Plasma processing method and plasma processing apparatus

Abstract

This plasma processing method includes: (a) a step for providing a substrate on a substrate support part within a chamber, in which the substrate has a base film, a first film on the base film, and a second film on the first film, the first film and the second film are provided with an opening for exposing the base film, and the second film contains silicon; and (b) a step for removing the second film by a plasma generated from a processing gas before not supplying an electric bias to the substrate support part or supplying an electric bias having a level of 200 W or less or 1 kV or less to the substrate support part, wherein the plasma contains a hydrogen fluoride etchant.

Description

Plasma processing method and plasma processing apparatus

[0001] SUMMARY OF THE INVENTION An exemplary embodiment of the present disclosure relates to a plasma processing method and a plasma processing apparatus.

[0002] Patent Document 1 discloses a plasma etching method including a first step, a second step, and a third step. In the first step, a photoresist film having a pattern formed on a mask film is plasma-treated. In the second step, the mask film is etched with plasma along the pattern of the plasma-treated photoresist film to expose an organic film formed below the mask film. In the third step, O ２ , COS, and Cl ２ The organic film is etched by plasma of a mixed gas containing the compound.

[0003] JP 2015-12178 A

[0004] The present disclosure provides techniques that can selectively remove silicon-containing films relative to other films.

[0005] In one exemplary embodiment, a plasma processing method includes: (a) providing a substrate on a substrate support in a chamber, the substrate having an underlayer film, a first film on the underlayer film, and a second film on the first film, the first film and the second film providing an opening exposing the underlayer film, the second film comprising silicon; and (b) applying no electrical bias to the substrate support, or applying an electrical bias having a level of 200 W or less or 1 kV or less to the substrate support, and removing the second film with plasma generated from a process gas, the plasma comprising a hydrogen fluoride etchant.

[0006] According to one exemplary embodiment, a technique is provided that allows for selective removal of silicon-containing films relative to other films.

[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 an inductively coupled plasma processing apparatus. FIG. 3 is a flowchart of a plasma processing method according to an exemplary embodiment. FIG. 4 is a partially enlarged view of an exemplary substrate to which the method of FIG. 3 can be applied. FIG. 5 is a cross-sectional view illustrating a step of the plasma processing method according to an exemplary embodiment. FIG. 6 is a cross-sectional view illustrating a step of the plasma processing method according to an exemplary embodiment. FIG. 7 is a cross-sectional view illustrating a step of the plasma processing method according to an exemplary embodiment. FIG. 8 is a cross-sectional view illustrating a step of the plasma processing method according to an exemplary embodiment.

[0008] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements are designated by the same reference numerals, and redundant description will be omitted.

[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 an inductively coupled plasma processing apparatus as an example of the plasma processing apparatus 1. Fig. 2 is a diagram for explaining a configuration example of an inductively coupled plasma processing apparatus.

[0013] The inductively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply 30, and an exhaust system 40. The plasma processing chamber 10 includes a dielectric window 101. The plasma processing apparatus 1 also includes a substrate support 11, a gas inlet, and an antenna 14. The substrate support 11 is disposed within the plasma processing chamber 10. The antenna 14 is disposed on or above the plasma processing chamber 10 (i.e., on or above the dielectric window 101). The plasma processing chamber 10 has a plasma processing space 10s defined by the dielectric window 101, a sidewall 102 of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 is grounded.

[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 bias 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 bias electrode. Note that the conductive member of the base 1110 and the at least one RF / DC electrode may function as multiple bias electrodes. Alternatively, the electrostatic electrode 1111b may function as a bias electrode. Therefore, the substrate support 11 includes at least one bias 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 gas inlet is configured to introduce at least one process gas from the gas supply unit 20 into the plasma processing space 10s. In one embodiment, the gas inlet includes a center gas injector (CGI) 13. The center gas injector 13 is disposed above the substrate support 11 and attached to a central opening formed in the dielectric window 101. The center gas injector 13 has at least one gas supply port 13a, at least one gas flow path 13b, and at least one gas inlet port 13c. The process gas supplied to the gas supply port 13a passes through the gas flow path 13b and is introduced into the plasma processing space 10s from the gas inlet port 13c. Note that the gas inlet may include one or more side gas injectors (SGIs) attached to one or more openings formed in the sidewall 102 in addition to or instead of the center gas injector 13.

