Etching method and plasma processing apparatus

Abstract

Disclosed is an etching method which includes: (a) a step for providing a substrate on a substrate support part in a chamber, the substrate including a first region and a second region, the first region containing a first material that includes at least one substance selected from the group consisting of silicon oxide and carbon, and the second region containing a second material that is different from the first material; and (b) a step for exposing the substrate to a first plasma which is generated from a first processing gas that contains hydrogen fluoride without applying an electric bias to the substrate support part.

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 method for selectively etching a silicon nitride film, which includes a first step of placing a substrate having a silicon nitride film in a processing space, a second step of introducing a gas containing H and F into the processing space, and a third step of selectively introducing radicals of an inert gas into the processing space.

[0003] Japanese Patent Application Laid-Open No. 2019-12759

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

[0005] In one exemplary embodiment, an etching method includes: (a) providing a substrate on a substrate support in a chamber, the substrate including a first region and a second region, the first region including a first material including at least one selected from the group consisting of silicon oxide and carbon, and the second region including a second material different from the first material; and (b) exposing the substrate to a first plasma generated from a first process gas including hydrogen fluoride without applying an electrical bias to the substrate support.

[0006] According to one exemplary embodiment, an etching method and a plasma processing apparatus capable of improving etching selectivity are provided.

[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 an etching method according to an exemplary embodiment. FIG. 4 is a partial enlarged view of an example substrate to which the method of FIG. 3 can be applied. FIG. 5 is a cross-sectional view illustrating a step of the etching method according to an exemplary embodiment. FIG. 6 is a cross-sectional view illustrating a step of the etching method according to an exemplary embodiment. FIG. 7 is a flowchart of the etching method according to an exemplary embodiment. FIG. 8 is a graph illustrating an example of the relationship between film species and etching amount. FIG. 9 is a partial enlarged view of an example substrate to which the method of FIG. 7 can be applied. FIG. 10 is a cross-sectional view illustrating a step of the etching method according to an exemplary embodiment. FIG. 11 is a flowchart of the etching method according to an exemplary embodiment. FIG. 12 is a partial enlarged view of an example substrate to which the method of FIG. 11 can be applied. FIG. 13 is a cross-sectional view illustrating a step of the etching method according to an exemplary embodiment. FIG. 14 is a cross-sectional view illustrating a step of the etching method according to an exemplary embodiment. FIG. 15 is a cross-sectional view illustrating a step of the etching method according to an exemplary embodiment. 16 is a cross-sectional view showing a step of an etching method according to an exemplary embodiment, FIG. 17 is a flowchart of an etching method according to an exemplary embodiment, and FIG. 18 is a cross-sectional view showing a step of an etching method according to an exemplary embodiment.

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

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

[0010] The plasma generating unit 12 is configured to generate plasma from at least one processing gas supplied into the plasma processing space. The plasma generated in the plasma processing space may be capacitively coupled plasma (CCP), inductively coupled plasma (ICP), electron-cyclotron-resonance plasma (ECR plasma), helicon wave plasma (HWP), surface wave plasma (SWP), or the like. Various types of plasma generators may be used, including alternating current (AC) plasma generators and direct current (DC) plasma generators. In one embodiment, the AC signal (AC power) used in the AC plasma generator has a frequency in the range of 100 kHz to 10 GHz. Thus, AC signals include radio frequency (RF) signals and microwave signals. In one embodiment, the RF signal has a frequency in the range of 100 kHz to 150 MHz.

[0011] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform various processes described in this disclosure. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to perform various processes described herein. In one embodiment, part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The control unit 2 may be implemented by, for example, a computer 2a. The processing unit 2a1 may be configured to read a program from the storage unit 2a2 and execute the read program to perform various control operations. This program may be stored in the storage unit 2a2 in advance or may be acquired via a medium when needed. The acquired program is stored in the storage unit 2a2 and read from the storage unit 2a2 by the processing unit 2a1 for execution. The medium may be various storage media readable by the computer 2a or a communication line connected to the communication interface 2a3. The processing unit 2a1 may be a CPU (Central Processing Unit). The storage unit 2a2 may include a random access memory (RAM), a read-only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a local area network (LAN).

[0012] The following describes a configuration example of 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 an etching method according to one exemplary embodiment. The etching method MT1 shown in FIG. 3 (hereinafter referred to as "method MT1") can be performed by the plasma processing apparatus 1 of the above embodiment. The method MT1 can be applied to the substrate W of FIG.

