Etching method and plasma processing apparatus

Abstract

To provide a substrate processing method and a plasma processing apparatus, capable of improving an etching selection ratio.SOLUTION: In one exemplary embodiment, an etching method includes the steps of: (a) preparing a substrate, the substrate including a first region that includes a first material containing silicon and a second region that includes a second material different from the first material; and (b) etching the first region using plasma generated from a processing gas that includes a gas containing carbon and fluorine, a nitrogen-containing gas, and a metal halide gas. In the (b), the flow rate of the metal halide gas is less than the flow rate of the gas containing carbon and fluorine and the flow rate of the nitrogen-containing gas.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a method of etching an insulating film using plasma. In this method, etching is performed while forming a conductive layer on the surface of the insulating film during etching. In the etching, plasma generated from a mixed gas of WF6 and C4F8 is used.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a substrate processing method and a plasma processing apparatus capable of improving an etching selectivity ratio.

Means for Solving the Problems

[0005] In one exemplary embodiment, an etching method includes: (a) a step of preparing a substrate, the substrate including a first region including a first material containing silicon and a second region including a second material different from the first material; and (b) a step of etching the first region with plasma generated from a processing gas including a gas containing carbon and fluorine, a nitrogen-containing gas, and a metal halide gas, wherein in (b), a flow rate of the metal halide gas is less than a flow rate of the gas containing carbon and fluorine and a flow rate of the nitrogen-containing gas.

Effects of the Invention

[0006] According to one exemplary embodiment, a substrate processing method and a plasma processing apparatus capable of improving the etching selectivity ratio are provided. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic diagram showing a plasma processing apparatus according to one exemplary embodiment. [Figure 2] Figure 2 is a schematic diagram showing a plasma processing apparatus according to one exemplary embodiment. [Figure 3] Figure 3 is a flowchart of an etching method according to one exemplary embodiment. [Figure 4] Figure 4 is a cross-sectional view of an example substrate to which the method in Figure 3 may be applied. [Figure 5] Figure 5 is a cross-sectional view showing one step of an etching method according to one exemplary embodiment. [Figure 6] Figure 6 shows an example of a TEM image of a cross-section of a substrate obtained by performing the etching method in the first experiment. [Figure 7] Figure 7 shows an example of a TEM image of a cross-section of a substrate obtained by performing the etching method in the second experiment. [Figure 8] Figure 8 is a graph showing an example of the relationship between hydrogen gas flow rate and etching amount or etching selectivity ratio. [Modes for carrying out the invention]

[0008] Various exemplary embodiments will be described in detail below with reference to the drawings. In each drawing, the same or corresponding parts will be denoted by the same reference numerals.

[0009] Figure 1 is a diagram illustrating an example 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 unit 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 outlet for discharging gas from the plasma processing space. The gas supply port is connected to a gas supply unit 20, which will be described later, and the gas outlet is connected to an exhaust system 40, which will be described later. The substrate support unit 11 is located in the plasma processing space and has a substrate support surface for supporting a substrate.

[0010] The plasma generation unit 12 is configured to generate plasma from at least one processing gas supplied into the plasma processing space. The plasma formed in the plasma processing space may be a capacitively coupled plasma (CCP), an inductively coupled plasma (ICP), an electron-cyclotron-resonance plasma (ECR), a helicon-wave excited plasma (HWP), or a surface wave plasma (SWP), etc. Various types of plasma generation units, including an AC (Alternating Current) plasma generation unit and a DC (Direct Current) plasma generation unit, may also be used. In one embodiment, the AC signal (AC power) used in the AC plasma generation unit has a frequency in the range of 100 kHz to 10 GHz. Therefore, the AC signal includes an RF (Radio Frequency) signal and a microwave signal. In one embodiment, the RF signal has a frequency in the range of 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 herein. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to perform the 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 is implemented, for example, by a computer 2a. The processing unit 2a1 may be configured to perform various control operations by reading a program from the storage unit 2a2 and executing the read program. This program may be stored in the storage unit 2a2 in advance, or it may be obtained via a medium when needed. The obtained program is stored in the storage unit 2a2 and read from the storage unit 2a2 and executed by the processing unit 2a1. The medium may be various storage media readable by the computer 2a, or it may be a communication line connected to the communication interface 2a3. The processing unit 2a1 may be a CPU (Central Processing Unit). The memory unit 2a2 may include RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing device 1 via a communication line such as a LAN (Local Area Network).