[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 gas inlet through 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 bias electrode and the antenna 14. This causes a plasma to be formed 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 generating unit 12. Furthermore, by supplying a bias RF signal to the at least one bias electrode, a bias potential is generated on the substrate W, thereby attracting ions 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 the antenna 14 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 the antenna 14.

[0022] The second RF generator 31b is coupled to at least one bias 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 bias 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 bias DC generator 32a. In one embodiment, the bias DC generator 32a is connected to at least one bias electrode and configured to generate a bias DC signal. The generated bias DC signal is applied to the at least one bias electrode.

[0024] In various embodiments, the bias DC signal may be pulsed. In this case, a sequence of voltage pulses is applied to at least one bias electrode. The voltage pulses may have a rectangular, trapezoidal, triangular, or combination thereof. In one embodiment, a waveform generator for generating the sequence of voltage pulses from the DC signal is connected between the bias DC generator 32a and at least one bias electrode. Thus, the bias DC generator 32a and the waveform generator constitute a voltage pulse generator. The voltage pulses may have 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 cycle. Note that the bias DC generator 32a may be provided in addition to the RF power supply 31 or may be provided instead of the second RF generator 31b.

[0025] The antenna 14 includes one or more coils. In one embodiment, the antenna 14 may include an outer coil and an inner coil arranged coaxially. In this case, the RF power supply 31 may be connected to both the outer coil and the inner coil, or to either the outer coil or the inner coil. In the former case, the same RF generator may be connected to both the outer coil and the inner coil, or separate RF generators may be connected to the outer coil and the inner coil separately.

[0026] 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.

[0027] 3 is a flowchart of a plasma processing method according to one exemplary embodiment. The plasma processing 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 W of FIG. 4.

[0028] Figure 4 is a cross-sectional view of an example substrate to which the method of Figure 3 can be applied. As shown in Figure 4, in one embodiment, the substrate W has an undercoat film UF, a first film F1 on the undercoat film UF, and a second film F2 on the first film F1. The undercoat film UF, the first film F1, and the second film F2 may comprise different materials.

[0029] The first film F1 may be a carbon-containing film or a metal-containing film. The carbon-containing film may contain at least one selected from the group consisting of spin-on carbon and amorphous carbon. The metal-containing film may contain aluminum oxide (Al ２ O ３ ), titanium nitride (TiN), tungsten carbide (WC) and zirconium oxide (ZrO ２ The first film F1 may not contain silicon.

[0030] The second film F2 contains silicon. That is, the second film F2 is a silicon-containing film. The silicon-containing film includes silicon oxynitride (SiON), SOG (Spin On Glass), silicon oxide (SiO ２ ), silicon carbide (SiC), and silicon nitride (SiN).

[0031] The base film UF may be a metal-containing film or a silicon-containing film. Examples of the metal-containing film and the silicon-containing film may be the same as those in the first film F1 or the second film F2. The base film UF may be a silicon-containing film of a different type from that of the second film F2. The base film UF may be a metal-containing film of a different type from that of the first film F1.

[0032] The substrate W may further include a mask MK on the second film F2. The mask MK may include photoresist. The mask MK may include at least one opening OPM. The pitch of the openings OPM may be 80 nm or less. The pitch of the openings OPM may be measured at the top ends of the openings OPM (the top surface of the mask MK).

[0033] Method MT1 will be described below with reference to FIGS. 3 to 8, 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. 5 to 8 are cross-sectional views showing steps of a plasma processing 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 control unit 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.

