Etching method and plasma treatment device

Abstract

An etching method according to an exemplary embodiment of the present invention includes: (a) a step for forming a protective film on an inner wall of a gas inlet of a shower head including silicon by supplying a film forming gas into a chamber via the gas inlet; and (b) a step in which an etching gas is supplied into the chamber via the gas inlet on which the protective film was formed, and plasma generated from the etching gas is used to etch a substrate in the chamber.

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 Document 1 discloses a plasma etching method. This method includes a film formation process and an etching process. In the film formation process, a film formation gas containing carbon and fluorine is supplied into a processing vessel, and the film formation gas is converted into plasma to form a film containing carbon and fluorine inside the processing vessel by using the plasma. In the etching process, a substrate is placed on a mounting table inside the processing vessel, and an etching gas is supplied into the processing vessel. The etching gas is converted into plasma to etch the substrate by using the plasma.

[0003] JP 2009-188257 A

[0004] The present disclosure provides a technique for protecting the inner wall of a gas inlet of a showerhead.

[0005] In one exemplary embodiment, an etching method is provided, which includes the steps of: (a) supplying a deposition gas into a chamber through a gas inlet of a silicon-containing showerhead to form a protective film on an inner wall of the gas inlet; and (b) supplying an etching gas into the chamber through the gas inlet on which the protective film has been formed, and etching a substrate in the chamber with plasma generated from the etching gas.

[0006] According to one exemplary embodiment, the inner wall of the gas inlet of the showerhead can be protected.

[0007] FIG. 1 is a diagram illustrating an example of the configuration of a plasma processing system. FIG. 2 is a diagram illustrating an example of the configuration of a capacitively coupled plasma processing apparatus. FIG. 3 is a flowchart of an etching method according to an exemplary embodiment. FIG. 4 is an enlarged cross-sectional view of a showerhead in a step of the etching method according to an exemplary embodiment. FIG. 5 is an enlarged cross-sectional view of a showerhead in a step of the etching method according to an exemplary embodiment. FIG. 6 is an enlarged cross-sectional view of a showerhead in a step of the etching method according to an exemplary embodiment. FIG. 7 is an enlarged cross-sectional view of a showerhead in a step of the etching method according to an exemplary embodiment. FIG. 8 is a cross-sectional view of a plasma processing chamber according to a modified example. FIG. 9 is a cross-sectional view of a plasma processing chamber according to another modified example.

[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 exemplary embodiment. The etching method MT1 (hereinafter referred to as "method MT1") shown in FIG. 3 can be performed by the plasma processing apparatus 1 of the above embodiment.

[0027] Method MT1 will be described below with reference to FIGS. 2 to 7, taking as an example a case where method MT1 is applied to a substrate W using the plasma processing apparatus 1 of the above embodiment. FIGS. 4 to 7 are enlarged cross-sectional views of a showerhead in a step 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 a controller 2. In method MT1, a substrate W on a substrate support 11 disposed in a plasma processing chamber 10 is processed, as shown in FIG. 2.

[0028] 3, the method MT1 may include steps ST1 to ST5. Steps ST1 to ST5 may be performed in order. The method MT1 may not include at least one of steps ST1, ST3, and ST4. Step ST3 may be performed before step ST2. Step ST4 may be performed before step ST3, before step ST2, or before step ST1.

[0029] (Step ST1) As shown in FIG. 4, the silicon oxide film OX formed on the surface of the shower head 13 of the plasma processing apparatus 1 is removed. The shower head 13 contains silicon. The shower head 13 may contain crystalline silicon. The silicon oxide film OX may be a native oxide film. The silicon oxide film OX may be removed by an etching gas such as hydrogen fluoride gas.

[0030] The etching gas may be supplied from the gas supply unit 20 (see FIG. 2) into the plasma processing chamber 10 through the gas inlet 13c of the shower head 13. The supply of the etching gas may be stopped at the end of step ST1. In step ST1, plasma may not be generated in the plasma processing chamber 10. In step ST1, the substrate W may not be placed on the substrate support 11 (see FIG. 2), or a dummy substrate different from the substrate W may be placed thereon.

