Etching method and plasma treatment device

Abstract

The etching method comprises: (a) a step for preparing a substrate that has a silicon-containing film and a metal-containing mask on the silicon-containing film, wherein the silicon-containing film comprises a first film containing silicon and oxygen and a second film containing silicon and nitrogen, and the metal-containing mask has at least one opening; (b1) a step for exposing the substrate to a first plasma generated from a first treatment gas containing carbon and fluorine; (b2) a step for exposing the substrate to a second plasma generated from a second treatment gas containing a nitrogen-containing gas that does not contain halogen; (c1) a step for exposing the substrate to a third plasma generated from a third treatment gas containing carbon, hydrogen, and fluorine; and (c2) a step for exposing the substrate to a fourth plasma generated from a fourth treatment gas containing a nitrogen-containing gas that does not contain halogen.

Description

Etching method and plasma processing apparatus

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

[0002] Patent Literature 1 discloses a method for etching a silicon-containing film on a substrate having the silicon-containing film and a mask on the silicon-containing film. In this method, the silicon-containing film is first partially etched. Next, a carbon-containing film is formed on the silicon-containing film without generating plasma. Next, the silicon-containing film on which the carbon-containing film has been formed is further etched using plasma.

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

[0004] The present disclosure provides an etching method and a plasma processing apparatus that can improve the etching profile.

[0005] In one exemplary embodiment, an etching method includes: (a) preparing a substrate having a silicon-containing film and a metal-containing mask on the silicon-containing film, the silicon-containing film including a first film including silicon and oxygen and a second film including silicon and nitrogen, the metal-containing mask having at least one opening; (b) etching the first film; and (c) etching the second film. (b) includes: (b1) exposing the substrate to a first plasma generated from a first process gas including carbon and fluorine, and (b2) exposing the substrate to a second plasma generated from a second process gas including a nitrogen-containing gas without a halogen. (c) includes: (c1) exposing the substrate to a third plasma generated from a third process gas including carbon, hydrogen, and fluorine, and (c2) exposing the substrate to a fourth plasma generated from a fourth process gas including a nitrogen-containing gas without a halogen.

[0006] According to one exemplary embodiment, an etching method and a plasma processing apparatus are provided that can improve the etching profile.

[0007] FIG. 1 is a schematic diagram of a plasma processing system according to an exemplary embodiment. FIG. 2 is a schematic diagram of a plasma processing apparatus according to an exemplary embodiment. FIG. 3 is a flowchart of an etching method according to an exemplary embodiment. FIG. 4 is a partial enlarged view of an example substrate to which the etching method of FIG. 3 can be applied. FIG. 5 is a cross-sectional view showing a step of an etching method according to an exemplary embodiment. FIG. 6 is a cross-sectional view showing a step of an etching method according to an exemplary embodiment. FIG. 7 is a cross-sectional view showing a step of an etching method according to an exemplary embodiment. FIG. 8 is a cross-sectional view showing a step of an etching method according to an exemplary embodiment. FIG. 9 is a cross-sectional view showing a step of an etching method according to an exemplary embodiment. FIG. 10 is a cross-sectional view showing a step of an etching method according to an exemplary embodiment. FIG. 11 is a cross-sectional view showing a step of an etching method according to an exemplary embodiment. FIG. 12 is a cross-sectional view showing a step of an etching method according to an exemplary embodiment. FIG. 13 is a cross-sectional view showing a step of an etching method according to an exemplary embodiment.

[0008] Various exemplary embodiments will be described in detail below with reference to the drawings, in which the same or equivalent parts are designated by the same reference numerals.

[0009] FIG. 1 is a diagram illustrating an exemplary configuration of a plasma processing system. In one embodiment, the plasma processing system includes a plasma processing apparatus 1 and a control unit 2. The plasma processing system is an example of a substrate processing system, and the plasma processing apparatus 1 is an example of a substrate processing apparatus. The plasma processing apparatus 1 includes a plasma processing chamber 10, a substrate support 11, and a plasma generation unit 12. The plasma processing chamber 10 has a plasma processing space. The plasma processing chamber 10 also has at least one gas supply port for supplying at least one processing gas to the plasma processing space and at least one gas exhaust port for exhausting gas from the plasma processing space. The gas supply port is connected to a gas supply unit 20 (described later), and the gas exhaust port is connected to an exhaust system 40 (described later). The substrate support 11 is disposed in the plasma processing space and has a substrate support surface for supporting a substrate.

[0010] 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.

[0011] 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).

[0012] 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.

