Etching method and etching device

Abstract

Provided is a technique for improving the pattern shape of an etched etching target film. This etching method includes: (a) a step for providing a substrate having an etching target film and a mask on the etching target film, the mask having at least one opening; (b) a step for forming a deposited film containing a group 14 element on a surface of the substrate; (c) a step for heating the deposited film to a glass transition temperature or higher to implement a heat reflow treatment on the deposited film; and (d) a step for etching the etching target film.

Description

Etching method and etching apparatus

[0001] SUMMARY OF THE INVENTION Exemplary embodiments of the present disclosure relate to an etching method and an etching apparatus.

[0002] Japanese Patent Application Laid-Open No. 2003-144222 discloses a technique for etching a film to be etched, on which a carbon-containing film is formed.

[0003] Japanese Patent Application Laid-Open No. 2016-21546

[0004] The present disclosure provides a technique for improving the shape of a pattern formed on a film to be etched.

[0005] An etching method in one exemplary embodiment of the present disclosure includes the steps of: (a) providing a substrate having a film to be etched and a mask on the film to be etched, the mask having at least one opening; (b) forming a deposited film containing a Group 14 element on a surface of the substrate; (c) heating the deposited film to a temperature equal to or higher than the glass transition temperature to subject the deposited film to a thermal reflow treatment; and (d) etching the film to be etched.

[0006] According to one exemplary embodiment of the present disclosure, a technique for improving the shape of a pattern formed on a film to be etched can be provided.

[0007] FIG. 1 is a diagram for explaining an example of the configuration of a plasma processing system. FIG. 2 is a diagram for explaining an example of the configuration of an inductively coupled plasma processing apparatus. FIG. 3 is a flowchart showing an example of a substrate processing method. FIG. 4 is a diagram showing an example of a cross-sectional structure of a substrate in process ST1. FIG. 5 is a diagram showing an example of a cross-sectional structure of a substrate in process ST2. FIG. 6 is a diagram showing an example of a cross-sectional structure of a substrate in process ST3. FIG. 7 is a diagram showing an example of a cross-sectional structure of a substrate in process ST4.

[0008] Hereinafter, each embodiment of the present disclosure will be described.

[0009] In one exemplary embodiment, an etching method is provided, including: (a) providing a substrate having a film to be etched and a mask on the film to be etched, the mask having at least one opening; (b) forming a deposited film containing a Group 14 element on a surface of the substrate; (c) heating the deposited film to a glass transition temperature or higher to subject the deposited film to a thermal reflow treatment; and (d) etching the film to be etched.

[0010] In one exemplary embodiment, step (c) is performed after step (b).

[0011] In one exemplary embodiment, in step (b), the deposited film is formed by chemical vapor deposition, atomic layer deposition, or molecular layer deposition.

[0012] In one exemplary embodiment, in step (c), the deposited film is heated using at least one selected from the group consisting of a heater, a lamp, plasma, an electron beam, and an ion beam.

[0013] In one exemplary embodiment, a cycle comprising steps (b) and (c) is repeated.

[0014] In one exemplary embodiment, steps (b) and (c) are performed simultaneously or in this order.

[0015] In one exemplary embodiment, in steps (b) and (c), the substrate is exposed to a plasma generated from a first process gas containing a Group 14 element.

[0016] In one exemplary embodiment, the first process gas comprises a halogen.

[0017] In one exemplary embodiment, step (d) is performed after step (c).

[0018] In one exemplary embodiment, steps (c) and (d) are performed using a plasma, where in (c) no bias signal is applied to the substrate support, and in (d) a bias signal is applied to the substrate support to irradiate the surface of the substrate with ions.

[0019] In one exemplary embodiment, the cycle comprising steps (c) and (d) is repeated.

[0020] In one exemplary embodiment, steps (c) and (d) are performed simultaneously.

[0021] In one exemplary embodiment, steps (c) and (d) expose the substrate to a plasma generated from a second process gas that includes an etching gas.

[0022] In one exemplary embodiment, the second process gas comprises a halogen.

[0023] In one exemplary embodiment, steps (b), (c) and (d) are performed in this order.

[0024] In one exemplary embodiment, a cycle comprising steps (b), (c), and (d) is repeated.

[0025] In one exemplary embodiment, steps (b), (c), and (d) are performed simultaneously.

[0026] In one exemplary embodiment, in steps (b), (c), and (d), the substrate is exposed to a plasma generated from a third process gas including a Group 14 element and an etching gas.

[0027] In one exemplary embodiment, the third process gas includes a hydrogenated halogen gas and a carbon-containing gas.

[0028] In one exemplary embodiment, the hydrogenated halogen gas has a volume fraction of 85% or more in the third process gas, excluding the noble gas and nitrogen gas.

[0029] In one exemplary embodiment, the carbon-containing gas has a volume fraction of less than or equal to 10% in the third process gas.

[0030] In one exemplary embodiment, the carbon-containing gas is halogen-free.

[0031] In one exemplary embodiment, the energy of the ions incident on the substrate is 1 keV or less.

[0032] In one exemplary embodiment, the third process gas comprises a halogen.

[0033] In one exemplary embodiment, an etching apparatus is provided that includes a chamber, a substrate support disposed in the chamber, a plasma generating unit, and a controller, wherein the controller is configured to: (a) control providing a substrate having a film to be etched and a mask on the film to be etched to the substrate support, the mask having at least one opening; b) control forming a deposited film containing a Group 14 element on a surface of the substrate; (c) control heating the deposited film to a glass transition temperature or higher to subject the deposited film to a thermal reflow treatment; and (d) control etching the film to be etched.