[0031] Step ST1 may be performed as follows: The gas supply unit 20 supplies an etching gas into the plasma processing chamber 10. The control unit 2 controls the gas supply unit 20 and the plasma generation unit 12 so that plasma is not generated.

[0032] (Step ST2) As shown in FIG. 5, a film-forming gas CG is supplied into the plasma processing chamber 10 through the gas inlet 13c of the shower head 13 to form a protective film PF on the inner wall 13cw of the gas inlet 13c.

[0033] The film formation gas CG may be supplied from the gas supply unit 20 into the plasma processing chamber 10 through the gas inlet 13c of the shower head 13. The supply of the film formation gas CG may be stopped at the end of step ST2. In step ST2, the substrate W may not be placed on the substrate support unit 11, or a dummy substrate different from the substrate W may be placed thereon.

[0034] The deposition gas CG may contain a metal. The deposition gas CG may contain a metal fluoride gas. The metal fluoride gas may be tungsten hexafluoride (WF ６ ) gas and molybdenum hexafluoride (MoF ６ The deposition gas CG may contain at least one selected from the group consisting of hydrogen (H ２ The film-forming gas CG may further include a reducing gas such as argon (Ar) gas. The film-forming gas CG may further include a noble gas such as oxygen (O ２ The deposition gas CG may further contain an oxygen-containing gas such as a halogen-containing gas. The oxygen-containing gas can form an oxide film as the protective film PF. Examples of the oxide film include a metal oxide film. The deposition gas CG does not need to contain a halogen-containing gas other than the metal fluoride gas.

[0035] The flow rate of the film-forming gas CG may be greater than the flow rate of the etching gas EG in step ST5. This allows the thickness of the protective film PF to be increased. The flow rate of the metal fluoride gas contained in the film-forming gas CG may be greater than the flow rate of the metal fluoride gas contained in the etching gas EG.

[0036] The protective film PF may include a metal. The metal may include at least one selected from the group consisting of tungsten and molybdenum. When the deposition gas CG includes tungsten, the protective film PF includes tungsten. When the deposition gas CG includes molybdenum, the protective film PF includes molybdenum.

[0037] The protective film PF may be formed on the lower surface 13L of the showerhead 13. The showerhead 13 may constitute at least a portion of the ceiling of the plasma processing chamber 10. Therefore, the lower surface 13L faces the plasma processing space 10s of the plasma processing chamber 10. Therefore, the lower surface 13L may be exposed to plasma generated in the plasma processing chamber 10. The protective film PF may be formed on a region of the surface of the showerhead 13 excluding the inner wall 13cw of the gas inlet 13c and the lower surface 13L (e.g., the inner wall of the gas diffusion chamber 13b shown in FIG. 2). The protective film PF may be formed on the surface of a silicon-containing member other than the showerhead 13. The silicon-containing member may constitute at least a portion of the plasma processing chamber 10. By setting the temperature of the silicon-containing member lower than the temperature of the showerhead 13, the protective film PF can be selectively formed on the surface of the showerhead 13 without forming the protective film PF on the surface of the silicon-containing member.

[0038] The protective film PF may have a thickness of 100 nm to 10 μm. The protective film PF may have a first thickness TH1 on the inner wall 13cw of the gas inlet 13c. The protective film PF may have a second thickness TH2 on the lower surface 13L of the shower head 13. The second thickness TH2 is smaller than the first thickness TH1.

[0039] In step ST2, plasma may not be generated in the plasma processing chamber 10, or plasma may be generated from the film forming gas CG.

[0040] The temperature of the shower head 13 in step ST2 may be higher than the temperature of the shower head 13 in step ST5. The temperature of the shower head 13 in step ST2 may be 200° C. or higher, or 300° C. or higher. The temperature of the shower head 13 in step ST2 may be 800° C. or lower. The temperature of the shower head 13 may be adjusted by a temperature control module included in the plasma processing apparatus 1. Alternatively, the shower head 13 may be heated by plasma generated from a processing gas containing a noble gas in the plasma processing chamber 10.