[0028] FIG. 4 is a cross-sectional view of an example substrate to which the method of FIG. 3 can be applied. As shown in FIG. 4, in one embodiment, the substrate W may include a first region R1 and a second region R2. The first region R1 may be a mask. The first region R1 may have at least one opening OP. The at least one opening OP may be a hole or a slit. The first region R1 may have multiple openings OP. The first region R1 may be a region above the second region R2. The second region R2 may be an etching target film. The substrate W may further include an underlayer region UR. The second region R2 may be a region above the underlayer region UR. The first region R1, the second region R2, and the underlayer region UR may be arranged in this order. Each of the first region R1, the second region R2, and the underlayer region UR may be a film.

[0029] The first region R1 includes a first material. The first material is silicon oxide (SiOｘ ) and carbon, where x is a positive real number. The first material may be a carbon-containing material other than a fluorocarbon. The first material may be at least one carbon-containing material selected from the group consisting of a photoresist (polymer) and amorphous carbon.

[0030] The second region R2 includes a second material. The second material is different from the first material. The second material may be silicon oxide, silicon nitride (SiN ｘ The second material may include at least one selected from the group consisting of silicon oxynitride (SiON), polysilicon, a metal, and carbon. x is a positive real number. The second material may include at least one metal selected from the group consisting of tungsten (W), molybdenum (Mo), and titanium (Ti). The second material may be a compound containing a metal element and a non-metal element. The second material may be at least one selected from the group consisting of metal silicide, metal nitride, and metal carbide. The second material may be tungsten silicide (WSi). The second material may be fluorocarbon.

[0031] The underlying region UR may include metal or silicon.

[0032] Method MT1 will be described below with reference to FIGS. 3 to 6, 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 6 are cross-sectional views showing 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 control unit 2. In method MT1, a substrate W on a substrate support 11 arranged in a plasma processing chamber 10 is processed, as shown in FIG. 2.

[0033] 3, the method MT1 may include steps ST1 to ST4. Steps ST1 to ST4 may be performed in order. Step ST2 may be performed after step ST3. The method MT1 may not include at least one of steps ST2 and ST4.

[0034] (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.

[0035] (Process ST2) In process ST2, as shown in FIG. 5 , the substrate W is exposed to a second plasma PL2 generated from the second process gas while an electric bias is supplied to the substrate support 11. This etches the second region R2. A recess RS is formed in the second region R2 by the etching. The recess RS corresponds to the opening OP in the first region R1. The electric bias supplied to the substrate support 11 may be bias RF power or bias DC power. The supply of the second process gas may be stopped at the end of process ST2.

[0036] The second process gas may include a fluorocarbon gas. Examples of fluorocarbon gases include C ４ F ６ The second process gas may further include an oxygen-containing gas. An example of the oxygen-containing gas includes oxygen gas. The second process gas may include a noble gas and nitrogen (N ２ The gas may further include at least one inert gas selected from the group consisting of: argon (Ar) gas, helium (He) gas, xenon (Xe) gas, and neon (Ne) gas.

[0037] The duration of step ST2 may be 0.1 to 100 seconds, or may be 10 to 50 seconds.

[0038] In step ST2, the temperature of the substrate support part 11 may be 10° C. or higher, 30° C. or higher, or 40° C. or higher. In step ST2, the temperature of the substrate support part 11 may be 150° C. or lower, 120° C. or lower, or 80° C. or lower.

[0039] In step ST2, the pressure inside the plasma processing chamber 10 may be 10 mTorr (1.3 Pa) or more, or 100 mTorr (13 Pa) or less.

[0040] Step ST2 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 so that a second plasma PL2 is generated from the second process gas. The control unit 2 controls the power supply 30 so that an electric bias is supplied to the substrate support unit 11.

[0041] (Process ST3) In process ST3, as shown in FIG. 6 , the substrate W is exposed to a first plasma PL1 generated from a first process gas without supplying an electric bias to the substrate support 11. High-frequency power does not have to be supplied to the substrate support 11. The recess RS may be etched by the first plasma PL1. Deposits attached to the opening OP in process ST2 may be removed by the first plasma PL1. Etching residues from process ST2 may be removed by the first plasma PL1. The supply of the first process gas may be stopped at the end of process ST3.