[0034] Hereinafter, each embodiment of the present disclosure will be described in detail with reference to the drawings. In each drawing, the same or similar elements are designated by the same reference numerals, and redundant explanations will be omitted. Unless otherwise specified, the positional relationships, such as up, down, left, and right, will be described based on the positional relationships shown in the drawings. The dimensional ratios in the drawings do not represent actual ratios, and the actual ratios are not limited to the ratios shown in the drawings.

[0035] <Example of Plasma Processing System> FIG. 1 is a diagram illustrating an example of the configuration of a plasma processing system. In one embodiment, the plasma processing system includes a plasma processing apparatus 1 and a control unit 2. The plasma processing system is an example of a substrate processing system, and the plasma processing apparatus 1 is an example of a substrate processing apparatus. The plasma processing apparatus 1 includes a plasma processing chamber 10, a substrate support 11, and a plasma generation unit 12. The plasma processing chamber 10 has a plasma processing space. The plasma processing chamber 10 also has at least one gas supply port for supplying at least one processing gas to the plasma processing space and at least one gas exhaust port for exhausting gas from the plasma processing space. The gas supply port is connected to a gas supply unit 20 (described later), and the gas exhaust port is connected to an exhaust system 40 (described later). The substrate support 11 is disposed in the plasma processing space and has a substrate support surface for supporting a substrate.

[0036] The plasma generating unit 12 is configured to generate plasma from at least one processing gas supplied into the plasma processing space. The plasma generated in the plasma processing space may be capacitively coupled plasma (CCP), inductively coupled plasma (ICP), electron-cyclotron-resonance plasma (ECR plasma), helicon wave plasma (HWP), surface wave plasma (SWP), or the like. Various types of plasma generators may be used, including alternating current (AC) plasma generators and direct current (DC) plasma generators. In one embodiment, the AC signal (AC power) used in the AC plasma generator has a frequency in the range of 100 kHz to 10 GHz. Thus, AC signals include radio frequency (RF) signals and microwave signals. In one embodiment, the RF signal has a frequency in the range of 100 kHz to 150 MHz.

[0037] The controller 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform various processes described in this disclosure. The controller 2 may be configured to control each element of the plasma processing apparatus 1 to perform various processes described herein. In one embodiment, part or all of the controller 2 may be included in the plasma processing apparatus 1. The controller 2 may include, for example, a computer 2a. The computer 2a may include, for example, a processing unit (CPU: Central Processing Unit) 2a1, a storage unit 2a2, and a communication interface 2a3. The processing unit 2a1 may be configured to read a program from the storage unit 2a2 and execute the read program to perform various control operations. The program may be stored in the storage unit 2a2 in advance or may be acquired via a medium when needed. The acquired program is stored in the storage unit 2a2 and read from the storage unit 2a2 by the processing unit 2a1 for execution. The medium may be various storage media readable by the computer 2a or a communication line connected to the communication interface 2a3. The storage unit 2a2 may include a random access memory (RAM), a read-only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a local area network (LAN).

[0038] An example of the configuration of an inductively coupled plasma processing apparatus will be described below as an example of the plasma processing apparatus 1. FIG. 2 is a diagram illustrating the configuration of an inductively coupled plasma processing apparatus. The inductively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply 30, and an exhaust system 40. The plasma processing chamber 10 includes a dielectric window 101. The plasma processing apparatus 1 also includes a substrate support 11, a gas inlet unit, and an antenna 14. The substrate support 11 is disposed within the plasma processing chamber 10. The antenna 14 is disposed on or above the plasma processing chamber 10 (i.e., on or above the dielectric window 101). The plasma processing chamber 10 has a plasma processing space 10s defined by the dielectric window 101, a sidewall 102 of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 is grounded.

[0039] The substrate support 11 includes a main body 111 and a ring assembly 112. The main body 111 has a central region 111a for supporting a substrate W and an annular region 111b for supporting the ring assembly 112. A wafer is an example of a substrate W. The annular region 111b of the main body 111 surrounds the central region 111a of the main body 111 in a plan view. The substrate W is disposed on the central region 111a of the main body 111, and the ring assembly 112 is disposed on the annular region 111b of the main body 111 so as to surround the substrate W on the central region 111a of the main body 111. Therefore, the central region 111a is also called a substrate support surface for supporting the substrate W, and the annular region 111b is also called a ring support surface for supporting the ring assembly 112.

[0040] In one embodiment, the main body 111 includes a base 1110 and an electrostatic chuck 1111. The base 1110 includes a conductive member. The conductive member of the base 1110 can function as a bias electrode. The electrostatic chuck 1111 is disposed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic electrode 1111b disposed within the ceramic member 1111a. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Note that the annular region 111b may also be provided by another member surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member. In this case, the ring assembly 112 may be disposed on the annular electrostatic chuck or the annular insulating member, or may be disposed on both the electrostatic chuck 1111 and the annular insulating member. Alternatively, an RF or DC electrode may be disposed within the ceramic member 1111a, in which case the RF or DC electrode functions as a bias electrode. Note that both the conductive member of the base 1110 and the RF or DC electrode may function as two bias electrodes.

[0041] The ring assembly 112 includes one or more annular members. In one embodiment, the one or more annular members include one or more edge rings and at least one cover ring. The edge rings are formed of a conductive or insulating material, and the cover rings are formed of an insulating material.

[0042] The substrate support 11 may also include a temperature adjustment module configured to adjust at least one of the electrostatic chuck 1111, the ring assembly 112, and the substrate to a target temperature. The temperature adjustment module may include a heater, a heat transfer medium, a flow passage 1110a, or a combination thereof. A heat transfer fluid such as brine or a gas flows through the flow passage 1110a. In one embodiment, the flow passage 1110a is formed in the base 1110, and one or more heaters are disposed in the ceramic member 1111a of the electrostatic chuck 1111. The substrate support 11 may also include a heat transfer gas supply configured to supply a heat transfer gas between the backside of the substrate W and the central region 111a.

