CN117995672A

CN117995672A - Etching method and plasma processing apparatus

Info

Publication number: CN117995672A
Application number: CN202311397947.6A
Authority: CN
Inventors: 高桥笃史; 户村幕树; 松原稜
Original assignee: Tokyo Electron Ltd
Current assignee: Tokyo Electron Ltd
Priority date: 2022-11-04
Filing date: 2023-10-26
Publication date: 2024-05-07

Abstract

An etching method, comprising: (a) Providing a substrate having a film to be etched and a mask on the film to be etched to a substrate support of a plasma processing apparatus including a chamber, the substrate support, a plasma generating section to which source power is supplied, and a bias electrode to which bias power is supplied; and (b) etching the film to be etched to form a recess. In (b), the source power and the bias power are periodically supplied at a period including the 1 st period and the 2 nd period. The etching target film is etched in the 1 st period, and the 2 nd process gas is adsorbed to the etching target film in the 2 nd period.

Description

Etching method and plasma processing apparatus

Technical Field

Exemplary embodiments of the present invention relate to an etching method and a plasma processing apparatus.

Background

In the manufacture of electronic devices, a silicon-containing film of a substrate is subjected to plasma etching. In plasma etching, a silicon-containing film is etched using a plasma generated from a process gas. Patent document 1 discloses a process gas containing fluorocarbon gas as a process gas for plasma etching of a silicon-containing film.

U.S. patent application publication 2016/0343580 specification

Disclosure of Invention

The invention provides a technology for suppressing abnormal shape and etching a film.

In an exemplary embodiment, an etching method includes: (a) A step of supplying a substrate having an etching target film and a mask on the etching target film to a substrate support of a plasma processing apparatus provided with a chamber, the substrate support supporting the substrate in the chamber, a plasma generating section to which a source power is supplied, and a bias electrode to which a bias power is supplied; and (b) etching the etching target film to form a recess. In the (b), the source power and the bias power are supplied periodically with a period including a 1 st period in which the source power and the bias power are supplied at prescribed power values, respectively, and a 2 nd period in which at least one of the source power and the bias power or a power value is not supplied and is maintained lower than a power value in the 1 st period. During the 1 st period, the etching target film is etched by the 1 st plasma generated from the 1 st process gas supplied into the chamber, and during the 2 nd period, the 2 nd process gas supplied into the chamber is adsorbed to the etching target film.

Effects of the invention

According to one exemplary embodiment, a technique for suppressing shape anomalies and etching a film is provided.

Drawings

Fig. 1 schematically shows a plasma processing apparatus according to an exemplary embodiment.

Fig. 2 schematically shows a plasma processing apparatus according to an exemplary embodiment.

Fig. 3 is a flow chart of an etching method according to an exemplary embodiment.

Fig. 4 is a cross-sectional view of a substrate to which one example of the method of fig. 3 can be applied.

Fig. 5 is a cross-sectional view showing a process of an etching method according to an exemplary embodiment.

Fig. 6 is a cross-sectional view showing a process of the etching method according to an exemplary embodiment.

Fig. 7 is a cross-sectional view showing a process of an etching method according to an exemplary embodiment.

Fig. 8 is a cross-sectional view of an example substrate that can be manufactured by the etching method according to an exemplary embodiment.

Fig. 9 is a timing chart showing an example of an etching method according to an exemplary embodiment.

Fig. 10 is a timing chart showing an example of an etching method according to an exemplary embodiment.

Fig. 11 is a timing chart showing an example of an etching method according to an exemplary embodiment.

Fig. 12 is a timing chart showing an example of an etching method according to an exemplary embodiment.

Fig. 13 is a timing chart showing an example of an etching method according to an exemplary embodiment.

Detailed Description

Various exemplary embodiments are described below.

In an exemplary embodiment, an etching method includes: (a) Providing a substrate having an etching target film and a mask on the etching target film to a substrate supporter of a plasma processing apparatus; and (b) etching the etching target film to form a recess. The plasma processing device is provided with: a chamber; a substrate supporter for supporting a substrate in the chamber; a plasma generating section for supplying source power for generating plasma; and a bias electrode for supplying bias power for etchant induction.

In the above (b), the source power and the bias power are periodically supplied at a period including the 1 st period and the 2 nd period. The 1 st period is a period in which the source power and the bias power are supplied at predetermined power values, respectively. The 2 nd period is a period in which at least one of the source power and the bias power is not supplied or a power value is maintained lower than that in the 1 st period. In the 1 st period, the etching target film is etched by the 1 st plasma generated from the 1 st process gas supplied into the chamber, and in the 2 nd period, the 2 nd process gas supplied into the chamber is adsorbed on the etching target film.

In the etching method, in the step (b), the source power and the bias power are periodically supplied at a cycle including the 1 st period and the 2 nd period. The 1 st period is a period in which etching of the etching target film is easy, and the 2 nd period is a period in which etching of the etching target film is difficult as compared with the 1 st period. Therefore, in the etching method described above, the temperature of the substrate that has risen during the etching in the 1 st period can be reduced during the 2 nd period, and the temperature control of the substrate can be easily performed.

In the etching method, the 2 nd process gas is supplied during the 2 nd period, and the 2 nd process gas is adsorbed on the etching target film. The 2 nd process gas adsorbed on the etching target film or the protective portion derived from the 2 nd process gas suppresses etching in a direction other than the desired etching direction in the following 1 st period, thereby suppressing the shape abnormality of the recess. The desired etching direction can also be referred to as a vertical direction with respect to the film to be etched or a direction from the plasma generating section toward the bias electrode.

In the etching method, the 2 nd process gas may contain a silylation agent having an alkyl group. In this case, the alkyl group of the silylation agent adsorbed on the surface of the etching target film suppresses etching (e.g., side etching) in a direction different from the desired direction, and thus suppresses shape abnormality of the recess.

In the etching method, the silylation agent having an alkyl group may have 1 to 20 carbon atoms in the alkyl group.

In the above etching method, the silylating agent having the alkyl group may have at least 1 reactive group selected from the group consisting of hydroxyl group (-OH), alkoxy group (-OR ¹), aryloxy group (-OR ²) amino group (-NR ³R⁴) and halogeno group (-X) (wherein R ¹ represents alkyl group, R ² represents aryl group, and R ³ and R ⁴ each independently represent hydrogen atom, alkyl group OR aryl group).

In the above etching method, the silylating agent having the alkyl group may contain at least 1 selected from the group consisting of N, N-dimethyltrimethylsilylamine, decyldimethylchlorosilane, dimethyl-N-octylchlorosilane, and decyldimethylmethoxysilane.

In the etching method, the 2 nd process gas may contain a silylation agent having an alkyl group, and the 1 st process gas may contain a tungsten-containing gas. In this case, in the period 2, the silylation agent having an alkyl group is adsorbed on the film to be etched, and in the subsequent period 1, tungsten is trapped by the alkyl group, whereby a protective portion containing tungsten is formed on the film to be etched. By this protection portion, etching (for example, side etching) in a direction different from a desired direction is suppressed, and shape abnormality of the concave portion is suppressed.

In the etching method, the substrate may contain a silicon nitride film, and the 2 nd process gas may contain an acid component. In this case, the acid component is adsorbed on the etching target film in the 2 nd period, and ammonia generated by etching the silicon nitride film reacts with the acid component to form a salt in the 1 st period. The salt formed on the etching target film suppresses etching (e.g., side etching) in a direction different from the desired direction, thereby suppressing abnormal shapes of the recesses.