[0012] The following describes an example configuration of a capacitively coupled plasma processing apparatus as an example of plasma processing apparatus 1. Figure 2 is a diagram illustrating an example configuration of a capacitively coupled plasma processing apparatus.

[0013] The capacitively 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 apparatus 1 also includes a substrate support unit 11 and a gas introduction unit. The gas introduction unit is configured to introduce at least one processing gas into the plasma processing chamber 10. The gas introduction unit includes a shower head 13. The substrate support unit 11 is located inside the plasma processing chamber 10. The shower head 13 is located above the substrate support unit 11. In one embodiment, the shower head 13 constitutes 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 shower head 13, the side walls 10a of the plasma processing chamber 10, and the substrate support unit 11. The plasma processing chamber 10 is grounded. The shower head 13 and the substrate support unit 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0014] The substrate support portion 11 includes a main body portion 111 and a ring assembly 112. The main body portion 111 has a central region 111a for supporting the substrate W and an annular region 111b for supporting the ring assembly 112. A wafer is an example of the substrate W. The annular region 111b of the main body portion 111 surrounds the central region 111a of the main body portion 111 in a plan view. The substrate W is placed on the central region 111a of the main body portion 111, and the ring assembly 112 is placed on the annular region 111b of the main body portion 111 so as to surround the substrate W on the central region 111a of the main body portion 111. Therefore, the central region 111a is also called the substrate support surface for supporting the substrate W, and the annular region 111b is also called the 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 other members surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member, may have the annular region 111b. In this case, the ring assembly 112 may be disposed on the annular electrostatic chuck or the annular insulating member, or may be disposed on both the electrostatic chuck 1111 and the annular insulating member. Also, at least one RF / DC electrode coupled to an RF power supply 31 and / or a DC power supply 32 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 described later is supplied to the at least one RF / DC electrode, the RF / DC electrode is also referred to as a bias electrode. Note that the conductive member of the base 1110 and the at least one RF / DC electrode may function as a plurality of lower electrodes. Also, the electrostatic electrode 1111b may function as a lower electrode. Accordingly, 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 ring is formed of a conductive material or an insulating material, and the cover ring is formed of an insulating material.

[0017] Further, the substrate support portion 11 may include a temperature control 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 control module may include a heater, a heat transfer medium, a flow path 1110a, or a combination thereof. A heat transfer fluid such as brine or gas flows through the flow path 1110a. In one embodiment, the flow path 1110a is formed in the base 1110, and one or more heaters are disposed within the ceramic member 1111a of the electrostatic chuck 1111. Further, the substrate support portion 11 may include a heat transfer gas supply portion configured to supply a heat transfer gas to a gap between the back surface of the substrate W and the central region 111a.

[0018] The shower head 13 is configured to introduce at least one process gas from the gas supply unit 20 into the plasma processing space 10s. The shower head 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and a plurality of gas introduction ports 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 plurality of gas introduction ports 13c. Further, the shower head 13 includes at least one upper electrode. The gas introduction portion may include, in addition to the shower head 13, one or more side gas injection portions (SGI: Side Gas Injector) attached to one or more openings formed in the side wall 10a.

[0019] The gas supply unit 20 may include at least one gas source 21 and at least one flow rate controller 22. In one embodiment, the gas supply unit 20 is configured to supply at least one process gas from the corresponding gas source 21 to the shower head 13 via the corresponding flow rate controller 22. Each flow rate controller 22 may include, for example, a mass flow controller or a pressure-controlled flow rate controller. Further, the gas supply unit 20 may include at least one flow rate modulation device for modulating or pulsing the flow rate of 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 causes plasma to be formed from at least one processing gas supplied to the plasma processing space 10s. Thus, the RF power supply 31 can function as at least part of the plasma generation unit 12. In addition, by supplying a bias RF signal to at least one lower electrode, a bias potential is generated on the substrate W, and ionic components in the formed plasma can be drawn into the substrate W.