[0042] The first process gas is different from the second process gas. The first process gas contains hydrogen fluoride gas. The first process gas may further contain at least one inert gas selected from the group consisting of noble gases and nitrogen gas. The flow rate of hydrogen fluoride gas may be the highest among all the flow rates of gases contained in the first process gas. The inert gas that may be contained in the first process gas may be the same as or different from the inert gas contained in the second process gas in step ST2. The first process gas does not need to contain any fluorine-containing gas other than hydrogen fluoride gas.

[0043] The duration of step ST3 may be shorter than the duration of step ST2. The duration of step ST3 may be 0.1 to 100 seconds, or 1 to 5 seconds.

[0044] In step ST3, the temperature of the substrate support part 11 may be 10° C. or higher, 30° C. or higher, or 50° C. or higher. In step ST3, the temperature of the substrate support part 11 may be 150° C. or lower, or 120° C. or lower.

[0045] The pressure in the plasma processing chamber 10 at step ST3 may be higher than the pressure in the plasma processing chamber 10 at step ST2. At step ST3, the pressure in the plasma processing chamber 10 may be 10 mTorr (1.3 Pa) or higher. Alternatively, the pressure in the plasma processing chamber 10 may be 1000 mTorr (130 Pa) or lower.

[0046] Step ST3 may be performed as follows: The gas supply unit 20 supplies a first process 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 a first plasma PL1 is generated from the first process gas. The control unit 2 controls the power supply 30 so that an electrical bias is not supplied to the substrate support unit 11.

[0047] (Step ST4) In step ST4, steps ST2 and ST3 are repeated, thereby increasing the etching amount in the second region R2 and deepening the recess RS.

[0048] According to the method MT1, in step ST3, etching of the first region R1 is suppressed compared to when an electric bias is supplied to the substrate support 11. As a result, the etching selectivity of the second region R2 relative to the first region R1 can be improved.

[0049] Furthermore, in the method MT1, deposits (e.g., deposits containing fluorocarbon) attached to the opening OP in step ST2 can be removed in step ST3. This can prevent the opening OP from being blocked (clogging) by the deposits. Furthermore, the flow rate of the gas (e.g., oxygen-containing gas) for preventing clogging, which is included in the second process gas in step ST2, can be reduced.

[0050] 7 is a flowchart of an etching method according to one example embodiment. The etching method MT2 shown in FIG. 7 (hereinafter referred to as "method MT2") can be performed by the plasma processing apparatus 1 according to the above embodiment. The method MT2 can be applied to the substrate W shown in FIG.

[0051] Method MT2 will be described below with reference to Figures 4, 6, and 7, taking as an example a case where method MT2 is applied to a substrate W using the plasma processing apparatus 1 of the above embodiment. When the plasma processing apparatus 1 is used, method MT2 can be performed in the plasma processing apparatus 1 by controlling each part of the plasma processing apparatus 1 with the control unit 2. In method MT2, a substrate W on a substrate support 11 arranged in a plasma processing chamber 10 is processed, as shown in Figure 2.

[0052] 7, the method MT2 may include steps ST1 and ST3. The steps ST1 and ST3 may be performed in sequence.

[0053] 4 is provided on the substrate support 11 in the plasma processing chamber 10. In this embodiment, the second material included in the second region R2 may include at least one selected from the group consisting of silicon nitride, silicon oxynitride, polysilicon, and a metal.

[0054] 6, in step ST3, the substrate W is exposed to a first plasma PL1 generated from a first process gas containing hydrogen fluoride gas without supplying an electric bias to the substrate support 11. This etches the second region R2. A recess RS is formed in the second region R2 by the etching. The supply of the first process gas may be stopped at the end of step ST3.

[0055] According to the method MT2, in step ST3, etching of the first region R1 is suppressed compared to when an electric bias is supplied to the substrate support 11. As a result, the etching selectivity of the second region R2 relative to the first region R1 can be improved.

[0056] Various experiments conducted to evaluate Methods MT1 and MT2 will be described below, but the experiments described below do not limit the present disclosure.

[0057] In the first experiment, a substrate was provided on a substrate support in a chamber of a plasma processing apparatus (step ST1). The substrate had a silicon oxide film and a mask on the silicon oxide film. The mask contained amorphous carbon.