[0034] 3, the method MT1 may include steps ST1 to ST6. Steps ST1 to ST6 may be performed in order. Step ST4 may be performed before step ST5 or simultaneously with step ST5. The method MT1 may not include at least one of steps ST2 to ST4 and ST6.

[0035] (Step ST1) In step ST1, the substrate W shown in FIG. 4 is provided on the substrate support 11 in the plasma processing chamber 10.

[0036] 5, in step ST2, the second film F2 is etched through the opening OPM of the mask MK by a plasma PL generated from a processing gas to form a first opening OP1 in the second film F2. The first opening OP1 corresponds to the opening OPM. The first opening OP1 exposes the first film F1.

[0037] Step ST2 may be performed as follows: The gas supply unit 20 supplies a processing gas into the plasma processing chamber 10. The control unit 2 controls the gas supply unit 20 and the plasma generation unit 12 to generate a plasma PL from the processing gas.

[0038] (Process ST3) In process ST3, as shown in FIG. 6 , the first film F1 is etched by a first plasma PL1 generated from the first process gas to form second openings OP2 in the first film F1. The second openings OP2 correspond to the first opening OP1. The openings OP, including the first opening OP1 and the second opening OP2, expose the base film UF. That is, the first film F1 and the second film F2 provide openings OP that expose the base film UF. The pitch of the openings OP may be 80 nm or less. The pitch of the openings OP may be measured at the upper ends of the openings OP (the upper surfaces of the second film F2). If the method MT1 does not include processes ST2 to ST4, then the substrate W shown in FIG. 6 may be provided on the substrate support 11 in process ST1. If the method MT1 does not include processes ST2 and ST4, then the substrate W shown in FIG. 5 may be provided on the substrate support 11 in process ST1.

[0039] Step ST3 may be performed as follows: The gas supply unit 20 supplies a first processing gas into the plasma processing chamber 10. The control unit 2 controls the gas supply unit 20 and the plasma generation unit 12 to generate a first plasma PL1 from the first processing gas.

[0040] (Step ST4) In step ST4, as shown in FIG. 7, a deposit DP is formed on the base film UF exposed in the opening OP. The deposit DP may be formed by plasma PLD. The plasma PLD may be generated from a process gas containing a hydrogen halide gas and a carbon-containing gas without supplying an electric bias to the substrate support 11. The hydrogen halide gas may be hydrogen fluoride (HF) gas, hydrogen chloride (HCl) gas, or hydrogen bromide (HBr) gas. The carbon-containing gas may be a hydrocarbon (C ｘ H ｙ ) gas, fluorocarbon (C ｘ F ｙ ) gas or hydrofluorocarbon (C ｘ H ｙ F ｚ ) gas. Each of x, y, and z is a positive real number. The deposit DP may contain carbon. The deposit DP may be formed by a flowable carbon-containing substance moving on the sidewall of the opening OP and accumulating on the undercoat film UF.

[0041] Step ST4 may be performed as follows: The gas supply unit 20 supplies a processing gas into the plasma processing chamber 10. The control unit 2 controls the gas supply unit 20 and the plasma generation unit 12 to generate a plasma PLD from the processing gas.

[0042] (Process ST5) In process ST5, as shown in FIG. 8, the second film F2 is removed by a second plasma PL2 generated from the second processing gas. The second plasma PL2 contains a hydrogen fluoride etchant (HF etchant). At the end of process ST5, a deposit DP may remain on the base film UF. The hydrogen fluoride etchant etches the second film F2, which is a silicon-containing film. The hydrogen fluoride etchant may contain hydrogen fluoride active species and neutral hydrogen fluoride molecules. The hydrogen fluoride active species may contain hydrogen fluoride ions and hydrogen fluoride radicals. Since H—F bonds are difficult to dissociate in the second plasma PL2, a hydrogen fluoride etchant having H—F bonds is generated.