[0021] In one embodiment, the RF power supply 31 includes a first RF generation unit 31a and a second RF generation unit 31b. The first RF generation 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 generation unit 31a may be configured to generate a plurality of source RF signals having different frequencies. One or more generated source RF signals are supplied to at least one lower electrode and / or at least one upper electrode.

[0022] The second RF generation unit 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 generation unit 31b may be configured to generate a plurality of bias RF signals having different frequencies. One or more generated 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 generation unit 32a and a second DC generation unit 32b. In one embodiment, the first DC generation unit 32a is connected to at least one lower electrode and configured to generate a first DC signal. The generated first DC signal is applied to at least one lower electrode. In one embodiment, the second DC generation unit 32b is connected to at least one upper electrode and configured to generate a second DC signal. The generated second DC signal is applied to 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 a combination thereof pulse waveform. In one embodiment, a waveform generation unit for generating a sequence of voltage pulses from the DC signal is connected between the first DC generation unit 32a and at least one lower electrode. Thus, the first DC generation unit 32a and the waveform generation unit constitute a voltage pulse generation unit. When the second DC generation unit 32b and the waveform generation unit constitute a voltage pulse generation unit, the voltage pulse generation unit is connected to at least one upper electrode. The voltage pulses may have positive or negative polarity. The sequence of voltage pulses may also include one or more positive voltage pulses and one or more negative voltage pulses within one period. The first and second DC generation units 32a and 32b may be provided in addition to the RF power supply 31, and the first DC generation unit 32a may be provided in place of the second RF generation unit 31b.

[0025] The exhaust system 40 may be connected to, for example, a gas outlet 10e located 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 regulating valve regulates the pressure in the plasma processing space 10s. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

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

[0027] Figure 4 is a cross-sectional view of an example substrate to which the method of Figure 3 may be applied. As shown in Figure 4, in one embodiment, the substrate W includes a first region R1 and a second region R2. The second region R2 may have at least one aperture OP. The second region R2 may have multiple apertures OP. The apertures OP may have a hole pattern or a line pattern. The critical dimension (CD) of the apertures OP may be 100 nm or less, 50 nm or less, or 30 nm or less. The second region R2 may be on the first region R1. The substrate W may further include a base region UR. The base region UR may be below the first region R1.

[0028] The first region R1 contains a first material containing silicon. The first region R1 may be a silicon oxide film. The first region R1 may be an SOG (Spin on Glass) film.

[0029] The second region R2 contains a second material different from the first material of the first region R1. The second region R2 may be a mask having an aperture OP on the first region R1. The second region R2 may be a photoresist film. The second region R2 may be a photoresist film for EUV exposure.

[0030] The base region UR may include a first base region UR1, a second base region UR2, and a third base region UR3. The first base region UR1, the second base region UR2, and the third base region UR3 are arranged in order. The third base region UR3 is provided between the first region R1 and the second base region UR2. The first base region UR1, the second base region UR2, and the third base region UR3 may be laminated films.

[0031] The first substrate region UR1 may contain silicon and nitrogen. The first substrate region UR1 may contain silicon nitride (SiN x The second substrate region UR2 may contain silicon oxide (SiO2). The second substrate region UR2 may contain silicon and oxygen. x) may include. The third substrate region UR3 may be an SOC (Spin on Carbon) film or a carbon-containing film.

[0032] The following describes method MT1, taking as an example the case where method MT1 is applied to the substrate W using the plasma processing apparatus 1 of the above embodiment, with reference to Figures 3 to 5. Figure 5 is a cross-sectional view showing one step of an etching method according to one exemplary embodiment. When the plasma processing apparatus 1 is used, method MT1 can be executed in the plasma processing apparatus 1 by the control unit 2 controlling each part of the plasma processing apparatus 1. In method MT1, as shown in Figure 2, the substrate W on the substrate support part 11 arranged in the plasma processing chamber 10 is processed.

[0033] As shown in Figure 3, method MT1 may include steps ST1 and ST2. Steps ST1 and ST2 may be performed in sequence.

[0034] (Process ST1) In step ST1, the substrate W shown in Figure 4 is provided. The substrate W can be supported by the substrate support 11 within the plasma processing chamber 10.

