Etching method and etching device

Abstract

An etching method according to the present disclosure comprises: (a) a step for preparing, on a substrate support part which is disposed in a chamber, a substrate containing a silicon-containing film and a mask film on the silicon-containing film, wherein the mask film includes at least one opening; (b) a step for supplying, into the chamber, processing gas containing CxFy gas (x is an integer of 2 or 3, and y is an integer of not more than two times x), the step being (b-1) a step for supplying, into the chamber, the CxFy gas at a first flow rate, (b-2) a step for supplying, into the chamber, the CxFy gas at a second flow rate, which is smaller than the first flow rate, (b-3) a step for supplying, into the chamber, the CxFy gas at a third flow rate, which is smaller than the second flow rate, (b-4) a step for supplying the CxFy gas at a fourth flow rate, which is between the second flow rate and the third flow rate; and (c) a step for using a source RF signal to generate plasma from the processing gas and etch the silicon-containing film in said at least one opening, while the step (b) is carried out.

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. 2003-124222 discloses a technique for etching silicon oxide films and silicon nitride films with plasma generated from fluorocarbon gas.

[0003] US Patent Application Publication No. 2018 / 0204728

[0004] The present disclosure provides a technique that can suppress necking during etching.

[0005] In one exemplary embodiment of the present disclosure, an etching method is provided, the etching method including the steps of: (a) providing a substrate including a silicon-containing film and a mask film on the silicon-containing film on a substrate support disposed in a chamber, the mask film including at least one opening; ｘ F ｙ (b-1) a step of supplying a process gas containing a gas (where x is an integer of 2 or 3, and y is an integer equal to or less than twice x), the process comprising: ｘ F ｙ (b-2) supplying a gas into a chamber at a first flow rate; ｘ F ｙ (b-3) supplying a gas into the chamber at a second flow rate, the second flow rate being less than the first flow rate; and (b-4) ｘ F ｙ (b-4) supplying a gas into the chamber at a third flow rate, the third flow rate being less than the second flow rate; ｘ F ｙ (c) while (b) is being performed, generating a plasma from the process gas using a source RF signal to etch the silicon-containing film in the at least one opening.

[0006] According to one exemplary embodiment of the present disclosure, a technique can be provided that can suppress necking during etching.

[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 a capacitively coupled plasma processing apparatus. FIG. 3 is a flowchart showing an etching method according to an exemplary embodiment. FIG. 4 is a diagram showing an example of the cross-sectional structure of a substrate W prepared in process ST1. FIG. 5 is a diagram showing an example of a timing chart for processes ST2 and ST3. FIG. 6 is a diagram showing an example of the cross-sectional structure of a substrate W after processes ST2 and ST3 have been performed. FIG. 7 is a diagram showing an example of the cross-sectional shape of a part of a carbon-containing film CF. FIG. 8 is a diagram showing an example of the cross-sectional structure of a substrate W after processes ST2 and ST3 have been further performed.

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

[0009] In one exemplary embodiment, an etching method is provided, the etching method including the steps of: (a) providing a substrate, including a silicon-containing film and a mask film on the silicon-containing film, on a substrate support disposed in a chamber, the mask film including at least one opening; ｘ F ｙ (b-1) a step of supplying a process gas containing a gas (where x is an integer of 2 or 3, and y is an integer equal to or less than twice x), the process comprising: ｘ F ｙ (b-2) supplying a gas into a chamber at a first flow rate; ｘ F ｙ (b-3) supplying a gas into the chamber at a second flow rate, the second flow rate being less than the first flow rate; and (b-4) ｘ F ｙ (b-4) supplying a gas into the chamber at a third flow rate, the third flow rate being less than the second flow rate; ｘ F ｙ(c) while (b) is being performed, generating a plasma from the process gas using a source RF signal to etch the silicon-containing film at the at least one opening.

[0010] In one exemplary embodiment, the etching method further includes (d) providing a bias DC signal to the substrate support while (c) is being performed.

