Etching method and substrate processing apparatus

Abstract

The present invention provides a technique for suppressing shape abnormalities in etching. This etching method comprises (a) a step for preparing a substrate having a silicon-containing film containing nitrogen and a mask on the silicon-containing film, the mask including at least one opening, and (b) a step for etching the silicon-containing film to form a recess, wherein (b) includes (b1) a step for generating a first plasma from a first processing gas containing fluorocarbon gas to etch the silicon-containing film, the fluorocarbon gas having the highest flow rate in the first processing gas, and (b2) a step for generating a second plasma from a second processing gas containing hydrogen fluoride gas to etch the silicon-containing film.

Description

Etching method and substrate processing apparatus

[0001] SUMMARY OF THE INVENTION Exemplary embodiments of the present disclosure relate to etching processes and substrate processing apparatus.

[0002] Patent Document 1 discloses a technique for etching a silicon-containing film by generating plasma from a processing gas.

[0003] Patent No. 6990799

[0004] The present disclosure provides a technique capable of suppressing shape abnormalities during etching.

[0005] In one exemplary embodiment of the present disclosure, an etching method includes: (a) preparing a substrate having a silicon-containing film containing nitrogen and a mask on the silicon-containing film, where the mask includes at least one opening; and (b) etching the silicon-containing film to form a recess, wherein (b) includes: (b1) generating a first plasma from a first process gas including a fluorocarbon gas to etch the silicon-containing film, where the fluorocarbon gas has the highest flow rate among the first process gases; and (b2) generating a second plasma from a second process gas including a hydrogen fluoride gas to etch the silicon-containing film.

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

[0007] 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 plasma processing apparatus; FIG. 3 is a flowchart for explaining an example of an etching method; FIG. 4 is a diagram for explaining an example of a cross-sectional structure of a substrate in process ST1; FIG. 5 is a diagram for explaining an example of a cross-sectional structure of a substrate in process ST2; FIG. 6 is a flowchart for explaining an example of a process ST2; FIG. 7 is a diagram for explaining an example of a sidewall of a recess in process ST2-2; FIG. 8 is a diagram for explaining an example of a sidewall of a recess in process ST2-1; FIG. 9 is a diagram for explaining an example of a cross-sectional structure of a substrate at the end of process ST2; FIG. 10 is a diagram depicting images of substrates in an example and a comparative example; FIG. 11 is a diagram for explaining an example of a cross-sectional structure of a substrate having two types of silicon-containing films in process ST1; FIG. 12 is a diagram for explaining an example of a cross-sectional structure of a substrate having two types of silicon-containing films in process ST2;

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

[0009] In one exemplary embodiment, an etching method is provided, comprising: (a) providing a substrate having a nitrogen-containing silicon-containing film and a mask on the silicon-containing film, the mask including at least one opening; and (b) etching the silicon-containing film to form a recess, wherein (b) comprises: (b1) generating a first plasma from a first process gas including a fluorocarbon gas to etch the silicon-containing film, the fluorocarbon gas having the highest flow rate among the first process gases; and (b2) generating a second plasma from a second process gas including a hydrogen fluoride gas to etch the silicon-containing film.

[0010] In one exemplary embodiment, the hydrogen fluoride gas has the highest flow rate among the second process gases.

[0011] In one exemplary embodiment, the first process gas does not contain hydrogen fluoride gas or contains hydrogen fluoride gas at a flow rate that is less than the flow rate of hydrogen fluoride gas contained in the second process gas.

[0012] In one exemplary embodiment, the second process gas does not contain any fluorocarbon gas or contains a fluorocarbon gas at a flow rate that is less than the flow rate of the fluorocarbon gas contained in the first process gas.

[0013] In one exemplary embodiment, the first process gas includes two or more fluorocarbon gases having different fluorine to carbon composition ratios.

[0014] In one exemplary embodiment, the second process gas comprises a fluorocarbon gas, and the first process gas comprises a fluorocarbon gas having a higher fluorine to carbon composition ratio than the fluorocarbon gas of the second process gas.

[0015] In one exemplary embodiment, at least one of the first process gas and the second process gas comprises an oxygen-containing gas.

[0016] In one exemplary embodiment, at least one of the first process gas and the second process gas comprises at least one gas selected from the group consisting of a noble gas, a nitrogen gas, a metal-containing gas, and a halogen-containing gas.

[0017] In one exemplary embodiment, the cycle comprising (b1) and (b2) is repeated multiple times.

[0018] In one exemplary embodiment, (b1) is followed by (b2).

[0019] In one exemplary embodiment, (b2) includes depositing a reaction product containing nitrogen on the sidewall of the recess, and (b1) includes removing the reaction product deposited on the sidewall of the recess.

[0020] In one exemplary embodiment, (b1) includes forming a carbon-containing film on the sidewalls of the recess.

[0021] In one exemplary embodiment, the line edge roughness of the recess after (b1) is less than the line edge roughness of the recess after (b2) which is performed immediately before.

[0022] In one exemplary embodiment, the processing time of (b1) is equal to or less than the processing time of (b2).