In the etching method, the 2 nd process gas may contain an acid component, and the 3 rd process gas containing an alkali component may be supplied into the chamber after the 2 nd process gas is adsorbed on the etching target film during the 2 nd period. In this case, the acid component is adsorbed on the etching target film, and then the acid component reacts with the alkali component to form a salt. The salt formed on the etching target film suppresses etching (e.g., side etching) in a direction different from the desired direction, thereby suppressing abnormal shapes of the recesses.

In the etching method, the acid component may contain at least 1 selected from the group consisting of formic acid, acetic acid, HCl, HBr, HI, trichloroacetic acid, and citric acid.

In the etching method, the alkali component may contain at least 1 selected from the group consisting of ammonia, dimethylamine, trimethylamine, pyridine, pyrrolidine, tetrazole, and piperazine.

In the etching method, the 1 st process gas may contain a phosphorus-containing gas and a fluorine-containing gas. In this case, the film to be etched is etched by a fluorine chemical species from a plasma generated from a fluorine-containing gas. In addition, in a state where a phosphorus species generated from a phosphorus-containing gas exists on the surface of the film to be etched, the adsorption of a fluorine chemical species generated from a fluorine-containing gas (i.e., etchant) to the film to be etched is promoted. Therefore, in the above method, the supply of the etchant to the etching target film (particularly, the bottom of the recess of the etching target film) is promoted by the adsorption of the phosphorus species generated from the phosphorus-containing gas to the surface of the etching target film, thereby improving the etching rate.

In the etching method, the 1 st process gas may contain a fluorine-hydrogen gas.

In the etching method, the 1 st process gas may further contain a phosphorus-containing gas.

In the etching method, the 1 st process gas may further contain at least 1 selected from the group consisting of a carbon-containing gas, a metal-containing gas, an oxygen-containing gas, and a halogen-containing gas.

In the etching method, the etching target film may contain a silicon-containing film.

In the etching method, the pressure in the plasma processing chamber in the 2 nd period is lower than the pressure in the plasma processing chamber in the 1 st period.

In the etching method, the 1 st period and the 2 nd period may be respectively 0.0005 seconds to 50 seconds.

In the etching method, the 1 st process gas may be supplied into the chamber at a1 st flow rate during the 1 st period, and the 1 st process gas may not be supplied into the chamber or may be supplied at a2 nd flow rate lower than the 1 st flow rate during the 2 nd period.

In the etching method, the 2 nd process gas may be supplied into the chamber at a 3 rd flow rate during the 1 st period and the 2 nd period.

In an exemplary embodiment, a plasma processing apparatus includes a chamber, a substrate supporter for supporting a substrate in the chamber, a plasma generating section (e.g., an upper electrode), a bias electrode (e.g., a lower electrode), a1 st power supply, a2 nd power supply, a gas supply section, and a control section. The plasma generating section supplies source power for generating plasma. The bias electrode supplies bias power for inducing an etchant. The 1 st power supply is connected to the plasma generating section and supplies the source power to the plasma generating section. The 2 nd power supply is connected to the bias electrode and supplies the bias power to the bias electrode. The gas supply unit is configured to supply the 1 st process gas and the 2 nd process gas into the chamber. The plasma generating unit is configured to generate a plasma from the 1 st process gas in the chamber.

The control unit is configured to control the 1 st power supply, the 2 nd power supply, the gas supply unit, and the plasma generation unit to periodically supply the source power and the bias power in a period including a 1 st period and a 2 nd period, and to supply the 1 st process gas into the chamber during the 1 st period and to supply the 2 nd process gas into the chamber during the 2 nd period. The 1 st period is a period in which the source power and the bias power are supplied at predetermined power values, respectively. The 2 nd period is a period in which at least one of the source power and the bias power is not supplied or a power value is maintained lower than that in the 1 st period. In the 1 st period, the etching target film is etched by a plasma generated by the 1 st process gas supplied into the chamber. In the 2 nd period, the 2 nd process gas is supplied into the chamber, and the 2 nd process gas is adsorbed on the etching target film.

According to the plasma processing apparatus, the 2 nd process gas can be supplied during the 2 nd period, and the 2 nd process gas can be adsorbed on the etching target film. The 2 nd process gas adsorbed on the etching target film or the protective portion derived from the 2 nd process gas suppresses etching in a direction other than the desired etching direction in the following 1 st period, thereby suppressing the shape abnormality of the recess. The desired etching direction can also be referred to as a vertical direction with respect to the film to be etched or a direction from the plasma generating section toward the bias electrode.

Various exemplary embodiments are described in detail below with reference to the accompanying drawings. In the drawings, the same or corresponding portions may be denoted by the same reference numerals.

Fig. 1 is a diagram for explaining a configuration example 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 generating section 12. The plasma processing chamber 10 has a plasma processing space. The plasma processing chamber 10 includes: at least 1 gas supply port for supplying at least 1 process gas to the plasma processing space; and at least 1 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 discharge 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.

The plasma generating section 12 is configured to generate plasma from at least 1 kind of process gas supplied into the plasma processing space. The plasma formed in the plasma processing space may be a capacitively coupled plasma (CCP; CAPACITIVELY COUPLED PLASMA), an inductively coupled plasma (ICP; ind uctively Coupled Plasma), an ECR plasma (Electron-Cyclotron-Resonance plasma: electron Cyclotron resonance plasma), a Helicon wave excited plasma (HWP: helicon WAVE PLASMA), or a Surface wave plasma (SWP: surface WAVE PLASMA), or the like. Also, various types of plasma generating sections including an AC (ALTERNATING CURRENT: alternating Current) plasma generating section and a DC (Direct Current) plasma generating section may be used. In one embodiment, the AC signal (AC power) used in the AC plasma generating section has a frequency in the range of 100kHz to 10 GHz. Thus, the AC signal includes an RF (Radio Frequency) signal and a microwave signal. In one embodiment, the RF signal has a frequency in the range of 100kHz to 150 MHz.

The control unit 2 processes computer-executable instructions for causing the plasma processing apparatus 1 to execute various steps described in the present invention. The control unit 2 can be configured to control the respective elements of the plasma processing apparatus 1 so as to perform the various steps described herein. In one embodiment, a part or the whole of the control section 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 is realized by a computer 2a, for example. The processing unit 2a1 can be configured to read a program from the storage unit 2a2 and execute the read program, thereby performing various control operations. The program may be stored in the storage unit 2a2 in advance, or may be acquired via a medium when necessary. The acquired program is stored in the storage unit 2a2, and is read from the storage unit 2a2 by the processing unit 2a1 and executed. The medium may be various storage media readable to the computer 2a, or may be a communication line connected to the communication interface 2a3. The processing unit 2a1 may be a CPU (Central Processing Unit: central processing unit). The storage section 2a2 may include RAM (Random Access Memory: random access Memory), ROM (Read Only Memory), HDD (HARD DISK DRIVE: hard disk drive), SSD (Solid STATE DRIVE: solid state drive), or a combination thereof. The communication interface 2a3 can communicate with the plasma processing apparatus 1 via a communication line such as a LAN (Local Area Network: local area network).