[0043] In step ST5, the second process gas may contain hydrogen and fluorine. The second process gas may contain at least one gas selected from the group consisting of a mixed gas containing a hydrogen-containing gas and a fluorine-containing gas, a hydrogen fluoride gas, and a hydrofluorocarbon gas. The hydrogen-containing gas may be, for example, H ２ Gas, NH ３ Gas, H ２ O gas, H ２ O ２ Gas or hydrocarbon (CH ４ Gas, C ３ H ６ The fluorine-containing gas may be NF ３ Gas, SF ６ Gas, WF ６ Gas, XeF ２ In one example, the gas mixture containing hydrogen and fluorine is H ２ Gas and CF ４ The hydrofluorocarbon gas may include CHF ３ , C.H. ２ F ２ , C.H. ３ F, C ２ HF ５ , C ２ H ２ F ４ , C ２ H ３ F ３ , C ２ H ４ F ２ , C ３ HF ７ , C ３ H ２ F ２ , C ３ H ２ F ６ , C ３ H ２ F ４ , C ３ H ３ F ５ , C ４ H ５ F ５ , C ４ H ２ F ６ , C ５ H２ F １０ , c-C ５ H ３ F ７、 and C ３ H ２ F ４ It may be at least one selected from the group consisting of:

[0044] In step ST5, the second processing gas is an inert gas, a fluorocarbon gas (C ｘ F ｙ The inert gas may further include at least one selected from the group consisting of a noble gas or nitrogen (N ２ ) gas. An example of a noble gas includes argon gas. Fluorocarbon gases include CF ４ , C ２ F ２ , C ２ F ４ , C ３ F ８ , C ４ F ６ , C ４ F ８ , and C ５ F ８ The phosphorus-containing gas may be at least one selected from the group consisting of phosphorus trifluoride gas (PF ３ gas), phosphorus pentafluoride gas (PF ５ gas), phosphorus trichloride gas (PCl ３ gas), phosphorus pentachloride gas (PCl ５ gas), phosphorus tribromide gas (PBr ３ gas), phosphorus pentabromide gas (PBr ５ gas), and phosphorus iodide gas (PI ３ The gas may include at least one selected from the group consisting of:

[0045] In step ST5, the second process gas may not contain a carbon-containing gas. Of all gases contained in the second process gas, excluding noble gases, the flow rate of hydrogen fluoride gas may be the highest. The ratio of the total flow rate of the fluorocarbon gas and hydrofluorocarbon gas to the total flow rate of the second process gas may be 0.1 or less. The ratio of the flow rate of the phosphorus-containing gas to the total flow rate of the second process gas may be 0.1 or less.

[0046] In step ST5, no electric bias may be supplied to the substrate support 11, or an electric bias having a level lower than the level of the electric bias supplied to the substrate support 11 in step ST3 may be supplied to the substrate support 11. In step ST5, no electric bias may be supplied to the substrate support 11, or an electric bias having a level of 200 W or less or 1 kV or less may be supplied to the substrate support 11.

[0047] The electric bias may be bias RF power. In this case, the level of the electric bias is the power level (effective value) of the bias RF power. The level of the electric bias may be 200 W or less, 100 W or less, or 50 W or less.

[0048] The electric bias may be a direct current (DC) voltage. 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. The level of the electric bias may be 1 kV or less, 500 V or less, or 100 V or less.

[0049] In step ST5, an electric bias may be supplied to the substrate support 11. In this case, the energy of ions generated from the second plasma PL2 and incident on the substrate W may be 500 eV or less. The ion energy of the present disclosure may be the average ion energy incident on the upper surface of the substrate. The average ion energy may be calculated, for example, from the process conditions and the magnitude of the electric bias supplied to the substrate support 11 (the power level of the bias RF power and the voltage level of the voltage pulse), or may be calculated based on the results of a simulation.

[0050] In step ST5, the temperature of the substrate support 11 may be 60° C. or less, or 30° C. or less. In step ST5, the pressure in the plasma processing chamber 10 may be 6.67 Pa (50 mTorr) or more, or 13.3 Pa (100 mTorr) or more.