[0035] (Process ST2) In step ST2, as shown in Figure 5, the first region R1 is etched by plasma PL generated from the processing gas. This can form a recess RS in the first region R1 that corresponds to the opening OP in the second region R2. The recess RS may also be an opening.

[0036] The process gas in step ST2 includes a gas containing carbon and fluorine, a nitrogen-containing gas, and a metal halide gas. The process gas may further contain a hydrogen-containing gas.

[0037] Gases containing carbon and fluorine are fluorocarbons (C x F y ) gas and hydrofluorocarbon (C x H y F z) may contain at least one of the following gases. Examples of fluorocarbon gases include CF4 gas, C3F6 gas, C3F8 gas, C4F8 gas, and C4F6 gas. Examples of hydrofluorocarbon gases include CH2F2 gas, CHF3 gas, and CH3F gas.

[0038] The nitrogen-containing gas may also contain nitrogen (N2) gas.

[0039] The metal halide gas may contain at least one of the following metals: tungsten, titanium, molybdenum, vanadium, platinum, hafnium, niobium, tantalum, and rhenium. The metal halide gas may also contain fluorine. The metal halide gas may contain at least one of the following: tungsten hexafluoride (WF6) gas, tungsten hexabromide (WBr6) gas, tungsten hexachloride (WCl6) gas, WF5Cl gas, titanium tetrachloride (TiCl4) gas, molybdenum pentafluoride (MoF5) gas, vanadium hexafluoride (VF6) gas, platinum hexafluoride (PtF6) gas, hafnium tetrafluoride (HfF4) gas, and niobium pentafluoride (NbF5) gas.

[0040] The hydrogen-containing gas may include at least one of the following: hydrogen (H2) gas, monosilane (SiH4) gas, and ammonia (NH3) gas.

[0041] In step ST2, the flow rate of the metal halide gas is less than the flow rate of the carbon and fluorine-containing gas and the flow rate of the nitrogen-containing gas. The flow rate of the nitrogen-containing gas may be greater than or less than the flow rate of the carbon and fluorine-containing gas. The flow rate of the hydrogen-containing gas may be less than the flow rate of the carbon and fluorine-containing gas and the flow rate of the nitrogen-containing gas. The flow rate of the metal halide gas may be less than the flow rate of the hydrogen-containing gas. The flow rate of the metal halide gas may be 20 sccm or less, 10 sccm or less, or 3 sccm or more. The flow rate of the hydrogen-containing gas may be 20 sccm or less.

[0042] In step ST2, the temperature of the substrate support portion 11 may be 10°C or higher, or 30°C or lower.

[0043] After step ST2, the third substrate region UR3 may be etched. Subsequently, the second substrate region UR2 may be etched.

[0044] According to the method MT1 described above, the etching selectivity ratio of the first region R1 to the second region R2 can be improved. The mechanism is presumed to be as follows, but is not limited thereto. In step ST2, carbon-containing deposits and metal-containing deposits are formed on the second region R2, thereby reducing the etching amount of the second region R2. The carbon-containing deposits originate from gases containing carbon and fluorine. The metal-containing deposits originate from metal halide gases. The metal-containing deposits may also contain nitrogen. When the etching selectivity ratio of the first region R1 to the second region R2 is improved, the thickness of the second region R2 can be reduced.

[0045] Furthermore, by reducing the flow rate of the metal halide gas, etching of the sidewalls of the recesses RS formed in the first region R1 can be suppressed. This suppresses shape abnormalities (boeing) of the sidewalls of the recesses RS. It is presumed that if the halogen contained in the metal halide gas is excessive, the sidewalls of the recesses RS will be excessively etched, but the mechanism is not limited to this.

[0046] Furthermore, according to the above method MT1, the verticality of the side walls of the recess RS formed in the first region R1 is improved. That is, the taper of the side walls of the recess RS is suppressed. This improves the dimensional uniformity at the bottom of the recess RS. The value of LCDU (Local CD Uniformity) (3σ) is used as an indicator of dimensional uniformity. It is presumed that the verticality of the side walls of the recess RS is improved by reducing the amount of etching in the second region R2, but the mechanism is not limited to this.