A configuration example of a capacitive coupling type plasma processing apparatus as an example of the plasma processing apparatus 1 will be described below. Fig. 2 is a diagram for explaining a configuration example of the capacitive coupling type plasma processing apparatus.

The capacitively-coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply section 20, a power supply 30, and an exhaust system 40. The plasma processing apparatus 1 further includes a substrate support portion 11 and a gas introduction portion. The gas introduction portion is configured to introduce at least 1 kind of process gas into the plasma processing chamber 10. The gas introduction part includes a showerhead 13. The substrate support 11 is disposed in the plasma processing chamber 10. The shower head 13 is disposed above the substrate support 11. In one embodiment, the showerhead 13 forms at least a portion of a ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a shower head 13, a plasma processing space 10s defined by a sidewall 10a of the plasma processing chamber 10 and a substrate support 11. The plasma processing chamber 10 is grounded. The showerhead 13 and the substrate support 11 are electrically insulated from the frame of the plasma processing chamber 10.

The substrate support portion 11 includes a main body portion 111 and a ring assembly 112. The main body 111 has a central region 111a for supporting the substrate W and an annular region 111b for supporting the ring assembly 112. The wafer is an example of the substrate W. The annular region 111b of the main body 111 surrounds the central region 111a of the main body 111 in 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 referred to as a substrate support surface for supporting the substrate W, and the annular region 111b is also referred to as a ring support surface for supporting the ring assembly 112.

In one embodiment, the 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 in the ceramic member 1111 a. Ceramic component 1111a has a central region 111a. In one embodiment, ceramic component 1111a also has an annular region 111b. In addition, the annular electrostatic chuck or another member surrounding the electrostatic chuck 1111 such as an annular insulating member may have an annular region 111b. 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. At least 1 RF/DC electrode bonded to the RF power source 31 and/or the DC power source 32 described later may be disposed in the ceramic member 1111 a. In this case, at least 1 RF/DC electrode functions as a lower electrode. In the case where bias RF signals and/or DC signals described later are supplied to at least 1 RF/DC electrode, the RF/DC electrode is also referred to as a bias electrode. In addition, the conductive member of the base 1110 and at least 1 RF/DC electrode may function as a plurality of lower electrodes. The electrostatic electrode 1111b may function as a lower electrode. Thus, the substrate support 11 includes at least 1 lower electrode.

The ring assembly 112 includes 1 or more ring members. In one embodiment, the 1 or more annular members include 1 or more edge rings and at least 1 cover ring. The edge ring is formed of a conductive material or an insulating material, and the cover ring is formed of an insulating material.

The substrate support 11 may include a temperature adjustment module configured to adjust at least 1 of the electrostatic chuck 1111, the ring assembly 112, and the substrate to a target temperature. The temperature regulation module may include a heater, a heat transfer medium, a flow path 1110a, or a combination thereof. A heat transfer fluid such as brine or gas flows through the flow path 1110 a. In one embodiment, a flow path 1110a is formed within the base 1110 and 1 or more heaters are disposed within the ceramic component 1111a of the electrostatic chuck 1111. Also, the substrate support part 11 may include a heat transfer gas supply part configured to supply a heat transfer gas into a gap between the rear surface of the substrate W and the central region 111 a.

The showerhead 13 is configured to introduce at least 1 kind of process gas from the gas supply section 20 into the plasma processing space 10 s. The showerhead 13 has at least 1 gas supply port 13a, at least 1 gas diffusion chamber 13b, and a plurality of gas introduction ports 13c. The process gas supplied to the gas supply port 13a is introduced into the plasma processing space 10s from the plurality of gas introduction ports 13c through the gas diffusion chamber 13 b. And, the showerhead 13 includes at least 1 upper electrode. The gas introduction portion may include, in addition to the shower head 13, 1 or more side gas injection portions (SGI: side Gas Injector) attached to 1 or more openings formed in the side wall 10 a.

The gas supply 20 may include at least 1 gas source 21 and at least 1 flow controller 22. In one embodiment, the gas supply 20 is configured to supply at least 1 process gas from a respective corresponding gas source 21 to the showerhead 13 via a respective corresponding flow controller 22. Each flow controller 22 includes, for example, a mass flow controller or a pressure control type flow controller. In addition, the gas supply part 20 may include at least 1 flow modulation device that modulates or pulses the flow of at least 1 process gas.

The power supply 30 includes an RF power supply 31 that is coupled to the plasma processing chamber 10 via at least 1 impedance match circuit. The RF power source 31 is configured to supply at least 1 RF signal (RF power) to at least 1 lower electrode and/or at least 1 upper electrode. Thereby, plasma is formed from at least 1 kind of process gas supplied to the plasma processing space 10 s. Thus, the RF power source 31, at least 1 lower electrode, and/or at least 1 upper electrode can function as at least a portion of the plasma generating section 12. Further, by supplying a bias RF signal to at least 1 lower electrode, a bias potential is generated on the substrate W, and ion components in the formed plasma can be absorbed into the substrate W.

In one embodiment, the RF power supply 31 includes a1 st RF generating unit 31a and a2 nd RF generating unit 31b. The 1 st RF generation section 31a is configured to generate a source RF signal (source RF power) for generating plasma, which is bonded to at least 1 lower electrode and/or at least 1 upper electrode via at least 1 impedance matching circuit. In one embodiment, the source RF signal has a frequency in the range of 10MHz to 150 MHz. In an embodiment, the 1 st RF generation section 31a may be configured to generate a plurality of source RF signals having different frequencies. The generated 1 or more source RF signals are supplied to at least 1 lower electrode and/or at least 1 upper electrode.

The 2 nd RF generating section 31b is configured to generate a bias RF signal (bias RF power) by being bonded to at least 1 lower electrode via at least 1 impedance matching circuit. 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 that is lower than the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 100kHz to 60 MHz. In an embodiment, the 2 nd RF generating part 31b may be configured to generate a plurality of bias RF signals having different frequencies. The generated 1 or more bias RF signals are supplied to at least 1 lower electrode. In various embodiments, at least 1 of the source RF signal and the bias RF signal may be pulsed.

Also, the power supply 30 may include a DC power supply 32 bonded to the plasma processing chamber 10. The DC power supply 32 includes a1 st DC generation section 32a and a2 nd DC generation section 32b. In one embodiment, the 1 st DC generation unit 32a is connected to at least 1 lower electrode, and generates the 1 st DC signal. The generated 1 st DC signal is supplied to at least 1 lower electrode. In one embodiment, the 2 nd DC generation unit 32b is connected to at least 1 upper electrode, and generates a2 nd DC signal. The generated 2 nd DC signal is supplied to at least 1 upper electrode.

In various embodiments, the 1 st and 2 nd DC signals may be pulsed. In this case, a voltage pulse sequence is supplied to at least 1 lower electrode and/or at least 1 upper electrode. The voltage pulses may have a pulse shape that is rectangular, trapezoidal, triangular, or a combination thereof. In an embodiment, a waveform generation section for generating a voltage pulse train from a DC signal is connected between the 1 st DC generation section 32a and at least 1 lower electrode. Therefore, the 1 st DC generation section 32a and the waveform generation section constitute a voltage pulse generation section. When the 2 nd DC generation unit 32b and the waveform generation unit constitute a voltage pulse generation unit, the voltage pulse generation unit is connected to at least 1 upper electrode. The voltage pulse may have a positive polarity or a negative polarity. And, the voltage pulse train may include 1 or more positive polarity voltage pulses and 1 or more negative polarity voltage pulses within 1 period. The 1 st and 2 nd DC generation units 32a and 32b may be added to the RF power supply 31, or the 1 st DC generation unit 32a may be provided in place of the 2 nd RF generation unit 31 b.