[0023] In one exemplary embodiment, the processing time of (b1) is longer than the processing time of (b2).

[0024] In one exemplary embodiment, the ratio of the processing time of (b2) to the processing time of (b1) is changed as etching of the recess progresses.

[0025] In one exemplary embodiment, the silicon-containing film includes at least one film selected from the group consisting of a silicon oxide film, a silicon nitride film, and a stacked film including a silicon oxide film and a silicon nitride film.

[0026] In one exemplary embodiment, the silicon-containing film includes a first silicon-containing film and a second silicon-containing film different from the first silicon-containing film, the first silicon-containing film being a stacked film in which silicon oxide films and silicon nitride films are alternately stacked, and the second silicon-containing film being a silicon oxide film.

[0027] In one exemplary embodiment, the mask comprises at least one film selected from the group consisting of a silicon-containing film different from the silicon-containing film, a carbon-containing film, and a metal-containing film.

[0028] In one exemplary embodiment, there is provided a substrate processing apparatus including a chamber, a substrate support within the chamber, a plasma generating unit, and a controller, wherein the controller is configured to: (a) control preparing a substrate having a nitrogen-containing silicon-containing film and a mask on the silicon-containing film on the substrate support within the chamber, the mask including at least one opening; and (b) control etching the silicon-containing film on the substrate on the substrate support to form a recess, wherein the control of (b) is configured to: (b1) control generating a first plasma from a first process gas including a fluorocarbon gas, the fluorocarbon gas having the largest flow rate among the first process gases, by the plasma generating unit, to etch the silicon-containing film; and (b2) control generating a second plasma from a second process gas including a hydrogen fluoride gas, the second plasma being generated by the plasma generating unit, to etch the silicon-containing film.

[0029] 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.

[0030] First Embodiment <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.

[0031] 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.

[0032] 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).

[0033] 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.

[0034] The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10 (also simply referred to as the "chamber"), a gas supply unit 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] <Example of Etching Method> Fig. 3 is a flowchart illustrating an example of an etching method (hereinafter also referred to as "this processing method") according to an exemplary embodiment. As shown in Fig. 3, in one embodiment, this processing method includes a step ST1 of preparing a substrate and a step ST2 of etching a silicon-containing film on the substrate to form a recess. The processing in each step may be performed in the plasma processing system shown in Fig. 2. The following describes an example in which the controller 2 controls each part of the plasma processing apparatus 1 to perform this processing method on a substrate W.

[0048] (Process ST1: Preparation of Substrate) In one embodiment, in process ST1, a substrate W is provided in a plasma processing chamber 10 (hereinafter also referred to as "chamber 10") as shown in Fig. 2. In one embodiment, the substrate W may be 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.

[0049] 4 is a diagram illustrating an example of the cross-sectional structure of the substrate W provided in step ST1. The substrate W includes an underlayer UF, a silicon-containing film SiF on the underlayer UF, and a mask MK on the silicon-containing film SiF. The substrate W may be used in the manufacture of semiconductor devices. Examples of semiconductor devices include memory devices such as DRAMs and 3D-NAND flash memories, and logic devices.

[0050] In one embodiment, 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, or the like. The base film UF may be configured by stacking multiple films.

[0051] In one embodiment, the silicon-containing film SiF is a film to be etched in this processing method. In one embodiment, the silicon-containing film SiF may contain nitrogen. The silicon-containing film SiF may be a laminated film including two or more different types of silicon-containing films. The silicon-containing film SiF may be a laminated film in which silicon oxide films SiF1-1 and silicon nitride films SiF1-2 are alternately laminated. The silicon-containing film SiF may be a laminated film having 20 or more layers, 50 or more layers, or 100 or more layers.

[0052] In one embodiment, the mask MK is a film that functions as a mask in etching the silicon-containing film SiF. The mask MK may be a film containing at least one selected from the group consisting of a silicon-containing film, a carbon-containing film, and a metal-containing film. The silicon-containing film of the mask MK may be different from the silicon-containing film of the silicon-containing film SiF. The carbon-containing film of the mask MK may be an amorphous carbon (ACL) film or a spin-on carbon (SOC) film. The metal-containing film of the mask MK may be a film containing at least one selected from the group consisting of tungsten, molybdenum, titanium, and ruthenium. The metal-containing film of the mask MK may be a film containing at least one selected from the group consisting of WSi (tungsten silicide), WC (tungsten carbide), WSiC, and WSiN. The mask MK may be a single-layer mask consisting of one film, or a multi-layer mask consisting of two or more films.

[0053] 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 an opening OP1. The opening OP1 may be a space above the silicon-containing film SiF and may be surrounded by the sidewall S1 of the mask MK.

[0054] The opening OP1 may have any shape in a plan view of 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. Furthermore, the multiple openings OP1 may each have a hole shape and form an array pattern.

[0055] Each of the films constituting the substrate W (the base film UF, the silicon-containing film SiF, and the mask MK) may be formed by any method. The base film UF, the silicon-containing film SiF, 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.

[0056] At least a part of the process of forming the base film UF, the silicon-containing film SiF, 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 mask MK in step ST1 and step ST2, which will be described later, 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.