[0043] The gas inlet is configured to introduce at least one process gas from the gas supply unit 20 into the plasma processing space 10s. In one embodiment, the gas inlet includes a center gas injector (CGI) 13. The center gas injector 13 is disposed above the substrate support 11 and attached to a central opening formed in the dielectric window 101. The center gas injector 13 has at least one gas supply port 13a, at least one gas flow path 13b, and at least one gas inlet port 13c. The process gas supplied to the gas supply port 13a passes through the gas flow path 13b and is introduced into the plasma processing space 10s from the gas inlet port 13c. Note that the gas inlet may include one or more side gas injectors (SGIs) attached to one or more openings formed in the sidewall 102 in addition to or instead of the center gas injector 13.

[0044] The gas supply unit 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply unit 20 is configured to supply at least one process gas from a corresponding gas source 21 to the gas inlet through a corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, the gas supply unit 20 may include at least one flow modulation device that modulates or pulses the flow rate of the at least one process gas.

[0045] The power supply 30 includes an RF power supply 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power supply 31 is configured to supply at least one RF signal (RF power), such as a source RF signal and a bias RF signal, to at least one bias electrode and the antenna 14. This causes a plasma to be formed from at least one processing gas supplied to the plasma processing space 10s. Therefore, the RF power supply 31 can function as at least a part of the plasma generating unit 12. Furthermore, by supplying a bias RF signal to the at least one bias electrode, a bias potential is generated on the substrate W, thereby attracting ions in the formed plasma to the substrate W.

[0046] In one embodiment, the RF power supply 31 includes a first RF generating unit 31a and a second RF generating unit 31b. The first RF generating unit 31a is coupled to the antenna 14 via at least one impedance matching circuit and is configured to generate a source RF signal (source RF power) for plasma generation. In one embodiment, the source RF signal has a frequency in the range of 10 MHz to 150 MHz. In one embodiment, the first RF generating unit 31a may be configured to generate multiple source RF signals having different frequencies. The generated one or more source RF signals are supplied to the antenna 14.

[0047] The second RF generator 31b is coupled to at least one bias electrode via at least one impedance matching circuit and is configured to generate a bias RF signal (bias RF power). The frequency of the bias RF signal may be the same as or different from the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency lower than the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 100 kHz to 60 MHz. In one embodiment, the second RF generator 31b may be configured to generate multiple bias RF signals having different frequencies. The generated one or more bias RF signals are supplied to at least one bias electrode. In various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0048] The power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a bias DC generator 32a. In one embodiment, the bias DC generator 32a is connected to at least one bias electrode and configured to generate a bias DC signal. The generated bias DC signal is applied to the at least one bias electrode.

[0049] In various embodiments, the bias DC signal may be pulsed. In this case, a sequence of DC-based voltage pulses is applied to at least one bias electrode. The voltage pulses may have a rectangular, trapezoidal, triangular, or combination thereof. In one embodiment, a waveform generator for generating the sequence of voltage pulses from the DC signal is connected between the bias DC generator 32a and at least one bias electrode. Thus, the bias DC generator 32a and the waveform generator constitute a voltage pulse generator. The voltage pulses may have positive or negative polarity. Furthermore, the sequence of voltage pulses may include one or more positive voltage pulses and one or more negative voltage pulses within one cycle. Note that the bias DC generator 32a may be provided in addition to the RF power supply 31 or may be provided instead of the second RF generator 31b.

[0050] The antenna 14 includes one or more coils. In one embodiment, the antenna 14 may include an outer coil and an inner coil arranged coaxially. In this case, the RF power supply 31 may be connected to both the outer coil and the inner coil, or to either the outer coil or the inner coil. In the former case, the same RF generator may be connected to both the outer coil and the inner coil, or separate RF generators may be connected to the outer coil and the inner coil separately.

[0051] The exhaust system 40 may be connected to, for example, a gas exhaust port 10e provided at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure in the plasma processing space 10s is regulated by the pressure regulating valve. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0052] <Example of Etching Method> Figure 3 is a flowchart showing an example of an etching method (hereinafter also referred to as "this processing method") according to one illustrative embodiment. As shown in Figure 3, in one embodiment, this processing method includes step ST1 of providing a substrate, step ST2 of forming a deposited film on the surface of the substrate, step ST3 of performing a thermal reflow treatment on the deposited film, and step ST4 of etching the etching target film. The processing in each step may be performed in the plasma processing system shown in Figure 2. Below, an example will be described in which the control unit 2 controls each part of the plasma processing apparatus 1 to perform this processing method on a substrate W.

[0053] (Process ST1: Providing a Substrate) In process ST1, a substrate W is provided to a plasma processing chamber 10 (hereinafter also referred to as "chamber 10") as shown in Fig. 2. In one embodiment, the substrate W is carried into the chamber 10 by a transport arm, placed on a substrate support 11 by a lifter, and held on the substrate support 11 by suction.

[0054] 4 is a diagram showing an example of the cross-sectional structure of the substrate W in step ST1. The substrate W has an etching target film EF and a mask MK stacked in this order from bottom to top on an undercoat film UF. The substrate W may be used for manufacturing semiconductor devices. Examples of semiconductor devices include memory devices such as DRAMs and 3D-NAND flash memories, and logic devices.

[0055] The mask MK may be a film that functions as a mask in etching the etching target film EF. The mask MK may have a sidewall S1 that defines at least one opening OP1 on the etching target film EF. That is, the mask MK may have at least one opening OP1. The opening OP1 may be a space above the etching target film EF and may be surrounded by the sidewall S1 of the mask MK. That is, the upper surface of the etching target film EF may have a region covered by the mask MK and a region exposed at the bottom of the opening OP1.