[0041] Step ST2 may be performed as follows: The gas supply unit 20 supplies the film forming gas CG into the plasma processing chamber 10. The control unit 2 controls the gas supply unit 20 and the plasma generation unit 12 so that no plasma is generated and a protective film PF is formed on the inner wall 13cw of the gas inlet 13c.

[0042] (Step ST3) As shown in FIG. 6 , a precoat film PC is formed on the inner wall of the plasma processing chamber 10. The inner wall of the plasma processing chamber 10 includes the lower surface 13L of the shower head 13 and the side wall 10a of the plasma processing chamber 10 (see FIG. 2 ). Thus, the precoat film PC is formed on the lower surface 13L of the shower head 13 and the side wall 10a of the plasma processing chamber 10. When step ST3 is performed after step ST2, the precoat film PC may be formed on the protective film PF. The precoat film PC is formed on the protective film PF on the lower surface 13L of the shower head 13. The precoat film PC may also be formed on the protective film PF on the inner wall 13cw of the gas inlet 13c. When step ST2 is performed after step ST3, the protective film PF may be formed on the precoat film PC.

[0043] The deposition gas for the precoat PC may be supplied from the gas supply unit 20 into the plasma processing chamber 10 through the gas inlet 13c of the shower head 13. The supply of the deposition gas may be stopped at the end of step ST3. In step ST3, the substrate W may not be placed on the substrate support unit 11, or a dummy substrate different from the substrate W may be placed thereon.

[0044] The deposition gas for the precoat PC may include a carbon-containing gas. The deposition gas may be a gas that does not contain fluorine. The carbon-containing gas may be CO, CO ２ , COS, and hydrocarbons. The hydrocarbons may include one or more selected from the group consisting of CH ４ , C ２ H ２ , C ３ H ６ The precoat PC may be formed by a CVD (chemical vapor deposition) method, an MLD (molecular layer deposition) method, or an ALD (atomic layer deposition) method. In step ST3, plasma may be generated from a film formation gas in the plasma processing chamber 10.

[0045] The precoat film PC may contain carbon. The precoat film PC may have a thickness greater than that of the protective film PF formed in step ST2. The precoat film PC has high plasma resistance.

[0046] Step ST3 may be performed as follows: The gas supply unit 20 supplies a film formation gas for the precoat PC into the plasma processing chamber 10. The control unit 2 controls the gas supply unit 20 and the plasma generation unit 12 so that the precoat PC is formed on the inner wall of the plasma processing chamber 10.

[0047] 2, a substrate W is provided in the plasma processing chamber 10. The substrate W may be transported from outside the plasma processing chamber 10 into the plasma processing chamber 10 by a transport mechanism. The substrate W may be placed on a substrate support 11. In steps ST1 to ST3, if a dummy substrate is placed on the substrate support 11, the dummy substrate is transported out of the plasma processing chamber 10 before step ST4.

[0048] 7 , an etching gas EG is supplied into the plasma processing chamber 10 through the gas inlet 13c on which the protective film PF is formed, and the substrate W in the plasma processing chamber 10 is etched by the plasma PL generated from the etching gas EG. In step ST5, a film to be etched included in the substrate W may be etched. The film to be etched may be a silicon-containing film.

[0049] The etching gas EG may be supplied from the gas supply unit 20 into the plasma processing chamber 10 through the gas inlet 13c of the shower head 13. The supply of the etching gas EG may be stopped at the end of step ST5.

[0050] The etching gas EG may be the same as or different from the film-forming gas CG in step ST2. The etching gas EG may contain the same gas as the film-forming gas CG. The etching gas EG may contain a metal fluoride gas. The metal fluoride gas may contain at least one selected from the group consisting of tungsten hexafluoride gas and molybdenum hexafluoride gas. The etching gas EG may further contain a fluorine-containing gas other than the metal fluoride gas. The fluorine-containing gas may contain at least one selected from the group consisting of a fluorocarbon gas, a hydrofluorocarbon gas, and a hydrogen fluoride gas.