[0057] In one embodiment, the temperature of the substrate support 11 or the substrate W may be controlled to a given temperature by a temperature adjustment 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, for example, 50°C or lower or -50°C or higher. The given temperature may be 0°C or lower. 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 provided to the substrate support 11, or may be simultaneous with the provision of the substrate W. The temperature of the substrate support 11 or the substrate W may be changed in each of the processes ST1, ST2-1, and ST2-2.

[0058] 5 is a diagram illustrating an example of a cross-sectional structure of the substrate W in step ST2. In one embodiment, in step ST2, the silicon-containing film SiF is etched by plasma generated from a processing gas, and a recess R1 is formed in the silicon-containing film SiF.

[0059] 6 is a flowchart illustrating an example of step ST2. In one embodiment, step ST2 includes step ST2-1 of generating a first plasma from a first process gas containing a fluorocarbon gas to etch the silicon-containing film, and step ST2-2 of generating a second plasma from a second process gas containing a hydrogen fluoride gas to etch the silicon-containing film.

[0060] In one embodiment, in step ST2-1, a first process gas is supplied into the plasma processing space 10s from the shower head 13 shown in FIG. 2 . The first process gas contains a fluorocarbon gas. The fluorocarbon gas has the largest flow rate among the gas species in the first process gas. The first process gas does not need to contain hydrogen fluoride gas. The first process gas may contain hydrogen fluoride gas at a flow rate (partial pressure) lower than the flow rate (partial pressure) of hydrogen fluoride gas contained in a second process gas (described later).

[0061] The first process gas may contain two or more fluorocarbon gases having different fluorine to carbon composition ratios (F / C). ４ F ６ Gas and C ４ F ８ The first process gas may include a fluorocarbon gas, such as C ４ F ６ Gas, C ４ F ８ Gas, C ３ F ８ Gas, CF ４ Gas, C ３ F ６ Gas, C ２ F ２ Gas, C ２ F ４ Gas, and C ５ F ８The first process gas may contain at least one gas selected from the group consisting of CHF gas (hydrofluorocarbon gas) and CH gas. When the second process gas described below contains a fluorocarbon gas, the first process gas may contain a fluorocarbon gas having a higher fluorine to carbon composition ratio (F / C) than the fluorocarbon gas of the second process gas.

[0062] The first process gas may further include an oxygen-containing gas. The first process gas may include O ２ gas, CO gas and CO ２ The gas may include at least one gas selected from the group consisting of gases.

[0063] The first process gas may further include at least one gas selected from the group consisting of a noble gas, nitrogen gas, a metal-containing gas, and a halogen-containing gas. The first process gas may include at least one gas selected from the group consisting of Ar gas, He gas, and Kr gas as the noble gas. The first process gas may include at least one gas selected from the group consisting of WF as the metal-containing gas. ６ The first process gas may include a halogen-containing gas, such as HBr gas, HCl gas, and Cl gas. ２ Gas, boron-containing gas (BCl ３ The first process gas may include at least one gas selected from the group consisting of a halogen-containing gas that does not include fluorine.

[0064] The temperature of the substrate support 11 or the substrate W may be controlled to a first temperature. The first temperature may be 0° C. or lower, or −10° C. or lower. The pressure in the chamber 10 may be adjusted to a first pressure. The first pressure may be in the range of 1 mTorr to 1000 mTorr, or in the range of 1 mTorr to 100 mTorr.

[0065] In one embodiment, a first plasma is generated from a first process gas supplied into the chamber 10. In this case, a source RF signal is supplied from the power supply 30 to the upper electrode and / or the lower electrode, which generates a high-frequency electric field on the substrate support 11 and generates a first plasma from the first process gas in the plasma processing space 10s. The source RF signal may have a frequency of 1 kHz or more, 1 MHz or more, or 13 MHz or more. The source RF signal may have a first power, which may be 1 kW or more.

[0066] When generating plasma, a bias signal may be supplied to the substrate support 11. The bias signal may be a bias RF signal supplied from the RF power supply 31 or a bias DC signal supplied from the DC power supply 32. The bias DC signal may be a DC pulse signal. This generates a bias potential 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 silicon-containing film SiF is etched by the active species. Step ST2-1 includes etching the bottom of the recess R1 in the depth direction. Step ST2-1 includes forming a carbon-containing film on the sidewall S2 of the recess R1. Step ST2-1 includes removing reaction products adhering to the sidewall S2 of the recess R1.

[0067] In one embodiment, in step ST2-2, a second process gas is supplied into the plasma processing space 10s from the shower head 13 shown in FIG. 2 . The second process gas contains hydrogen fluoride (HF) gas. The hydrogen fluoride gas may have the largest flow rate among the gas species in the second process gas. The second process gas does not need to contain a fluorocarbon gas. The second process gas may contain a fluorocarbon gas at a flow rate (partial pressure) lower than the flow rate (partial pressure) of the fluorocarbon gas contained in the first process gas.