[0056] The opening OP1 may have any shape when viewed from above the substrate W, i.e., when the substrate W is viewed from top to bottom in FIG. 4 . The shape may be, for example, a circle, an ellipse, a rectangle, a line, or a combination of one or more of these. The mask MK may have multiple side walls S1, and the multiple side walls S1 may define multiple openings OP1. The multiple openings OP1 may each have a linear shape and be arranged at regular or varying intervals to form a line-and-space pattern. Alternatively, the multiple openings OP1 may each have a hole shape and form an array pattern.

[0057] The mask MK may be an organic resist film, an amorphous carbon (ACL) film, a metal-containing resist film, a metal oxide resist film, etc. The mask MK may be a single-layer mask consisting of one layer, or may be a multi-layer mask consisting of two or more layers.

[0058] The etching target film EF is a silicon oxynitride film (SiON film), a spin-on carbon (SOC) film, a silicon oxide film (SiO ２ The film may be a silicon carbide film (SiC film), an amorphous silicon film, or the like.

[0059] The base film UF may be a silicon wafer, an organic film formed on a silicon wafer, a dielectric film, a metal film, a semiconductor film, etc. The base film UF may be configured by laminating a plurality of films.

[0060] Each film constituting the substrate W may be formed by any method. The base film UF, the etching target film EF, and the mask MK may be formed by a CVD method, an ALD method, an MLD method, a PVD method, a spin coating method, or the like. The opening OP1 in the mask MK may be formed by etching. The opening OP1 in the mask MK may be formed by a lithography method. Note that each film may be a flat film or may have an uneven surface. The substrate W may further have another film below the base film UF.

[0061] At least a part of the process of forming the base film UF, the etching target film EF, and the mask MK on the substrate W may be performed in the chamber 10 as part of step ST1. For example, the opening OP1 in the mask MK may be formed by etching in step ST1. In this case, the etching of the mask MK in step ST1 and steps ST2, ST3, and ST4 described below may be performed consecutively in the chamber 10. In one embodiment, the substrate W may be provided in the chamber 10 after all or part of the film on the substrate W has been formed in an apparatus or chamber external to the plasma processing apparatus 1.

[0062] In one embodiment, after the substrate W is provided on the substrate support 11, the temperature of the substrate support 11 or the substrate W is controlled to a given temperature by a temperature control module. Controlling the temperature of the substrate support 11 or the substrate W to a given temperature may include setting the temperature of the heat transfer fluid flowing through the flow path 1110a or the heater temperature to a given temperature, or setting them to a temperature different from the given temperature. The given temperature may be in the range of 60°C or less and -50°C or more. Note that the timing at which the temperature of the substrate support 11 or the substrate W starts to be controlled to a given temperature may be before or after the substrate W is placed on the substrate support 11, or may be simultaneous with the placement of the substrate W on the substrate support 11. The temperature of the substrate support 11 or the substrate W may be changed in each of the processes ST1 to ST4.

[0063] 5 is a diagram illustrating an example of a cross-sectional structure of a substrate W on which a deposited film DF is formed in step ST2. In one embodiment, in step ST2, the substrate W is exposed to a first processing gas to form a deposited film DF on the surface of the substrate W. The deposited film DF may be formed using a plasma CVD method.

[0064] In one embodiment, in step ST2, a first process gas is supplied into the chamber 10 from the central gas inlet 13 shown in FIG. 2 . The temperature of the substrate support 11 or the substrate W may be controlled to a first temperature. The first temperature may be in a range of 80° C. or less and −50° C. or more, or in a range of 80° C. or less and 0° C. or more. The pressure in the chamber 10 may be adjusted to a first pressure. The first pressure may be in a range of 1 mTorr to 1000 Torr or less, or in a range of 50 mTorr to 500 mTorr or less.

[0065] The first process gas may be a gas containing a Group 14 element. The Group 14 element may be any one of C, Si, Ge, and Sn. The first process gas may contain, as the gas containing a Group 14 element, at least one selected from the group consisting of a CF-based gas, a CHF-based gas, a CBr-based gas, a CHBr-based gas, a SiCl-based gas, a SiH-based gas, a SiF-based gas, and a SiBr-based gas. The CF-based gas (fluorocarbon gas) may be CF ４ Gas, C ２ F ２ Gas, C ２ F ４ Gas, C ３ F ６ Gas, C ３ F ８ Gas, C ４ F ６ Gas, C ４ F ８ Gas and C ５ F ８ The CHF-based (hydrofluorocarbon gas) may contain at least one selected from the group consisting of CH ２ F ２ Gas, CH ３ F gas and CHF ３ The gas may include at least one selected from the group consisting of:

[0066] The first process gas may further contain a halogen. The first process gas may contain a single halogen gas or a hydrogen halide. The halogen may be any of F, Cl, Br, and I. The first process gas may contain at least one hydrogen halide selected from the group consisting of HF gas, HCl gas, HBr gas, and HI gas. The first process gas may further contain an inert gas. The inert gas may be a noble gas such as Ar gas, He gas, or Kr gas, or N ２ It may be a gas.

[0067] In one embodiment, plasma is generated from a first process gas supplied into the chamber 10. In this case, a source RF signal is supplied from the first RF generator 31a to the antenna 14, which generates a high-frequency electric field between the antenna 14 and the substrate support 11, generating plasma from the first process gas in the plasma processing space 10s. The source RF signal may have a frequency of 10 MHz or more. The source RF signal may have a first power. The first power may be 1 kW or more.

[0068] When plasma is generated, a bias signal may be supplied to the substrate support 11. The bias signal may be a bias RF signal supplied from an RF power supply 31 or a bias DC signal supplied from a DC power supply 32. In this case, a bias potential is generated between the plasma and the substrate W. Ions and dissociated neutral species in the plasma are attracted to the substrate W.