[0013] The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply 20, a power supply 30, and an exhaust system 40. The plasma processing apparatus 1 also includes a substrate support 11 and a gas inlet. The gas inlet is configured to introduce at least one process gas into the plasma processing chamber 10. The gas inlet includes a showerhead 13. The substrate support 11 is disposed within the plasma processing chamber 10. The showerhead 13 is disposed above the substrate support 11. In one embodiment, the showerhead 13 forms at least a portion of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the showerhead 13, a sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 is grounded. The showerhead 13 and the substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 3 is a flowchart of an etching method according to one example embodiment. The etching method MT1 shown in FIG. 3 (hereinafter referred to as "method MT1") can be performed by the plasma processing apparatus 1 of the above embodiment. The method MT1 can be applied to the substrate W1 of FIG.

[0027] Figure 4 is a cross-sectional view of an example substrate W1 to which the method of Figure 3 can be applied. As shown in Figure 4, in one embodiment, the substrate W1 includes a silicon-containing film SF1 and a metal-containing mask MK1 on the silicon-containing film SF1. The substrate W1 may further include an underlayer film UF1. The silicon-containing film SF1 may be on the underlayer film UF1.

[0028] The metal-containing mask MK1 has at least one opening OP1. The at least one opening OP1 may be a hole or a slit. The metal-containing mask MK1 may include a plurality of openings OP1.

[0029] The metal-containing mask MK1 may include at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, and titanium. The metal-containing mask MK1 may be a tungsten-containing film, a molybdenum-containing film, a ruthenium-containing film, or a titanium-containing film. The metal-containing mask MK1 may further include at least one element selected from the group consisting of silicon, carbon, and nitrogen. The metal-containing mask MK1 may be WSi, WC, WN, MoSi ２ , Mo ２ C, MoN, TiSi ２ , TiC, and TiN.

[0030] The silicon-containing film SF1 includes a first film F1 and a second film F2. The first film F1 may be on the second film F2. The silicon-containing film SF1 may further include a third film F3, a fourth film F4, and a fifth film F5. The fourth film F4 may be on the base film UF1. The third film F3 may be on the fourth film F4. The second film F2 may be on the third film F3. The fifth film F5 may be on the first film F1. That is, on the substrate W1, the metal-containing mask MK1, the fifth film F5, the first film F1, the second film F2, the third film F3, the fourth film F4, and the base film UF1 may be arranged downward in this order.

[0031] 4, the silicon-containing film SF1 has a five-layer structure including a first film F1, a second film F2, a third film F3, a fourth film F4, and a fifth film F5. In one example, the silicon-containing film SF1 may have a multilayer structure including one or more silicon nitride films and one or more silicon oxide films that are alternately stacked. Alternatively, the silicon-containing film SF1 may have a multilayer structure including a plurality of silicon nitride films and a plurality of silicon oxide films that are alternately stacked. Alternatively, the silicon-containing film SF1 may have a multilayer structure including at least two of a silicon oxide film, a silicon nitride film, and a polycrystalline silicon film.

[0032] The first film F1 contains silicon and oxygen. The first film F1 is made of silicon oxide (SiO ｘ ), where x is a positive real number. The first film F1 may be a silicon oxide film. The second film F2 contains silicon and nitrogen. The second film F2 may be silicon nitride (SiN ｘ ) where x is a positive real number. The second film F2 may be a silicon nitride film.

[0033] The third film F3 may contain silicon and oxygen. ｘ The third film F3 may be a silicon oxide film. The fourth film F4 may contain silicon and nitrogen. The fourth film F4 may be a silicon nitride (SiN ｘ The fourth film F4 may be a silicon nitride film.

[0034] The fifth film F5 may contain silicon and nitrogen. The fifth film F5 may be silicon nitride (SiN ｘ The fifth film F5 may be a silicon nitride film.

[0035] The first film F1 may have a thickness of 500 nm or less. The first film F1 may have a thickness of 100 nm or more. The second film F2 may have a thickness of 50 nm or less. The second film F2 may have a thickness of 10 nm or more. The third film F3 may have a thickness of 500 nm or less. The third film F3 may have a thickness of 200 nm or more. The fourth film F4 may have a thickness of 30 nm or less. The fourth film F4 may have a thickness of 5 nm or more. The fifth film F5 may have a thickness of 350 nm or less. The fifth film F5 may have a thickness of 40 nm or more.

[0036] The first film F1 may have a thickness greater than the thickness of the second film F2 and the thickness of the fourth film F4. The first film F1 may have a thickness, for example, more than twice the thickness of the second film F2. The third film F3 may have a thickness greater than the thickness of the second film F2 and the thickness of the fourth film F4. The third film F3 may have a thickness, for example, more than twice the thickness of the fourth film F4. The fifth film F5 may have a thickness greater than the thickness of the second film F2 and the thickness of the fourth film F4. The fifth film F5 may have a thickness less than the thickness of the first film F1 and the thickness of the third film F3.