[0068] The second process gas is a fluorocarbon gas, ４ F ６ The second process gas may contain a fluorocarbon gas having a smaller fluorine to carbon composition ratio (F / C) than the fluorocarbon gas of the first process gas. The second process gas may contain a fluorocarbon gas containing C４ F ６ Gas, C ４ F ８ Gas, C ３ F ８ Gas, CF ４ Gas, C ３ F ６ Gas, C ２ F ２ Gas, C ２ F ４ Gas, and C ５ F ８ The second process gas may include at least one gas selected from the group consisting of CHF gas (hydrofluorocarbon gas) and CH gas.

[0069] The second process gas may further include an oxygen-containing gas. The second process gas may include O ２ gas, CO gas and CO ２ The gas may include at least one gas selected from the group consisting of gases.

[0070] The second process gas may further include at least one gas selected from the group consisting of a noble gas, nitrogen gas, a metal-containing gas, and a halogen-containing gas. The second process gas may include at least one gas selected from the group consisting of Ar gas, He gas, and Kr gas as the noble gas. The second process gas may include at least one gas selected from the group consisting of WF as the metal-containing gas. ６ The second process gas may include a halogen-containing gas, such as HBr gas, HCl gas, and Cl. ２ Gas, boron-containing gas (BCl ３ The second process gas may include at least one gas selected from the group consisting of a halogen-containing gas that does not contain fluorine, a phosphorus-containing gas, and a PF5 gas as the phosphorus-containing gas. ３ Gas, PCl ３ Gas, PF ５ Gas, PCl ５ Gas, POCl ３ Gas, pH ３ Gas, PBr ３ gas, and PBr ５The gas may include at least one gas selected from the group consisting of gases.

[0071] The temperature of the substrate support 11 or the substrate W may be controlled to a second temperature. The second temperature may be 0° C. or lower, or −10° C. or lower. The pressure in the chamber 10 may be adjusted to a second pressure. The second pressure may be in the range of 1 mTorr to 1000 mTorr, or in the range of 1 mTorr to 100 mTorr.

[0072] In one embodiment, a second plasma is generated from a second process gas supplied into the chamber 10. In this case, a source RF signal is supplied from the power supply 30 to the upper electrode and / or the lower electrode, which generates a high-frequency electric field on the substrate support 11 and generates a first plasma from the first process gas in the plasma processing space 10s. The source RF signal may have a frequency of 1 kHz or more, 1 MHz or more, or 13 MHz or more. The source RF signal may have a second power. The second power may be 1 kW or more.

[0073] When generating plasma, a bias signal may be supplied to the substrate support 11. The bias signal may be a bias RF signal supplied from the RF power supply 31 or a bias DC signal supplied from the DC power supply 32. The bias DC signal may be a DC pulse signal. This generates a bias potential 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 silicon-containing film SiF is etched by the active species. Step ST2-2 includes etching the bottom of the recess R1 in the depth direction. Step ST2-2 includes depositing a reaction product containing nitrogen on the sidewall S2 of the recess R1.

[0074] 6, in one embodiment, a cycle including steps ST2-1 and ST2-2 may be performed multiple times. As shown in FIG. 7, in step ST2-2, a reaction product D1 containing nitrogen may be attached to the side wall S2 of the recess R1. As shown in FIG. 8, in step ST2-1, the reaction product D1 attached to the side wall S2 of the recess R1 may be removed. The reaction product D1 may include ammonium hexafluorosilicate (AFS).

[0075] As shown in FIG. 6 , if a cycle including steps ST2-1 and ST2-2 has not been performed a predetermined number of times, the cycle is performed again. When a cycle including steps ST2-1 and ST2-2 has been performed a predetermined number of times, step ST2 may be completed, and the processing method may end. At this time, as shown in FIG. 9 , an opening OP2 may be formed in the silicon-containing film SiF so that the base film UF is exposed. The predetermined number of cycles may be 2 or more, 5 or more, 10 or more, 20 or more, 30 or more, or 40 or more. The predetermined number of cycles may be 1.

[0076] The cycle may include step ST2-1 and step ST2-2 in this order. Alternatively, the cycle may include step ST2-2 and step ST2-1 in this order. That is, either step ST2-1 or step ST2-2 may be performed first. The cycle may be performed at a cycle time of 100 (sec / time) or less, or 50 (sec / time) or less. In one embodiment, the cycle time may be changed as etching of the recesses in step ST2 progresses. As etching of the recesses progresses, the cycle time may be increased or decreased.

[0077] In one embodiment, the processing time (plasma generation time) of step ST2-1 may be equal to or shorter than the processing time of step ST2-2. The ratio of the processing time of step ST2-1 to the processing time of step ST2-2 may be 1:1 to 4:1. The processing time of step ST2-1 may be longer than the processing time of step ST2-2. In one embodiment, as etching of the recess in step ST2 progresses, the ratio of the processing time of step ST2-2 to the processing time of step ST2-1 may be changed. As etching of the recess progresses, the ratio of the processing time of step ST2-2 to the processing time of step ST2-1 may be increased. As etching of the recess progresses, the ratio of the processing time of step ST2-2 to the processing time of step ST2-1 may be decreased. In step ST2 (ST2-1 and ST2-2), the source RF signal for plasma generation may be continuously supplied to the upper electrode or the lower electrode without being turned off, and the gas supplied to the chamber 10 may be switched between the first processing gas and the second processing gas. During this period, plasma may be continuously generated. The ratio of the supply time of the first process gas (the processing time of step ST2-1) to the supply time of the second process gas (the processing time of step ST2-2) may be 1:1 to 100. The ratio of the supply time of the first process gas to the supply time of the second process gas may be 1:2 to 80, or 1:3 to 70.