[0051] The etching gas EG may contain a fluorine-containing gas as a fluorine source and a hydrogen-containing gas as a hydrogen source. ２ , C.H. ４ , C.H. ２ F ２ , C.H. ３ F, CHF ３ , H ２ The etching gas EG may contain one or more of O, HF, HCl, HBr, HI, etc. The etching gas EG may contain CF as a fluorine source. ４ , C ４ F ８ , C ４ F ６ , C ３ F ８ , C ５ F ８, S.F. ６、 NF ３ , XeF ２ , P.F. ３ , P.F. ５ , C.F. ３ I, C ２ F ５ I, C ３ F ７ I, IF ５ , IF ７ , W.F. ６ , HF, SiF ４ It may include one or more of the following:

[0052] The etching gas EG may further include one or more phosphorus-containing molecules. The one or more phosphorus-containing molecules may be tetraphosphorus decoxide (P ４ O １０ ), tetraphosphorus octoxide (P ４ O ８ ), tetraphosphorus hexaoxide (P ４ O ６ ) may contain oxides such as tetraphosphorus decaoxide and diphosphorus pentaoxide (P ２ O ５ The one or more phosphorus-containing molecules may be called 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 The one or more phosphorus-containing molecules may include halides such as phosphoryl fluoride (POF ３ ), phosphoryl chloride (POCl ３ ), phosphoryl bromide (POBr ３ The one or more phosphorus-containing molecules may include a phosphoryl halide such as a phosphine (PH ３ ), calcium phosphide (Ca ３ P ２ etc.), phosphoric acid (H ３ P.O. ４ ), sodium phosphate (Na ３ P.O. ４ ), hexafluorophosphate (HPF ６The one or more phosphorus-containing molecules may include fluorophosphines (H ｘ PF ｙ ) wherein the sum of x and y is 3 or 5. Fluorophosphines include HPF ２ , H ２ PF ３ is exemplified.

[0053] The temperature of the shower head 13 in step ST5 may be lower than 200° C. or may be equal to or lower than 150° C. The temperature of the shower head 13 in step ST5 may be equal to or higher than −20° C.

[0054] Step ST5 may be performed as follows: The gas supply unit 20 supplies the etching gas EG into the plasma processing chamber 10. The control unit 2 controls the gas supply unit 20 and the plasma generation unit 12 to generate plasma PL from the etching gas EG and etch the substrate W.

[0055] According to the method MT1, the inner wall 13cw of the gas inlet 13c can be protected by the protective film PF in step ST2. Therefore, corrosion of the inner wall 13cw of the gas inlet 13c by the etching gas EG can be suppressed in step ST5. When the film-forming gas CG in step ST2 contains tungsten hexafluoride gas, the tungsten hexafluoride reacts with silicon contained in the shower head 13 to form tungsten and silicon tetrafluoride (SiF ４ As a result, a tungsten film can be formed as the protective film PF.

[0056] In the method MT1, step ST4 may be performed between step ST3 and step ST5. In this case, exposure of the substrate W to the film formation gas in steps ST2 and ST3 can be suppressed. Therefore, formation of an unintended film on the substrate W due to the film formation gas can be suppressed.

[0057] In the method MT1, the temperature of the shower head 13 in step ST2 may be higher than the temperature of the shower head 13 in step ST5. In this case, the formation of the protective film PF is promoted in step ST2, but the protective film PF is difficult to remove in step ST5.

[0058] Fig. 8 is a cross-sectional view of a plasma processing chamber according to a modified example. Plasma processing chamber 10 of plasma processing apparatus 1 shown in Fig. 2 may be replaced with plasma processing chamber 110 shown in Fig. 8. Plasma processing chamber 110 shown in Fig. 8 has the same configuration as plasma processing chamber 10, except that it includes a shower head 113 instead of shower head 13.

[0059] The shower head 113 may include a top plate 114 containing silicon, a temperature control module 115, a support member 116 containing an insulator, and a member 117 containing silicon.

[0060] The top plate 114 may be an upper electrode. The lower surface of the shower head 113 (top plate 114) faces the plasma processing space 10s. The top plate 114 has a plurality of gas inlets 114c.