[0069] 5, ions and dissociated neutral species in the plasma are deposited on the surface of the substrate W to form a deposited film DF. The deposited film DF may be formed on the upper surface of the mask MK, the sidewall S1 of the opening OP1, and the upper surface of the etching target film EF exposed in the opening OP1.

[0070] The formation of the deposited film DF in step ST2 is not limited to the plasma CVD method, and may be performed using various methods such as atomic layer deposition (ALD), molecular layer deposition (MLD), and other chemical vapor deposition (CVD) methods.

[0071] 6 is a diagram illustrating an example of a cross-sectional structure of a substrate W in which the deposited film DF has been subjected to thermal reflow treatment in step ST3. In one embodiment, in step ST3, the deposited film DF is heated to a temperature equal to or higher than the glass transition temperature, and the deposited film DF is subjected to thermal reflow treatment.

[0072] In one embodiment, in step ST3, plasma may be used as a heat source for heating the deposited film DF. For example, in step ST3, plasma may be generated from the second process gas supplied from the central gas inlet 13 into the chamber 10. In this case, a source RF signal is supplied from the first RF generator 31a to the antenna 14, thereby generating a high-frequency electric field between the antenna 14 and the substrate support 11, and plasma is generated from the second process gas in the plasma processing space 10s. The source RF signal may have a frequency of 10 MHz or more. The source RF signal may have a second power. The second power may be 300 W or more, 500 W or more. The second power may be greater than the first power. The temperature of the substrate support 11 or the substrate W may be controlled to a second temperature. The second temperature may be 60° C. or less, 50° C. or less. The pressure in the chamber 10 may be adjusted to a second pressure. The second pressure may be 1000 Torr or less. In step ST3, a bias signal does not need to be supplied to the substrate support portion 11.

[0073] The second process gas supplied into the chamber 10 may include a halogen. The second process gas may include a hydrogen halide. The second process gas may include at least one hydrogen halide selected from the group consisting of HF gas, HCl gas, HBr gas, and HI gas. The second process gas may be the same as the first process gas.

[0074] The heat of the plasma heats the deposited film DF to above its glass transition temperature, and the deposited film DF is subjected to a thermal reflow process. At this time, the rigidity and viscosity of the deposited film DF decrease, and the deposited film DF becomes fluid (soft, rubbery). This causes the deposited film DF to flow, flattening its surface. For more information on the "thermal reflow process," please refer to the following webpage: https: / / www.sciencedirect.com / science / article / pii / S0167931722001332.

[0075] The heat source for heating the deposited film DF in step ST3 is not limited to plasma, and a heater, a lamp, an electron beam, or an ion beam may be used. The heater may be provided in the substrate support part 11. The lamp may be an infrared lamp and may be provided in the chamber 10. When an electron beam or an ion beam is used as the heat source, an electron beam irradiation part or an ion beam irradiation part may be provided in the chamber 10.

[0076] Steps ST2 and ST3 may be performed simultaneously or consecutively in this order. In this case, the first process gas (second process gas) may contain a Group 14 element and a halogen. In this processing method, a cycle including steps ST2 and ST3 may be repeated multiple times.

[0077] (Process ST4: Etching) FIG. 7 is a diagram illustrating an example of the cross-sectional structure of the substrate W in process ST4. FIG. 8 is a diagram illustrating an example of the cross-sectional structure of the substrate W after the etching target film EF has been etched in process ST4. In one embodiment, in process ST4, the etching target film EF is etched. The upper surface of the etching target film EF exposed in the opening OP1 is etched. As shown in FIG. 7, the etching progresses in the depth direction, and a recess R1 is formed in the etching target film EF. As shown in FIG. 8, as the etching progresses further, an opening OP2 is formed in the etching target film EF.

[0078] In one embodiment, in step ST4, an etching gas is supplied into the chamber 10 from the central gas inlet 13 shown in FIG. 2. The etching gas may include a gas containing carbon and fluorine. The etching gas may include a CF-based gas or a CHF-based gas. The CF-based gas (fluorocarbon gas) includes C ４ F ６ Gas, C ４ F ８ Gas, C ３ F ８ Gas, CF ４ Gas, C ２ F ２ Gas, C ２ F ４ Gas, C ３ F ６ Gas and C ５ F ８ The CHF-based gas (hydrofluorocarbon gas) may be at least one selected from the group consisting of CHF ３ Gas, CH ２ F ２ Gas, CH ３ F gas, C ３ H ２ F ４ Gas, C ４ H ２ F ６ Gas, C ２ HF ５ Gas, C ２ H ２ F ４ Gas, C ２ H ３ F ３ Gas, C ２ H ４ F ２ Gas, C ３ HF ７ Gas, C ３ H ２ F ２ Gas, C ３ H ２ F ６ Gas, C ３ H ３ F ５ Gas, C ４ H ５ F ５ Gas, C ４ H ２ F ８ Gas, C５ H ２ F ６ Gas, C ５ H ２ F １０ Gas and C ５ H ３ F ７ The etching gas may include at least one selected from the group consisting of a SiH-based gas, a SiF-based gas, and a SiBr-based gas.

[0079] Plasma is generated from the etching gas supplied into the chamber 10. In this case, a source RF signal is supplied to the antenna 14, which generates a high-frequency electric field between the antenna 14 and the substrate support 11, generating plasma from the etching gas in the plasma processing space 10s. The source RF signal may have a frequency of 10 MHz or higher. The temperature of the substrate support 11 or the substrate W may be controlled to a third temperature. The third temperature may be 60° C. or lower. The pressure in the chamber 10 may be adjusted to a third pressure. The third pressure may be 1000 Torr or lower.