[0078] After step ST2, 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. In this manner, the present processing method may be completed.

[0079] According to this exemplary embodiment, the substrate processing method includes: (a) preparing a substrate W having a nitrogen-containing silicon-containing film SiF and a mask MK on the silicon-containing film SiF; and (b) etching the silicon-containing film SiF to form a recess R1, where (b) includes: (b1) generating a first plasma from a first process gas containing a fluorocarbon gas to etch the silicon-containing film SiF, where the fluorocarbon gas has the largest flow rate among the first process gases; and (b2) generating a second plasma from a second process gas containing hydrogen fluoride gas to etch the silicon-containing film SiF. Etching the nitrogen-containing silicon-containing film SiF generates a nitrogen-containing reaction product D1, which may adhere to the sidewall S2 of the recess R1. According to this embodiment, for example, the reaction product D1 adhered to the sidewall S2 of the recess R1 is removed by the step (b-1). Therefore, the reaction products adhering to the sidewall S2 of the recess R1 are prevented from interfering with the etching of the silicon-containing film SiF, and shape abnormalities during etching can be suppressed.

[0080] Example 1 Fig. 10(A) is a diagram depicting a cross-sectional image of a substrate including a silicon-containing film in Comparative Example 1. Fig. 10(B) is a diagram depicting a top view image of the vicinity of the bottom of the substrate from which the silicon-containing film of Fig. 10(A) has been removed. Fig. 10(C) is a diagram depicting a cross-sectional image of a substrate including a silicon-containing film in Example 1. Fig. 10(D) is a diagram depicting a top view image of the vicinity of the bottom of the substrate from which the silicon-containing film of Fig. 10(C) has been removed. Fig. 10 is based on an image captured by a scanning electron microscope. In Example 1 and Comparative Example 1, a plurality of linear openings were formed in the silicon-containing film SiF on the substrate W.

[0081] Comparative Example 1 corresponds to an example in which only the above-mentioned step ST2-2 was performed in the etching step, and was carried out under the following condition A.

[0082] <Condition A> Source RF signal: 5.5 kW (40 MHz) Bias signal: 9 kV (400 kHz) Second process gas: HF gas, fluorocarbon gas (C ４ F ６Gas), O ２ Gas, halogen gas Processing temperature: -20°C

[0083] Example 1 corresponds to an example in which both the above-described steps ST2-1 and ST2-2 were performed in the etching process. In Example 1, a cycle including the following treatment under condition B-1 and treatment under condition B-2 in this order was repeated 10 times.

[0084] <Condition B-1> Source RF signal: 5.5 kW (40 MHz) Bias signal: 9 kV (400 kHz) First process gas: fluorocarbon gas (C ４ F ６ Gas, C ４ F ８ Gas), O ２ Gas (Fluorocarbon gas is the maximum flow rate in the first processing gas) Processing temperature: -20°C

[0085] <Condition B-2> Source RF signal: 5.5 kW (40 MHz) Bias signal: 9 kV (400 kHz) Second process gas: HF gas, fluorocarbon gas (C ４ F ８ Gas), O ２ Gas, halogen gas (HF gas is the maximum flow rate of the second processing gas) Processing temperature: -20°C

[0086] 10B and 10D, the line edge roughness (LER) near the bottom of the substrate was calculated. The LER near the bottom of the substrate in Example 1 was reduced to about 30% of the LER near the bottom of the substrate in Comparative Example 1.

[0087] Example 2 In Example 2 and Comparative Example 2, a plurality of hole-shaped openings were formed in the silicon-containing film on the substrate W.

[0088] Comparative Example 2 corresponds to an example in which only the above-mentioned step ST2-2 was performed in the etching step, and was carried out under the following condition C.

[0089] <Condition C> Source RF signal: 5.5 kW (40 MHz) Bias signal: 9 kV (400 kHz) Second process gas: HF gas, fluorocarbon gas (C ４ F ６gas), hydrofluorocarbon gas (CH ２ F ２ gas), halogen-containing gas (HF gas is the maximum flow rate of the second processing gas) Processing temperature: 0°C Gas supply time: 1200 seconds

[0090] Example 2 corresponds to an example in which both step ST2-2 and step ST2-1 were performed in the etching process. In Example 2, a cycle including step ST2-2 and step ST2-1 in this order was repeated 19 times. Step ST2-2 was performed under the following condition D-1, and step ST2-1 was performed under the following condition D-2.