[0061] The temperature adjustment module 115 is provided on the top plate 114 and is configured to adjust the temperature of the top plate 114. The temperature adjustment module 115 includes a flow path 115a for flowing a cooling fluid to cool the top plate 114 and a heater HT for heating the top plate 114. The inlet and outlet of the flow path 115a are connected to a chiller unit outside the plasma processing chamber 110. The temperature adjustment module 115 may also include a mechanism for discharging the cooling fluid in the flow path 115a using gas when heating is performed by the heater HT. The temperature adjustment module 115 includes a gas diffusion chamber 115b and multiple gas inlets 115c communicating with the gas diffusion chamber 115b. The gas diffusion chamber 115b is connected to the gas supply unit 20 (see FIG. 2) via a gas supply path. The multiple gas inlets 115c are each communicating with the multiple gas inlets 114c. The flow path 115a, the heater HT, the gas diffusion chamber 115b, and the plurality of gas inlets 115c may be disposed in the body of the temperature control module 115. The body of the temperature control module 115 includes a metal such as aluminum. The heater HT may be disposed between the flow path 115a and the gas diffusion chamber 115b. The process gas supplied from the gas supply unit 20 is supplied to the gas diffusion chamber 115b, passes through the plurality of gas inlets 115c, and is introduced into the plasma processing chamber 110 from the plurality of gas inlets 114c.

[0062] The support member 116 supports the temperature control module 115. The support member 116 is connected to the sidewall 10a of the plasma processing chamber 110. A silicon-containing member 117 is disposed between the support member 116 and the sidewall 10a. The silicon-containing member 117 can be grounded by the sidewall 10a.

[0063] Fig. 9 is a cross-sectional view of a plasma processing chamber according to another modification. Plasma processing chamber 10 of plasma processing apparatus 1 shown in Fig. 2 may be replaced with plasma processing chamber 210 shown in Fig. 9. Plasma processing chamber 210 shown in Fig. 9 has the same configuration as plasma processing chamber 110, except that it further includes a chiller unit 70.

[0064] The output port of the chiller unit 70 is connected to the inlet 115e of the flow path 115a. The return port of the chiller unit 70 is connected to the outlet 115d of the flow path 115a. The chiller unit 70 outputs cooling fluid from the output port and supplies the cooling fluid from the inlet 115e to the flow path 115a. The cooling fluid supplied to the flow path 115a is returned to the chiller unit 70 via the outlet 115d and the return port. In other words, the cooling fluid circulates between the flow path 115a and the chiller unit 70.

[0065] The chiller unit 70 is a direct expansion type chiller unit. The chiller unit 70 has a compressor 71, a condenser 72, and an expansion valve 73. The compressor 71, the condenser 72, and the expansion valve 73 are connected in sequence between the outlet 115d and the inlet 115e of the flow path 115a. The top plate 114 constitutes an evaporator. The input of the compressor 71 is connected to the outlet 115d of the flow path 115a via a return port of the chiller unit 70. The output of the compressor 71 is connected to the input of the condenser 72. The output of the condenser 72 is connected to the input of the expansion valve 73. The output of the expansion valve 73 is connected to the inlet 115e of the flow path 115a via an output port of the chiller unit 70.

[0066] The cooling fluid output from outlet 115d of flow path 115a is returned to the input of compressor 71 and compressed by the compressor 71. The high-pressure cooling fluid output from compressor 71 is cooled and liquefied by condenser 72. The liquid cooling fluid output from condenser 72 is depressurized by expansion valve 73. The cooling fluid supplied from expansion valve 73 to flow path 115a absorbs heat from top plate 114 and vaporizes. The cooling fluid output from flow path 115a is then returned to the input of compressor 71 again. The opening degree of expansion valve 73 is variable. The lower the opening degree of expansion valve 73, the lower the pressure of the cooling fluid and the lower the evaporation temperature. Therefore, the temperature of top plate 114 can be cooled to a lower temperature.