[0080] A bias signal may be supplied to the substrate support 11. The bias signal may be a bias RF signal supplied from an RF power supply 31 or a bias DC signal supplied from a DC power supply 32. In this case, a bias potential is generated between the plasma and the substrate W. Active species such as ions and radicals in the plasma are attracted to the substrate W, and the etching target film EF is etched in the depth direction by these active species. The bias RF signal may have a power (effective value) of 500 W or less. The bias signal supplied in process ST4 may be greater than the bias signal supplied in process ST2.

[0081] After the process ST4, the substrate W may be transferred from the chamber 10 to the outside. In one embodiment, the substrate W may be transferred from the substrate support 11 to the outside of the chamber 10 by a lifter and a transport arm.

[0082] Note that step ST3 and step ST4 may be performed simultaneously or consecutively in this order. When step ST3 and step ST4 are performed simultaneously, the second process gas may contain an etching gas. When step ST3 and step ST4 are performed consecutively, in step ST3, a bias signal may not be supplied to the substrate support part 11 while plasma is generated, and in step ST4, a bias signal may be supplied to the substrate support part 11 while plasma is generated, to irradiate ions onto the surface of the substrate W. That is, step ST3 may be switched to step ST4 by turning on and off the supply of the bias signal to the substrate support part 11.

[0083] In this processing method, a cycle including steps ST3 and ST4 may be repeated multiple times. In this case, steps ST3 and ST4 may be alternately switched by turning on and off the supply of a bias signal to the substrate support 11.

[0084] Furthermore, steps ST2, ST3, and ST4 may be performed simultaneously or consecutively in this order. When steps ST2, ST3, and ST4 are performed simultaneously, the substrate W may be exposed to plasma generated from a third process gas containing a Group 14 element and an etching gas. The third process gas may further contain a halogen. In this processing method, a cycle including steps ST2, ST3, and ST4 may be repeated multiple times.

[0085] According to this exemplary embodiment, the substrate processing method includes a step ST12 of providing a substrate W, a step ST2 of forming a deposited film DF containing a Group 14 element on the surface of the substrate W, a step of heating the deposited film DF to a temperature equal to or higher than the glass transition temperature to subject the deposited film DF to a thermal reflow treatment, and a step of etching the etching target film EF. Subjecting the deposited film DF to the thermal reflow treatment flattens the surface of the deposited film DF. This improves the roughness of the pattern surface of the mask MK. Furthermore, when holes are formed as the pattern of the mask MK, the circularity of the holes is improved. As a result, the shape (roughness, circularity) of the pattern formed in the etching target film can be improved.

[0086] By including at least one of the first processing gas, the second processing gas, and the third processing gas in a halogen, the thermal reflow processing of the deposited film DF can be performed appropriately, and the pattern shape (roughness, circularity) formed on the film to be etched can be improved.

[0087] When the above-described steps ST2, ST3, and ST4 are performed simultaneously, the third process gas may contain a hydrogenated halogen gas and a carbon-containing gas. The hydrogenated halogen gas is an example of an etching gas. The carbon-containing gas is an example of a gas containing a Group 14 element. The hydrogenated halogen gas may have a volume ratio of 85% or more in the third process gas, excluding the noble gas and nitrogen gas. The carbon-containing gas may have a volume ratio of 10% or less in the third process gas. Furthermore, the carbon-containing gas may have a volume ratio of 10% or less in the third process gas, excluding the noble gas and nitrogen gas.

[0088] The halogen hydride gas may include at least one selected from the group consisting of HF gas, HCl gas, HBr gas, and HI gas.

[0089] The carbon-containing gas may include at least one gas selected from the group consisting of a CH-based gas, a CF-based gas, a CHF-based gas, a CBr-based gas, and a CHBr-based gas. ４ The carbon-containing gas may be a halogen-free gas.

[0090] The third process gas may further include an inert gas, such as a noble gas, such as Ar gas, He gas, or Kr gas, or N ２ It may be a gas.

[0091] In this embodiment in which steps ST2, ST3, and ST4 are performed simultaneously, first, a third process gas is supplied into the chamber 10. The third process gas is supplied into the chamber 10 from the central gas inlet 13 shown in FIG.

[0092] Next, plasma is generated from the third process gas supplied into the chamber 10. In this case, a source RF signal is supplied to the antenna 14, which generates a high-frequency electric field between the antenna 14 and the substrate support 11, generating plasma from the third process gas in the plasma processing space 10s. The source RF signal may have a power of 500 W or more, or 1 kW or more. The temperature of the substrate support 11 or the substrate W may be set to 30° C. or less, or 10° C. or less. The pressure in the chamber 10 may be adjusted to 100 mTorr or less, or 80 mTorr or less.

[0093] A bias signal may be supplied to the substrate support 11. The bias signal may be a bias RF signal supplied from an RF power supply 31 or a bias DC signal supplied from a DC power supply 32. The bias signal may have a power of 50 W or less. The energy of the ions incident on the substrate may be 1 keV or less.

[0094] According to this embodiment, the deposition film DF is formed, the deposition film DF is thermally reflowed, and the etching target film EF is etched simultaneously. By performing these processes using plasma generated from a third process gas containing a hydrogenated halogen gas and a carbon-containing gas, the pattern shape (roughness, roundness) formed on the etching target film can be improved.

[0095] The process of this embodiment may be used for etching to form a fine pattern with a line-and-space pitch of 60 nm or less in a film to be etched. The process of this embodiment may be used for etching using an EUV mask or a resist film (metal oxide resist film, chemically amplified resist film) as a mask. The plasma may be remote plasma, in which plasma generated from a third process gas outside the chamber is supplied into the chamber.

