Method of etching a film and plasma processing apparatus

Abstract

A method of etching a film and a plasma processing apparatus are provided. The method of one example embodiment includes a step of forming a precursor layer on a substrate by supplying a precursor gas. The substrate has a film, and an opening is provided. The method further includes a step of etching the film with chemical species from a plasma formed from a process gas. In the step of etching the film, a depth of the opening is increased, and a protective region is formed from the precursor layer with the chemical species from the plasma or other chemical species. A plurality of cycles each including the step of forming the precursor layer and the step of etching the film are performed. A temperature of the substrate during performance of the step of etching the film included in at least one cycle and a temperature of the substrate during performance of the step of etching the film included in at least one other cycle are set to different temperatures from each other. According to the present invention, a technique capable of protecting a side wall surface of a film and controlling a width of an opening formed in a depth direction of the film can be provided.

Description

Technical Field

[0001] The exemplary embodiments of the present invention relate to a method for etching a film and a plasma processing apparatus. Background Technology

[0002] In the manufacture of electronic devices, plasma etching of films is performed. In plasma etching, plasma is generated from gas within a chamber. The film of a substrate disposed within the chamber is etched by chemical agents from the plasma.

[0003] In plasma etching, in order to suppress the expansion of openings formed in the film in the lateral direction (i.e., in a direction orthogonal to the film thickness direction), a protective region is sometimes formed on the sidewall surface of the film defining the opening. Techniques including the steps of forming the protective region and etching the film are described, for example, in Patent Documents 1-3.

[0004] In the technologies described in Patent Documents 1-3, the organic film is etched. In the technologies described in Patent Documents 1 and 2, a silicon-containing protective region is formed on the sidewall surface using a sputtering ring. This protective region protects the organic film from the oxidizing agents that etch it. In the technology described in Patent Document 3, the organic film is etched using plasma etching with a gas containing carbonyl sulfide, oxygen, and chlorine. When plasma is generated, sulfur and silicon chloride chemical seeds are produced. These sulfur and silicon chloride chemical seeds form a protective region on the sidewall surface. In the technology described in Patent Document 3, the protective region is formed simultaneously with the etching of the organic film.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent document 1: Japanese Patent Application Publication No. 2012-204668.

[0008] Patent Document 2: Japanese Patent Application Publication No. 2009-049141.

[0009] Patent document 3: Japanese Patent Application Publication No. 2015-012178. Summary of the Invention

[0010] The technical problem that the invention aims to solve

[0011] The present invention provides a protective film sidewall surface and a technique for controlling the width of the opening formed in the depth direction of the opening in the film.

[0012] Technical means for solving problems

[0013] According to an exemplary embodiment, a method for etching a film is provided. The substrate having the film includes a sidewall surface and a bottom surface defining an opening. The method includes the step of forming a precursor layer on the substrate by supplying a precursor gas. The method further includes the step of etching the film using a chemical seed from a plasma generated from a treatment gas. In the film etching step, the depth of the opening is increased by etching, and a protective region is formed from the precursor layer using a chemical seed or other chemical seed from the plasma. Multiple cycles comprising the steps of forming the precursor layer and etching the film are performed. The substrate temperature during the execution of the film etching step included in at least one cycle and the substrate temperature during the execution of the film etching step included in at least one other cycle are set to different temperatures from each other.

[0014] Invention Effects

[0015] According to one exemplary embodiment, a technique is available to provide a protective film sidewall surface and to control the width of the opening in the depth direction of the opening formed in the film. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating an exemplary embodiment of a method for etching a film.

[0017] Figure 2 This is a magnified cross-sectional view of a substrate as an example.

[0018] Figure 3 This is a diagram that schematically illustrates a plasma processing apparatus of an exemplary embodiment.

[0019] Figure 4 This is an enlarged cross-sectional view of an electrostatic chuck in a plasma processing apparatus according to an exemplary embodiment.

[0020] Figure 5 middle, Figure 5 (a) is used to explain Figure 1 The steps of the method shown in the figure are an example of STa. Figure 5 (b) is a partial enlarged cross-sectional view of the substrate in an example state after step STa has been performed.

[0021] Figure 6 It was executed. Figure 1 A partially enlarged cross-sectional view of a substrate in an example state after step ST1 of the method shown.

[0022] Figure 7 middle, Figure 7 (a) is used to explain Figure 1 The diagram shows an example of step ST4 of the method. Figure 7(b) is a partial enlarged cross-sectional view of the substrate in an example state after step ST4 has been performed.

[0023] Figure 8 middle, Figure 8 (a) is a partial enlarged cross-sectional view of the substrate in an example state after step ST4 has been performed. Figure 8 (b) is a partial enlarged cross-sectional view of the substrate in an example state after step ST7 has been performed.

[0024] Figure 9 It was executed. Figure 1 A magnified cross-sectional view of a substrate in an example state after the method shown.

[0025] Explanation of reference numerals in the attached figures

[0026] MT...method, CY...circulation, EF...membrane, OP...opening, SS...sidewall, BS...bottom, PL...precursor layer, PR...protection zone, P4...plasma. Detailed Implementation

[0027] The following describes various illustrative implementation methods.

[0028] According to an exemplary embodiment, a method for etching a film is provided. The substrate having the film includes a sidewall surface and a bottom surface defining an opening. The method includes the step of forming a precursor layer on the substrate by supplying a precursor gas. The method further includes the step of etching the film using a chemical seed from a plasma generated from a treatment gas. In the film etching step, the depth of the opening is increased by etching, and a protective region is formed from the precursor layer using a chemical seed or other chemical seed from the plasma. Multiple cycles comprising the steps of forming the precursor layer and etching the film are performed. The substrate temperature during the execution of the film etching step included in at least one cycle and the substrate temperature during the execution of the film etching step included in at least one other cycle are set to different temperatures from each other.