[0011] In one exemplary embodiment, in (d), the absolute value of the voltage of the bias DC signal is a first voltage while (b-1) is being performed, a second voltage lower than the first voltage while (b-2) is being performed, a third voltage lower than the second voltage while (b-3) is being performed, and a fourth voltage higher than the second voltage while (b-4) is being performed.

[0012] In one exemplary embodiment, the fourth voltage is equal to the first voltage.

[0013] In one exemplary embodiment, the silicon-containing film includes a sidewall defining at least one opening, the first flow rate and the second flow rate are performed at (b-1) and (b-2), respectively, at flow rates during which a carbon-containing film is formed on the sidewall of the silicon-containing film, and the third flow rate and the fourth flow rate are performed at (b-3) and (b-4), respectively, at flow rates during which the carbon-containing film formed on the sidewall is etched.

[0014] In one exemplary embodiment, the mask film is a carbon-containing film.

[0015] In one exemplary embodiment, an etching apparatus is provided that includes a chamber, a substrate support disposed in the chamber, a gas supply unit that supplies a gas into the chamber, a plasma generation unit that generates plasma in the chamber, and a controller, wherein the controller (a) controls a control to prepare a substrate, including a silicon-containing film and a mask film on the silicon-containing film, on the substrate support disposed in the chamber, the mask film including at least one opening; ｘ F ｙ (b-1) Control of supplying a process gas containing a gas (where x is an integer of 2 or 3, and y is an integer equal to or less than twice x), ｘ F ｙ (b-2) controlling the supply of gas into the chamber at a first flow rate; ｘ F ｙ (b-3) supplying the gas into the chamber at a second flow rate, the second flow rate being less than the first flow rate; and (b-4) supplying the gas into the chamber at a second flow rate, the second flow rate being less than the first flow rate. ｘ F ｙ (b-4) supplying the gas into the chamber at a third flow rate, the third flow rate being less than the second flow rate; and (b-5) supplying the gas into the chamber at a third flow rate, the third flow rate being less than the second flow rate. ｘ F ｙ (c) while (b) is being performed, controlling to supply gas into the chamber at a fourth flow rate, the fourth flow rate being between the second flow rate and the third flow rate, and (c) while (b) is being performed, generating a plasma from the process gas using a source RF signal to etch the silicon-containing film in the at least one opening.

[0016] 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.

[0017] FIG. 1 is a diagram illustrating an exemplary 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.

[0018] 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.

[0019] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform various processes described in this disclosure. The control unit 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 control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The control unit 2 may be implemented by, for example, a computer 2a. 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. This 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 processing unit 2a1 may be a CPU (Central Processing Unit). 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).

[0020] The following describes a configuration example of a capacitively coupled plasma processing apparatus as an example of the plasma processing apparatus 1. Fig. 2 is a diagram for explaining a configuration example of a capacitively coupled plasma processing apparatus.

[0021] The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply 20, a power supply 30, and an exhaust system 40. The plasma processing apparatus 1 also includes a substrate support 11 and a gas inlet. The gas inlet is configured to introduce at least one process gas into the plasma processing chamber 10. The gas inlet includes a showerhead 13. The substrate support 11 is disposed within the plasma processing chamber 10. The showerhead 13 is disposed above the substrate support 11. In one embodiment, the showerhead 13 forms at least a portion of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the showerhead 13, a sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 is grounded. The showerhead 13 and the substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0022] 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.

[0023] 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 lower 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. Furthermore, at least one RF / DC electrode coupled to an RF power supply 31 and / or a DC power supply 32, which will be described later, may be disposed within the ceramic member 1111a. In this case, the at least one RF / DC electrode functions as a lower electrode. When a bias RF signal and / or a DC signal, which will be described later, is supplied to the at least one RF / DC electrode, the RF / DC electrode is also called a bias electrode. Note that the conductive member of the base 1110 and the at least one RF / DC electrode may function as multiple lower electrodes. Furthermore, the electrostatic electrode 1111b may function as a lower electrode. Therefore, the substrate support 11 includes at least one lower electrode.