[0037] Method MT1 will be described below with reference to FIGS. 5 to 13, taking as an example a case where method MT1 is applied to substrate W1 using the plasma processing apparatus 1 of the above embodiment. FIGS. 5 to 13 are cross-sectional views showing steps of an etching method according to one exemplary embodiment. When the plasma processing apparatus 1 is used, method MT1 can be performed in the plasma processing apparatus 1 by controlling each part of the plasma processing apparatus 1 with the control unit 2. In method MT1, substrate W1 is etched instead of substrate W on substrate support 11 disposed in plasma processing chamber 10, as shown in FIG. 2.

[0038] 3, the method MT1 may include steps ST11 to ST15, which may be performed in order. The method MT1 may not include at least one of steps ST12 and ST15.

[0039] 4 is prepared. The substrate W1 may be provided in the plasma processing chamber 10. The substrate W1 may be supported by a substrate support 11 in the plasma processing chamber 10.

[0040] (Process ST12) In process ST12, the fifth film F5 is etched. Process ST12 may include process ST12a and process ST12b. As shown in FIG. 3, process ST12b may be performed after process ST12a. Alternatively, process ST12a and process ST12b may be performed simultaneously. In process ST12, the temperature of the substrate support 11 may be, for example, 20° C. or higher and 150° C. or lower.

[0041] (Process ST12a) In process ST12a, as shown in FIG. 5, the substrate W1 is exposed to a third plasma PL3 generated from the third process gas. This may etch the fifth film F5. That is, in process ST12a, the fifth film F5 may be etched using the third plasma PL3. The supply of the third process gas may be stopped at the end of process ST12a.

[0042] The third process gas contains carbon, hydrogen, and fluorine. The third process gas may contain a hydrofluorocarbon gas or a mixture of a fluorocarbon gas and a hydrogen-containing gas. The hydrofluorocarbon gas contained in the third process gas is CHF ３ Gas, CH ２ F ２ Gas, CH ３ F gas, C ２ HF ５ Gas, C ２ H ２ F ４ Gas, C ２ H ３ F ３ Gas, C ２ H ４ F ２ Gas, C ３ HF ７ Gas, C ３ H ２ F ２ Gas, C ３ H ２ F ４Gas, C ３ H ２ F ６ Gas, C ３ H ３ F ５ Gas, C ４ H ２ F ６ Gas, C ４ H ５ F ５ Gas, C ４ H ２ F ８ Gas, C ５ H ２ F ６ Gas, C ５ H ２ F １０ Gas, and C ５ H ３ F ７ The gas may contain at least one selected from the group consisting of:

[0043] The fluorocarbon gas contained in the third process gas is CF ４ Gas, C ２ F ２ Gas, C ２ F ４ Gas, C ３ F ６ Gas, C ３ F ８ Gas, C ４ F ６ Gas, C ４ F ８ Gas, and C ５ F ８ The hydrogen-containing gas may contain at least one selected from the group consisting of H ２ Gas, NH ３ Gas, H ２ 0 gas, and H ２ O ２ The gas may contain at least one selected from the group consisting of:

[0044] The third process gas is NF ３ The third process gas may further include an oxygen-containing gas. The oxygen-containing gas included in the third process gas may be O ２ Gas, CO gas, CO ２ Gas, H ２ O gas and H２ O ２ The gas may contain at least one selected from the group consisting of:

[0045] The third process gas may further contain a halogen-containing gas other than fluorine. The halogen-containing gas other than fluorine contained in the third process gas may include at least one gas selected from the group consisting of a chlorine-containing gas, a bromine-containing gas, and an iodine-containing gas.

[0046] The chlorine-containing gas is Cl ２ Gas, SiCl ２ Gas, SiCl ４ Gas, CCl ４ Gas, SiH ２ Cl ２ Gas, Si ２ Cl ６ Gas, CHCl ３ Gas, SO ２ Cl ２ Gas, BCl ３ Gas, PCl ３ Gas, PCl ５ gas, and POCl ３ The gas may contain at least one selected from the group consisting of:

[0047] The bromine-containing gas is Br ２ Gas, HBr gas, CBr ２ F ２ Gas, C ２ F ５ Br gas, PBr ３ Gas, PBr ５ Gas, POBr ３ gas, and BBr ３ The gas may contain at least one selected from the group consisting of:

[0048] Iodine-containing gases include HI gas and CF ３ I Gas, C ２ F ５ I Gas, C ３ F ７ I gas, IF ５ Gas, IF ７ Gas, I ２ Gas and PI ３ The gas may contain at least one selected from the group consisting of:

[0049] The third process gas may further include a phosphorus-containing gas. The phosphorus-containing gas included in the third process gas may include at least one selected from the group consisting of phosphorus oxide, phosphorus halide, phosphonium halide, and fluorophosphine. The phosphorus oxide may include P ４ O １０ , P ４ O ８ , and P ４ O ６ The phosphorus halide may include at least one selected from the group consisting of PF ３ , P.F. ５ , PCl ３ , PCl ５ , PBr ３ , PBr ５ , and P.I. ３ The halogenated phosphorus may include at least one selected from the group consisting of POF ３ , POCl ３ , and POBr ３ The fluorophosphine may include at least one selected from the group consisting of HPF ２ and H ２ PF ３ The phosphorus-containing gas contained in the third process gas may include at least one selected from the group consisting of PH ３ , Ca ３ P ２ , H ３ P.O. ４ , Na ３ P.O. ４ , HPF ６ The composition may include at least one selected from the group consisting of:

[0050] The third process gas may further contain a metal-containing gas. The metal-containing gas contained in the third process gas may include at least one gas selected from the group consisting of a tungsten-containing gas, a titanium-containing gas, and a molybdenum-containing gas. The tungsten-containing gas may be WF ２ Gas, WF ４ Gas, WF ５ Gas, WF ６ Gas, WCl ２ Gas, WCl ４ Gas, WCl５ Gas, and WCl ６ The gas may contain at least one selected from the group consisting of:

[0051] The third process gas may further include a noble gas, and the noble gas included in the third process gas may include at least one gas selected from the group consisting of Ar gas, He gas, and Kr gas.

[0052] The processing time of step ST12a may be longer than the processing time of step ST12b. The processing time of step ST12a may be, for example, 500 seconds or less, or 350 seconds or less. The processing time of step ST12a may be, for example, 200 seconds or more, or 300 seconds or more.

[0053] In step ST12a, a third electric bias may be applied to the substrate support 11. The third electric bias may be a direct current (DC) current. The DC voltage may include a voltage pulse. In this case, the level of the electric bias is the absolute value of the voltage level of the voltage pulse. When the third electric bias is a DC current, the level of the third electric bias may be 2000 V or more.

[0054] The third electrical bias may be bias RF power, in which case the level of the third electrical bias is the power level (effective value) of the bias RF power.

[0055] (Process ST12b) In process ST12b, as shown in FIG. 6, the substrate W1 is exposed to a fourth plasma PL4 generated from a fourth process gas. As a result, a protective film PF1 may be formed on the surface of the metal-containing mask MK1. That is, in process ST12b, the protective film PF1 may be formed on the surface of the metal-containing mask MK1 using the fourth plasma PL4. The supply of the fourth process gas may be stopped at the end of process ST12b. The fourth process gas contains a nitrogen-containing gas. The nitrogen-containing gas contained in the fourth process gas does not contain a halogen. The fourth process gas contains N ２ It may include a gas.

[0056] The protective film PF1 may contain nitrogen. The protective film PF1 may be a nitride film such as a metal nitride film. The protective film PF1 may contain at least one selected from the group consisting of tungsten, molybdenum, ruthenium, titanium, silicon, and carbon. In step ST12b, the protective film PF1 may be formed by a reaction between the fourth plasma PL4 and the metal-containing mask MK1. The protective film PF1 may function as a protective film for suppressing shape deterioration of the metal-containing mask MK1 in etching performed in subsequent steps.

[0057] The processing time of step ST12b may be, for example, 80 seconds or less, or 50 seconds or less, or may be, for example, 10 seconds or more, or 30 seconds or more.

[0058] In step ST12b, no electric bias may be applied to the substrate support part 11. Alternatively, in step ST12b, a fourth electric bias may be applied to the substrate support part 11. The fourth electric bias may be smaller than the third electric bias.

[0059] The fourth electrical bias may be a direct current (DC) current. The DC voltage may include a voltage pulse. In this case, the level of the electrical bias is the absolute value of the voltage level of the voltage pulse. When the fourth electrical bias is a DC current, the level of the fourth electrical bias may be 200 V or less.

[0060] The fourth electrical bias may be a bias RF power, in which case the level of the fourth electrical bias is the power level (effective value) of the bias RF power.

[0061] (Process ST13) In process ST13, the first film F1 is etched. Process ST13 may include process ST13a and process ST13b. As shown in FIG. 3, process ST13b may be performed after process ST13a. Alternatively, process ST13a and process ST13b may be performed simultaneously. In process ST13, the temperature of the substrate support 11 may be, for example, 20° C. or higher and 150° C. or lower.

[0062] (Process ST13a) In process ST13a, as shown in FIG. 7, the substrate W1 is exposed to a first plasma PL1 generated from a first process gas. This may etch the first film F1. That is, in process ST13a, the first film F1 may be etched using the first plasma PL1. At this time, the entire protective film PF1 formed in process ST12b may be removed, or only a portion of the protective film PF1 may be removed. The supply of the first process gas may be stopped at the end of process ST13a.

[0063] The first process gas contains carbon and fluorine. The first process gas may contain a fluorocarbon gas or a mixture of a fluorine-containing gas and a carbon-containing gas.