The exhaust system 40 can be connected to a gas exhaust port 10e provided at the bottom of the plasma processing chamber 10, for example. 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 a pressure regulating valve. The vacuum pump may comprise a turbo molecular pump, a dry pump, or a combination thereof.

Fig. 3 is a flow chart of an etching method according to an exemplary embodiment. The etching method MT1 shown in fig. 3 (hereinafter, referred to as "method MT 1") can be performed by the plasma processing apparatus 1 of the above-described embodiment. The method MT1 can be applied to the substrate W1. That is, the substrate W may be the substrate W1.

Fig. 4 is a cross-sectional view of a substrate to which one example of the method of fig. 3 can be applied. As shown in fig. 4, in one embodiment, the substrate W1 includes the etching target film RE and the mask MK on the etching target film RE. The etching target film ER may be provided on the base film UR. Mask MK may have at least 1 opening OP.

The etching target film RE may include at least 1 of a silicon-containing film and an organic film. The silicon-containing film may include at least 1 of a silicon film, a silicon germanium film, a silicon oxide film, and a silicon nitride film. The silicon oxide film may contain impurities such as phosphorus, boron, nitrogen, and the like. The silicon nitride film may contain impurities such as phosphorus and boron. The silicon-containing film may be a laminated film in which silicon oxide films and silicon nitride films are alternately laminated. The organic film may be an amorphous carbon film. The etching target film RE may be, for example, a film used for a memory device such as a DRAM or a 3D-NAND.

The mask MK may contain at least 1 of a silicon-containing substance, an organic substance, and a metal. The silicon-containing material may contain polysilicon. The organic material may contain at least 1 of photoresist and SOC (Spin On Carbon). The metal may contain at least 1 selected from the group consisting of tungsten, molybdenum, titanium, and ruthenium. The mask may contain the above-mentioned metal carbide or silicide, and may contain, for example, at least 1 selected from the group consisting of WC (tungsten carbide), WS i (tungsten silicide), WSiN, and WSiC. When the etching target film RE includes a silicon-containing film, the mask MK may contain at least 1 of a 2 nd silicon-containing material, an organic material, and a metal, which are different from the 1 st silicon-containing material constituting the silicon-containing film. When the etching target film RE includes an organic film, the mask MK may contain at least 1 of a silicon-containing material, a 2 nd organic material different from the 1 st organic material constituting the organic film, and a metal.

The base film UR may contain a material different from the etching target film RE. The base film UR may contain at least 1 of a silicon-containing film, an organic film, and a metal-containing film.

The method MT1 will be described below with reference to fig. 3 to 8, taking as an example a case where the method MT1 uses the plasma processing apparatus 1 of the above embodiment and is applied to the substrate W1. Fig. 5 to 7 are cross-sectional views each showing a process of an etching method according to an exemplary embodiment. In the case of using the plasma processing apparatus 1, the method MT1 may be executed in the plasma processing apparatus 1 by controlling each part of the plasma processing apparatus 1 by the control part 2. In the method MT1, as shown in fig. 2, a substrate W (for example, a substrate W1) placed on a substrate support 11 (substrate support) in the plasma processing chamber 10 can be processed.

As shown in fig. 3, the method MT1 can include a step ST1 and a step ST2. The process ST1 and the process ST2 can be sequentially performed.

In step ST1, a substrate W1 shown in fig. 4 is provided. The substrate W1 can be carried into the plasma processing chamber 10. The substrate W1 can be supported by the substrate support 11 in the plasma processing chamber 10.

As shown in fig. 3 to 7, in step ST2, the etching target film RE is etched to form a recess RS.

The process ST2 includes a1 ST period and a2 nd period. In the 1 st period, a source power for plasma generation and a bias power for etchant induction are supplied at predetermined power values, respectively, and the 1 st process gas is supplied into the chamber. During period 2, at least one of the source power and the bias power is maintained at a power value lower than that during period 1, and a2 nd process gas is supplied into the chamber.

As shown in fig. 5, in the 1 st period, the 1 st plasma PL1 generated from the 1 st process gas etches the etching target film RE to form the recess RS. The recess RS can correspond to the opening OP of the mask MK.

The 1 st process gas may be any gas capable of generating plasma for etching the etching target film RE. The 1 st process gas may contain, for example, HF gas. The flow rate of the HF gas may be the largest among the 1 st process gases, except for the inert gas. In one example, the HF gas may be 50% by volume or more, 60% by volume or more, 70% by volume or more, or 80% by volume or more, relative to the total flow rate of the inert gases other than the 1 st process gas. As the HF gas, a high purity gas, for example, a gas having a purity of 99.999% or more can be used.

The process gas may contain a gas capable of generating HF species in the plasma instead of or in addition to HF gas. The HF species contains at least one of a fluorine-hydrogen gas, radicals, and ions.

In one example, as a gas capable of generating HF species, a hydrofluorocarbon gas may be used. The number of carbon atoms of the hydrofluorocarbon gas is 2 or more, 3 or more or 4 or more. In one example, at least one selected from the group consisting of CH ₂F₂ gas, C ₃H₂F₄ gas, C ₃H₂F₆ gas, C ₃H₃F₅ gas, C ₄H₂F₆ gas, C ₄H₅F₅ gas, C ₄H₂F₈ gas, C ₅H₂F₆ gas, C ₅H₂F₁₀ gas, and C ₅H₃F₇ gas may be used as the hydrofluorocarbon gas. In one example, at least 1 selected from the group consisting of CH ₂F₂ gas, C ₃H₂F₄ gas, C ₃H₂F₆ gas, and C ₄H₂F₆ gas is used as the hydrofluorocarbon gas.

In one example, as the gas capable of generating HF species, a fluorine-containing gas and a hydrogen-containing gas can be used. In one example, a fluorocarbon gas may be used as the fluorine-containing gas. The fluorocarbon gas may contain at least 1 selected from the group consisting of C ₂F₂ gas, C ₂F₄ gas, C ₃F₆ gas, C ₃F₈ gas, C ₄F₆ gas, C ₄F₈ gas, and C ₅F₈ gas. In one example, the fluorine-containing gas may be NF ₃ gas or SF ₆ gas. In one example, the hydrogen-containing gas may be H ₂ gas, CH ₄ gas, or NH ₃ gas.