[0029] In one exemplary embodiment, a protective region is formed on the sidewall surface of the film defining the opening. Therefore, the sidewall surface of the film can be protected from the effects of the etching chemicals. Furthermore, the process of forming the protective region from the precursor layer is performed simultaneously with the etching of the film. Additionally, in this method, the substrate temperature during the etching step included in one cycle and the substrate temperature during the etching step included in at least one other cycle are set to different temperatures. The higher the substrate temperature during the etching step, the greater the lateral etching amount of the film due to the spontaneous reaction. Therefore, the lateral etching amount of the film in at least one cycle and the lateral etching amount of the film in at least one other cycle can be controlled independently. Therefore, the width of the opening formed in the depth direction of the opening in the film can be controlled.

[0030] In one exemplary embodiment of the method, at least one additional cycle may be performed after at least one additional cycle. The substrate temperature during the execution of the etching step included in the at least one additional cycle may be set to a higher temperature than the substrate temperature during the execution of the etching step included in the at least one cycle. In one exemplary embodiment of the method, at least one additional cycle may be performed when etching a film at a location deeper than the depth direction of the film etched in the at least one cycle.

[0031] In one illustrative implementation, as multiple cycles are executed, the protected area extends along the sidewall of the opening in the depth direction of the opening.

[0032] In one exemplary embodiment, the substrate may also have a mask disposed on the film.

[0033] In one exemplary embodiment of the method, the method may further include a step of reducing the thickness of the protected region by plasma etching between at least two cycles in a plurality of cycles.

[0034] In one exemplary embodiment of the method, the method may further include the step of forming the opening having the aforementioned bottom surface on the membrane before performing multiple cycles.

[0035] In one exemplary embodiment, multiple cycles can be performed within a continuously depressurized space within a plasma processing apparatus chamber without removing the substrate from the chamber.

[0036] In one exemplary embodiment, the plasma processing apparatus can be a capacitively coupled plasma processing apparatus. The plasma processing apparatus may include a chamber, a support stage, a gas supply unit, a first high-frequency power supply, and a second high-frequency power supply. The support stage includes a lower electrode and is configured to support a substrate within the chamber. The gas supply unit is configured to supply precursor gas and processing gas into the chamber. An upper electrode is disposed above the support stage. The first high-frequency power supply is configured to supply the upper electrode with a first high-frequency electrical power for generating plasma. The second high-frequency power supply is configured to supply the lower electrode with a second high-frequency electrical power for attracting ions to the substrate.

[0037] In one exemplary embodiment, the film may be an organic film. The etchant chemical may include oxidizing agents, or the precursor contained in the precursor layer may be oxidized using oxidizing agents. In one exemplary embodiment, the precursor may contain silicon or a metal. The metal may be tungsten or titanium.

[0038] In one exemplary embodiment, the film may be a low-dielectric-constant film containing silicon, carbon, oxygen, and hydrogen. The precursor layer may contain silicon. The etched film may contain fluorine and nitrogen chemicals. In the method of this embodiment, the precursor is nitrided with nitrogen chemicals.

[0039] In one exemplary embodiment, the film may be a low-dielectric-constant film containing silicon, carbon, oxygen, and hydrogen. The precursor layer may contain a metal. The etched film may contain fluorine and nitrogen chemicals. In the method of this embodiment, other chemicals may include oxidizing chemicals. In the method of this embodiment, the precursor is oxidized with oxidizing chemicals. The metal may be tungsten or titanium.

[0040] In one exemplary embodiment, the film may be a polycrystalline silicon film. The precursor contained in the precursor layer may contain silicon or a metal. The chemical species used to etch the film may contain halogen chemical species. Other chemical species may contain oxidizing chemical species. In the method of this embodiment, the precursor is oxidized with an oxidizing chemical species. The metal may be tungsten or titanium.

[0041] In one exemplary embodiment, the film may be a silicon nitride film. The precursor contained in the precursor layer may contain silicon or a metal. The etchant chemical may contain a chemical formed from hydrofluorocarbons in the process gas. Other chemical may contain oxidizing agents. In the method of this embodiment, the precursor is oxidized with an oxidizing agent. The metal may be tungsten or titanium.

[0042] In another exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a support stage, a gas supply unit, a plasma generation unit, a temperature control mechanism, and a control unit. The support stage is configured to support a substrate within the chamber. The gas supply unit is configured to supply precursor gas and processing gas into the chamber. The plasma generation unit is configured to generate plasma of the processing gas. The temperature control mechanism is configured to regulate the temperature of the substrate placed on the support stage. The control unit is configured to execute multiple control cycles, each including a first control and a second control. In the first control, the control unit controls the gas supply unit to supply precursor gas into the chamber, thereby forming a precursor layer on the substrate placed on the support stage. In the second control, the control unit controls the gas supply unit and the plasma generation unit to supply processing gas into the chamber and generate plasma of the processing gas within the chamber. The second control is executed such that the depth of the opening provided by the substrate is increased by etching a film on the substrate, and the precursor layer is modified to form a protective region. The control unit controls the temperature regulation mechanism such that the temperature of the substrate during the execution of the second control in at least one control cycle and the temperature of the substrate during the execution of the second control in at least one other control cycle are set to different temperatures from each other.

[0043] Hereinafter, various exemplary embodiments will be described in detail with reference to the accompanying drawings. Furthermore, the same or corresponding parts will be labeled with the same reference numerals in each drawing.

[0044] Figure 1 This is a flowchart illustrating an exemplary embodiment of a method for etching a film. Figure 1 The method shown, MT, is performed to etch the film on the substrate. Figure 2 This is a magnified cross-sectional view of a substrate as an example. Figure 2 The substrate W shown has a film EF. The substrate W may also have a substrate region UR and a mask MK.

[0045] A film EF is formed on a substrate region UR. A mask MK is formed on the film EF. The mask MK is patterned; that is, the mask MK provides more than one opening. Specifically, the substrate W has sidewalls and a bottom surface defining each of the more than one opening. Figure 2 In the substrate W shown, a mask MK is provided on the sidewalls, and a film EF is provided on the bottom surface. The film EF is partially exposed through an opening in the mask MK. The film EF can be formed of any material. The mask MK can be formed of any material as long as the film EF can be selectively etched relative to the mask MK in step ST4 described later.