[0064] The fluorocarbon gas contained in the first process gas may be the same as the fluorocarbon gas contained in the third process gas. The fluorine-containing gas may include HF gas. The carbon-containing gas may include at least one gas selected from the group consisting of a hydrocarbon gas, a fluorocarbon gas, and a hydrofluorocarbon gas.

[0065] The first process gas is NF ３ The first process gas may further include an oxygen-containing gas. The oxygen-containing gas contained in the first process gas may be the same as the oxygen-containing gas contained in the third process gas.

[0066] The first process gas may further contain a halogen-containing gas other than fluorine. The halogen-containing gas other than fluorine contained in the first process gas may be the same as the halogen-containing gas other than fluorine contained in the third process gas.

[0067] The first process gas may further include a phosphorus-containing gas, and the phosphorus-containing gas included in the first process gas may be the same as the phosphorus-containing gas included in the third process gas.

[0068] The first process gas may further include a metal-containing gas, and the metal-containing gas included in the first process gas may be the same as the metal-containing gas included in the third process gas.

[0069] The first process gas may further include a noble gas, which may be the same as the noble gas included in the third process gas.

[0070] The processing time of step ST13a may be longer than the processing time of step ST13b. The processing time of step ST13a may be, for example, 120 seconds or less, or 90 seconds or less. The processing time of step ST13a may be, for example, 50 seconds or more, or 70 seconds or more.

[0071] In step ST13a, a first electric bias may be applied to the substrate support 11. The first electric bias may be a direct current (DC) current. The DC voltage may include a voltage pulse. In this case, the level of the electric bias is the absolute value of the voltage level of the voltage pulse. When the first electric bias is a DC current, the level of the first electric bias may be 7000 V or more.

[0072] The first electrical bias may be a bias RF power, in which case the level of the first electrical bias is the power level (effective value) of the bias RF power.

[0073] (Process ST13b) In process ST13b, as shown in FIG. 8, the substrate W1 is exposed to a second plasma PL2 generated from the second process gas. This may form a protective film PF1 on the surface of the metal-containing mask MK1. That is, in process ST13b, the protective film PF1 may be formed on the surface of the metal-containing mask MK1 using the second plasma PL2. In process ST13b, the protective film PF1 may be formed by a reaction between the second plasma PL2 and the metal-containing mask MK1. The supply of the second process gas may be stopped at the end of process ST13b. The second process gas contains a nitrogen-containing gas. The nitrogen-containing gas contained in the second process gas does not contain a halogen. The second process gas may contain N ２ It may include a gas.

[0074] The processing time of step ST13b may be, for example, 80 seconds or less, or 50 seconds or less, or may be, for example, 10 seconds or more, or 30 seconds or more.

[0075] In step ST13b, no electric bias may be applied to the substrate support part 11. Alternatively, in step ST13b, a second electric bias may be applied to the substrate support part 11. The second electric bias may be smaller than the first electric bias.

[0076] The second electrical bias may be a direct current (DC) current. The DC voltage may include a voltage pulse. In this case, the level of the electrical bias is the absolute value of the voltage level of the voltage pulse. When the second electrical bias is a DC current, the level of the second electrical bias may be 200 V or less.

[0077] The second electrical bias may be bias RF power, in which case the level of the second electrical bias is the power level (effective value) of the bias RF power.

[0078] (Process ST14) In process ST14, the second film F2 is etched. Process ST14 may include process ST14a and process ST14b. As shown in FIG. 3, process ST14b may be performed after process ST14a. Alternatively, process ST14a and process ST14b may be performed simultaneously. In process ST14, the temperature of the substrate support 11 may be, for example, 20° C. or higher and 150° C. or lower.

[0079] (Process ST14a) In process ST14a, as shown in FIG. 9, the substrate W1 is exposed to the third plasma PL3. This may etch the second film F2. That is, in process ST14a, the second film F2 may be etched using the third plasma PL3. At this time, the protective film PF1 formed in process ST13b may be entirely removed, or only a portion of the protective film PF1 may be removed. The supply of the third process gas may be stopped at the end of process ST14a.

[0080] The processing time of step ST14a may be longer than the processing time of step ST14b. The processing time of step ST14a may be, for example, 100 seconds or less, or 70 seconds or less. The processing time of step ST14a may be, for example, 30 seconds or more, or 50 seconds or more. In step ST14a, a third electric bias may be applied to the substrate support 11.

[0081] (Process ST14b) In process ST14b, as shown in FIG. 10 , the substrate W1 is exposed to a fourth plasma PL4. As a result, a protective film PF1 may be formed on the surface of the metal-containing mask MK1. That is, in process ST14b, the protective film PF1 may be formed on the surface of the metal-containing mask MK1 using the fourth plasma PL4. In process ST14b, the protective film PF1 may be formed by a reaction between the fourth plasma PL4 and the metal-containing mask MK1. The supply of the fourth process gas may be stopped at the end of process ST14b.