The 1 st process gas may contain a phosphorus-containing gas. The phosphorus-containing gas is a gas containing phosphorus-containing molecules. The phosphorus-containing molecule may be oxide such as tetraphosphorus decaoxide (P ₄O₁₀), tetraphosphorus octaoxide (P ₄O₈), tetraphosphorus hexaoxide (P ₄O₆), etc. Tetraphosphorus decaoxide is sometimes referred to as phosphorus pentoxide (P ₂O₅). The phosphorus-containing molecule may be a halide (phosphorus halide) such as phosphorus trifluoride (PF ₃), phosphorus pentafluoride (PF ₅), phosphorus trichloride (PCl ₃), phosphorus pentachloride (PCl ₅), phosphorus tribromide (PBr ₃), phosphorus pentabromide (PBr ₅), phosphorus iodide (PI ₃). That is, the phosphorus-containing molecule may be phosphorus fluoride or the like, and fluorine is contained as a halogen element. Or the phosphorus-containing molecule may contain a halogen element other than fluorine as the halogen element. The phosphorus-containing molecule may be a phosphoryl halide such as phosphoryl fluoride (POF ₃), phosphoryl chloride (POCl ₃), phosphoryl bromide (POBr ₃). The phosphorus-containing molecule may be phosphine (PH ₃), calcium phosphide (Ca ₃P₂, etc.), phosphoric acid (H ₃PO₄), sodium phosphate (Na ₃PO₄), hexafluorophosphoric acid (HPF ₆), etc. The phosphorus-containing molecule may be a fluorophosphine (H _gPF_h). Here, the sum of g and h is 3 or 5. HPF ₂、H₂PF₃ is exemplified as the fluorophosphine.

The 1 st process gas may contain 1 or more kinds of phosphorus-containing molecules among the above-mentioned phosphorus-containing molecules as at least 1 kind of phosphorus-containing molecules. For example, the treatment gas can contain at least 1 of PF ₃、PCl₃、PF₅、PCl₅、POCl₃、PH₃、PBr₃ and PBr ₅ as at least 1 phosphorus-containing molecule. In the case where each of the phosphorus-containing molecules contained in the 1 st process gas is a liquid or a solid, each of the phosphorus-containing molecules can be vaporized by heating or the like and supplied into the plasma processing chamber 10.

The 1 st process gas may contain a carbon-containing gas. The carbon-containing gas may be at least any 1 or 2 of fluorocarbon gas or hydrofluorocarbon gas. The fluorocarbon gas may contain at least 1 selected from the group consisting of C ₂F₂ gas, C ₂F₄ gas, C ₃F₆ gas, C ₃F₈ gas, C ₄F₆ gas, C ₄F₈ gas, and C ₅F₈ gas. The hydrofluorocarbon gas may contain at least 1 selected from the group consisting of CHF ₃ gas, CH ₂F₂ gas, CH ₃ F gas, C ₂HF₅ gas, C ₂H₂F₄ gas, C ₂H₃F₃ gas, C ₂H₄F₂ gas, C ₃HF₇ gas, C ₃H₂F₂ gas, C ₃H₂F₄ gas, C ₃H₂F₆ gas, C ₃H₃F₅ gas, C ₄H₂F₆ gas, C ₄H₅F₅ gas, C ₄H₂F₈ gas, C ₅H₂F₆ gas, C ₅H₂F₁₀ gas, and C ₅H₃F₇ gas. The carbon-containing gas may be a linear gas having an unsaturated bond. As the linear carbon-containing gas having an unsaturated bond, for example, a gas selected from the group consisting of C ₃F₆ (hexafluoropropylene) gas, C ₄F₈ (octafluoro-1-butene) octafluoro-2-butene) gas, C ₃H₂F₄ (1, 3-tetrafluoropropene) gas C ₄H₂F₆ (trans-1, 4-hexafluoro-2-butene) gas at least 1 selected from the group consisting of C ₄F₈ O (pentafluoroethyl trifluorovinyl ether) gas, CF ₃ COF gas (1, 2-tetrafluoroethane-1-one), CHF ₂ COF (difluoro-acetic acid fluoride) gas, and COF ₂ (carbonyl fluoride) gas.

The 1 st process gas may also contain a metal-containing gas. The metal-containing gas may be a tungsten-containing gas. The tungsten-containing gas may be a gas containing tungsten and halogen, and in one example is WF _aCl_b gas (a and b are integers of 0 to 6, respectively, and the sum of a and b is 2 to 6). Specifically, the tungsten-containing gas may be a gas containing tungsten and chlorine, such as a tungsten 2 fluoride (WF ₂) gas, a tungsten 4 fluoride (WF ₄) gas, a tungsten 5 fluoride (WF ₅) gas, a tungsten 6 fluoride (WF ₆) gas, a tungsten 2 chloride (WCl ₂) gas, a tungsten 4 chloride (WCl ₄) gas, a tungsten 5 chloride (WCl ₅) gas, or a tungsten 6 chloride (WCl ₆) gas. Wherein, the gas may be at least any one of WF ₆ gas and WCl ₆ gas. The flow rate of the tungsten-containing gas may be, for example, 5% by volume or less, or 1% by volume or less, 0.5% by volume or less, or 0.2% by volume or less, relative to the total flow rate of the process gas other than the inert gas. The total flow rate of the tungsten-containing gas may be, for example, 0.01% by volume or more with respect to the total amount of the process gas other than the inert gas.

As the metal-containing gas, at least one of a molybdenum-containing gas and a titanium-containing gas may be used instead of or in addition to.

The 1 st process gas may further contain an oxygen-containing gas. The oxygen-containing gas may be, for example, at least 1 gas selected from the group consisting of O ₂、CO、CO₂、H₂ O and H ₂O₂. In one example, the 1 st process gas may contain at least 1 gas selected from the group consisting of O ₂、CO、CO₂ and H ₂O₂, which is an oxygen-containing gas other than H ₂ O. The flow rate of the oxygen-containing gas may be adjusted according to the flow rate of the carbon-containing gas such as fluorocarbon gas or hydrofluorocarbon gas.

The 1 st process gas may further contain a halogen-containing gas. The halogen-containing gas may be, for example, at least 1 selected from the group consisting of Cl ₂、Br₂、HCl、HBr、HI、BCl₃、ClF₃、IF₅、IF₇ and BrF ₃. The halogen-containing gas may contain carbon, or may contain carbon and 2 or more kinds of halogens. The halogen-containing gas containing carbon may be, for example, at least 1 selected from the group consisting of C _xH_yCl_z、C_xF_yBr_z、C_xF_yI_z and C _xF_yCl_z. Here, x and z are integers of 1 or more, and y is an integer of 0 or more. The halogen-containing gas containing carbon may contain, for example, 1 or more of CHCl ₃、CH₂Cl₂、CF₂Br₂ gas.

The process gas may contain a rare gas such as Ar gas, he gas, kr gas, or Xe gas, or an inert gas such as nitrogen gas.

During the 1 st period, the 1 st process gas is supplied into the plasma processing chamber 10 through the gas supply unit 20, and the 1 st plasma PL1 is generated from the 1 st process gas through the plasma generating unit 12 in the plasma processing chamber by supplying the source power and the bias power at predetermined power values, respectively. The control unit 2 may control the power supply 30, the gas supply unit 20, and the plasma generation unit 12 so that the 1 st plasma PL1 etches the etching target film RE to form the recess RS.

During the 2 nd period, the 2 nd process gas supplied into the plasma processing chamber 10 is adsorbed to the etching target film RE. As shown in fig. 6, during the 2 nd period, a protective portion PR derived from the 2 nd process gas may be formed on the etching target film RE. The protection portion PR may be formed in the 1 st period after the 2 nd period. The 2 nd process gas may be adsorbed to the mask MK, and the protection portion PR may be formed on the mask MK. In fig. 6, the protective portion PR is shown as a layer, but the protective portion derived from the 2 nd process gas is not necessarily required to be a layer. That is, the protective portion PR in fig. 6 schematically represents only a portion where the protective portion derived from the 2 nd process gas is formed, and in the method MT1, it is not necessary to form a layer corresponding to the protective portion PR on the substrate W1.