[0024] 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.

[0025] 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 to a gap between the backside of the substrate W and the central region 111a.

[0026] The showerhead 13 is configured to introduce at least one process gas from the gas supply unit 20 into the plasma processing space 10s. The showerhead 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and multiple gas inlets 13c. The process gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s from the multiple gas inlets 13c. The showerhead 13 also includes at least one upper electrode. In addition to the showerhead 13, the gas inlet may also include one or more side gas injectors (SGIs) attached to one or more openings formed in the sidewall 10a.

[0027] 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 showerhead 13 via 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.

[0028] 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) to at least one lower electrode and / or at least one upper electrode. This generates a plasma 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 generation unit 12. Furthermore, by supplying a bias RF signal to the at least one lower electrode, a bias potential is generated on the substrate W, thereby attracting ion components in the formed plasma to the substrate W.

[0029] 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 at least one lower electrode and / or at least one upper electrode 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 at least one lower electrode and / or at least one upper electrode.

[0030] The second RF generator 31b is coupled to at least one lower 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 lower electrode. In various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0031] 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 first DC generator 32a and a second DC generator 32b. In one embodiment, the first DC generator 32a is connected to the at least one lower electrode and configured to generate a first DC signal. The generated first DC signal is applied to the at least one lower electrode. In one embodiment, the second DC generator 32b is connected to the at least one upper electrode and configured to generate a second DC signal. The generated second DC signal is applied to the at least one upper electrode.

[0032] In various embodiments, the first and second DC signals may be pulsed. In this case, a sequence of voltage pulses is applied to at least one lower electrode and / or at least one upper electrode. The voltage pulses may have a rectangular, trapezoidal, triangular, or combination thereof pulse waveform. In one embodiment, a waveform generator for generating the sequence of voltage pulses from the DC signal is connected between the first DC generator 32a and at least one lower electrode. Thus, the first DC generator 32a and the waveform generator constitute a voltage pulse generator. When the second DC generator 32b and the waveform generator constitute a voltage pulse generator, the voltage pulse generator is connected to at least one upper electrode. The voltage pulses may have either 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 period. The first and second DC generating units 32a and 32b may be provided in addition to the RF power supply 31, or the first DC generating unit 32a may be provided instead of the second RF generating unit 31b.

[0033] 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.

[0034] <Example of the Present Method> Figure 3 is a flowchart showing an etching method (hereinafter also referred to as "the present method") according to one exemplary embodiment. The present method includes a step (ST1) of preparing a substrate, a step (ST2) of supplying a processing gas, and a step (ST3) of generating plasma. In one embodiment, the processes in each step may be performed in a plasma processing apparatus 1 (see Figures 1 and 2). In the following example, the present method is performed by a control unit 2 controlling each part of a capacitively coupled plasma processing apparatus 1 (see Figure 2). Furthermore, steps ST2 and ST3 may be performed simultaneously.

[0035] (Process ST1: Preparation of Substrate) In process ST1, a substrate is prepared. In process ST1, the substrate W is placed in the central region 111a of the substrate support part 11 and is held on the substrate support part 11 by an electrostatic chuck 1111. FIG. 4 is a diagram showing an example of the cross-sectional structure of the substrate W prepared in process ST1. As shown in FIG. 4, the substrate W includes a base film UF, a silicon-containing film SF, and a mask film MF. The substrate W may be used in the manufacture of a semiconductor device. As an example, the substrate W may be a substrate for forming a plurality of DRAM elements.

[0036] In one embodiment, the underlayer UF is a silicon wafer, an organic film, a dielectric film, a metal film, a semiconductor film, or the like formed on the silicon wafer. In one embodiment, it may be a film that constitutes a part of a DRAM element formed on the substrate W.