[0058] Next, while an electric bias was applied to the substrate support, the silicon oxide film was etched through the openings in the mask by a second plasma generated from a second process gas (step ST2). The second process gas was a mixed gas of fluorocarbon gas, Ar gas, and oxygen gas. The temperature of the substrate support in step ST2 was 50°C. The duration of step ST2 was 30 seconds.

[0059] Next, without supplying an electric bias to the substrate support, the substrate was exposed to a first plasma generated from a first process gas (step ST3). The first process gas was a mixed gas of HF gas and Ar gas. The temperature of the substrate support in step ST3 was 60°C. The duration of step ST3 was 2 seconds. Next, steps ST2 and ST3 were repeated 10 times (step ST4).

[0060] (Second Experiment) The second experiment was carried out in the same manner as the first experiment, except that the duration of step ST2 was 25 seconds and step ST4 was carried out so that the number of cycles was 12.

[0061] (Third Experiment) The third experiment was carried out in the same manner as the first experiment, except that the duration of step ST2 was 20 seconds and step ST4 was carried out so that the number of cycles was 15.

[0062] (Fourth Experiment) The fourth experiment was carried out in the same manner as the first experiment, except that the duration of step ST2 was 300 seconds and steps ST3 and ST4 were not carried out.

[0063] (Results of First Experiment) In each of the first to fourth experiments, the cross section of the substrate was observed. The etching amount of the mask and the etching amount of the silicon oxide film were measured, and the etching selectivity ratio of the silicon oxide film to the mask was calculated. The etching selectivity ratio in the first experiment was 5.82. The etching selectivity ratio in the second experiment was 5.63. The etching selectivity ratio in the third experiment was 5.49. The etching selectivity ratio in the fourth experiment was 4.84. Therefore, it was found that performing step ST3 improved the etching selectivity ratio.

[0064] Furthermore, the surface of the substrate was observed in each of the first to fourth experiments. In the fourth experiment, clogging of the mask openings was observed. In the first to third experiments, the occurrence of clogging was suppressed compared to the fourth experiment. Therefore, it was found that performing step ST3 can suppress the occurrence of clogging.

[0065] (Fifth Experiment) In the fifth experiment, first, a substrate was provided on a substrate support in a chamber of a plasma processing apparatus (step ST1). ２ It has a membrane.

[0066] Next, without supplying an electric bias to the substrate support, the substrate was exposed to plasma generated from the process gas (step ST3). The process gas was a mixed gas of HF gas and Ar gas. The temperature of the substrate support in step ST3 was 60° C. The duration of step ST3 was 300 seconds.

[0067] (Sixth Experiment) The sixth experiment was carried out in the same manner as the fifth experiment, except that a substrate having a SiN film on its surface was used.

[0068] (Seventh Experiment) The seventh experiment was carried out in the same manner as the fifth experiment, except that a substrate having a photoresist film on its surface was used.

[0069] (Eighth Experiment) An eighth experiment was carried out in the same manner as the fifth experiment, except that a substrate having a polysilicon film on its surface was used.

[0070] (Ninth Experiment) A ninth experiment was carried out in the same manner as the fifth experiment, except that a substrate having a WSi film on its surface was used.

[0071] (Tenth Experiment) A tenth experiment was carried out in the same manner as the fifth experiment, except that a substrate having a fluorocarbon film on its surface was used.

[0072] (Results of the Second Experiment) In each of the fifth to tenth experiments, the amount of etching of the films included in the substrate was measured. The results are shown in FIG. 8. As shown in FIG. 8, it was found that the WSi film, polysilicon (Poly-Si) film, SiN film, and fluorocarbon (CF) film were most easily etched in this order. SiO ２ It was also found that the SiO film and photoresist (PR) film were hardly etched. ２ The reason why the SiO film is more difficult to etch than the SiN film is thought to be, but is not limited to, the following: ２ The activation energy of the reaction between SiO and HF is much larger than the activation energy of the reaction between SiN and HF. ２ The formation energy of the reaction between SiN and HF is also larger than that of the reaction between SiN and HF.

[0073] 9 is a cross-sectional view of an example substrate to which the method of FIG. 7 can be applied. As shown in FIG. 9, the first region R1 of the substrate W in this embodiment includes a first portion R11 and a second portion R12. The first portion R11 is disposed between the second region R2 and the second portion R12. The base region UR and the first portion R11 may each include silicon oxide. The second region R2 may include metal. The second portion R12 may include carbon, such as SOC (spin-on carbon).