A period for purging the 1 st process gas supplied during the 1 st period may be provided between the 1 st period and the 2 nd period. Further, a period for purging the 2 nd process gas supplied during the 2 nd period may be provided between the 2 nd period and the 1 st period of the next cycle. The method of purging the 1 st process gas or the 2 nd process gas is not particularly limited, and examples thereof include a method of supplying an inert gas into the plasma processing chamber 10. The purge time may be, for example, 1 second or more and less than 180 seconds.

In one embodiment, the 2 nd process gas may contain a silylating agent having an alkyl group. In this case, the alkyl group of the silylation agent adsorbed on the surface of the etching target film RE functions as a protecting portion PR. The shape abnormality of the recess RS is suppressed by the alkyl group.

When the 2 nd process gas contains a silylation agent having an alkyl group, the film to be etched RE may contain a silicon-containing film or a silicon oxide film. Since the silicon-containing film (particularly, the silicon oxide film) easily adsorbs the silylation agent, the protective portion PR is easily formed by supplying the 2 nd process gas.

The number of carbon atoms of the alkyl group in the silyl group may be, for example, 1 to 20 inclusive, 1 to 16 inclusive, 1 to 12 inclusive, 1 to 8 inclusive, or 1 to 4 inclusive.

The silylation agent may react with hydroxyl groups present on the surface of the silicon-containing film, or may have a reactive group capable of forming a linking group that links a silicon atom in the silicon-containing film to an atom in the silylation agent. The linking group may be, for example, a group represented by-O-.

The reactive group may be a group bonded to a silicon atom in the silylating agent. In this case, a linking group linking the silicon atom in the silicon-containing film and the silicon atom in the silylation agent is formed. The reactive group may be, for example, a hydroxyl group (-OH), an alkoxy group (-OR ¹), an aryloxy group (-OR ²) amino group (-NR ³R⁴), a halo group (-X), OR the like.

R ¹ represents an alkyl group having, for example, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. R ² represents an aryl group, and the number of carbon atoms of the aryl group may be, for example, 6 or more and 18 or less, or 6 or more and 12 or less, or 6 or more and 10 or less. The aryl group may be, for example, phenyl.

R ³ and R ⁴ are each independently a hydrogen atom, an alkyl group or an aryl group, and the number of carbon atoms of the alkyl group may be, for example, 1 to 20, 1 to 16, 1 to 12, 1 to 8 or 1 to 4. The number of carbon atoms of the aryl group may be, for example, 6 to 18, 6 to 12, or 6 to 10, and the aryl group may be, for example, phenyl.

X represents a halogen atom. X may be, for example, a chlorine atom, a bromine atom or an iodine atom. X may be, for example, a chlorine atom.

The boiling point of the silylation agent may be, for example, 400℃or lower, or 350℃or lower or 300℃or lower. The boiling point of the silylation agent may be, for example, 50℃or higher, or 100℃or higher or 150℃or higher.

Examples of the silylating agent include N, N-dimethyltrimethylsilylamine, decyldimethylchlorosilane, dimethyl-N-octylchlorosilane, and decyldimethylmethoxysilane.

In another embodiment, the 2 nd process gas contains a silylation agent having an alkyl group, and the 1 st process gas may contain a tungsten-containing gas. In this case, the silylation agent is adsorbed on the etching target film RE in the period 2, and the alkyl group of the silyl group reacts with the tungsten-containing gas in the subsequent period 1, thereby forming the tungsten-containing protective portion PR on the etching target film RE. The silylation agent and the tungsten-containing gas may be as described above.

In yet other embodiments, the 2 nd process gas may contain an acid component and the substrate contains a silicon nitride film. In this case, the acid component is adsorbed on the etching target film RE in the 2 nd period, and ammonia generated by etching the silicon nitride film reacts with the acid component in the 1 st period. Thus, a salt, which is a reactant of the acid component and ammonia, is attached to the etching target film RE, and the salt functions as the protective portion PR.

The acid component may be, for example, an inorganic acid or an organic acid. If the acid component is an organic acid and has a low boiling point, it is easily supplied as a gas. From this point of view, the acid component may be, for example, formic acid, acetic acid, HCl, HBr, HI, trichloroacetic acid, citric acid, or the like. The boiling point of the acid component may be, for example, 300℃or lower. The boiling point of the acid component may be, for example, at-100℃or higher.

In still other embodiments, the 3rd process gas containing the alkali component may be supplied into the plasma processing chamber 10 after the 2 nd process gas containing the acid component is supplied into the plasma processing chamber 10 during the 2 nd period. In this case, the acid component adsorbed on the etching target film RE reacts with the alkali component supplied as the 3rd process gas, and thereby a salt, which is a reactant of the acid component and the alkali component, adheres to the etching target film RE, and the salt functions as the protection portion PR. The acid component may be as described above.

The base component may be an organic base. The base component may be a halogen-free organic base. If the boiling point of the alkali component is low, it is easy to supply as a gas. The boiling point of the alkali component may be, for example, 300℃or lower. The boiling point of the alkali component may be, for example, at-50℃or higher. The base component may be, for example, ammonia, an amine (e.g., dimethylamine, trimethylamine, etc.), a nitrogen-containing heterocyclic compound (e.g., pyridine, pyrrolidine, tetrazole, piperazine, etc.), or the like.

During period 2, at least one of the source power and the bias power is not supplied or the power value is maintained lower than that during period 1. During period 2, the etching may be substantially stopped. In the 2 nd period, plasma may or may not be generated.

In the 2 nd period, at least one of the source power and the bias power becomes lower in power value, and the 2 nd process gas is supplied into the plasma processing chamber 10 through the gas supply portion 20. The control unit 2 may control the power supply 30, the gas supply unit 20, and the plasma generation unit 12 so that etching is stopped and the 2 nd process gas is adsorbed on the etching target film RE.

During period 2, the pressure within the plasma processing chamber 10 may be reduced as compared to period 1. This effectively reduces the substrate temperature in the plasma processing chamber 10.

In step ST2, a cycle including the 1 ST period and the 2 nd period is repeatedly executed. As shown in fig. 7, in the 1 st period after the 2 nd period, the 1 st plasma PL1 generated from the 1 st process gas etches the etching target film RE, and the recess RS is deepened. At this time, since the etching of the side wall of the recess RS is suppressed by the protection portion PR, the recess RS can be deepened while suppressing the dimensional change of the side wall in the vicinity of the opening of the recess RS. Therefore, as shown in fig. 8, according to the method MT1, a substrate W1 having a recess RS with a small difference in size between the upper portion and the lower portion can be manufactured while suppressing shape abnormality. The size of the recess RS at the upper end of the recess RS may be 100nm or less. The bottom of the recess RS may or may not reach the base film UR.

The aspect ratio of the recess RS may be, for example, 5 or more, or may be 10 or more, 20 or more, 30 or more, 40 or more, or 50 or more. The aspect ratio of the recess RS may be 200 or less, for example. In addition, the aspect ratio of the recess RS indicates the ratio of the depth of the recess RS to the maximum width dimension of the recess RS.