[0037] The silicon-containing film SF is a film to be etched in this processing method. The silicon-containing film SF may be a stacked film including a plurality of silicon-containing films. In this processing method, the silicon-containing film SF includes silicon-containing films SF-1 to SF-4.

[0038] The silicon-containing film SF-1 is formed on the underlayer UF. In one embodiment, the silicon-containing film SF-1 may be a film containing silicon and oxygen. As an example, the film containing silicon and oxygen may be a silicon oxide film.

[0039] The silicon-containing film SF-2 is formed on the silicon-containing film SF-1. In one embodiment, the silicon-containing film SF-2 may be a film containing silicon and nitrogen. As an example, the film containing silicon and nitrogen may be a silicon nitride film.

[0040] The silicon-containing film SF-3 is formed on the silicon-containing film SF-2. In one embodiment, the silicon-containing film SF-3 may be a film containing silicon and oxygen. As an example, the film containing silicon and oxygen may be a silicon oxide film.

[0041] The silicon-containing film SF-4 is formed on the silicon oxide film SF-3. In one embodiment, the silicon-containing film SF-4 may be a film containing silicon and oxygen. As an example, the film containing silicon and nitrogen may be a silicon nitride film.

[0042] The mask film MF is formed on the silicon-containing film SF. The mask film MF has at least one opening on the silicon-containing film SF. That is, the mask film MF can include, in a plan view, a region including an upper surface TS of the mask film MF and a region including at least one opening OP. As an example, the opening OP is a space above the silicon-containing film SF and is surrounded by a sidewall SS-1 of the mask film MF. That is, in FIG. 4, the upper surface of the silicon-containing film SF (silicon-containing film SF-4) has a region covered by the mask film MF and a region exposed at the bottom of the opening OP.

[0043] The openings OP may have any shape when viewed from above the substrate W, i.e., when viewing the substrate W 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 film MF may include multiple openings OP. As an example, the mask film MF may have multiple side walls, each of which may define one opening OP. The multiple openings OP may each have a linear shape in a planar view and be arranged at regular intervals to form a line-and-space pattern. Alternatively, the multiple openings OP may each have a hole shape in a planar view and form an array pattern.

[0044] The mask film MF may be a carbon-containing film. As an example, the carbon-containing film may be an amorphous carbon film. In one embodiment, the mask film MF may be a metal-containing film. The mask film MF may be a single-layer mask consisting of one layer, or a multi-layer mask consisting of two or more layers. The mask film MF may be formed by a CVD method, a spin coating method, or the like. The mask film MF may be formed by lithography. The opening OP may be formed by etching the mask film MF.

[0045] (Step ST2: Supply of Processing Gas) Next, in step ST2, a processing gas is supplied into the plasma processing chamber 10. In one embodiment, the processing gas is a C ｘ F ｙ gas (where x is an integer of 2 or 3, and y is an integer equal to or less than twice x) (hereinafter, referred to as C ｘ F ｙ The gas is also referred to as a "reaction gas." As an example, the process gas may be ２ F ４ , C ３ F ４ and C ３ F ６ In one embodiment, the process gas may include one or more gases selected from the group consisting of a noble gas such as Ar gas, He gas, Kr gas, or Xe gas, and N ２ The gas may include an inert gas such as a gas.

[0046] (Step ST3: Plasma Generation) Next, in step ST3, plasma is generated in the plasma processing chamber 10. In step ST3, a source RF signal (RF power) is supplied from the first RF generator 31a to the upper electrode or the lower electrode. In one embodiment, the frequency of the source RF signal may be 13 MHz to 100 MHz. When the source RF signal is supplied to the upper electrode or the lower electrode, plasma is generated from the processing gas supplied in step ST2. In addition, a bias DC signal is supplied from the first DC generator 32a to the substrate support member 11 as a bias signal. The bias DC signal may be a sequence of voltage pulses. When the bias DC signal is supplied to the substrate support member 11, a bias potential is generated in the substrate W. As a result, activated species in the plasma generated from the processing gas are attracted to the substrate W and collide with the silicon-containing film SF through the opening OP in the mask film MF, thereby etching the silicon-containing film SF.