[0074] 7 is applied to the substrate W shown in FIG. 9 using the plasma processing apparatus 1 according to the embodiment, the method will be described below with reference to FIGS. 9 and 10. FIG. 10 is a cross-sectional view showing a step of the etching method according to one exemplary embodiment.

[0075] (Step ST1) In step ST1, the substrate W shown in Fig. 9 is provided on the substrate support 11 in the plasma processing chamber 10. The opening OP in the first region R1 may be formed by etching.

[0076] (Process ST3) In process ST3, as shown in FIG. 10 , the substrate W is exposed to a first plasma PL1 generated from a first process gas containing hydrogen fluoride gas without supplying an electric bias to the substrate support 11. This etches the second region R2. A recess RS is formed in the second region R2 by the etching. The underlying region UR can function as an etching stop layer. In process ST3, the second portion R12 can be removed, but the first portion R11 is difficult to etch.

[0077] 11 is a flowchart of an etching method according to one example embodiment. The etching method MT3 shown in FIG. 11 (hereinafter referred to as "method MT3") can be performed by the plasma processing apparatus 1 of the above embodiment. The method MT3 can be applied to the substrate W of FIG. 12.

[0078] 12 is a cross-sectional view of an example substrate to which the method of FIG. 11 can be applied. As shown in FIG. 12, in one embodiment, the substrate W further includes a base region UR in addition to the first region R1 and the second region R2. The first region R1 and the second region R2 are regions above the base region UR. At least an apex R1t of the first region R1 is exposed. At least an apex R2t of the second region R2 is exposed. The second region R2 is adjacent to the first region R1. The second region R2 may be disposed between a pair of first regions R1. The pair of first region R1 and second region R2 may form a protrusion PT. A plurality of protrusions PT may be arranged spaced apart from one another on the base region UR.

[0079] The first region R1 may include at least one selected from the group consisting of silicon oxide and carbon. The second region R2 may include at least one selected from the group consisting of silicon nitride, polysilicon, fluorocarbon, and metal. The metal that may be included in the second region R2 may include at least one selected from the group consisting of tungsten, molybdenum, niobium (Nb), tantalum (Ta), and titanium. The tungsten that may be included in the second region R2 may be WSi ｘ , W.C. ｘ , W.N. ｘ , W.C. ｘ N ｙ , WSi ｘ Nｙ and W.O. ｘ The x and y may be positive real numbers.

[0080] Method MT3 will be described below with reference to FIGS. 11 to 16, taking as an example a case where method MT3 is applied to the substrate W of FIG. 12 using the plasma processing apparatus 1 of the above embodiment. FIGS. 13 to 16 are cross-sectional views showing steps of an etching method according to one exemplary embodiment. When the plasma processing apparatus 1 is used, method MT3 can be performed in the plasma processing apparatus 1 by controlling each part of the plasma processing apparatus 1 with the control unit 2. In method MT3, a substrate W on a substrate support 11 disposed in a plasma processing chamber 10 is processed, as shown in FIG. 2.

[0081] 11 , the method MT3 may include steps ST1 and ST3. Steps ST1 and ST3 may be performed in sequence. Step ST1 may include steps ST11 to ST13. Steps ST11 to ST13 may be performed in sequence.

[0082] (Step ST1) In step ST1, the substrate W shown in FIG. 12 is provided on the substrate support 11 in the plasma processing chamber 10.

[0083] (Process ST3) In process ST3, as shown in FIG. 13 , without supplying an electric bias to the substrate support 11, the substrate W is exposed to a first plasma PL1 generated from a first process gas containing hydrogen fluoride gas. This etches the second region R2. The second region R2 is selectively etched relative to the first region R1. The second region R2 is removed by etching. As a result, a plurality of first regions R1 are arranged spaced apart from one another on the underlying region UR. The supply of the first process gas may be stopped at the end of process ST3.

[0084] According to the method MT3, in step ST3, etching of the first region R1 is suppressed compared to when an electric bias is supplied to the substrate support 11. As a result, the etching selectivity of the second region R2 relative to the first region R1 can be improved.

[0085] When the step ST1 includes the steps ST11 to ST13, the substrate W shown in FIG. 12 is provided as follows.