Fig. 9 to 13 are examples of time charts showing time-dependent changes in power values of the source power and the bias power and time-dependent changes in the amounts of the 1 st process gas and the 2 nd process gas supplied. These timing charts relate to step ST 2.

The source power may be, for example, a source RF power supplied from the 1 st RF generating section 31a of the plasma processing apparatus 1. The bias power may be, for example, bias RF power supplied from the 2 nd RF generating section 31b of the plasma processing apparatus 1.

As shown in fig. 9, in step ST2, pulses of source power may be supplied, and pulses of bias power may be supplied. The source power and the bias power may be supplied periodically in a period CY. The period CY can include a1 st period PA and a2 nd period PB. In fig. 9, the 1 ST period PA is described as being executed first and then the 2 nd period PB is executed second, but in the step ST2, the 2 nd period PB may be executed first and then the 1 ST period PA may be executed second. During period 1PA, the source power and bias power can be maintained at high power H. During period PB 2, the source power and bias power can be maintained at low power L. The low power L may be 0W. During period 1PA, the 1 st process gas can be maintained at a high supply amount H, and the 2 nd process gas can be maintained at a low supply amount L. During period 2 PB, the 1 st process gas can be maintained at a low supply amount L, and the 2 nd process gas can be maintained at a high supply amount H. The low supply L may be 0.

The period PA1 may be, for example, 0.0005 seconds or longer, or 0.005 seconds or longer. The period PA1 may be 50 seconds or less, or 5 seconds or less, for example. The time of the 2 nd period PB may be, for example, 0.0005 seconds or more, or 0.005 seconds or more. The time of the 2 nd period PB may be 50 seconds or less, or may be 5 seconds or less, for example. The period CY may be, for example, 0.001 seconds or longer, or 0.01 seconds or longer. The period CY may be, for example, 100 seconds or less or 10 seconds or less.

As shown in fig. 10, in step ST2, a continuous wave of source power may be supplied, and pulses of bias power may be supplied. The source power and the bias power may be supplied periodically in a period CY. The period CY can include a 1 st period PA and a 2 nd period PB. In fig. 10, the 1 ST period PA is described as being executed first and then the 2 nd period PB is executed second, but in the step ST2, the 2 nd period PB may be executed first and then the 1 ST period PA may be executed second. During period 1 PA, the source power and bias power can be maintained at high power H. During period PB 2, the source power can be maintained at high power H and the bias power is maintained at low power L. The low power L may be 0W. During period 1 PA, the 1 st process gas can be maintained at a high supply amount H, and the 2 nd process gas is maintained at a low supply amount L. During period 2 PB, the 1 st process gas is maintained at a low supply amount L, and the 2 nd process gas is maintained at a high supply amount H. The low supply L may be 0.

As shown in fig. 11, in step ST2, pulses of source power may be supplied, and a continuous wave of bias power may be supplied. The source power and the bias power may be supplied periodically in a period CY. The period CY can include a 1 st period PA and a 2 nd period PB. In fig. 11, the 1 ST period PA is described as being executed first and then the 2 nd period PB is described as being executed second, but in the step ST2, the 2 nd period PB may be executed first and then the 1 ST period PA may be executed second. During period 1 PA, the source power and bias power can be maintained at high power H. During period PB 2, the source power can be maintained at low power L and the bias power at high power H. The low power L may be 0W. During period 1 PA, the 1 st process gas can be maintained at a high supply amount H, and the 2 nd process gas is maintained at a low supply amount L. During period 2 PB, the 1 st process gas is maintained at a low supply amount L, and the 2 nd process gas is maintained at a high supply amount H. The low supply L may be 0.

As shown in fig. 12, in step ST2, pulses of source power may be supplied, and pulses of bias power may be supplied. The source power and the bias power may be supplied periodically in a period CY. The period CY can include a1 st period PA and a2 nd period PB. In fig. 12, the 1 ST period PA is described as being executed first and then the 2 nd period PB is described as being executed second, but in the step ST2, the 2 nd period PB may be executed first and then the 1 ST period PA may be executed second. During period 1 PA, the source power and bias power can be maintained at high power H. During period PB 2, the source power and bias power can be maintained at low power L. The low power L may be 0W. During period 1 PA, the 1 st process gas can be maintained at a high supply amount H, and the 2 nd process gas is maintained at a low supply amount L. In the 2 nd period PB, the 1 st process gas and the 2 nd process gas can be maintained at high supply amounts H. The low supply L may be 0.

As shown in fig. 13, in step ST2, pulses of source power may be supplied, and pulses of bias power may be supplied. The source power and the bias power may be supplied periodically in a period CY. The period CY can include a1 st period PA and a2 nd period PB. In fig. 13, the 1 ST period PA is described as being executed first and then the 2 nd period PB is executed second, but in the step ST2, the 2 nd period PB may be executed first and then the 1 ST period PA may be executed second. During period 1 PA, the source power and bias power can be maintained at high power H. During period PB 2, the source power and bias power can be maintained at low power L. The low power L may be 0W. During period 1 PA, the 1 st process gas and the 2 nd process gas can be maintained at high supply amounts H. During period 2 PB, the 1 st process gas is maintained at a low supply amount L, and the 2 nd process gas is maintained at a high supply amount H. The low supply L may be 0.

In addition, in any of fig. 9 to 13, the high power H in the source power and the high power H in the bias power need not be the same value, and may be the same or different. The low power L in the source power and the low power L in the bias power need not be the same value, and may be the same or different. The high supply amount H of the 1 st process gas and the high supply amount H of the 2 nd process gas need not be the same value, and may be the same or different. The low supply amount L of the 1 st process gas and the low supply amount L of the 2 nd process gas are not necessarily the same value, and may be the same or different.

While various exemplary embodiments have been described above, the present invention is not limited to the above exemplary embodiments, and various additions, omissions, substitutions, and modifications can be made. Further, elements of different embodiments can be combined to form other embodiments.

Various exemplary embodiments included in the present invention are described in [ E1] to [ E20] below.

[E1]

An etching method, comprising: (a) A step of supplying a substrate having an etching target film and a mask on the etching target film to a substrate support of a plasma processing apparatus provided with a chamber, the substrate support supporting the substrate in the chamber, a plasma generating section to which a source power is supplied, and a bias electrode to which a bias power is supplied; and

(B) A step of etching the etching target film to form a recess,

In the (b), the source power and the bias power are supplied periodically with a period including a1 st period in which the source power and the bias power are supplied at prescribed power values, respectively, and a 2nd period in which at least one of the source power and the bias power is not supplied or a power value is maintained lower than a power value in the 1 st period,

Etching the etching target film by a1 st plasma generated from a1 st process gas supplied into the chamber during the 1 st period,

During the 2 nd period, the 2 nd process gas supplied into the chamber is adsorbed to the etching target film.

[E2]

The etching method according to [ E1], wherein,

The 2 nd treatment gas contains a silylation agent having an alkyl group.

[E3]

The etching method according to [ E2], wherein,

The alkyl group of the silylation agent having an alkyl group has 1 to 20 carbon atoms.

[E4]

The etching method according to [ E2], wherein,

The silylating agent having the alkyl group has at least 1 reactive group selected from the group consisting of hydroxyl group (-OH), alkoxy group (-OR ¹), aryloxy group (-OR ²) amino group (-NR ³R⁴) and halo group (-X) (wherein R ¹ represents alkyl group, R ² represents aryl group, and R ³ and R ⁴ each independently represent a hydrogen atom, alkyl group OR aryl group).