[0091] <Condition D-1> Source RF signal: 5.5 kW (40 MHz) Bias signal: 9 kV (400 kHz) Second process gas: HF gas, fluorocarbon gas (C ４ F ６ gas), hydrofluorocarbon gas (CH ２ F ２ gas), halogen-containing gas (HF gas is the maximum flow rate among the second processing gases) Processing temperature: 0°C Gas supply time for each cycle: 60 seconds

[0092] <Condition D-2> Source RF signal: 5.5 kW (40 MHz) Bias signal: 9 kV (400 kHz) First process gas: fluorocarbon gas (C ４ F ６ Gas, C ４ F ８ Gas), O ２ Gas treatment temperature: 0°C Gas supply time for each cycle: 2 seconds

[0093] The hole bowing width (maximum hole diameter) and hole bottom position variation were measured for the holes formed in Example 2 and Comparative Example 2. The hole bottom position variation is the variation (3σ) in the spacing between multiple holes at the hole bottoms of multiple holes. The bowing width in Example 2 was reduced to approximately 96% of the bowing width in Comparative Example 2. The hole bottom position variation in Example 2 was reduced to approximately 70% of the hole bottom position variation in Comparative Example 2. Generally, there is a trade-off between the hole bowing width and the hole bottom position variation, but it was found that Example 2 was able to improve both the hole bowing width and the hole bottom position variation.

[0094] In this exemplary embodiment, the first process gas supplied in step ST2-1 does not contain hydrogen fluoride gas, or contains hydrogen fluoride gas at a flow rate lower than the flow rate of hydrogen fluoride gas contained in the second process gas. This makes it possible to suppress the generation of reaction products containing nitrogen in step ST2-1. Furthermore, the reaction products in step ST2-1 can be efficiently removed.

[0095] In this exemplary embodiment, the second process gas supplied in step ST2-2 does not contain a fluorocarbon gas or contains a fluorocarbon gas at a flow rate lower than the flow rate of the fluorocarbon gas contained in the first process gas, thereby preventing excessive deposition on the mask or the sidewalls of the recess in step ST2-2.

[0096] In this exemplary embodiment, when the second process gas contains a fluorocarbon gas, the first process gas contains a fluorocarbon gas having a higher fluorine to carbon composition ratio than the fluorocarbon gas of the second process gas, which allows efficient removal of reaction products containing nitrogen in step ST2-1.

[0097] In this exemplary embodiment, a cycle including steps ST2-1 and ST2-2 is repeated multiple times. This allows, for example, the reaction products containing nitrogen to be removed in step ST2-1 before they adhere in large amounts to the sidewalls in step ST2-2. This allows etching in step ST2 to be performed without being hindered by the reaction products, thereby suppressing shape abnormalities during etching.

[0098] In this exemplary embodiment, since step ST2-2 is performed after step ST2-1, a protective film is formed on the mask and the sidewalls of the recesses in step ST2-1, which can prevent bowing, in which the width of the recesses is partially widened, from occurring in step ST2-2.

[0099] In this exemplary embodiment, the processing time of step ST2-1 is equal to or shorter than the processing time of step ST2-2, so that excessive deposition on the mask and the sidewalls of the recess can be suppressed.

[0100] Second Embodiment In one embodiment, the silicon-containing film SiF on the substrate W may include at least one film selected from the group consisting of a silicon oxide film, a silicon nitride film, and a stacked film including a silicon oxide film and a silicon nitride film. FIG. 11 is a diagram for explaining a configuration example of a substrate W having two types of silicon-containing films. In one embodiment, the silicon-containing film SiF may include a first silicon-containing film SiF1 and a second silicon-containing film SiF2 different from the first silicon-containing film SiF1. The first silicon-containing film SiF1 may be a stacked film in which silicon oxide films SiF1-1 and silicon nitride films SiF1-2 are alternately stacked, as in the first embodiment. The second silicon-containing film SiF2 may be a silicon oxide film. The silicon oxide film may be doped with nitrogen. The second silicon-containing film SiF2 may be a silicon nitride film.

[0101] 3, a substrate W including a first silicon-containing film SiF1 and a second silicon-containing film SiF2 is prepared. In step ST2, the first silicon-containing film SiF1 and the second silicon-containing film SiF2 are etched. In step ST2, as shown in FIG. 12, a recess R1 is formed in the first silicon-containing film SiF1, and a recess R3 is formed in the second silicon-containing film SiF2.

[0102] In one embodiment, a cycle including steps ST2-1 and ST2-2 may be repeated multiple times. In one embodiment, in step ST2-2, a reaction product D1 containing nitrogen may be attached to the sidewall S2 of the recess R1 in the first silicon-containing film SiF1 and the sidewall S3 of the recess R3 in the second silicon-containing film SiF2, and in step ST2-1, the reaction product D1 attached to the sidewall S2 of the recess R1 and the sidewall S3 of the recess R3 may be removed.

[0103] In step ST2-2, the etching rate of the first silicon-containing film SiF1 may be higher than the etching rate of the second silicon-containing film SiF2, and in step ST2-1, the etching rate of the second silicon-containing film SiF2 may be higher than the etching rate of the first silicon-containing film SiF1. By repeating a cycle including steps ST2-1 and ST2-2 multiple times, the difference between the etching depth of the first silicon-containing film SiF1 and the etching depth of the second silicon-containing film SiF2 may be reduced. Other conditions in the second embodiment may be similar to those in the first embodiment.