[0082] The processing time of step ST14b may be, for example, 80 seconds or less, or 50 seconds or less. The processing time of step ST14b may be, for example, 10 seconds or more, or 30 seconds or more. In step ST14b, an electric bias does not need to be applied to the substrate support part 11. Alternatively, in step ST14b, a fourth electric bias may be applied to the substrate support part 11.

[0083] (Process ST15) In process ST15, at least processes ST13a, ST13b, and ST14a are repeated. Hereinafter, the repetition of process ST15 will be described in more detail using substrate W1 as an example. In this example, the treatment performed on the first film F1 in processes ST13a and ST13b is performed on the third film F3, and the treatment performed on the second film F2 in process ST14a is performed on the fourth film F4.

[0084] 11 , in the process ST15 for the substrate W1, the substrate W1 is first exposed to a first plasma PL1. This may etch the third film F3. That is, the third film F3 may be etched using the first plasma PL1. At this time, the protective film PF1 formed immediately before (in the process ST14a) may be entirely removed, or only a part of the protective film PF1 may be removed.

[0085] 12, the substrate W1 is exposed to a second plasma PL2. As a result, a protective film PF1 may be formed on the surface of the metal-containing mask MK1. That is, the protective film PF1 may be formed on the surface of the metal-containing mask MK1 using the second plasma PL2.

[0086] 13, the substrate W1 is then exposed to the third plasma PL3. This may etch the fourth film F4. That is, the fourth film F4 may be etched using the third plasma PL3. At this time, the protective film PF1 formed immediately before may be entirely removed, or only a portion of the protective film PF1 may be removed.

[0087] In this way, in the step of etching the lowermost film of the silicon-containing film SF1, the substrate W1 may be exposed to one of the first plasma PL1 and the third plasma PL3 that corresponds to the film. In other words, the step of etching the lowermost film of the silicon-containing film SF1 does not have to include the step of exposing the substrate W1 to one of the second plasma PL2 and the fourth plasma PL4 that corresponds to the film.

[0088] According to the above-described plasma processing apparatus 1 and method MT1, the substrate W1 is exposed to the second plasma PL2 in step ST13b and the fourth plasma PL4 in step ST14b, thereby forming a protective film PF1 on the metal-containing mask MK1, which can function as a protective film. This prevents the shape of the metal-containing mask MK1 from being deteriorated by etching in each step. As a result, the etching shapes of the recesses formed in the first film F1 and the second film F2 can be improved.

[0089] Various experiments performed to evaluate Method MT1 are described below, but the experiments described below are not intended to limit the present disclosure.

[0090] (First Experiment) In the first experiment, a substrate having a silicon nitride film and a tungsten silicide film on the silicon nitride film was prepared. The tungsten silicide film had an opening. Then, the silicon nitride film was etched. At this time, hydrofluorocarbon gas and N ２The substrate was exposed to a plasma generated from a process gas containing the gas.

[0091] (Second Experiment) In the second experiment, the processing gas was N ２ The second experiment was conducted in the same manner as the first experiment, except that no gas was included. That is, in the second experiment, when etching the silicon nitride film, the substrate was exposed to plasma generated from a process gas containing a hydrofluorocarbon gas.

[0092] (Results of the first experiment) In each of the first and second experiments, the shape of the tungsten silicide film after etching of the silicon nitride film was observed. As a result, in the second experiment, the sidewall of the tungsten silicide film was scraped off, causing a deterioration in the shape of the tungsten silicide film. In contrast, in the first experiment, such a deterioration in the shape of the tungsten silicide film did not occur. From this, it can be seen that N ２ It was found that by exposing the substrate to the plasma generated from the gas, the deterioration of the shape of the tungsten silicide film was suppressed.

[0093] (Third Experiment) In the third experiment, a substrate having a silicon-containing film and a tungsten silicide film on the silicon-containing film was prepared. The silicon-containing film included a silicon oxide film and a silicon nitride film on the silicon oxide film. The tungsten silicide film had an opening. The silicon nitride film was then etched. In this case, the substrate was first exposed to plasma generated from a process gas containing hydrofluorocarbon gas. Then, N ２ The substrate was exposed to plasma generated from the gas, and then the silicon oxide film was etched by exposing the substrate to a process gas containing fluorocarbon gas.

[0094] (Fourth Experiment) In the fourth experiment, N ２ A fourth experiment was carried out in the same manner as the third experiment, except that the substrate was not exposed to the plasma generated from the gas.

[0095] (Results of the Second Experiment) In each of the third and fourth experiments, the shape of the tungsten silicide film after etching of the silicon oxide film was observed. As a result, in the fourth experiment, the sidewall of the tungsten silicide film was scraped off, causing a deterioration in the shape of the tungsten silicide film. In contrast, in the third experiment, such a deterioration in the shape of the tungsten silicide film did not occur. From this, it can be seen that N ２ It was found that by exposing the substrate to the plasma generated from the gas, the deterioration of the shape of the tungsten silicide film was suppressed.