[0047] In this processing method, steps ST2 and ST3 may be performed simultaneously. Furthermore, steps ST2 and ST3 may be repeatedly performed, with a cycle consisting of a plurality of periods. In each period included in the cycle, the flow rate of the processing gas, the power of the source RF signal, and the voltage of the bias DC signal may be set arbitrarily.

[0048] FIG. 5 is a diagram showing an example of a timing chart of steps ST2 and ST3. In FIG. 5, the horizontal axis represents time, and the vertical axis represents the flow rate of the reactive gas contained in the process gas, the power of the source RF signal, and the voltage of the bias DC signal. The power of the source RF signal is the effective value of the power. The voltage of the bias DC signal is the absolute value of the effective value of the voltage. In FIG. 5, the vertical axis indicates larger values ​​as it goes up. Note that the flow rates S1 to S4 in FIG. 5 do not necessarily represent absolute relationships in terms of flow rate. Also, the powers P1 and P2 in FIG. 5 do not necessarily represent absolute relationships in terms of power. Also, the voltages V1 to V3 in FIG. 5 do not necessarily represent absolute relationships in terms of voltage.

[0049] 5, process ST2 and process ST3 are performed simultaneously. Also, in the example shown in FIG. 5, the period during which process ST2 and process ST3 are performed includes period 1 to period 4. The flow rate of the reactive gas, the power of the source RF signal, and the voltage of the bias DC signal can be set individually for each of periods 1 to 4. The operation of the control unit 2 to control the flow rate of the reactive gas, the power of the source RF signal, and the voltage of the bias DC signal for each period will be described below.

[0050] (Reactant Gas Flow Rate) The reactant gas flow rate may be different in each of Periods 1 to 4. In one embodiment, the reactant gas flow rate in Periods 1 and 2 may be higher than the reactant gas flow rate in Periods 3 and 4. Note that in Steps ST2 and ST3, the plasma generated from the processing gas may cause both a reaction in which a carbon-containing film is formed on the surface of the mask film MF and / or the silicon-containing film SF (hereinafter also referred to as a "deposition reaction") and a reaction in which the carbon-containing film is etched (hereinafter also referred to as an "etching reaction"). In one embodiment, when the deposition reaction exceeds the etching reaction, a carbon-containing film may be formed on the surface of the mask film MF and / or the silicon-containing film SF. On the other hand, when the etching reaction exceeds the deposition reaction, the carbon-containing film formed on the surface of the mask film MF and / or the silicon-containing film SF may be etched. Hereinafter, a state in which the deposition reaction exceeds the etching reaction may also be referred to as "the deposition reaction is dominant." Furthermore, a state in which the etching reaction exceeds the deposition reaction may also be referred to as "the etching reaction is dominant."

[0051] In the example shown in FIG. 5 , the flow rate of the reaction gas is first set to a flow rate S1 during period 1. In one embodiment, the flow rate S1 may be the maximum flow rate of the reaction gas during periods 1 to 4. The flow rate S1 is also a flow rate at which a carbon-containing film CF (see FIG. 6 ) is produced on the surface of the mask film MF and / or the silicon-containing film SF by plasma generated from the reaction gas. That is, during period 1, the flow rate S1 may be a flow rate value at which the deposition reaction becomes dominant. As an example, the flow rate S1 may be set to 50 sccm to 70 sccm.

[0052] Next, in period 2, the flow rate of the reaction gas is set to flow rate S2. In one embodiment, flow rate S2 may be a flow rate between flow rate S1 and the flow rate of the reaction gas in period 3 and / or period 4. Flow rate S2 may be a flow rate at which the deposition reaction is dominant. As an example, flow rate S2 may be set to 30 sccm to 50 sccm.