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

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

[0106] (Supplementary Note 1) An etching method comprising: (a) preparing a substrate having a silicon-containing film containing nitrogen and a mask on the silicon-containing film, the mask including at least one opening; and (b) etching the silicon-containing film to form a recess, wherein (b) comprises: (b1) generating a first plasma from a first process gas including a fluorocarbon gas to etch the silicon-containing film, the fluorocarbon gas having the highest flow rate among the first process gases; and (b2) generating a second plasma from a second process gas including a hydrogen fluoride gas to etch the silicon-containing film.

[0107] (Supplementary Note 2) The etching method according to Supplementary Note 1, wherein the hydrogen fluoride gas has the largest flow rate among the second process gases.

[0108] (Supplementary Note 3) The etching method according to Supplementary Note 1 or 2, wherein the first process gas does not contain hydrogen fluoride gas, or contains hydrogen fluoride gas at a flow rate smaller than a flow rate of the hydrogen fluoride gas contained in the second process gas.

[0109] (Supplementary Note 4) The etching method according to any one of Supplementary Notes 1 to 3, wherein the second process gas does not contain a fluorocarbon gas or contains a fluorocarbon gas at a flow rate smaller than a flow rate of the fluorocarbon gas contained in the first process gas.

[0110] (Supplementary Note 5) The etching method according to any one of Supplementary Notes 1 to 4, wherein the first process gas contains two or more fluorocarbon gases having different composition ratios of fluorine to carbon.

[0111] (Supplementary Note 6) The etching method according to any one of Supplementary Notes 1 to 5, wherein the second process gas contains a fluorocarbon gas, and the first process gas contains the fluorocarbon gas having a larger fluorine to carbon composition ratio than the fluorocarbon gas of the second process gas.

[0112] (Supplementary Note 7) The etching method according to any one of Supplementary Notes 1 to 6, wherein at least one of the first process gas and the second process gas contains an oxygen-containing gas.

[0113] (Supplementary Note 8) The etching method according to any one of Supplementary Notes 1 to 7, wherein at least one of the first process gas and the second process gas contains at least one gas selected from the group consisting of a noble gas, a nitrogen gas, a metal-containing gas, and a halogen-containing gas.

[0114] (Supplementary Note 9) The etching method according to any one of Supplementary Notes 1 to 8, wherein a cycle including (b1) and (b2) is repeated multiple times.

[0115] (Supplementary Note 10) The etching method according to Supplementary Note 9, wherein (b2) is carried out after (b1).

[0116] (Supplementary Note 11) The etching method according to Supplementary Note 9 or 10, wherein (b2) includes adhering a reaction product containing nitrogen to a side wall of the recess, and (b1) includes removing the reaction product adhering to the side wall of the recess.

[0117] (Supplementary Note 12) The etching method according to any one of Supplementary Notes 9 to 11, wherein (b1) includes forming a carbon-containing film on a side wall of the recess.

[0118] (Supplementary Note 13) The etching method according to any one of Supplementary Notes 9 to 12, wherein the line edge roughness of the recessed portion after the step (b1) is smaller than the line edge roughness of the recessed portion after the step (b2) which is performed immediately before the step (b1).

[0119] (Supplementary Note 14) The etching method according to any one of Supplementary Notes 9 to 13, wherein the treatment time of (b1) is equal to or shorter than the treatment time of (b2).

[0120] (Supplementary Note 15) The etching method according to any one of Supplementary Notes 9 to 13, wherein the treatment time of (b1) is longer than the treatment time of (b2).

[0121] (Supplementary Note 16) The etching method according to any one of Supplementary Notes 9 to 15, wherein the ratio of the treatment time of (b2) to the treatment time of (b1) is changed as etching of the recessed portion progresses.

[0122] (Supplementary Note 17) The etching method according to any one of Supplementary Notes 1 to 16, wherein the silicon-containing film includes at least one film selected from the group consisting of a silicon oxide film, a silicon nitride film, and a stacked film including a silicon oxide film and a silicon nitride film.

[0123] (Supplementary Note 18) The etching method according to any one of Supplementary Notes 1 to 17, wherein the silicon-containing film includes a first silicon-containing film and a second silicon-containing film different from the first silicon-containing film, the first silicon-containing film is a stacked film in which a silicon oxide film and a silicon nitride film are alternately stacked, and the second silicon-containing film is a silicon oxide film.

[0124] (Supplementary Note 19) The etching method according to any one of Supplementary Notes 1 to 18, wherein the mask includes at least one film selected from the group consisting of a silicon-containing film different from the silicon-containing film, a carbon-containing film, and a metal-containing film.