[0096] Although various exemplary embodiments have been described above, the present invention is not limited to the above-described exemplary embodiments, and various additions, omissions, substitutions, and modifications may be made. Furthermore, elements in different embodiments may be combined to form other embodiments.

[0097] Various exemplary embodiments included in the present disclosure are now described in [E1] to [E16] below.

[0098] [E1] An etching method comprising: (a) preparing a substrate having a silicon-containing film and a metal-containing mask on the silicon-containing film, the silicon-containing film including a first film including silicon and oxygen and a second film including silicon and nitrogen, the metal-containing mask having at least one opening; (b) etching the first film; and (c) etching the second film, wherein (b) comprises: (b1) exposing the substrate to a first plasma generated from a first process gas including carbon and fluorine; and (b2) exposing the substrate to a second plasma generated from a second process gas including a nitrogen-containing gas that does not include a halogen; and wherein (c) comprises: (c1) exposing the substrate to a third plasma generated from a third process gas including carbon, hydrogen, and fluorine; and (c2) exposing the substrate to a fourth plasma generated from a fourth process gas including a nitrogen-containing gas that does not include a halogen.

[0099] According to the etching method [E1], the etching shape can be improved.

[0100] [E2] The etching method according to [E1], wherein (b2) is performed after (b1).

[0101] [E3] The etching method according to [E1] or [E2], wherein (c2) is carried out after (c1).

[0102] [E4] The etching method according to any one of [E1] to [E3], wherein the metal-containing mask contains at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, and titanium.

[0103] [E5] The etching method according to any one of [E1] to [E4], wherein the first film has a thickness greater than a thickness of the second film.

[0104] [E6] The etching method according to any one of [E1] to [E5], wherein the first process gas contains a fluorocarbon gas or a mixed gas of a fluorine-containing gas and a carbon-containing gas.

[0105] [E7] The second process gas is N ２ The etching method according to any one of [E1] to [E6], which includes a gas.

[0106] [E8] The etching method according to any one of [E1] to [E7], wherein the third process gas contains a hydrofluorocarbon gas or a mixed gas of a fluorocarbon gas and a hydrogen-containing gas.

[0107] [E9] The fourth process gas is N ２ The etching method according to any one of [E1] to [E8], which includes a gas.

[0108] [E10] The etching method according to any one of [E1] to [E9], wherein in (b) and (c), the temperature of a substrate support part that supports the substrate is 20°C or higher and 150°C or lower.

[0109] [E11] The etching method according to any one of [E1] to [E10], wherein the treatment time of (b1) is longer than the treatment time of (b2).

[0110] [E12] The etching method according to any one of [E1] to [E11], wherein the treatment time of (c1) is longer than the treatment time of (c2).

[0111] [E13] The etching method according to any one of [E1] to [E12], wherein in (b1), a first electric bias is applied to a substrate support part that supports the substrate, and in (b2), either no electric bias is applied to the substrate support part, or a second electric bias smaller than the first electric bias is applied to the substrate support part.

[0112] [E14] The etching method according to any one of [E1] to [E13], wherein in (c1), a third electric bias is applied to a substrate support part that supports the substrate, and in (c2), either no electric bias is applied to the substrate support part, or a fourth electric bias smaller than the third electric bias is applied to the substrate support part.

[0113] [E15] An etching method comprising: (a) preparing a substrate having a silicon-containing film and a metal-containing mask on the silicon-containing film, the metal-containing mask having at least one opening; and (b) etching the silicon-containing film, wherein (b) comprises: (b1) exposing the substrate to a first plasma generated from a first process gas containing a fluorine-containing gas; and (b2) exposing the substrate to a second plasma generated from a second process gas containing a nitrogen-containing gas that does not contain a halogen.

[0114] [E16] A method for etching a substrate, comprising: a chamber; a substrate support for supporting a substrate in the chamber, the substrate having a silicon-containing film and a metal-containing mask on the silicon-containing film, the silicon-containing film including a first film including silicon and oxygen and a second film including silicon and nitrogen, the metal-containing mask having at least one opening; a gas supply unit configured to supply a first process gas, a second process gas, a third process gas, and a fourth process gas into the chamber, the first process gas including carbon and fluorine, the second process gas including a nitrogen-containing gas without a halogen, the third process gas including carbon, hydrogen, and fluorine, and the fourth process gas including a nitrogen-containing gas without a halogen; a plasma generation unit configured to generate a first plasma from the first process gas, a second plasma from the second process gas, a third plasma from the third process gas, and a fourth plasma from the fourth process gas; and a controller, wherein the controller is configured to: etch the first film, a plasma processing apparatus configured to control the gas supply unit and the plasma generation unit so that, in the step of etching the second film, the substrate is exposed to the first plasma, the substrate is exposed to the second plasma, and in the step of etching the second film, the substrate is exposed to the third plasma, and the substrate is exposed to the fourth plasma.