[0067] The chiller unit 70 further includes a diverter valve 74. The diverter valve 74 is connected between the compressor 71 and the inlet 115e of the flow path 115a so as to bypass the condenser 72 and the expansion valve 73. That is, the input of the diverter valve 74 is connected to the output of the compressor 71. The output of the diverter valve 74 is connected to the inlet 115e of the flow path 115a. The opening degree of the diverter valve 74 is variable. The wider the opening degree of the diverter valve 74, the higher the dryness of the cooling fluid supplied to the flow path 115a. The higher the dryness, the lower the heat removal capacity of the cooling fluid. Therefore, by opening the diverter valve 74, the top plate 114 can be heated.

[0068] In the plasma processing chambers 110 and 210 shown in FIGS. 8 and 9, the top plate 114 of the shower head 113 can also be heated or cooled.

[0069] Although various exemplary embodiments have been described above, the present invention is not limited to the above-described exemplary embodiments, and various omissions, substitutions, and modifications may be made. Furthermore, elements in different embodiments may be combined to form other embodiments.

[0070] Various exemplary embodiments included in the present disclosure are now described in [E1] to [E19] below.

[0071] [E1] An etching method comprising: (a) supplying a film-forming gas into a chamber through a gas inlet of a showerhead containing silicon, and forming a protective film on an inner wall of the gas inlet; and (b) supplying an etching gas into the chamber through the gas inlet on which the protective film has been formed, and etching a substrate in the chamber with plasma generated from the etching gas.

[0072] According to the above method [E1], in (b), the inner wall of the gas inlet can be protected by the protective film.

[0073] [E2] The etching method according to [E1], further comprising the step of: (c) providing the substrate in the chamber between steps (a) and (b).

[0074] In this case, the substrate can be prevented from being exposed to the film forming gas.

[0075] [E3] The etching method according to [E1] or [E2], wherein the temperature of the shower head in (a) is higher than the temperature of the shower head in (b).

[0076] In this case, the formation of the protective film is promoted in (a), while the protective film is difficult to remove in (b).

[0077] [E4] The etching method according to any one of [E1] to [E3], wherein the protective film contains a metal.

[0078] [E5] The etching method according to [E4], wherein the film-forming gas contains a metal fluoride gas.

[0079] [E6] The etching method according to [E5], wherein the protective film contains tungsten and the film-forming gas contains tungsten hexafluoride gas.

[0080] [E7] The etching method according to [E5] or [E6], wherein the protective film contains molybdenum and the film-forming gas contains molybdenum hexafluoride gas.

[0081] [E8] The etching method according to any one of [E1] to [E7], wherein in (a), no plasma is generated in the chamber.

[0082] [E9] The etching method according to any one of [E1] to [E8], further comprising: (d) before (a), a step of removing a silicon oxide film formed on the surface of the shower head.

[0083] [E10] The etching method according to [E9], wherein the silicon oxide film is removed by hydrogen fluoride gas.

[0084] [E11] The etching method according to any one of [E1] to [E10], wherein the etching gas contains a metal fluoride gas.

[0085] [E12] The etching method according to any one of [E1] to [E11], wherein the protective film has a thickness of 100 nm or more and 10 μm or less.

[0086] [E13] The etching method according to any one of [E1] to [E12], wherein the flow rate of the film-forming gas is greater than the flow rate of the etching gas.

[0087] In this case, the protective film can be made thicker.

[0088] [E14] The etching method according to any one of [E1] to [E13], wherein the shower head constitutes at least a part of the ceiling of the chamber, and in (a), the protective film is also formed on the underside of the shower head.

[0089] [E15] The etching method according to [E14], wherein the protective film has a first thickness on the inner wall of the gas inlet and a second thickness on the lower surface that is smaller than the first thickness.

[0090] [E16] The etching method according to any one of [E1] to [E15], further comprising the step of: (e) forming a precoat on the inner wall of the chamber before (b).

[0091] [E17] The etching method according to [E16], wherein (e) is performed between (a) and (b).

[0092] [E18] The etching method according to [E16] or [E17], wherein the precoat contains carbon.