[0047] If the processing gas in step ST2 further contains hydrogen-containing gas, the etching selectivity ratio of the first region R1 to the second region R2 can be further improved. The mechanism is presumed to be, but is not limited to, the following: In step ST2, more deposits are formed on the second region R2. For example, deposits containing carbon and hydrogen are formed on the second region R2. Alternatively, a metal halide gas is reduced by the hydrogen-containing gas, and metal deposits are formed on the second region R2.

[0048] In step ST2, if the flow rate of nitrogen-containing gas is less than the flow rate of carbon and fluorine-containing gas, the amount of deposits formed on the second region R2 can be reduced. Therefore, blockage of the recess RS by deposits can be suppressed.

[0049] The following describes various experiments conducted to evaluate Method MT1. The experiments described below are not intended to limit this disclosure.

[0050] (Experiment 1) In the first experiment, a substrate W shown in Figure 4 was prepared. The substrate W included a first region R1 which was a silicon oxide film and a second region R2 which was a photoresist film for EUV exposure. Subsequently, process ST2 was performed on the substrate W using the plasma processing apparatus 1.

[0051] In process ST2, plasma PL was generated in the plasma processing chamber 10 from a processing gas containing WF6 gas, N2 gas, and CF4 gas, and the first region R1 was etched with the plasma PL. The processing gas did not contain any other gases. The flow rate of N2 gas was 250 sccm. The flow rate of WF6 gas was less than that of N2 gas. The flow rate of CF4 gas was greater than that of both WF6 gas and N2 gas.

[0052] (Experiment 2) The second experiment was conducted in the same manner as the first experiment, except that WF6 gas was not used in process ST2.

[0053] (Results of the first experiment) In both the first and second experiments, the etching amount of the first region R1 and the etching amount of the second region R2 were measured, and the etching selectivity ratio of the first region R1 to the second region R2 was calculated. The etching selectivity ratio in the first experiment was 1.45. The etching selectivity ratio in the second experiment was 1.11. Therefore, it can be seen that the etching selectivity ratio is improved by adding WF6 gas.

[0054] Furthermore, TEM images of the cross-section of the substrate W obtained in the first and second experiments were observed. Figure 6 shows an example of a TEM image of the cross-section of the substrate obtained by performing the etching method in the first experiment. Figure 7 shows an example of a TEM image of the cross-section of the substrate obtained by performing the etching method in the second experiment. The side walls of the recesses RS formed in the first region R1 in the first experiment had higher perpendicularity than the side walls of the recesses RS formed in the first region R1 in the second experiment. Therefore, it can be seen that the perpendicularity of the side walls of the recesses RS is improved by the addition of WF6 gas.

[0055] (Experiment 3) The third experiment was conducted in the same manner as the first experiment, except that the processing gas in step ST2 contained additional H2 gas and the N2 gas flow rate was different. The H2 gas flow rate was 10 sccm. The N2 gas flow rate was 240 sccm.

[0056] (Experiment 4) Experiment 4 was conducted in the same manner as Experiment 3, except that the flow rates of H2 gas and N2 gas were different in process ST2. The flow rate of H2 gas was 15 sccm. The flow rate of N2 gas was 235 sccm.

[0057] (Experiment 5) Experiment 5 was conducted in the same manner as Experiment 3, except that the flow rates of H2 gas and N2 gas were different in process ST2. The flow rate of H2 gas was 20 sccm. The flow rate of N2 gas was 230 sccm.

[0058] (Experiment 6) Experiment 6 was conducted in the same manner as Experiment 3, except that the flow rates of H2 gas and N2 gas were different in process ST2. The flow rate of H2 gas was 25 sccm. The flow rate of N2 gas was 225 sccm.

[0059] (Experiment 7) Experiment 7 was conducted in the same manner as Experiment 3, except that the flow rates of H2 gas and N2 gas were different in process ST2. The flow rate of H2 gas was 30 sccm. The flow rate of N2 gas was 220 sccm.

[0060] (Experiment 8) Experiment 8 was conducted in the same manner as Experiment 3, except that the flow rates of H2 gas and N2 gas were different in process ST2. The flow rate of H2 gas was 40 sccm. The flow rate of N2 gas was 210 sccm.