[0053] Next, in period 3, the flow rate of the reaction gas is set to flow rate S3. In one embodiment, flow rate S3 may be the minimum flow rate of the reaction gas in periods 1 to 4. Flow rate S3 may be a flow rate at which the etching reaction is dominant. As an example, flow rate S3 may be set to 5 sccm to 15 sccm.

[0054] Next, in period 4, the flow rate of the reaction gas is set to flow rate S4. In one embodiment, flow rate S4 may be a flow rate between flow rate S3 and the flow rate of the reaction gas in period 1 and / or period 2. Flow rate S4 may be a flow rate at which the etching reaction is dominant. As an example, flow rate S4 may be set to 15 sccm to 25 sccm.

[0055] (Power of Source RF Signal) The effective value of the power of the source RF signal may be set to a constant value from Period 1 to Period 4. In one embodiment, the source RF signal may be a continuous wave. Also, in one embodiment, the source RF signal may be a pulse wave. In the example shown in FIG. 5, the source RF signal is a continuous wave. Also, the effective value of the power of the source RF signal is power P1. Note that power P2 in FIG. 5 is lower than power P1. When the source RF signal is a pulse wave, as an example, the effective value of the power of the source RF signal periodically repeats power P1 and power P2. Power P2 may be zero power or power close to zero power. Note that the effective value of the power of the source RF signal may be set to different power values ​​in each of Periods 1 to 4.

[0056] (Voltage of Bias DC Signal) The voltage of the bias DC signal may be different in each of Periods 1 to 4. In one embodiment, the voltage of the bias DC signal may be the same in at least two of Periods 1 to 4. In one embodiment, the voltage in Periods 2 and 3 may be lower than the voltage in Periods 1 and 4.

[0057] 5, the absolute value of the voltage of the bias DC signal (hereinafter also simply referred to as "voltage") is first set to voltage V1 in period 1. In one embodiment, voltage V1 may be the maximum voltage of the bias DC signal in periods 1 to 4. As an example, voltage V1 may be set to 7.0 kV to 9.0 kV.

[0058] Next, in period 2, the voltage of the bias DC signal is set to voltage V2. In one embodiment, voltage V2 may be a voltage between voltage V1 and the voltage of the bias DC signal in period 3. As an example, voltage V2 may be set to 4.5 kV to 6.5 kV. Also, as an example, the magnitude of voltage V2 relative to voltage V1 may be 50% to 95%.

[0059] Next, in Period 3, the voltage of the bias DC signal is set to voltage V3. In one embodiment, voltage V3 may be the minimum voltage of the bias DC signal in Periods 1 to 4. As an example, voltage V3 may be set to 3.0 kV to 5.0 kV. Also, as an example, the magnitude of voltage V3 relative to voltage V1 may be 30% to 75%.

[0060] Next, in period 4, the voltage of the bias DC signal is set to voltage V1. In one embodiment, the voltage of the bias DC signal in period 4 may be set to a voltage between voltage V1 and voltage V2. As an example, the voltage of the bias DC signal in period 4 may be set to 7.0 kV to 9.0 kV. Also, as an example, the ratio of voltage V4 to voltage V1 may be 75% to 130%.

[0061] 6 is a diagram showing an example of a cross-sectional structure of the substrate W after performing step ST2 and step ST3 one or more cycles. In one embodiment, by repeating step ST2 and step ST3, the silicon-containing film SF can be etched while a carbon-containing film CF is formed on the upper surface TS and sidewall SS-1 of the mask film MF, as shown in FIG. 6. Furthermore, in step ST2 and step ST3, the silicon-containing film SF may be etched while a carbon-containing film CF is also formed on the sidewall SS-2 of the silicon-containing film SF.

[0062] 7 is a diagram showing an example of a cross-sectional shape of a portion of the carbon-containing film CF formed on the upper surface TS and the sidewall SS-1, and shows the outline of the cross section of the portion of the carbon-containing film CF after the respective periods of step ST2 and step ST3 are completed.