[E5]

The etching method according to [ E2], wherein,

The silylating agent having an alkyl group contains at least 1 selected from the group consisting of N, N-dimethyltrimethylsilylamine, decyldimethylchlorosilane, dimethyl-N-octylchlorosilane, and decyldimethylmethoxysilane.

[E6]

The etching method according to [ E1], wherein,

The 2 nd treatment gas contains a silylation agent having an alkyl group,

The 1 st process gas contains a tungsten-containing gas.

[E7]

The etching method according to [ E1], wherein,

The substrate comprises a silicon nitride film and,

The 2 nd process gas contains an acid component.

[E8]

The etching method according to [ E1], wherein,

The 2 nd process gas contains an acid component,

In the 2 nd period, after the 2 nd process gas is adsorbed to the etching target film, a3 rd process gas containing an alkali component is supplied into the chamber.

[E9]

The etching method according to [ E7] or [ E8], wherein,

The acid component contains at least 1 selected from the group consisting of formic acid, acetic acid, HCl, HBr, HI, trichloroacetic acid, and citric acid.

[E10]

The etching method according to [ E8], wherein,

The base component contains at least 1 selected from the group consisting of ammonia, dimethylamine, trimethylamine, pyridine, pyrrolidine, tetrazole, and piperazine.

[E11]

The etching method according to any one of [ E1] to [ E5], wherein,

The 1 st process gas contains a phosphorus-containing gas and a fluorine-containing gas.

[E12]

The etching method according to [ E1], wherein,

The 1 st process gas contains a fluorine-hydrogen gas.

[E13]

The etching method according to [ E12], wherein,

The 1 st process gas further comprises a phosphorus-containing gas.

[E14]

The etching method according to [ E12], wherein,

The 1 st process gas further contains at least 1 selected from the group consisting of a carbon-containing gas, a metal-containing gas, an oxygen-containing gas, and a halogen-containing gas.

[E15]

The etching method according to [ E1], wherein,

The etching target film includes a silicon-containing film.

[E16]

The etching method according to "E1", wherein,

The pressure within the plasma processing chamber during the 2 nd period is less than the pressure within the plasma processing chamber during the 1 st period.

[E17]

The etching method according to "E1", wherein,

The 1 st period and the 2 nd period are respectively 0.0005 seconds to 50 seconds.

[E18]

The etching method according to [ E1], wherein,

During the 1 st period, the 1 st process gas is supplied into the chamber at a1 st flow rate,

During the 2 nd period, the 1 st process gas is not supplied into the chamber or is supplied at a2 nd flow rate lower than the 1 st flow rate.

[E19]

The etching method according to [ E18 ], wherein,

During the 1 st and 2 nd periods, the 2 nd process gas is supplied into the chamber at a3 rd flow rate.

[E20]

A plasma processing apparatus is provided with:

A chamber;

a substrate supporter for supporting a substrate having an etching target film including a silicon-containing film and a mask on the etching target film in the chamber;

a gas supply unit configured to supply a1 st process gas and a2 nd process gas into the chamber;

a plasma generating unit configured to be supplied with source power and generate a plasma from the 1 st process gas in the chamber;

A bias electrode supplied with bias power;

A1 st power supply connected to the plasma generating section and supplying the source power to the plasma generating section;

A 2 nd power supply connected to the bias electrode and supplying the bias power to the bias electrode; and

The control part is used for controlling the control part to control the control part,

The control unit is configured as follows,

The source power and the bias power are supplied periodically with a period including a1 st period during which the source power and the bias power are supplied at prescribed power values, respectively, and a 2 nd period during which at least one of the source power and the bias power or a power value is not supplied and is maintained lower than a power value in the 1 st period,

And etching the etching target film by supplying the 1 st process gas into the chamber and generating plasma from the 1 st process gas during the 1 st period,

The 1 st power supply, the 2 nd power supply, the gas supply section, and the plasma generating section are controlled,

So that the 2 nd process gas is supplied into the chamber and the 2 nd process gas is adsorbed to the etching target film during the 2 nd period.

From the foregoing, it will be appreciated that various embodiments of the invention have been described herein for purposes of illustration, and that various modifications may be made without deviating from the scope and spirit of the invention. Accordingly, the various embodiments disclosed in the specification are not intended to be limiting, with a true scope and spirit being indicated by the following claims.

Symbol description

1-Plasma processing apparatus, 2-control part, 10-plasma processing chamber, 11-substrate support part, 12-plasma generating part, 20-gas supply part, MK-mask, PL 1-plasma, PR-protection part, RE-etching object film, RS-concave part, W, W-substrate.

Claims

1. An etching method, comprising:

(a) A step of supplying a substrate having an etching target film and a mask on the etching target film to a substrate support of a plasma processing apparatus provided with a chamber, the substrate support supporting the substrate in the chamber, a plasma generating section to which a source power is supplied, and a bias electrode to which a bias power is supplied; and

(B) A step of etching the etching target film to form a recess,

2. The etching method according to claim 1, wherein,

The 2 nd treatment gas contains a silylation agent having an alkyl group.

3. The etching method according to claim 2, wherein,

4. The etching method according to claim 2, wherein,

The silylating agent having the alkyl group has at least 1 reactive group selected from the group consisting of hydroxyl group (-OH), alkoxy group (-OR ¹), aryloxy group (-OR ²) amino group (-NR ³R⁴) and halo group (-X), wherein R ¹ represents alkyl group, R ² represents aryl group, and R ³ and R ⁴ each independently represent hydrogen atom, alkyl group OR aryl group.

5. The etching method according to claim 2, wherein,

6. The etching method according to claim 1, wherein,

The 2 nd treatment gas contains a silylation agent having an alkyl group,

The 1 st process gas contains a tungsten-containing gas.

7. The etching method according to claim 1, wherein,

The substrate comprises a silicon nitride film and,

The 2 nd process gas contains an acid component.

8. The etching method according to claim 1, wherein,

The 2 nd process gas contains an acid component,

9. The etching method according to claim 7 or 8, wherein,

The acid component contains at least 1 selected from the group consisting of formic acid, acetic acid, HCl, HBr, HI, trichloroacetic acid and citric acid.

10. The etching method according to claim 8, wherein,

11. The etching method according to claim 1, wherein,

12. The etching method according to claim 1, wherein,

The 1 st process gas contains a fluorine-hydrogen gas.

13. The etching method according to claim 12, wherein,

The 1 st process gas further comprises a phosphorus-containing gas.

14. The etching method according to claim 12, wherein,

15. The etching method according to claim 1, wherein,

The etching target film includes a silicon-containing film.

16. The etching method according to claim 1, wherein,

17. The etching method according to claim 1, wherein,

18. The etching method according to claim 1, wherein,

19. The etching method of claim 18, wherein,

20. A plasma processing apparatus is provided with:

A chamber;

A bias electrode supplied with bias power;

The control unit is configured as follows,

The 1 st power supply, the 2 nd power supply, the gas supply portion, and the plasma generation portion are controlled to supply the 2 nd process gas into the chamber and adsorb the 2 nd process gas to the etching target film during the 2 nd period.