[0096] Example 1 A substrate W having an etching target film EF of a silicon oxynitride film and a mask MK of a resist film (organic film) was prepared, and an etching process was performed in which steps ST2, ST3, and ST4 were simultaneously performed under the following conditions 1 and 2, to form a line and space pattern in the etching target film EF.

[0097] <Condition 1> Gas species: HF gas (volume ratio 95% excluding noble gas (Ar gas)), CH ４ Gas (volume ratio 5% excluding noble gas (Ar gas)), Ar gas Pressure: 10 mTorr Temperature: 0°C Source RF power: 1 kW Bias power: 30 W

[0098] <Condition 2> Gas type: CF ４ Gas (volume ratio 100% excluding noble gas (Ar gas)), Ar gas Pressure: 30 mTorr Temperature: 30°C Source RF power: 150 W / 50 W (36 cycles) Bias power: 50 W / 245 W (36 cycles)

[0099] When the LWR (Line Width Roughness), SWR (Space Width Roughness), and LER (Line Edge Roughness) of the line and space pattern of the etching target film EF formed by etching under condition 2 were set to 1, the LWR, SWR, and LER of the line and space pattern of the etching target film EF formed by etching under condition 1 were 0.96, 0.87, and 0.93.

[0100] (Example 2) A substrate W having an etching target film EF of a silicon oxynitride film and a mask MK of a resist film (organic film) was prepared, and an etching process was performed simultaneously to perform steps ST2, ST3, and ST4 under the following conditions 3 and 4, to form a hole pattern in the etching target film EF.

[0101] <Condition 3> Gas type: HF gas (volume ratio excluding noble gases: 96%), C ４ F ６ Gas (volume ratio 4% excluding noble gas (Ar gas)), Ar gas Pressure: 10 mTorr Temperature: 0°C RF power: 1 kW Bias power: 30 W

[0102] <Condition 4> Gas type: CHF ３ Gas and CH ３ F gas (volume ratio of carbon-containing gas excluding noble gas (Ar gas) 66%), NF ３ Gas: Ar gas Pressure: 10 mTorr Temperature: 30°C Source RF power: 1 kW Bias power: 50 W

[0103] When the circumferential roughness (CER (Contact Edge Roughness)) of the hole pattern of the etching target film EF formed by etching under condition 4 was set to 1, the circumferential roughness of the hole pattern of the etching target film EF formed by etching under condition 3 was 0.53.

[0104] In the above embodiments, the present processing method is not limited to an inductively coupled plasma processing apparatus, and may be performed in other types of plasma processing apparatuses, such as a plasma processing apparatus that generates capacitively coupled plasma, a plasma processing apparatus that generates ECR plasma, a plasma processing apparatus that generates helicon wave excited plasma, or a plasma processing apparatus that generates surface wave plasma.

[0105] Embodiments of the present disclosure further include the following aspects.

[0106] (Supplementary Note 1) An etching method comprising: (a) providing a substrate having a film to be etched and a mask on the film to be etched, the mask having at least one opening; (b) forming a deposited film containing a Group 14 element on a surface of the substrate; (c) heating the deposited film to a glass transition temperature or higher to perform a thermal reflow treatment on the deposited film; and (d) etching the film to be etched.

[0107] (Supplementary Note 2) The etching method according to Supplementary Note 1, wherein the step (c) is carried out after the step (b).

[0108] (Supplementary Note 3) The etching method according to Supplementary Note 2, wherein in the step (b), the deposited film is formed by chemical vapor deposition, atomic layer deposition, or molecular layer deposition.

[0109] (Supplementary Note 4) The etching method according to Supplementary Note 2 or 3, wherein in the step (c), the deposited film is heated using at least one selected from the group consisting of a heater, a lamp, plasma, an electron beam, and an ion beam.

[0110] (Supplementary Note 5) The etching method according to any one of Supplementary Notes 2 to 4, wherein a cycle including the steps (b) and (c) is repeated.

[0111] (Supplementary Note 6) The etching method according to Supplementary Note 1, wherein the steps (b) and (c) are carried out simultaneously or in this order.

[0112] (Supplementary Note 7) The etching method according to Supplementary Note 6, wherein in the steps (b) and (c), the substrate is exposed to plasma generated from a first process gas containing a Group 14 element.

[0113] (Supplementary Note 8) The etching method according to Supplementary Note 7, wherein the first process gas contains a halogen.

[0114] (Supplementary Note 9) The etching method according to Supplementary Note 1, wherein the step (d) is carried out after the step (c).

[0115] (Supplementary Note 10) The etching method according to Supplementary Note 9, wherein the steps (c) and (d) are performed using plasma, and in the step (c), a bias signal is not supplied to a substrate support part, and in the step (d), a bias signal is supplied to a substrate support part to irradiate ions onto the surface of the substrate.

[0116] (Supplementary Note 11) The etching method according to Supplementary Note 9 or 10, wherein a cycle including the step (c) and the step (d) is repeated.

[0117] (Supplementary Note 12) The etching method according to Supplementary Note 1, wherein the steps (c) and (d) are carried out simultaneously.

[0118] (Supplementary Note 13) The etching method according to Supplementary Note 12, wherein in the steps (c) and (d), the substrate is exposed to plasma generated from a second process gas containing an etching gas.

[0119] (Supplementary Note 14) The etching method according to Supplementary Note 13, wherein the second process gas contains a halogen.

[0120] (Supplementary Note 15) The etching method according to Supplementary Note 1, wherein the steps (b), (c), and (d) are carried out in this order.

[0121] (Supplementary Note 16) The etching method according to Supplementary Note 15, wherein a cycle including the steps (b), (c), and (d) is repeated.

[0122] (Supplementary Note 17) The etching method according to Supplementary Note 1, wherein the steps (b), (c), and (d) are carried out simultaneously.