[0046] In the first example of substrate W, film EF is an organic film. In the first example of substrate W, mask MK is a silicon-containing film. Silicon-containing films are, for example, antireflective films containing silicon.

[0047] In the second example of substrate W, film EF is a low dielectric constant film containing silicon, carbon, oxygen, and hydrogen. That is, in the second example of substrate W, film EF is a SiCOH film. In the second example of substrate W, mask MK is formed from a metal-containing film such as a tungsten-containing film or a titanium-containing film. In the second example of substrate W, mask MK can be formed from an organic film such as a photoresist film, a silicon nitride film, or a polycrystalline silicon film.

[0048] In the third example of substrate W, film EF is a polycrystalline silicon film. In the third example of substrate W, mask MK is formed from a metal-containing film such as a tungsten-containing film or a titanium-containing film. In the third example of substrate W, mask MK can be formed from an organic film such as a photoresist film or a silicon nitride film.

[0049] In the fourth example of substrate W, film EF is a silicon nitride film. In the fourth example of substrate W, mask MK is formed from a metal-containing film such as a tungsten-containing film or a titanium-containing film. In the fourth example of substrate W, mask MK can be formed from an organic film such as a photoresist film or a polycrystalline silicon film.

[0050] In one implementation, method MT is performed using a plasma processing device. Figure 3 This is a diagram that schematically illustrates a plasma processing apparatus of an exemplary embodiment. Figure 3 The plasma processing device 1 shown is a capacitively coupled plasma processing device.

[0051] The plasma processing apparatus 1 includes a chamber 10. The chamber 10 provides an internal space 10s therein. The chamber 10 includes a chamber body 12. The chamber body 12 has a generally cylindrical shape. The internal space 10s is provided inside the chamber body 12. The chamber body 12 is formed, for example, of aluminum. A corrosion-resistant film is formed on the inner wall surface of the chamber body 12. The corrosion-resistant film can be a film formed of ceramics such as alumina or yttrium oxide.

[0052] A passage 12p is formed on the side wall of the chamber body 12. When the substrate W is transported between the internal space 10s and the outside of the chamber 10, the substrate W passes through the passage 12p. The passage 12p can be opened and closed by a gate valve 12g. The gate valve 12g is provided along the side wall of the chamber body 12.

[0053] A support portion 13 is provided on the bottom of the chamber body 12. The support portion 13 is formed of 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 supports a support platform 14. The support platform 14 is disposed within the internal space 10s. The support platform 14 is configured to support the substrate W within the chamber 10, i.e., within the internal space 10s.

[0054] The support stage 14 has a lower electrode 18 and an electrostatic chuck 20. The support stage 14 may also have an electrode plate 16. The electrode plate 16 is formed, for example, of a conductor such as aluminum, and has a generally disc shape. The lower electrode 18 is disposed on the electrode plate 16. The lower electrode 18 is formed, for example, of a conductor such as aluminum, and has a generally disc shape. The lower electrode 18 is electrically connected to the electrode plate 16.

[0055] Figure 4 This is an enlarged cross-sectional view of an electrostatic chuck in an exemplary embodiment of a plasma processing apparatus. Below, referring to... Figure 3 and Figure 4 An electrostatic chuck 20 is disposed on the lower electrode 18. A substrate W is placed on the upper surface of the electrostatic chuck 20. The electrostatic chuck 20 has a body 20m and an electrode 20e. The body 20m has a generally disk-shaped form and is formed of a dielectric. The electrode 20e is a film-like electrode disposed within the body 20m. The electrode 20e is connected to a DC power supply 20p via a switch 20s. When a voltage from the DC power supply 20p is applied to the electrode 20e, an electrostatic attraction is generated between the electrostatic chuck 20 and the substrate W. Using the generated electrostatic attraction, the substrate W is attracted to the electrostatic chuck 20 and held by the electrostatic chuck 20.

[0056] The support stage 14 may have more than one heater HT. Each of the more than one heater HT can be a resistance heating element. The plasma processing apparatus 1 may also have a heater controller HC. Each of the more than one heater HT heats up in response to an electrical power applied individually from the heater controller HC. As a result, the temperature of the substrate W on the support stage 14 can be adjusted. The more than one heater HT constitutes the temperature regulation mechanism of the plasma processing apparatus 1. In one embodiment, the support stage 14 has multiple heaters HT. The multiple heaters HT are disposed in the electrostatic chuck 20.

[0057] An edge ring ER is disposed on the periphery of the support platform 14 in a manner that surrounds the edge of the substrate W. The substrate W is disposed on the electrostatic chuck 20 and within the area surrounded by the edge ring ER. The edge ring ER is used to improve the in-plane uniformity of the plasma processing of the substrate W. The edge ring ER is not limited and can be formed of silicon, silicon carbide, or quartz.

[0058] A flow path 18f is provided inside the lower electrode 18. A heat exchange medium (e.g., refrigerant) is supplied to the flow path 18f from a cooling unit 22 located outside the chamber 10 via a pipe 22a. The heat exchange medium supplied to the flow path 18f returns to the cooling unit 22 via a pipe 22b. In the plasma processing apparatus 1, the temperature of the substrate W placed on the electrostatic chuck 20 can be adjusted by heat exchange between the heat exchange medium and the lower electrode 18. The cooling unit 22 may also constitute a temperature control mechanism for the plasma processing apparatus 1.

[0059] The plasma processing apparatus 1 provides a gas supply line 24. The gas supply line 24 supplies heat transfer gas (e.g., He gas) from the heat transfer gas supply mechanism to the space between the upper surface of the electrostatic chuck 20 and the back surface of the substrate W.

[0060] The plasma processing apparatus 1 also includes an upper electrode 30. The upper electrode 30 is disposed above the support platform 14. The upper electrode 30 is supported on the upper part of the chamber body 12 via a component 32. The component 32 is formed of an insulating material. The upper electrode 30 and the component 32 close the upper opening of the chamber body 12.

