplied into the chamber 10, and plasma is generated from the cleaning gas. Chemical species from the generated cleaning gas remove the reaction product RP together with at least a portion of the protective film PF. The dry cleaning in step STc may completely remove the protective film PF as shown in FIG. 7. The dry cleaning in step STc may be performed such that the protective film PF partially remains while covering the surface inside the chamber 10.

[0077] When the protective film PF is made of a carbon-containing material, an oxygen-containing gas (e.g., O2 gas) is used as the cleaning gas. When the protective film PF is made of a silicon-containing material, a halogen-containing gas is used as the cleaning gas. When the protective film PF is made of a metal-containing material, the cleaning gas includes NF3, Cl2, BCl3, SiCl4, O2, CH3OH, C2H5OH, etc.

[0078] To perform dry cleaning in step STc, the control unit 80 controls the gas supply unit GS to supply a cleaning gas into the chamber 10. The control unit 80 controls the exhaust unit 50 to set the gas pressure in the chamber 10 to a designated pressure. The control unit 80 controls the plasma generation unit to generate plasma of the cleaning gas in the chamber 10. In the plasma processing apparatus 1, the control unit 80 controls the high frequency power supply 61 and / or the bias power supply 62 to supply high frequency power HF and / or an electric bias EB.

[0079] The method MT may further include a step STJ, in which it is determined whether a stop condition is satisfied. The stop condition is not satisfied if there are further substrates to be etched, whereas the stop condition is satisfied if etching of all substrates has been completed.

[0080] If it is determined that the stop condition is not satisfied in step STJ, the process continues to etch another substrate W. If the protective film PF is removed by the dry cleaning in step STc to expose the surface in the chamber 10, step STa is executed again. Thereafter, another substrate W is placed on the substrate support 16, and step STb is executed. Alternatively, if the protective film PF remains to cover the surface in the chamber 10 after the dry cleaning in step STc, another substrate W is placed on the substrate support 16, and step STb is executed without executing step STa. If it is determined that the stop condition is satisfied in step STJ, the method MT ends.

[0081] In method MT, a protective film PF is formed on the surface inside chamber 10 before etching film EF. The protective film PF is made of the same material as that of mask MK (e.g., a carbon-containing material), and is therefore difficult to etch. Therefore, method MT makes it possible to more effectively protect the surface inside chamber 10 from reactive species. As a result, corrosion of the surface of chamber 10 caused by etching in step STb is suppressed. In turn, changes over time in the process (step STb) are suppressed. Furthermore, according to method MT, the surface inside chamber 10 is protected by protective film PF, so that the surface of chamber 10 is made sputter-resistant, and particles of the material constituting the surface of chamber 10 are suppressed from scattering.

[0082] Reference is now made to FIG. 8. FIG. 8 is a cross-sectional view showing a protective film according to another exemplary embodiment. The protective film PF may be a laminated film including two or more different films. In one embodiment, the protective film PF may include a first film PF1 and a second film PF2. The first film PF1 is formed on a surface 10f of the chamber 10 (e.g., the lower surface of the top plate 34). The second film PF2 is formed on the first film PF1.

[0083] The first film PF1 may be made of silicon or silicon carbide. The second film PF2 may contain carbon. For the method of forming the film made of silicon or silicon carbide and the film containing carbon in the step STa, please refer to the above description. In one example, the first film PF1 is formed by a CVD method using a deposition gas containing SiCl4 gas and H2 gas, a deposition gas containing SiH4 gas, or a deposition gas containing SiH4 gas and a carbon-containing gas (e.g., a hydrocarbon gas such as CH4 gas). In one example, the second film PF2 is formed by a CVD method using a deposition gas containing a carbon-containing gas (e.g., a hydrocarbon gas such as CH4 gas).

[0084] The protective film PF may further include an intermediate film PFm provided between the first film PF1 and the second film PF2. In this case, the first film PF1 may be made of silicon, the intermediate film PFm may be made of silicon carbide, and the second film PF2 may contain carbon. For the method of forming the film made of silicon, the film made of silicon carbide, and the film containing carbon in the step STa, please refer to the above description. In one example, the first film PF1 is formed by a CVD method using a film forming gas containing SiCl4 gas and H2 gas or a film forming gas containing SiH4 gas. In one example, the intermediate film PFm is formed by a CVD method using a film forming gas containing SiH4 gas and a carbon-containing gas (e.g., a hydrocarbon gas such as CH4 gas). In one example, the second film PF2 is formed by a CVD method using a film forming gas containing a carbon-containing gas (e.g., a hydrocarbon gas such as CH4 gas).

[0085] Reference is now made to FIG. 9. (a) of FIG. 9 is a diagram showing an example of the distribution of carbon content in the thickness direction of a protective film according to yet another exemplary embodiment, and (b) of FIG. 9 is a diagram showing an example of the ratio of the flow rate of a carbon-containing gas to the total flow rate of a film-forming gas for forming a protective film. In (a) of FIG. 9, the horizontal axis indicates the distance in the thickness direction of the protective film PF from the surface of the chamber 10, and the vertical axis indicates the carbon content (or carbon concentration) of the protective film PF. In (b) of FIG. 9, the horizontal axis indicates the time within the period of step STa, and the vertical axis indicates the ratio of the flow rate of a carbon-containing gas to the total flow rate of a film-forming gas used in step STa.