[0051] Step ST5 may include a first period and a second period alternating with the first period. The first period and the second period are alternately arranged. In the first period, a first source RF signal for generating the second plasma PL2 is supplied. The first source RF signal has a first level. In the second period, either no source RF signal is supplied or a second source RF signal having a second level lower than the first level is supplied.

[0052] Step ST5 may be performed as follows: The gas supply unit 20 supplies a second process gas into the plasma processing chamber 10. The control unit 2 controls the gas supply unit 20 and the plasma generation unit 12 to generate a second plasma PL2 from the second process gas.

[0053] After step ST5, the base film UF may be etched by plasma generated from the processing gas. In this case, an opening corresponding to the second opening OP2 of the first film F1 is formed in the base film UF. If deposits DP remain on the base film UF at the end of step ST5, the deposits DP are removed by plasma generated from the processing gas, and then the base film UF is etched.

[0054] (Step ST6) In step ST6, the first film F1 is removed in the plasma processing chamber 10. The first film F1 may be removed by plasma generated from a processing gas containing an oxygen-containing gas. The oxygen-containing gas may be oxygen (O ２ Step ST6 may be performed in the same plasma processing chamber 10 as step ST5, or may be performed consecutively with step ST5.

[0055] According to the method MT1, the silicon-containing film (second film F2) can be selectively removed relative to the other film (first film F1) in step ST5. The hydrogen fluoride etchant contained in the second plasma PL2 reacts more easily with the silicon-containing film than with the other films. As a result, the etching rate of the first film F1 is smaller than the etching rate of the second film F2.

[0056] Furthermore, according to the method MT1, etching of the first film F1 can be suppressed, which in turn suppresses etching of the sidewall of the first film F1 that defines the second opening OP2, thereby suppressing the occurrence of shape abnormalities (bowing) in the sidewall that defines the second opening OP2.

[0057] If the base film UF is a metal-containing film, the hydrogen fluoride etchant contained in the second plasma PL2 does not easily etch the base film UF in step ST5, and therefore metal residues are not easily generated from the base film UF.

[0058] When the method MT1 includes the step ST4, the base film UF is protected by the deposit DP in the step ST5. Therefore, even when the base film UF is a silicon-containing film, the etching selectivity of the second film F2 to the base film UF can be improved.

[0059] If the pressure inside the plasma processing chamber 10 is 6.67 Pa or higher in step ST5, the etching selectivity of the second film F2 to the first film F1 can be improved in step ST5.

[0060] Various experiments performed to evaluate Method MT1 are described below, but the experiments described below are not intended to limit the present disclosure.

[0061] (First Experiment) In the first experiment, a substrate was first provided on a substrate support in a chamber of a plasma processing apparatus. The substrate had a structure similar to that of the substrate W shown in FIG. 6. The substrate had a silicon oxide film, an amorphous carbon film on the silicon oxide film, and a SiON film on the amorphous carbon film. The amorphous carbon film and the SiON film provided openings that exposed the silicon oxide film.

[0062] Next, without supplying an electric bias to the substrate support, plasma was generated from a process gas containing hydrogen fluoride gas and argon gas, and the SiON film was removed by the plasma. The temperature of the substrate support was 0°C. The pressure in the chamber was 66.7 Pa. The power level of the source RF power for generating the plasma was 1000 W.

[0063] (Second Experiment) An experiment was carried out in the same manner as the first experiment, except that the temperature of the substrate support part was set to 30°C.

[0064] (Third Experiment) An experiment was carried out in the same manner as the first experiment, except that the temperature of the substrate support part was set to 60°C.

[0065] (Results of First Experiment) In each of the first to third experiments, the cross section of the substrate was observed. In the first to third experiments, the SiON film was removed. In the first to third experiments, no shape abnormality (bowing) was observed on the sidewall defining the opening in the amorphous carbon film.

[0066] (Fourth Experiment) In the fourth experiment, a substrate was provided on a substrate support in the same manner as in the first experiment.