[0115] 1...plasma processing apparatus, 2...control unit, 11...substrate support unit, 12...plasma generation unit, 20...gas supply unit, F1...first film, F2...second film, MK1...metal-containing mask, OP1...opening, PL1...first plasma, PL2...second plasma, PL3...third plasma, PL4...fourth plasma, SF1...silicon-containing film, W, W1...substrate.

Claims

1. An etching method comprising: (a) providing a substrate having a silicon-containing film and a metal-containing mask on the silicon-containing film, the silicon-containing film comprising a first film comprising silicon and oxygen and a second film comprising silicon and nitrogen, the metal-containing mask having at least one opening; (b) etching the first film; and (c) etching the second film, wherein (b) comprises: (b1) exposing the substrate to a first plasma generated from a first process gas comprising carbon and fluorine; and (b2) exposing the substrate to a second plasma generated from a second process gas comprising a nitrogen-containing gas that does not contain a halogen; and (c) comprises: (c1) exposing the substrate to a third plasma generated from a third process gas comprising carbon, hydrogen, and fluorine; and (c2) exposing the substrate to a fourth plasma generated from a fourth process gas comprising a nitrogen-containing gas that does not contain a halogen.

2. The etching method according to claim 1, wherein (b2) is performed after (b1).

3. The etching method according to claim 1, wherein (c2) is performed after (c1).

4. The etching method of any one of claims 1 to 3, wherein the metal-containing mask comprises at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, and titanium.

5. An etching method according to any one of claims 1 to 3, wherein the first film has a thickness greater than a thickness of the second film.

6. The etching method according to any one of claims 1 to 3, wherein the first process gas contains a fluorocarbon gas or a mixture of a fluorine-containing gas and a carbon-containing gas.

7. The second process gas is N ２ The etching method according to any one of claims 1 to 3, comprising a gas.

8. The etching method according to any one of claims 1 to 3, wherein the third process gas contains a hydrofluorocarbon gas or a mixed gas of a fluorocarbon gas and a hydrogen-containing gas.

9. The fourth process gas is N ２ The etching method according to any one of claims 1 to 3, comprising a gas.

10. The etching method according to any one of claims 1 to 3, wherein in steps (b) and (c), the temperature of the substrate support part that supports the substrate is 20°C or higher and 150°C or lower.

11. The etching method according to any one of claims 1 to 3, wherein the treatment time of (b1) is longer than the treatment time of (b2).

12. The etching method according to any one of claims 1 to 3, wherein the treatment time of (c1) is longer than the treatment time of (c2).

13. An etching method according to any one of claims 1 to 3, wherein in (b1), a first electrical bias is applied to a substrate support part that supports the substrate, and in (b2), either no electrical bias is applied to the substrate support part, or a second electrical bias smaller than the first electrical bias is applied to the substrate support part.

14. An etching method according to any one of claims 1 to 3, wherein in (c1), a third electrical bias is applied to a substrate support part that supports the substrate, and in (c2), either no electrical bias is applied to the substrate support part, or a fourth electrical bias smaller than the third electrical bias is applied to the substrate support part.

15. An etching method comprising: (a) providing a substrate having a silicon-containing film and a metal-containing mask on the silicon-containing film, the metal-containing mask having at least one opening; and (b) etching the silicon-containing film, wherein (b) comprises: (b1) exposing the substrate to a first plasma generated from a first process gas comprising a fluorine-containing gas; and (b2) exposing the substrate to a second plasma generated from a second process gas comprising a nitrogen-containing gas that does not contain a halogen.

16. A method for etching a substrate, comprising: a chamber; a substrate support for supporting a substrate in the chamber, the substrate having a silicon-containing film and a metal-containing mask on the silicon-containing film, the silicon-containing film including a first film including silicon and oxygen and a second film including silicon and nitrogen, the metal-containing mask having at least one opening; a gas supply unit configured to supply a first process gas, a second process gas, a third process gas, and a fourth process gas into the chamber, the first process gas including carbon and fluorine, the second process gas including a nitrogen-containing gas without a halogen, the third process gas including carbon, hydrogen, and fluorine, and the fourth process gas including a nitrogen-containing gas without a halogen; a plasma generation unit configured to generate a first plasma from the first process gas, a second plasma from the second process gas, a third plasma from the third process gas, and a fourth plasma from the fourth process gas; and a controller, wherein the controller is configured to: etch the first film; a plasma processing apparatus configured to control the gas supply unit and the plasma generation unit so that, in the step of etching the second film, the substrate is exposed to the first plasma, the substrate is exposed to the second plasma, and in the step of etching the second film, the substrate is exposed to the third plasma, and the substrate is exposed to the fourth plasma.

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