[0086] In one embodiment, the protective film PF includes silicon and carbon. As shown in (a) of Fig. 9, the carbon content (or carbon concentration) in the protective film PF may increase with increasing distance from the surface of the chamber 10. The silicon content (or silicon concentration) in the protective film PF may decrease with increasing distance from the surface of the chamber 10.

[0087] In step STa, the protective film PF is formed by a CVD method using a deposition gas containing a silicon-containing gas such as SiH4 gas and a carbon-containing gas (e.g., a hydrocarbon gas such as CH4 gas). In step STa, as shown in FIG. 9(b), the ratio of the flow rate of the carbon-containing gas to the total flow rate of the deposition gas may be increased over time. The ratio of the flow rate of the silicon-containing gas to the total flow rate of the deposition gas may be decreased over time in step STa.

[0088] Although various exemplary embodiments have been described above, the present invention is not limited to the above-described exemplary embodiments, and various additions, omissions, substitutions, and modifications may be made. In addition, elements in different embodiments can be combined to form other embodiments.

[0089] For example, the plasma processing apparatus used to perform the method MT may be a capacitively coupled plasma processing apparatus different from the plasma processing apparatus 1. The plasma processing apparatus used to perform the method MT may be a type of plasma processing apparatus different from the capacitively coupled type. Such a plasma processing apparatus is, for example, an inductively coupled plasma processing apparatus, an electron cyclotron resonance (ECR) plasma processing apparatus, or a plasma processing apparatus that generates plasma from a gas by surface waves such as microwaves.

[0090] Furthermore, when step STa is being performed, that is, during the formation of the protective film PF, the upper electrode 30 may be heated by a heater. For example, in step STa, the upper electrode 30 may be heated to 150°C.

[0091] From the foregoing, it will be understood that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the appended claims. [Explanation of symbols]

[0092] Reference Signs List 1: plasma processing apparatus, 10: chamber, 61: high frequency power supply, 62: bias power supply, GS: gas supply unit, 80: control unit, W: substrate, EF: film, MK: mask.

Claims

1. (a) forming a carbon-containing protective film on a surface inside a chamber of a plasma processing apparatus; (b) etching an etching film on the substrate by plasma generated from an etching gas including hydrogen fluoride gas and a hydrofluorocarbon gas in the chamber; (c) performing a roughening treatment on the surface of the protective film after (a) and before (b); Including, The substrate includes the etching film, which is a silicon-containing film, and a mask containing carbon and provided on the etching film. Etching method.

2. The etching method of claim 1 , wherein the protective film is formed by chemical vapor deposition using a carbon-containing gas, molecular layer deposition, or sputter deposition.

3. The etching method according to claim 1 , wherein the protective film is a laminated film including two or more different films.

4. 4. The etching method according to claim 3, wherein the protective film includes a first film containing silicon and a second film containing carbon formed on the first film.

5. 3. The method of claim 1, wherein the protective film has a carbon content that increases with distance in its thickness direction from the surface within the chamber.

6. In the method (a), the protective film is formed using a film-forming gas; In the method (a), a ratio of a flow rate of a carbon-containing gas in the film forming gas to a total flow rate of the film forming gas is increased over time. The etching method according to claim 5 .

7. 7. The etching method according to claim 1, wherein the plasma processing apparatus is a capacitively coupled plasma processing apparatus and includes a substrate support provided in the chamber and an upper electrode provided on the substrate support.

8. 8. The etching method according to claim 7, wherein a surface of the upper electrode facing the internal space of the chamber is provided by a top plate made of silicon.

9. 9. The etching method according to claim 7, further comprising the step of: (d) applying a negative DC voltage to the upper electrode during (a) or after (a) and before (b).

10. The etching method according to any one of claims 1 to 9, further comprising the step of: (e) modifying a surface within the chamber before (a).

11. 11. The etching method according to claim 10, wherein in (e), a plasma is generated from a noble gas in the chamber after chamber cleaning is performed.

12. 12. The etching method according to claim 1, wherein in (c), plasma is generated from hydrogen gas in the chamber.

13. A chamber; a gas supply configured to supply a gas into the chamber; a plasma generating unit configured to generate a plasma from a gas in the chamber; A control unit configured to control the gas supply unit and the plasma generation unit; Equipped with The control unit is (a) controlling a gas supply unit to supply a deposition gas into the chamber to form a protective film containing carbon on a surface inside the chamber; (b) controlling the gas supply unit and the plasma generation unit to generate plasma generated from an etching gas including hydrogen fluoride gas and a hydrofluorocarbon gas in order to etch an etching film on a substrate in the chamber; (c) controlling the gas supply unit and the plasma generation unit to perform a roughening treatment on the surface of the protective film after (a) and before (b); It is structured as follows: the substrate includes the etching film and a mask containing carbon and provided on the etching film; Plasma processing equipment.

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