[0067] Next, without applying an electrical bias to the substrate support, hydrogen fluoride gas, CH ３ Plasma was generated from a processing gas containing F gas and argon gas, and the SiON film was removed by the plasma. The temperature of the substrate support was 0° C. The pressure in the chamber was 1.33 Pa. The power level of the source RF power for generating the plasma was 2000 W.

[0068] (Fifth Experiment) An experiment was carried out in the same manner as in the fourth experiment, except that the pressure in the chamber was set to 13.3 Pa.

[0069] (Sixth Experiment) An experiment was conducted in the same manner as the fourth experiment, except that a process gas containing nitrogen gas was used instead of argon gas, the temperature of the substrate support part was set to 60° C., and the pressure inside the chamber was set to 13.3 Pa.

[0070] (Experiment 7) CH ３ C instead of F gas ４ F ６ The experiment was carried out in the same manner as in the fourth experiment, except that a process gas containing a gas was used.

[0071] (Eighth Experiment) An experiment was carried out in the same manner as in the seventh experiment, except that the pressure in the chamber was set to 13.3 Pa.

[0072] (Ninth Experiment) An experiment was carried out in the same manner as in the seventh experiment, except that the temperature of the substrate support was set to 60° C. and the power level of the source RF power was set to 250 W.

[0073] (Tenth Experiment) An experiment was carried out in the same manner as in the seventh experiment, except that the temperature of the substrate support was set to 60° C., the power level of the source RF power was set to 250 W, and the pressure in the chamber was set to 13.3 Pa.

[0074] (Eleventh Experiment) An experiment was carried out in the same manner as the seventh experiment, except that a processing gas containing nitrogen gas was used instead of argon gas and the pressure inside the chamber was set to 13.3 Pa.

[0075] (Results of Second Experiment) The cross section of the substrate was observed in each of Experiments 4 to 11. In Experiments 4 to 11, deposits were formed on the silicon oxide film exposed in the openings in the amorphous carbon film (see FIG. 7).

[0076] 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.

[0077] Various exemplary embodiments included in the present disclosure are now described in [E1] to [E19] below.

[0078] [E1] A plasma processing method comprising: (a) providing a substrate on a substrate support in a chamber, the substrate having an underlayer film, a first film on the underlayer film, and a second film on the first film, the first film and the second film providing an opening exposing the underlayer film, the second film comprising silicon; and (b) applying no electric bias to the substrate support, or applying an electric bias having a level of 200 W or less or 1 kV or less to the substrate support, to remove the second film with plasma generated from a process gas, the plasma comprising a hydrogen fluoride etchant.

[0079] According to the plasma processing method [E1], the second film can be removed selectively with respect to the first film.

[0080] [E2] The plasma processing method according to [E1], wherein the processing gas contains hydrogen fluoride gas.

[0081] [E3] The plasma processing method according to [E1] or [E2], wherein the first film is a carbon-containing film or a metal-containing film.

[0082] [E4] The plasma processing method according to any one of [E1] to [E3], wherein the undercoat film is a metal-containing film.

[0083] In this case, since the base film is hardly etched in (b), metal residue is hardly generated from the base film.

[0084] [E5] The plasma processing method according to any one of [E1] to [E3], wherein the base film is a silicon-containing film.

[0085] [E6] The plasma processing method according to any one of [E1] to [E5], wherein the processing gas further contains at least one selected from the group consisting of an inert gas, a fluorocarbon gas, a hydrofluorocarbon gas, and a phosphorus-containing gas.

[0086] [E7] The plasma processing method according to any one of [E1] to [E6], further comprising the step of: (c) forming a deposit on the base film exposed in the opening.

[0087] In this case, the underlying film is less likely to be etched in (b).

[0088] [E8] The plasma processing method according to [E7], wherein in (c), plasma is generated from a processing gas containing a hydrogen halide gas and a carbon-containing gas without supplying an electric bias to the substrate support part.

[0089] [E9] The plasma processing method according to [E8], wherein the hydrogen halide gas is hydrogen fluoride gas, hydrogen chloride gas, or hydrogen bromide gas.