[0061] The upper electrode 30 may include a top plate 34 and a support 36. The lower surface of the top plate 34 is the lower surface of the side of the internal space 10s, defining the internal space 10s. The top plate 34 may be formed of a low-resistance conductor or semiconductor with low Joule heating. A plurality of gas venting holes 34a are formed in the top plate 34. The plurality of gas venting holes 34a penetrate the top plate 34 in its thickness direction.

[0062] The support body 36 supports the top plate 34 via a detachable top plate 34. The support body 36 is made of a conductive material such as aluminum. A gas diffusion chamber 36a is provided inside the support body 36. Multiple gas holes 36b are formed in the support body 36. The multiple gas holes 36b extend downward from the gas diffusion chamber 36a. The multiple gas holes 36b are respectively connected to multiple gas release holes 34a. A gas inlet 36c is formed in the support body 36. The gas inlet 36c is connected to the gas diffusion chamber 36a. The gas inlet 36c is connected to a gas supply pipe 38.

[0063] A gas source group 40 is connected to the gas supply pipe 38 via valve group 41, flow controller group 42, and valve group 43. The gas source group 40, valve group 41, flow controller group 42, and valve group 43 constitute the gas supply unit GS. The gas source group 40 includes multiple gas sources. These multiple gas sources include gas sources of multiple gases usable in method MT. Valve group 41 and valve group 43 each include multiple on / off valves. The flow controller group 42 includes multiple flow controllers. Each of the multiple flow controllers in the flow controller group 42 is a mass flow controller or a pressure-controlled flow controller. The multiple gas sources in the gas source group 40 are each connected to the gas supply pipe 38 via corresponding on / off valves of valve group 41, corresponding flow controllers of flow controller group 42, and corresponding on / off valves of valve group 43.

[0064] The plasma processing apparatus 1 may also include a shielding member 46. The shielding member 46 is detachably disposed along the inner wall surface of the chamber body 12. The shielding member 46 is also disposed on the outer periphery of the support portion 13. The shielding member 46 prevents etching byproducts from adhering to the chamber body 12. The shielding member 46 is constructed, for example, by forming a corrosion-resistant film on the surface of a component made of aluminum. The corrosion-resistant film may be a film formed of a ceramic such as yttrium oxide.

[0065] A baffle 48 is provided between the support portion 13 and the side wall of the chamber body 12. The baffle 48 is constructed, for example, by forming a corrosion-resistant film on the surface of a component made of aluminum. The corrosion-resistant film can be a film formed of ceramic such as yttrium oxide. A plurality of through holes are formed in the baffle 48. An exhaust port 12e is provided below the baffle 48 and at the bottom of the chamber body 12. An exhaust device 50 is connected to the exhaust port 12e via an exhaust pipe 52. The exhaust device 50 includes a pressure regulating valve and a vacuum pump such as a worm gear molecular pump.

[0066] The plasma processing apparatus 1 also includes a first high-frequency power supply 62 and a second high-frequency power supply 64. The first high-frequency power supply 62 is a power source that generates a first high-frequency electrical power. The first high-frequency electrical power has a frequency suitable for generating plasma. The frequency of the first high-frequency electrical power is, for example, in the range of 27 MHz to 100 MHz. The first high-frequency power supply 62 is connected to the upper electrode 30 via a matching device 66 and an electrode plate 16. The matching device 66 has circuitry for matching the output impedance of the first high-frequency power supply 62 with the impedance of the load side (upper electrode 30 side). Furthermore, the first high-frequency power supply 62 can also be connected to the lower electrode 18 via the matching device 66. The first high-frequency power supply 62 constitutes an example plasma generation unit.

[0067] The second high-frequency power supply 64 is a power source that generates a second high-frequency electrical power. This second high-frequency electrical power has a frequency lower than that of the first high-frequency electrical power. When using both the first and second high-frequency electrical power, the second high-frequency electrical power is used as a bias power source to attract ions to the substrate W. The frequency of the second high-frequency electrical power is, for example, in the range of 400 kHz to 13.56 MHz. The second high-frequency power supply 64 is connected to the lower electrode 18 via a matching adapter 68 and an electrode plate 16. The matching adapter 68 has circuitry for matching the output impedance of the second high-frequency power supply 64 with the impedance on the load side (lower electrode 18 side).

[0068] Alternatively, a second high-frequency power source can be used instead of the first high-frequency power source; that is, only one high-frequency power source can be used to generate plasma. In this case, the frequency of the second high-frequency power source can be a frequency greater than 13.56 MHz, for example, 40 MHz. In this case, the plasma processing apparatus 1 may also not have the first high-frequency power source 62 and the matching device 66. In this case, the second high-frequency power source 64 constitutes an example plasma generation unit.

[0069] When plasma is generated in the plasma processing apparatus 1, gas is supplied from the gas supply unit GS into the internal space for 10 seconds. Furthermore, a high-frequency electric field is generated between the upper electrode 30 and the lower electrode 18 by supplying a first high-frequency electric power and / or a second high-frequency electric power. The gas is excited by the generated high-frequency electric field. As a result, plasma is generated.

[0070] The plasma processing apparatus 1 may also include a control unit 80. The control unit 80 may be a computer having a processor, a memory (such as a storage unit), an input device, a display device, and a signal input / output structure. The control unit 80 controls each part of the plasma processing apparatus 1. In the control unit 80, the operator can manage the plasma processing apparatus 1 by inputting commands using the input device. Furthermore, the operating status of the plasma processing apparatus 1 can be visually displayed in the control unit 80 via the display device. Moreover, the control program and scheme data are stored in the storage unit of the control unit 80. The control program is executed by the processor of the control unit 80 to perform various processes in the plasma processing apparatus 1. The processor of the control unit 80 executes the control program and controls each part of the plasma processing apparatus 1 according to the scheme data, thereby enabling the execution of method MT in the plasma processing apparatus 1.

[0071] Refer again Figure 1 The method MT will be described in detail below. In the following description, plasma processing apparatus 1 will be used for processing. Figure 2The method MT will be explained using the substrate W shown as an example. Furthermore, other plasma processing apparatuses can also be used in method MT. Other substrates can also be processed in method MT.