[0063] 7 , in one embodiment, necking may occur near the upper portion of the mask film MF during periods 1 and 2. Then, the necking may decrease during period 3. Then, the necking may decrease further during period 4. In this manner, a carbon-containing film CF having a relatively flat profile can be formed on the sidewall SS-1. That is, the carbon-containing film CF can be formed on the sidewall SS-1 of the mask film MF and / or the sidewall SS-2 of the silicon-containing film SF while suppressing necking near the upper portion of the mask film MF. In one embodiment, the carbon-containing film CF can function as a protective film that protects the mask film MF and / or the silicon-containing film SF.

[0064] 8 is a diagram showing an example of the cross-sectional structure of the substrate W after further repetition of steps ST2 and ST3. As shown in FIG. 8, by repeating steps ST2 and ST3, the stacked film of the silicon-containing films SF-1 to SF-4 is etched while protecting the sidewalls SS-2 of the silicon-containing films SF-1 to SF-4. The silicon-containing film SF may be etched until the base film UF is exposed at the opening OP.

[0065] According to an embodiment of the present disclosure, a silicon-containing film can be etched while suppressing necking.

[0066] The present disclosure may include, for example, the following configurations.

[0067] (Supplementary Note 1) (a) preparing a substrate including a silicon-containing film and a mask film on the silicon-containing film on a substrate support disposed in a chamber, the mask film including at least one opening; (b) providing a C ｘ F ｙ(b-1) a step of supplying a process gas containing a gas (where x is an integer of 2 or 3, and y is an integer equal to or less than twice x), ｘ F ｙ (b-2) supplying a gas into the chamber at a first flow rate; ｘ F ｙ (b-3) supplying a gas into the chamber at a second flow rate, the second flow rate being less than the first flow rate; ｘ F ｙ (b-4) supplying a gas into the chamber at a third flow rate, the third flow rate being less than the second flow rate; ｘ F ｙ (c) while step (b) is being performed, generating a plasma from the process gas using a source RF signal to etch the silicon-containing film in the at least one opening.

[0068] (Supplementary Note 2) The etching method of Supplementary Note 1, further comprising the step of: (d) applying a bias DC signal to the substrate support while (c) is being performed.

[0069] (Supplementary Note 3) The etching method according to Supplementary Note 2, wherein in (d), the absolute value of the voltage of the bias DC signal is a first voltage while (b-1) is being performed, a second voltage lower than the first voltage while (b-2) is being performed, a third voltage lower than the second voltage while (b-3) is being performed, and a fourth voltage higher than the second voltage while (b-4) is being performed.

[0070] (Supplementary Note 4) The etching method according to Supplementary Note 3, wherein the fourth voltage is equal to the first voltage.

[0071] (Supplementary Note 5) The etching method according to any one of Supplementary Notes 1 to 4, wherein the silicon-containing film includes a sidewall that defines the at least one opening, the first flow rate and the second flow rate are flow rates at which a carbon-containing film is formed on the sidewall of the silicon-containing film while steps (b-1) and (b-2) are performed, respectively, and the third flow rate and the fourth flow rate are flow rates at which the carbon-containing film formed on the sidewall is etched while steps (b-3) and (b-4) are performed, respectively.

[0072] (Supplementary Note 6) The etching method according to any one of Supplementary Notes 1 to 5, wherein the mask film is a carbon-containing film.

[0073] (Supplementary Note 7) An etching apparatus including: a chamber; a substrate support part disposed in the chamber; a gas supply part that supplies a gas into the chamber; a plasma generation part that generates plasma in the chamber; and a control part, wherein the control part performs the following operations: (a) control to prepare a substrate including a silicon-containing film and a mask film on the silicon-containing film on the substrate support part disposed in the chamber, the mask film including at least one opening; and (b) control to provide a C ｘ F ｙ (b-1) Control of supplying a process gas containing a gas (where x is an integer of 2 or 3, and y is an integer equal to or less than twice the value of x), ｘ F ｙ (b-2) controlling the supply of gas into the chamber at a first flow rate; ｘ F ｙ (b-3) controlling the supply of gas into the chamber at a second flow rate, the second flow rate being less than the first flow rate; and ｘ F ｙ (b-4) controlling the supply of gas into the chamber at a third flow rate, the third flow rate being lower than the second flow rate; and ｘ F ｙ(c) while step (b) is being performed, generating a plasma from the process gas using a source RF signal to etch the silicon-containing film in the at least one opening.