[0090] [E10] The plasma processing method according to [E8] or [E9], wherein the carbon-containing gas is a hydrocarbon gas, a fluorocarbon gas, or a hydrofluorocarbon gas.

[0091] [E11] The plasma processing method according to any one of [E1] to [E10], wherein in (b), the temperature of the substrate support part is 30° C. or less.

[0092] [E12] The plasma processing method according to any one of [E1] to [E11], wherein in (b), the pressure inside the chamber is 6.67 Pa or higher.

[0093] In this case, in (b), the etching selectivity of the second film to the first film can be improved.

[0094] [E13] A plasma processing method comprising the steps of: (a) providing a substrate on a substrate support in a chamber, the substrate having an underlayer film, a first film on the underlayer film, and a second film on the first film, the second film having a first opening exposing the first film, the second film containing silicon; (b) etching the first film with a first plasma generated from a first process gas to form a second opening in the first film; and (c) removing the second film with a second plasma generated from a second process gas, the second plasma containing a hydrogen fluoride etchant; wherein in (c), no electric bias is supplied to the substrate support, or an electric bias of a level lower than the level of the electric bias supplied to the substrate support in (b) is supplied to the substrate support.

[0095] [E14] The plasma processing method according to any one of [E1] to [E12], wherein (b) includes: a first period during which a first source RF signal for generating the plasma is supplied, the first source RF signal having a first level; and a second period alternately with the first period, during which either no source RF signal is supplied or a second source RF signal having a second level lower than the first level is supplied.

[0096] [E15] A plasma processing method comprising: (a) providing a substrate on a substrate support in a chamber, the substrate having an underlayer film, a first film on the underlayer film, and a second film on the first film, the first film and the second film providing an opening exposing the underlayer film, and the second film comprising silicon; and (b) supplying an electric bias to the substrate support to remove the second film with plasma generated from a process gas, the plasma comprising a hydrogen fluoride etchant, and ion energy generated from the plasma and incident on the substrate is 500 eV or less.

[0097] [E16] The plasma processing method according to [E15], wherein the first film is a carbon-containing film, and the underlayer film is a metal-containing film.

[0098] [E17] The plasma processing method according to [E15] or [E16], further comprising: (c) removing the first film in the chamber after (b).

[0099] [E18] The plasma processing method according to any one of [E1] to [E17], wherein the pitch of the openings is 80 nm or less.

[0100] [E19] A plasma processing apparatus comprising: a chamber; and a substrate support part for supporting a substrate in the chamber, the substrate having an underlayer film, a first film on the underlayer film, and a second film on the first film, the first film and the second film providing an opening exposing the underlayer film, the second film including silicon; a gas supply part configured to supply a process gas into the chamber; and a plasma generation part configured to generate plasma from the process gas in the chamber, the plasma including a hydrogen fluoride etchant; and a controller, wherein the controller is configured to control the plasma processing apparatus to perform a plasma processing method, the plasma processing method including: (b) supplying no electric bias to the substrate support part, or supplying an electric bias having a level of 200 W or less or 1 kV or less to the substrate support part, and removing the second film by the plasma.

[0101] 1...plasma processing apparatus, 2...control unit, 10...plasma processing chamber, 11...substrate support unit, 12...plasma generation unit, 20...gas supply unit, F1...first film, F2...second film, OP...opening, OP1...first opening, OP2...second opening, PL1...first plasma, PL2...second plasma, UF...base film, W...substrate.

Claims

1. A plasma processing method comprising: (a) providing a substrate on a substrate support in a chamber, the substrate having an underlying film, a first film on the underlying film, and a second film on the first film, the first film and the second film providing an opening exposing the underlying film, the second film comprising silicon; and (b) providing no electrical bias to the substrate support, or providing an electrical bias to the substrate support having a level of 200 W or less or 1 kV or less, to remove the second film with a plasma generated from a process gas, the plasma comprising a hydrogen fluoride etchant.