[0061] (Results from the second experiment) In each of the first experiment and experiments 3 through 8, the etching amount of the first region R1 and the etching amount of the second region R2 were measured, and the etching selectivity ratio of the first region R1 to the second region R2 was calculated. The results are shown in Figure 8. Figure 8 is a graph showing an example of the relationship between the hydrogen gas flow rate and the etching amount or etching selectivity ratio. In the graph, Ox represents the etching amount of the first region R1. PR represents the etching amount of the second region R2. Sel. represents the etching selectivity ratio of the first region R1 to the second region R2.

[0062] As shown in Figure 8, it can be seen that the etching selectivity ratio increases with the addition of H2 gas. It can also be seen that the etching selectivity ratio increases as the flow rate of H2 gas increases. Furthermore, it can be seen that when the flow rate of H2 gas exceeds 25 sccm, the amount of etching in the first region R1 decreases.

[0063] (Results of Experiment 3) Furthermore, TEM images of the cross-section of the substrate W obtained in the second and fifth experiments were observed. In the fifth experiment, the sidewalls of the recesses RS formed in the first region R1 had higher perpendicularity than the sidewalls of the recesses RS formed in the first region R1 in the second experiment. Therefore, it can be seen that the perpendicularity of the sidewalls of the recesses RS is improved by the addition of WF6 gas and H2 gas.

[0064] Although various exemplary embodiments have been described above, the invention is not limited to the exemplary embodiments described above, and various additions, omissions, substitutions, and modifications may be made. Furthermore, it is possible to combine elements from different embodiments to form other embodiments.

[0065] Herein, various exemplary embodiments included in this disclosure are described in [E1] to [E10] below.

[0066] [E1] (a) A step of preparing a substrate, wherein the substrate includes a first region containing a first material containing silicon and a second region containing a second material different from the first material, (b) Etching the first region with a plasma generated from a processing gas containing a gas containing carbon and fluorine, a nitrogen-containing gas, and a metal halide gas; Includes, An etching method in which, in (b) above, the flow rate of the metal halide gas is less than the flow rate of the gas containing carbon and fluorine and the flow rate of the gas containing nitrogen.

[0067] According to method [E1], the etching selectivity ratio of the first region to the second region can be improved. The mechanism is presumed to be, but is not limited to, the following: In (b), the amount of etching of the second region is reduced by the formation of carbon-containing and metal-containing deposits on the second region.

[0068] [E2] The etching method according to [E1], wherein the processing gas further comprises a hydrogen-containing gas.

[0069] In this case, the etching selectivity ratio of the first region to the second region can be further improved. The mechanism is presumed to be, but is not limited to, the following: In (b), deposits containing carbon and hydrogen are formed on the second region. Alternatively, in (b), a metal halide gas is reduced by a hydrogen-containing gas, and metal deposits are formed on the second region.

[0070] [E3] The etching method according to [E1] or [E2], wherein the metal halide gas comprises at least one metal selected from tungsten, titanium, molybdenum, vanadium, platinum, hafnium, niobium, tantalum, and rhenium.

[0071] [E4] The etching method according to [E3], wherein the metal halide gas comprises at least one of tungsten hexafluoride gas, tungsten hexabromide gas, tungsten hexachloride gas, WF5Cl gas, titanium tetrachloride gas, molybdenum pentafluoride gas, vanadium hexafluoride gas, platinum hexafluoride gas, hafnium tetrafluoride gas, and niobium pentafluoride gas.

[0072] [E5] The etching method according to any one of [E1] to [E4], wherein the carbon and fluorine-containing gas comprises at least one of fluorocarbon gas and hydrofluorocarbon gas.

[0073] [E6] The etching method according to any one of [E1] to [E5], wherein the second region is a mask having an opening on the first region.

[0074] [E7] The second region is a photoresist film, and the etching method is as described in any one of [E1] to [E6].

[0075] [E8] The etching method according to [E7], wherein the photoresist film is a photoresist film for EUV exposure.

[0076] [E9] The first region is a silicon oxide film, and the etching method is as described in any one of [E1] to [E8].