[0123] (Supplementary Note 18) The etching method according to Supplementary Note 17, wherein in the steps (b), (c), and (d), the substrate is exposed to plasma generated from a third process gas containing a Group 14 element and an etching gas.

[0124] (Supplementary Note 19) The etching method according to Supplementary Note 18, wherein the third process gas contains a halogen.

[0125] (Supplementary Note 20) The etching method according to Supplementary Note 18, wherein the third process gas contains a hydrogenated halogen gas and a carbon-containing gas.

[0126] (Supplementary Note 21) The etching method according to Supplementary Note 20, wherein the hydrogenated halogen gas has a volume ratio of 85% or more in the third process gas, excluding a noble gas and a nitrogen gas.

[0127] (Supplementary Note 22) The etching method according to Supplementary Note 20 or 21, wherein the carbon-containing gas has a volume fraction of 10% or less in the third process gas.

[0128] (Supplementary Note 23) The etching method according to any one of Supplementary Notes 20 to 22, wherein the carbon-containing gas does not contain a halogen.

[0129] (Supplementary Note 24) The etching method according to any one of Supplementary Notes 20 to 23, wherein the energy of the ions incident on the substrate is 1 keV or less.

[0130] (Supplementary Note 25) An etching apparatus comprising a chamber, a substrate support part disposed in the chamber, a plasma generation part, and a control part, wherein the control part is configured to execute the following controls: (a) providing a substrate having a film to be etched and a mask on the film to be etched to the substrate support part, the mask having at least one opening; (b) forming a deposited film containing a Group 14 element on a surface of the substrate; (c) heating the deposited film to a glass transition temperature or higher to subject the deposited film to a thermal reflow treatment; and (d) etching the film to be etched.

[0131] The above embodiments are described for the purpose of explanation and are not intended to limit the scope of the present disclosure. Various modifications can be made to the above embodiments without departing from the scope and spirit of the present disclosure. For example, some components in one embodiment can be added to other embodiments. Also, some components in one embodiment can be replaced with corresponding components in other embodiments.

[0132] 1: plasma processing apparatus, 2: control unit, 10: plasma processing chamber, 11: substrate support unit, 12: plasma generation unit, W: substrate, MK: mask, OP1: opening, ER: film to be etched, DF: deposited film

Claims

1. An etching method comprising: (a) providing a substrate having a film to be etched and a mask on the film to be etched, the mask having at least one opening; (b) forming a deposited film containing a Group 14 element on a surface of the substrate; (c) heating the deposited film to a temperature equal to or higher than the glass transition temperature to subject the deposited film to a thermal reflow treatment; and (d) etching the film to be etched.

2. The etching method according to claim 1, wherein the step (c) is carried out after the step (b).

3. The etching method according to claim 2, wherein in step (b), the deposited film is formed by chemical vapor deposition, atomic layer deposition or molecular layer deposition.

4. The etching method according to claim 2, wherein in step (c), the deposited film is heated using at least one selected from the group consisting of a heater, a lamp, plasma, an electron beam, and an ion beam.

5. The etching method according to claim 2, wherein a cycle including steps (b) and (c) is repeated.

6. The etching method according to claim 1, wherein steps (b) and (c) are carried out simultaneously or in this order.

7. The etching method according to claim 6, wherein in steps (b) and (c), the substrate is exposed to plasma generated from a first process gas containing a Group 14 element.

8. The etching method of claim 7, wherein the first process gas comprises a halogen.

9. The etching method according to claim 1, wherein the step (d) is carried out after the step (c).

10. The etching method according to claim 9, wherein steps (c) and (d) are performed using plasma, and in step (c), no bias signal is supplied to a substrate support section, and in step (d), a bias signal is supplied to the substrate support section to irradiate ions onto the surface of the substrate.

11. The etching method according to claim 9, wherein a cycle including steps (c) and (d) is repeated.

12. The etching method according to claim 1, wherein steps (c) and (d) are carried out simultaneously.

13. The etching method according to claim 12, wherein in steps (c) and (d), the substrate is exposed to plasma generated from a second process gas containing an etching gas.

14. The etching method of claim 13, wherein the second process gas comprises a halogen.

15. The etching method according to claim 1, wherein steps (b), (c) and (d) are carried out in this order.

16. The etching method according to claim 15, wherein a cycle including steps (b), (c) and (d) is repeated.

17. The etching method according to claim 1, wherein steps (b), (c) and (d) are carried out simultaneously.

18. The etching method according to claim 17, wherein in steps (b), (c) and (d), the substrate is exposed to plasma generated from a third process gas containing a Group 14 element and an etching gas.

19. The etching method of claim 18, wherein the third process gas comprises a halogen.

20. The etching method of claim 18, wherein the third process gas comprises a hydrogenated halogen gas and a carbon-containing gas.

21. The etching method according to claim 20, wherein the hydrogenated halogen gas has a volume ratio of 85% or more in the third process gas, excluding a noble gas and nitrogen gas.

22. The etching method of claim 20, wherein the carbon-containing gas has a volume fraction of 10% or less in the third process gas.

23. The etching method of claim 20, wherein the carbon-containing gas is halogen-free.

24. The etching method according to claim 20, wherein the energy of the ions incident on the substrate is 1 keV or less.

25. An etching apparatus comprising a chamber, a substrate support part disposed within the chamber, a plasma generating part, and a control part, wherein the control part is configured to execute the following controls: (a) providing a substrate having a film to be etched and a mask on the film to be etched to the substrate support part, the mask having at least one opening; (b) forming a deposited film containing a Group 14 element on a surface of the substrate; (c) heating the deposited film to a glass transition temperature or higher to subject the deposited film to a thermal reflow process; and (d) etching the film to be etched.

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