[0072] Method MT is performed with the substrate W placed on the support stage 14. In one embodiment, method MT may begin at step STa. In step STa, the film EF is etched by plasma etching.

[0073] In step STa, plasma Pa is generated from the process gas within chamber 10. In the first example of processing the substrate W described above, i.e., when the film EF of the substrate W is an organic film, the process gas used in step STa may contain an oxygen-containing gas. The oxygen-containing gas may include, for example, oxygen, carbon monoxide, or carbon dioxide. Alternatively, in the first example of processing the substrate W, the process gas used in step STa may contain nitrogen and / or hydrogen.

[0074] In the second example of processing the substrate W described above, i.e., when the film EF of the substrate W is a low dielectric constant film, the processing gas used in step STa may contain a fluorine-containing gas. The fluorine-containing gas is, for example, a fluorocarbon gas. A fluorocarbon gas is, for example, C4F8 gas.

[0075] In the third example of processing substrate W described above, where the film EF of substrate W is a polycrystalline silicon film, the processing gas used in step STa may contain a halogen-containing gas. The halogen-containing gas may be, for example, HBr gas, Cl2 gas, or SF6 gas.

[0076] In the fourth example of processing substrate W described above, where the film EF of substrate W is a silicon nitride film, the processing gas used in step STa may contain hydrofluorocarbon gas. Hydrofluorocarbon gas, for example, is CH3F gas.

[0077] In step STa, as Figure 5 As shown in (a), a chemical seed from plasma Pa is irradiated onto the film EF, and the film EF is etched by the chemical seed. In step STa, the film EF is etched to a position between the lower surface and the upper surface of the film EF. The lower surface of the film EF is the surface of the film EF that contacts the substrate region UR. The upper surface of the film EF is the surface of the film EF exposed from the opening of the mask MK. When step STa is performed, as... Figure 5 As shown in (b), an opening OP is formed in the membrane EF. The opening OP is defined by the sidewall surface SS and the bottom surface BS of the membrane EF.

[0078] In step STa, the control unit 80 controls the exhaust device 50 to set the pressure of the gas in the chamber 10 to a specified pressure. In step STa, the control unit 80 controls the gas supply unit GS to supply the process gas into the chamber 10. In step STa, the control unit 80 controls the plasma generation unit to generate plasma from the process gas. In one embodiment, in step STa, 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 electrical power and / or the second high-frequency electrical power.

[0079] The plasma etching in step STa can also be the same plasma etching as that in step ST4, which will be described later. Details of the plasma etching in step STa and the control performed by the control unit 80 in step STa can be found in the description of step ST4.

[0080] Furthermore, method MT may also omit step STa. In this case, an opening OP is pre-formed in the film EF of the substrate to which method MT can be applied. Alternatively, if method MT does not include step STa, it may also be possible to... Figure 2 The substrate W shown applies multiple cycles CY, which will be described later.

[0081] Method MT includes the process of performing multiple loops CY. Each of the multiple loops CY includes steps ST1 and ST4. The multiple loops CY can be applied to a substrate W with openings. In one embodiment, the multiple loops CY are as follows: Figure 5 As shown in (b), it can be applied to a substrate W having an opening OP defined by a sidewall surface SS and a bottom surface BS. In order to execute method MT, the control unit 80 executes multiple control cycles, each including a first control and a second control.

[0082] In step ST1, a precursor layer PL is formed on the substrate W. The precursor layer PL is formed on the surface of the substrate W that defines the opening. In one embodiment, the precursor layer PL is as follows: Figure 6 As shown, a precursor layer PL is formed on the surface of the film EF that defines the opening OP. The surface of the film EF includes the sidewall surface and the bottom surface that define the opening OP. A precursor layer PL is also formed on the mask MK. The precursor contained in the precursor layer PL is deformed during the execution of step ST4 described later to form a protective region PR. The precursor contained in the precursor layer PL can be any precursor, as long as the protective region can protect the sidewall surface PR that defines the opening OP from the influence of the active species of the etched film EF.

[0083] In step ST1, a precursor gas is supplied to the substrate W having an opening OP. In one embodiment, the precursor gas is supplied to the internal space 10s. In step ST1, a carrier gas may also be supplied along with the precursor gas. The carrier gas can be an inert gas. An inert gas may be, for example, a rare gas or nitrogen. During the execution of step ST1, no plasma is generated within the chamber 10.

[0084] In processing any of the first to fourth examples of the substrate W described above, the precursor gas used in step ST1 can be either a silicon-containing gas or a metal-containing gas. The silicon-containing gas as a precursor contains silicon-containing materials. For example, the silicon-containing gas is an aminosilane gas. The metal-containing gas as a precursor contains metal-containing materials. For example, the metal-containing materials contain tungsten or titanium. The metal-containing gas is, for example, a tungsten-containing gas or a titanium-containing gas. The tungsten-containing gas can be a tungsten halide gas such as tungsten hexafluoride gas or tungsten hexachloride gas. The titanium-containing gas can be a titanium halide gas such as titanium tetrafluoride gas or titanium tetrachloride gas.

[0085] In step ST1, the control unit 80 performs a first control. In this first control, the control unit 80 controls the gas supply unit GS to supply the precursor gas into the chamber 10. Also in this first control, the control unit 80 controls the exhaust device 50 to set the pressure of the gas within the chamber 10 to a specified pressure. Alternatively, in this first control, the control unit 80 may supply a carrier gas into the chamber 10 along with the precursor gas. The carrier gas is an inert gas. Examples of inert gases include rare gases or nitrogen.

[0086] In method MT, step ST2 may also be performed between step ST1 and step ST4. In step ST2, the internal space is purged for 10 seconds. In step ST2, the control unit 80 controls the exhaust device 50 to perform exhaust of the internal space for 10 seconds. In step ST2, the control unit 80 may also control the gas supply unit GS to supply inactive gas into the chamber 10. By performing step ST2, the precursor gas in the chamber 10 is replaced with inactive gas. By performing step ST2, excess precursor adsorbed on the substrate W can also be removed. In this case, the result of the precursor gas supply in step ST1 and the purging in step ST2 is the formation of a precursor layer PL. The precursor layer PL can be a monolayer.