2. The plasma processing method according to claim 1, wherein the processing gas includes hydrogen fluoride gas.

3. The plasma processing method according to claim 1 or 2, wherein the first film is a carbon-containing film or a metal-containing film.

4. The plasma processing method according to claim 1 or 2, wherein the undercoat film is a metal-containing film.

5. The plasma processing method according to claim 1 or 2, wherein the base film is a silicon-containing film.

6. The plasma processing method according to claim 1 or 2, wherein the processing gas further contains at least one selected from the group consisting of an inert gas, a fluorocarbon gas, a hydrofluorocarbon gas, and a phosphorus-containing gas.

7. The plasma processing method according to claim 1 or 2, further comprising the step of: (c) forming a deposit on the base film exposed in the opening.

8. The plasma processing method according to claim 7, wherein in (c), the plasma is generated from a process gas containing a hydrogen halide gas and a carbon-containing gas without supplying an electrical bias to the substrate support.

9. The plasma processing method according to claim 8, wherein the hydrogen halide gas is hydrogen fluoride gas, hydrogen chloride gas or hydrogen bromide gas.

10. The plasma processing method according to claim 8, wherein the carbon-containing gas is a hydrocarbon gas, a fluorocarbon gas, or a hydrofluorocarbon gas.

11. The plasma processing method according to claim 1 or 2, wherein in (b), the temperature of the substrate support part is 30° C. or less.

12. The plasma processing method according to claim 1 or 2, wherein in (b), the pressure inside the chamber is 6.67 Pa or higher.

13. A plasma processing method comprising the steps of: (a) providing a substrate on a substrate support in a chamber, the substrate having an undercoat film, a first film on the undercoat film, and a second film on the first film, the second film having a first opening exposing the first film, the second film comprising silicon; (b) etching the first film with a first plasma generated from a first process gas to form a second opening in the first film; and (c) removing the second film with a second plasma generated from a second process gas, the second plasma comprising a hydrogen fluoride etchant; wherein in (c), either no electrical bias is supplied to the substrate support, or an electrical bias of a level lower than the level of the electrical bias supplied to the substrate support in (b) is supplied to the substrate support.

14. The plasma processing method of claim 1, wherein (b) includes: a first period during which a first source RF signal for generating the plasma is supplied, the first source RF signal having a first level; and a second period alternating with the first period during which either no source RF signal is supplied or a second source RF signal having a second level less than the first level is supplied.

15. A plasma processing method comprising: (a) providing a substrate on a substrate support in a chamber, the substrate having an undercoat film, a first film on the undercoat film, and a second film on the first film, the first film and the second film providing an opening exposing the undercoat film, the second film comprising silicon; and (b) providing an electrical bias to the substrate support to remove the second film with a plasma generated from a process gas, the plasma comprising a hydrogen fluoride etchant, and an ion energy generated from the plasma and incident on the substrate is 500 eV or less.

16. The plasma processing method according to claim 15, wherein the first film is a carbon-containing film, and the undercoat film is a metal-containing film.

17. The plasma processing method of claim 15, further comprising the step of: (c) removing the first film in the chamber after (b).

18. The plasma processing method according to claim 14, wherein the pitch of the openings is 80 nm or less.

19. A plasma processing apparatus comprising: a chamber; and a substrate support for supporting a substrate in the chamber, the substrate having an undercoat film, a first film on the undercoat film, and a second film on the first film, the first film and the second film providing an opening exposing the undercoat film, the second film comprising silicon; a gas supply unit configured to supply a process gas into the chamber; and a plasma generation unit configured to generate plasma from the process gas in the chamber, the plasma comprising a hydrogen fluoride etchant; and a control unit, wherein the control unit is configured to control the plasma processing apparatus to perform a plasma processing method, the plasma processing method comprising: (b) a step of removing the second film by the plasma by supplying no electric bias to the substrate support unit, or by supplying an electric bias having a level of 200 W or less or 1 kV or less to the substrate support unit.

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