[0125] (Supplementary Note 20) A substrate processing apparatus including a chamber, a substrate support part in the chamber, a plasma generation part, and a controller, wherein the controller executes: (a) control to prepare, on the substrate support part in the chamber, a substrate having a nitrogen-containing silicon-containing film and a mask on the silicon-containing film, the mask including at least one opening; and (b) control to etch the silicon-containing film of the substrate on the substrate support part to form a recess, wherein the control of (b) executes: (b1) control to generate a first plasma by the plasma generation part from a first process gas containing a fluorocarbon gas, to etch the silicon-containing film, the fluorocarbon gas having the largest flow rate among the first process gases; and (b2) control to generate a second plasma by the plasma generation part from a second process gas containing hydrogen fluoride gas, to etch the silicon-containing film.

[0126] 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.

[0127] 1: Plasma processing apparatus, 2: Control unit, 10: Plasma processing chamber, 11: Substrate support unit, 12: Plasma generation unit, W: Substrate, SiF: Silicon-containing film, MK: Mask, OP1: Opening, S1: Side wall, R1: Recess

Claims

1. A method of preparing a substrate having a silicon-containing film containing nitrogen and a mask on the silicon-containing film, the mask including at least one opening, the method including: (a) preparing the substrate; and (b) etching the silicon-containing film to form a recess, wherein (b) includes: (b1) generating a first plasma from a first processing gas including a fluorocarbon gas to etch the silicon-containing film, the fluorocarbon gas having the largest flow rate among the first processing gas; and (b2) generating a second plasma from a second processing gas including hydrogen fluoride gas to etch the silicon-containing film.

2. The etching method according to claim 1, wherein the hydrogen fluoride gas has the largest flow rate among the second processing gas.

3. The etching method according to claim 1, wherein the first processing gas does not contain hydrogen fluoride gas or contains hydrogen fluoride gas at a flow rate smaller than the flow rate of the hydrogen fluoride gas contained in the second processing gas.

4. The etching method according to claim 1, wherein the second processing gas does not contain a fluorocarbon gas or contains a fluorocarbon gas at a flow rate smaller than the flow rate of the fluorocarbon gas contained in the first processing gas.

5. The etching method according to claim 1, wherein the first processing gas contains two or more types of fluorocarbon gases having different composition ratios of fluorine to carbon.

6. The etching method according to claim 1, wherein the second processing gas contains a fluorocarbon gas, and the first processing gas contains a fluorocarbon gas having a larger composition ratio of fluorine to carbon than the fluorocarbon gas in the second processing gas.

7. The etching method according to claim 1, wherein at least one of the first processing gas and the second processing gas contains an oxygen-containing gas.

8. The etching method according to claim 1, wherein at least one of the first processing gas and the second processing gas contains at least one gas selected from the group consisting of noble gas, nitrogen gas, metal-containing gas, and halogen-containing gas.

9. The etching method according to claim 1, wherein a cycle including (b1) and (b2) is repeated a plurality of times.

10. The etching method according to claim 9, wherein (b2) is performed after (b1).

11. The (b2) includes attaching a reaction product containing nitrogen to the sidewall of the concave portion, and the (b1) includes removing the reaction product attached to the sidewall of the concave portion. The etching method according to claim 9.

12. The (b1) includes forming a carbon-containing film on the sidewall of the concave portion. The etching method according to claim 9.

13. The line edge roughness of the concave portion after the (b1) is smaller than the line edge roughness of the concave portion after the (b2) performed immediately before. The etching method according to claim 9.

14. The processing time of the (b1) is the same as or shorter than the processing time of the (b2). The etching method according to claim 9.

15. The processing time of the (b1) is longer than the processing time of the (b2). The etching method according to claim 9.

16. As the etching of the concave portion progresses, the ratio of the processing time of the (b2) to the processing time of the (b1) is changed. The etching method according to claim 9.

17. The silicon-containing film includes at least one film selected from the group consisting of a silicon oxide film, a silicon nitride film, and a laminated film including a silicon oxide film and a silicon nitride film. The etching method according to claim 1.

18. The silicon-containing film includes a first silicon-containing film and a second silicon-containing film different from the first silicon-containing film. The first silicon-containing film is a laminated film in which a silicon oxide film and a silicon nitride film are alternately laminated, and the second silicon-containing film is a silicon oxide film. The etching method according to claim 1.

19. The mask includes at least one film selected from the group consisting of a silicon-containing film different from the silicon-containing film, a carbon-containing film, and a metal-containing film. The etching method according to claim 1.

20. A substrate processing apparatus including a chamber, a substrate support portion within the chamber, a plasma generation portion, and a control portion, wherein the control portion: (a) controls to prepare a substrate having a silicon-containing film containing nitrogen and a mask on the silicon-containing film on the substrate support portion within the chamber, the mask including at least one opening; and (b) controls to etch the silicon-containing film of the substrate on the substrate support portion to form a recess, and the control of (b) is configured to execute: (b1) control to generate a first plasma from a first processing gas containing a fluorocarbon gas by the plasma generation portion to etch the silicon-containing film, the fluorocarbon gas having the largest flow rate among the first processing gas; and (b2) control to generate a second plasma from a second processing gas containing hydrogen fluoride gas by the plasma generation portion to etch the silicon-containing film.

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