[0087] In each of the multiple loops CY, step ST4 is executed after step ST1. For example... Figure 1 As shown, in one embodiment, step ST4 may also be performed after step ST2. In step ST4, the film EF is etched by plasma etching. In step ST4, plasma P4 is generated from the process gas within chamber 10. In step ST4, as... Figure 7As shown in (a), active species from plasma P4 are irradiated onto membrane EF, as... Figure 7 The film EF shown in (b) is etched. In step ST4, the chemical species used to etch the film EF, or other chemical species from plasma P4, react with the precursor contained in the precursor layer PL. As a result, a protective region PR is formed by the precursor layer PL. The protective region PR extends on the sidewall surface of the substrate W that defines the opening.

[0088] In the first example of processing substrate W described above, i.e., when the film EF of substrate W is an organic film, the processing gas used in step ST4 may contain an oxygen-containing gas. The oxygen-containing gas may include, for example, oxygen, carbon monoxide, or carbon dioxide. The processing gas may also contain carbonyl sulfide. In the first example of processing substrate W, film EF is etched using an oxidizing agent from plasma P4. Furthermore, a protective region PR is formed by the reaction of the oxidizing agent from plasma P4 with the precursor contained in the precursor layer PL. If the precursor contained in the precursor layer PL is silicon-containing, the protective region PR is formed from silicon oxide. If the precursor contained in the precursor layer PL is metal-containing, the protective region PR is formed from a metal oxide (e.g., tungsten oxide or titanium oxide).

[0089] In the second example of processing substrate W described above, i.e., when the film EF of substrate W is a low dielectric constant film, the processing gas used in step ST4 contains fluorine and nitrogen. For example, the processing gas contains a fluorocarbon gas and a nitrogen-containing gas. The fluorocarbon gas is, for example, C4F8 gas. The nitrogen-containing gas is, for example, nitrogen (N2 gas). The processing gas may also contain rare gases (e.g., Ar gas) and oxygen (O2 gas). In the second example of processing substrate W, the film EF is etched using fluorine and nitrogen chemical seeds from plasma P4. If the precursor contained in the precursor layer PL is silicon-containing, in step ST4, a protective region PR is formed by the reaction of nitrogen chemical seeds from plasma P4 with the silicon-containing material contained in the precursor layer PL. In this case, the protective region PR is formed of silicon nitride. If the precursor contained in the precursor layer PL is metal-containing, in step ST4, the protective region PR is formed by the reaction of oxidizing chemical seeds from plasma P4 with the metal-containing material contained in the precursor layer PL. In this case, the protective region PR is formed of a metal oxide (e.g., tungsten oxide or titanium oxide). Furthermore, the oxide species from plasma P4 reduce the amount of carbonaceous deposits formed on the substrate W in step ST4.

[0090] In the third example of processing substrate W, where the film EF of substrate W is a polycrystalline silicon film, the processing gas used in step ST4 may contain a halogen-containing gas and an oxygen-containing gas. The halogen-containing gas is HBr, Cl2, or SF6, and the oxygen-containing gas includes, for example, oxygen, carbon monoxide, or carbon dioxide. In the third example of processing substrate W, the film EF is etched using halogen chemical seeds from plasma P4. Furthermore, a protective region PR is formed by the reaction of oxidative seeds from plasma P4 with the precursor contained in the precursor layer PL. If the precursor contained in the precursor layer PL is silicon-containing, the protective region PR is formed of silicon oxide. If the precursor contained in the precursor layer PL is metal-containing, the protective region PR is formed of a metal oxide (e.g., tungsten oxide or titanium oxide).

[0091] In the fourth example of processing substrate W, where the film EF of substrate W is a silicon nitride film, the processing gas used in step ST4 may contain hydrofluorocarbon gas and oxygen-containing gas. Hydrofluorocarbon gas, for example, is CH3F gas. Oxygen-containing gas, for example, includes oxygen, carbon monoxide, or carbon dioxide. The processing gas may also contain rare gases (e.g., Ar gas). In the fourth example of processing substrate W, the film EF is etched using a chemical seed formed from the hydrofluorocarbon gas in the processing gas. Furthermore, a protective region PR is formed by the reaction of an oxidizing chemical seed from plasma P4 with the precursor contained in the precursor layer PL. If the precursor contained in the precursor layer PL is silicon-containing, the protective region PR is formed of silicon oxide. If the precursor contained in the precursor layer PL is metal-containing, the protective region PR is formed of a metal oxide (e.g., tungsten oxide or titanium oxide). Furthermore, the oxidizing chemical seed from plasma P4 reduces the amount of carbonaceous deposits formed on substrate W in step ST4.

[0092] In step ST4, the control unit 80 performs a second control. In this second control, the control unit 80 controls the gas supply unit GS to supply the processing gas into the internal space 10s. In this second control, the control unit 80 controls the exhaust device 50 to set the pressure of the gas within the chamber 10 to a specified pressure. In this second control, the control unit 80 controls the plasma generation unit to generate plasma from the processing gas. In one embodiment, the second control controls the first high-frequency power supply 62 and / or the second high-frequency power supply 64 to supply the first high-frequency electrical power and / or the second high-frequency electrical power.

[0093] In method MT, a protective region PR is formed on the sidewall of the film EF that defines the opening OP. The process of forming the protective region PR from the precursor layer PL is performed simultaneously with the etching of the film EF. The protective region PR protects the sidewall of the film EF from the chemical species used to etch the film EF. Therefore, it is possible to suppress the etching of the sidewall by the chemical species used to etch the film EF, thus preventing the opening OP from expanding laterally (i.e., in a direction orthogonal to the film thickness direction of the film EF).

[0094] In method MT, step ST5 can also be performed after step ST4. In step ST5, the internal space is purged for 10 seconds. Step ST5 is the same as step ST2.