[0093] [E19] A plasma processing apparatus comprising: a showerhead containing silicon and having a gas inlet; a chamber; a substrate support unit for supporting a substrate in the chamber; a gas supply unit configured to supply a film forming gas and an etching gas into the chamber through the gas inlet; a plasma generation unit configured to generate plasma from the etching gas in the chamber; and a control unit, wherein the control unit is configured to control the plasma processing apparatus to perform an etching method, the etching method comprising: (a) supplying the film forming gas into the chamber through the gas inlet of the showerhead to form a protective film on an inner wall of the gas inlet; and (b) supplying the etching gas into the chamber through the gas inlet with the protective film formed thereon, and etching the substrate in the chamber with the plasma generated from the etching gas.

[0094] From the foregoing, it will be understood that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the appended claims.

[0095] 1...plasma processing apparatus, 2...control unit, 10...plasma processing chamber, 11...substrate support unit, 12...plasma generation unit, 13...shower head, 13c...gas inlet, 20...gas supply unit, CG...film formation gas, EG...etching gas, PF...protective film, PL...plasma, W...substrate

Claims

1. An etching method comprising: (a) supplying a film-forming gas into a chamber through a gas inlet of a showerhead containing silicon, and forming a protective film on an inner wall of the gas inlet; and (b) supplying an etching gas into the chamber through the gas inlet on which the protective film has been formed, and etching a substrate in the chamber with plasma generated from the etching gas.

2. The etching method of claim 1, further comprising the step of: (c) between (a) and (b), providing the substrate in the chamber.

3. The etching method according to claim 1 or 2, wherein the temperature of the shower head in (a) is higher than the temperature of the shower head in (b).

4. The etching method according to claim 1 or 2, wherein the protective film contains a metal.

5. The etching method according to claim 4, wherein the deposition gas includes a metal fluoride gas.

6. The etching method according to claim 5, wherein the protective film contains tungsten and the deposition gas contains tungsten hexafluoride gas.

7. The etching method according to claim 5, wherein the protective film contains molybdenum, and the deposition gas contains molybdenum hexafluoride gas.

8. The etching method according to claim 1 or 2, wherein in (a), no plasma is generated in the chamber.

9. The etching method according to claim 1 or 2, further comprising the step of: (d) removing a silicon oxide film formed on the surface of the showerhead before (a).

10. The etching method according to claim 9, wherein the silicon oxide film is removed by hydrogen fluoride gas.

11. The etching method according to claim 1 or 2, wherein the etching gas includes a metal fluoride gas.

12. The etching method according to claim 1 or 2, wherein the protective film has a thickness of 100 nm or more and 10 μm or less.

13. The etching method according to claim 1 or 2, wherein the flow rate of the film forming gas is greater than the flow rate of the etching gas.

14. The etching method according to claim 1 or 2, wherein the showerhead constitutes at least a part of the ceiling of the chamber, and in (a), the protective film is also formed on the underside of the showerhead.

15. The etching method according to claim 14, wherein the protective film has a first thickness on the inner wall of the gas inlet and a second thickness on the lower surface that is smaller than the first thickness.

16. The etching method according to claim 1 or 2, further comprising the step of: (e) forming a precoat on the inner wall of the chamber before (b).

17. The etching method according to claim 16, wherein (e) is performed between (a) and (b).

18. The etching method of claim 16, wherein the precoat comprises carbon.

19. A plasma processing apparatus comprising: a showerhead containing silicon and having a gas inlet; a chamber; a substrate support for supporting a substrate in the chamber; a gas supply unit configured to supply a film forming gas and an etching gas into the chamber through the gas inlet; a plasma generation unit configured to generate plasma from the etching gas in the chamber; and a control unit, wherein the control unit is configured to control the plasma processing apparatus to perform an etching method, the etching method comprising: (a) supplying the film forming gas into the chamber through the gas inlet of the showerhead to form a protective film on an inner wall of the gas inlet; and (b) supplying the etching gas into the chamber through the gas inlet with the protective film formed thereon, and etching the substrate in the chamber with the plasma generated from the etching gas.

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