[0077] [E10] Chamber and, A substrate support portion for supporting a substrate within the chamber, wherein the substrate includes a first region containing a first material including silicon and a second region containing a second material different from the first material, A gas supply unit configured to supply a processing gas containing a carbon and fluorine-containing gas, a nitrogen-containing gas, and a metal halide gas into the chamber, A plasma generation unit configured to generate plasma from the processing gas within the chamber, Control unit and Equipped with, The control unit is configured to control the gas supply unit and the plasma generation unit so as to etch the first region with the plasma. Plasma processing apparatus, wherein the control unit is configured to control the gas supply unit such that, in the step of etching the first region, the flow rate of the metal halide gas is less than the flow rate of the gas containing carbon and fluorine and the flow rate of the nitrogen-containing gas.

[0078] From the above description, it will be understood that the various embodiments of this disclosure are described herein for illustrative purposes and can be modified in various ways without departing from the scope and spirit of this disclosure. Accordingly, the various embodiments disclosed herein are not intended to limit the scope and spirit, and the true scope and spirit are shown by the appended claims. [Explanation of Symbols]

[0079] 1...Plasma processing apparatus, 2...Control unit, 10...Plasma processing chamber, 11...Substrate support unit, 12...Plasma generation unit, 20...Gas supply unit, PL...Plasma, R1...First region, R2...Second region, W...Substrate.

Claims

1. (a) A step of preparing a substrate, wherein the substrate includes a first region containing a first material containing silicon and a second region containing a second material different from the first material, (b) A step of etching the first region with a plasma generated from a processing gas containing a gas containing carbon and fluorine, a nitrogen-containing gas, a metal halide gas, and a hydrogen-containing gas, wherein the hydrogen-containing gas contains at least one of hydrogen gas, monosilane gas, and ammonia gas. Includes, An etching method in which, in (b) above, the flow rate of the metal halide gas is less than the flow rate of the hydrogen-containing gas, and the flow rate of the hydrogen-containing gas is less than the flow rate of the gas containing carbon and fluorine and the flow rate of the nitrogen-containing gas.

2. The etching method according to claim 1, wherein the metal halide gas comprises at least one metal selected from tungsten, titanium, molybdenum, vanadium, platinum, hafnium, niobium, tantalum, and rhenium.

3. The aforementioned metal halide gases include tungsten hexafluoride gas, tungsten hexabromide gas, tungsten hexachloride gas, and WF ５ The etching method according to claim 2, comprising at least one of Cl gas, titanium tetrachloride gas, molybdenum pentafluoride gas, vanadium hexafluoride gas, platinum hexafluoride gas, hafnium tetrafluoride gas, and niobium pentafluoride gas.

4. The etching method according to any one of claims 1 to 3, wherein the carbon and fluorine-containing gas comprises at least one of fluorocarbon gas and hydrofluorocarbon gas.

5. The etching method according to any one of claims 1 to 3, wherein the second region is a mask having an opening on the first region.

6. The etching method according to any one of claims 1 to 3, wherein the second region is a photoresist film.

7. The etching method according to claim 6, wherein the photoresist film is a photoresist film for EUV exposure.

8. The etching method according to any one of claims 1 to 3, wherein the first region is a silicon oxide film.

9. Chamber and, A substrate support portion for supporting a substrate within the chamber, wherein the substrate includes a first region containing a first material including silicon and a second region containing a second material different from the first material, A gas supply unit configured to supply a processing gas containing a carbon and fluorine-containing gas, a nitrogen-containing gas, a metal halide gas, and a hydrogen-containing gas into the chamber, wherein the hydrogen-containing gas includes at least one of hydrogen gas, monosilane gas, and ammonia gas. A plasma generation unit configured to generate plasma from the processing gas within the chamber, Control unit and Equipped with, The control unit is configured to control the gas supply unit and the plasma generation unit so as to etch the first region with the plasma. Plasma processing apparatus, wherein the control unit is configured to control the gas supply unit in the step of etching the first region such that the flow rate of the metal halide gas is less than the flow rate of the hydrogen-containing gas, and the flow rate of the hydrogen-containing gas is less than the flow rate of the carbon and fluorine-containing gas and the flow rate of the nitrogen-containing gas.

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