[0095] In one embodiment, step ST6 may be executed after each loop CY has been executed. In step ST6, it is determined whether to execute step ST7. If step ST7 is to be executed, then step ST7 is executed following step ST6. On the other hand, if step ST7 is not executed, the process proceeds to step ST8. That is, in one embodiment, step ST7 is executed between at least two loops CY in the plurality of loops CY.

[0096] In step ST7, the thickness of the protective region PR is reduced by plasma etching. In step ST7, plasma is generated from the process gas within chamber 10. The process gas used in step ST7 contains a chemical species for etching the protective region PR. This chemical species is not limited and can be a chemical species that selectively etches the protective region PR relative to the mask MK and the film EF. Furthermore, in step ST7, the protective region PR can be partially removed. Alternatively, in step ST7, the entire protective region PR can be removed.

[0097] In step ST7, the control unit 80 controls the exhaust device 50 to set the pressure of the gas in the chamber 10 to a specified pressure. In step ST7, the control unit 80 controls the gas supply unit GS to supply the process gas into the chamber 10. In step ST7, the control unit 80 controls the plasma generation unit to generate plasma from the process gas. In one embodiment, in step ST7, 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 electrical power and / or the second high-frequency electrical power.

[0098] As the execution of multiple loops CY progresses, such as Figure 8 As shown in (a), the thickness of the protected region PR can be increased in a way that narrows the width of the upper end of the opening OP. When step ST7 is performed between at least two cycles CY, as Figure 8As shown in (b), the thickness of the protective region PR is reduced. As a result, in step ST4, which is performed after step ST7, ions from plasma P4 can easily reach the depth of the opening OP. Therefore, it is possible to suppress the narrowing of the opening OP at its depth.

[0099] In step ST8, it is determined whether the stopping condition is met. If the execution of multiple loops CY ends, it is determined that the stopping condition is met. In other words, if loop CY is to be executed again, the stopping condition is not met. In step ST8, if it is determined that the stopping condition is not met, loop CY is executed again. When loop CY is executed again, the control unit 80 executes the control loop including the first control and the second control again. As the execution of multiple loops CY progresses, the depth of the opening OP increases. Moreover, as the execution of multiple loops CY progresses, the protection region PR expands along the sidewall surface defining the opening OP in the depth direction of the opening OP. In step ST8, if it is determined that the stopping condition is met, method MT ends. In one embodiment, when method MT ends, as... Figure 9 As shown, the opening OP reaches the surface of the base region UR.

[0100] like Figure 1 As shown, each of the multiple cycles CY further includes step ST3. In step ST3, the temperature of the substrate W placed on the support stage 14 is adjusted. The temperature of the substrate W, adjusted in step ST3, is maintained during the execution of step ST4. In each of the multiple cycles CY, the adjustment of the substrate W's temperature in step ST3 begins before or simultaneously with step ST4. Figure 1 In this process, step ST3 begins between steps ST2 and ST4. Step ST3 may also begin before step ST1 or after the start time of execution of step ST1.

[0101] The temperature of the substrate W adjusted in step ST3 of at least one of the multiple cycles CY and the temperature of the substrate W adjusted in step ST3 of at least one other cycle CY are set to different temperatures. That is, the temperature of the substrate W during the execution of step ST4 of at least one cycle CY and the temperature of the substrate W during the execution of step ST4 of at least one other cycle CY are set to different temperatures. In order to execute step ST3, the control unit 80 controls the temperature adjustment mechanism of the plasma processing apparatus 1 described above. The higher the temperature of the substrate W during the execution of step ST4, the greater the lateral etching amount of the film EF caused by the spontaneous reaction. Therefore, it is possible to control the lateral etching amount of the film EF in at least one cycle CY and the lateral etching amount of the film EF in at least one other cycle CY independently. Therefore, it is possible to control the width of the opening OP formed in the film EF in the depth direction.

[0102] In one embodiment, at least one additional cycle CY may also be performed after at least one cycle CY. The temperature of the substrate W during the execution of step ST4 included in at least one additional cycle CY may also be set to a higher temperature than the temperature of the substrate W during the execution of step ST4 included in at least one cycle CY. In one embodiment, at least one additional cycle CY may also be performed when the film EF is to be etched at a location deeper than the depth direction location of the film EF etched in at least one cycle CY. According to these embodiments, the lateral etching amount of the film EF can be increased after the width of the protective region PR within the opening OP is increased. As a result, the uniformity of the width of the opening OP in the depth direction can be improved.

[0103] In one embodiment, multiple cycles of CY can be performed without removing the substrate W from the chamber 10. That is, multiple cycles of CY can be performed within a continuously depressurized space within a plasma processing apparatus without removing the substrate W from the chamber. According to this embodiment, the productivity of method MT is increased.

[0104] The above descriptions have illustrated various embodiments, but the implementation is not limited to these embodiments. Various additions, omissions, substitutions, and changes can be made. Furthermore, elements from different embodiments can be combined to form other embodiments.

[0105] For example, the apparatus used to perform step ST1 and the plasma processing apparatus used to perform step ST4 can be different apparatuses. The plasma apparatus used to perform step STa is also different from the apparatus used to perform step ST1 and the plasma processing apparatus used to perform step ST4.

[0106] Furthermore, the plasma processing apparatus used to perform method MT can be any type of plasma processing apparatus. For example, the plasma processing apparatus used to perform method MT can be a capacitively coupled plasma processing apparatus other than plasma processing apparatus 1. The plasma processing apparatus used to perform method MT can be an inductively coupled plasma processing apparatus, an ECR (electron cyclotron resonance) plasma processing apparatus, or a plasma processing apparatus that uses surface waves such as microwaves to generate plasma.

[0107] Furthermore, the temperature of the substrate W during the execution of each of the multiple loops CY (or step ST4 within them) can be set to the same temperature as the temperature of the substrate W during the execution of the other loops (or steps ST4 within them) contained in the multiple loops CY. That is, multiple loops CY can be executed without changing the temperature of the substrate W. Additionally, in method MT, steps ST1 and ST4 can be executed only once. That is, in method MT, the process containing steps ST1 and ST4 can be executed only once.