[0074] The exemplary embodiments described above may be modified in various ways without departing from the scope and spirit of the present disclosure. For example, some components in one embodiment may be added to other embodiments within the scope of ordinary creativity of a person skilled in the art. Also, some components in one embodiment may be replaced with corresponding components in other embodiments.

[0075] 11: substrate support, CF: carbon-containing film, MF: mask film, OP: opening, SF: silicon-containing film, SF-1 to SF-4: silicon-containing films, SS-1: side wall, SS-2: side wall, W: substrate

Claims

1. (a) providing a substrate, including a silicon-containing film and a mask film on the silicon-containing film, on a substrate support disposed in a chamber, the mask film including at least one opening; (b) providing a C ｘ F ｙ (b-1) a step of supplying a process gas containing a gas (where x is an integer of 2 or 3, and y is an integer equal to or less than twice x), ｘ F ｙ (b-2) supplying a gas into the chamber at a first flow rate; ｘ F ｙ (b-3) supplying a gas into the chamber at a second flow rate, the second flow rate being less than the first flow rate; ｘ F ｙ (b-4) supplying a gas into the chamber at a third flow rate, the third flow rate being less than the second flow rate; ｘ F ｙ (c) while step (b) is being performed, generating a plasma from the process gas using a source RF signal to etch the silicon-containing film in the at least one opening.

2. The etching method of claim 1, further comprising the step of: (d) applying a bias DC signal to said substrate support while (c) is being performed.

3. The etching method according to claim 2, wherein in (d), the absolute value of the voltage of the bias DC signal is a first voltage while (b-1) is being performed, a second voltage lower than the first voltage while (b-2) is being performed, a third voltage lower than the second voltage while (b-3) is being performed, and a fourth voltage higher than the second voltage while (b-4) is being performed.

4. The etching method of claim 3, wherein said fourth voltage is equal to said first voltage.

5. The etching method of claim 1, wherein the silicon-containing film includes a sidewall that defines the at least one opening, the first flow rate and the second flow rate are flow rates at which a carbon-containing film is formed on the sidewall of the silicon-containing film while steps (b-1) and (b-2) are performed, respectively, and the third flow rate and the fourth flow rate are flow rates at which the carbon-containing film formed on the sidewall is etched while steps (b-3) and (b-4) are performed, respectively.

6. The etching method according to any one of claims 1 to 5, wherein the mask film is a carbon-containing film.

7. An etching apparatus comprising: a chamber; a substrate support disposed in the chamber; a gas supply unit that supplies a gas into the chamber; a plasma generation unit that generates plasma in the chamber; and a control unit, wherein the control unit: (a) controls a substrate including a silicon-containing film and a mask film on the silicon-containing film to be prepared on the substrate support disposed in the chamber, the mask film including at least one opening; and (b) controls a C ｘ F ｙ (b-1) Control of supplying a process gas containing a gas (where x is an integer of 2 or 3, and y is an integer equal to or less than twice the value of x), ｘ F ｙ (b-2) controlling the supply of gas into the chamber at a first flow rate; ｘ F ｙ (b-3) controlling the supply of gas into the chamber at a second flow rate, the second flow rate being less than the first flow rate; and ｘ F ｙ (b-4) controlling the supply of gas into the chamber at a third flow rate, the third flow rate being lower than the second flow rate; and ｘ F ｙ (c) while step (b) is being performed, generating a plasma from the process gas using a source RF signal to etch the silicon-containing film in the at least one opening.

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