[0108] Based on the above description, various embodiments of the present invention have been described in this specification for illustrative purposes. It should be understood that various modifications can be made without departing from the scope and spirit of the invention. Therefore, the various embodiments disclosed in this specification are not intended to be limiting, and the true scope and spirit are given by the scope of the appended claims.

Claims

1. A method for etching a film, wherein, The substrate having the membrane includes a sidewall surface and a bottom surface defining an opening, and the method is characterized by comprising: The steps of forming a precursor layer on the substrate by supplying a precursor gas to the substrate; and The step of etching the film using a chemical seed from a plasma formed by processing a gas, wherein the etching increases the depth of the opening, and a protective region is formed from the precursor layer using the chemical seed or other chemicals from the plasma. Perform multiple cycles, each comprising the step of forming the precursor layer and the step of etching the film. The substrate temperature during the etching step of the film in at least one of the plurality of cycles, and the substrate temperature during the etching step of the film in at least one other of the plurality of cycles, are set to different temperatures from each other. The plurality of cycles further include, respectively, a step of adjusting the temperature of the substrate before the step of forming the precursor layer, or after the step of forming the precursor layer and before the step of etching the film. The temperature of the substrate, which is adjusted by the step of adjusting the temperature of the substrate, is maintained during the step of etching the film.

2. The method as described in claim 1, characterized in that: The at least one other loop is executed after the at least one loop. The temperature of the substrate during the execution of the step of etching the film included in the at least one other cycle is set to a higher temperature than the temperature of the substrate during the execution of the step of etching the film included in the at least one cycle.

3. The method as described in claim 2, characterized in that: The at least one other cycle is performed when the film is to be etched at a location deeper than the depth direction of the film etched in the at least one cycle.

4. The method according to any one of claims 1 to 3, characterized in that: As the execution of the plurality of cycles progresses, the protected area extends along the sidewall surface defining the opening in the depth direction of the opening.

5. The method according to any one of claims 1 to 3, characterized in that: The substrate also has a mask disposed on the membrane.

6. The method according to any one of claims 1 to 3, characterized in that: It also includes a step of reducing the thickness of the protected region by plasma etching between at least two of the plurality of cycles.

7. The method according to any one of claims 1 to 3, characterized in that: It also includes the step of forming the opening in the membrane before performing the plurality of cycles.

8. The method according to any one of claims 1 to 3, characterized in that: The multiple cycles are performed in a continuously depressurized space within a plasma processing apparatus chamber without removing the substrate from the chamber.

9. The method as described in claim 8, characterized in that: The plasma processing device is a capacitively coupled plasma processing device, which includes: The chamber; A support stage, which includes a lower electrode and is configured to support the substrate within the cavity; A gas supply unit configured to supply the precursor gas and the processing gas into the chamber; The upper electrode is disposed above the support platform; A first high-frequency power supply, configured to supply the upper electrode with a first high-frequency electrical power for generating plasma; and The second high-frequency power supply is configured to supply the lower electrode with a second high-frequency electrical power for attracting ions to the substrate.

10. The method according to any one of claims 1 to 3, characterized in that: The membrane is an organic membrane. The chemical species used to etch the film include oxidizing chemical species. The precursor contained in the precursor layer is oxidized using the oxidizing agent.

11. The method as described in claim 10, characterized in that: The precursor contains silicon or a metal.

12. The method according to any one of claims 1 to 3, characterized in that: The membrane is a low dielectric constant membrane containing silicon, carbon, oxygen, and hydrogen. The precursor layer contains a precursor that contains silicon. The chemical species used to etch the film include fluorine and nitrogen species. The precursor is nitrided using the nitrogen chemical species.

13. The method according to any one of claims 1 to 3, characterized in that: The membrane is a low dielectric constant membrane containing silicon, carbon, oxygen, and hydrogen. The precursor layer contains a metal precursor. The chemical species used to etch the film include fluorine and nitrogen species. The other chemical species include oxidizing chemical species.

14. The method according to any one of claims 1 to 3, characterized in that: The membrane is a polycrystalline silicon membrane. The precursor layer contains a precursor that contains silicon or a metal. The chemical species used to etch the film includes halogen chemical species. The other chemical species include oxidizing chemical species.

15. The method according to any one of claims 1 to 3, characterized in that: The membrane is a silicon nitride membrane. The precursor layer contains a precursor that contains silicon or a metal. The chemical species used to etch the film include those formed from hydrofluorocarbons in the processing gas. The other chemical species include oxidizing chemical species.

16. The method as described in claim 11, characterized in that: The metal is tungsten or titanium.

17. A plasma processing apparatus, characterized in that, include: chamber; It is configured as a support platform capable of supporting the substrate within the cavity; It is configured as a gas supply unit capable of supplying precursor gas and processing gas into the chamber; A plasma generation unit configured to generate plasma of the processed gas; It is configured as a temperature regulating mechanism capable of adjusting the temperature of a substrate placed on the support platform; and It is configured as a control unit capable of controlling the gas supply unit, the plasma generation unit, and the temperature regulation mechanism. The control unit is configured to perform the following processes: Execute multiple control loops, each containing a first control and a second control. In the first control, the gas supply unit is controlled to supply the precursor gas into the chamber, thereby forming a precursor layer on the substrate placed on the support platform. In the second control, the gas supply unit and the plasma generation unit are controlled to supply the processing gas into the chamber and generate a plasma of the processing gas in the chamber, such that the depth of the opening provided by the substrate is increased by etching the film on the substrate, and the precursor layer is modified to form a protective region. The temperature regulation mechanism is controlled such that the temperature of the substrate during the execution of the second control in at least one of the plurality of control cycles, and the temperature of the substrate during the execution of the second control in at least one other of the plurality of control cycles, are set to different temperatures from each other. The temperature regulating mechanism is controlled such that in each of the plurality of control cycles, before the first control or after the first control and before the second control, the temperature of the substrate is regulated and maintained during the second control.

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