[0086] (Process ST11) In process ST11, the substrate W of FIG. 14 is provided. The substrate W includes an underlying region UR, an etching target film R2a on the underlying region UR, and a mask MK on the etching target film R2a. The etching target film R2a includes a second material included in the second region R2. The mask MK includes at least one opening OP1. The mask MK may include carbon, such as amorphous carbon or SOC (Spin-on Carbon).

[0087] 15, in step ST12, the etching target film R2a is etched through the opening OP1 in the mask MK to form a second region R2. The second region R2 has an opening OP2 corresponding to the opening OP1. After the opening OP2 is formed, the mask MK may be removed.

[0088] (Step ST13) In step ST13, as shown in FIG. 16, a first material is deposited on the sidewall of the second region R2 to form the first region R1. After the deposition, a portion of the first region R1 may be removed by etching to expose the top portion R2t of the second region R2 and the underlying region UR. In this manner, the substrate W shown in FIG. 12 is provided.

[0089] The first material can be deposited on the sidewalls of the second region R2 by a method such as ALD or MLD. When depositing the first material by ALD, the substrate W is immersed in a silicon-containing precursor (aminosilane, SiCl ４ , SiF ４ The substrate W is then exposed to a process gas containing an oxygen-containing gas (O ２ , CO, CO ２The substrate W is exposed to plasma generated from a process gas containing a first organic compound, etc., thereby modifying the precursor layer to form a silicon oxide film. When depositing a first material by MLD, the substrate W is exposed to a first process gas containing a first organic compound, thereby forming an adsorption layer in which the first organic compound is adsorbed on the surface of the second region R2. Thereafter, the substrate W is exposed to a second process gas containing a second organic compound different from the first organic compound, thereby forming an organic film through a reaction between the first organic compound and the second organic compound.

[0090] 17 is a flowchart of an etching method according to one example embodiment. The etching method MT4 shown in FIG. 17 (hereinafter referred to as "method MT4") can be performed by the plasma processing apparatus 1 of the above embodiment. The method MT4 can be applied to the substrate W of FIG. 12.

[0091] Method MT4 will be described below with reference to FIGS. 13 and 17 to 18, taking as an example a case where method MT4 is applied to the substrate W of FIG. 12 using the plasma processing apparatus 1 of the above embodiment. FIG. 18 is a cross-sectional view showing a step of an etching method according to one exemplary embodiment. When the plasma processing apparatus 1 is used, method MT4 can be performed in the plasma processing apparatus 1 by controlling each part of the plasma processing apparatus 1 with the control unit 2. In method MT3, a substrate W on a substrate support 11 disposed in a plasma processing chamber 10 is processed as shown in FIG. 2.

[0092] 17, method MT4 may include steps ST1, ST31, and ST21. Steps ST1, ST31, and ST21 may be performed in this order. Step ST31 may be performed after step ST21. Step ST1 may include steps ST11 to ST13. Step ST1 may be performed in the same manner as step ST1 of method MT3.

[0093] (Process ST31) Process ST31 may be performed in the same manner as process ST3. In process ST31, as shown in FIG. 13 , the substrate W is exposed to a first plasma PL1 generated from a first process gas containing hydrogen fluoride gas, with no electric bias or a first level electric bias being supplied to the substrate support 11. This etches the second region R2. The second region R2 is selectively etched relative to the first region R1. The supply of the first process gas may be stopped at the end of process ST31.

[0094] When the electrical bias is bias RF power, the level of the electrical bias is the power level (effective value) of the bias RF power. When the electrical bias is bias DC power, the bias DC power may include a voltage pulse. In this case, the level of the electrical bias is the absolute value of the negative voltage level of the voltage pulse.

[0095] (Process ST21) Process ST21 may be performed in the same manner as process ST2. In process ST21, as shown in FIG. 18, the substrate W is exposed to a second plasma PL2 generated from a second process gas while a second level of electrical bias is supplied to the substrate support 11. The second level is greater than the first level that may be supplied to the substrate support 11 in process ST31. The second process gas may be the same as or different from the first process gas in process ST31. In process ST21, the base region UR may be etched. A recess RS1 is formed in the base region UR by etching. The recess RS1 corresponds to the opening OP in the first region R1. The supply of the second process gas may be stopped at the end of process ST21.

[0096] According to the method MT4, etching of the first region R1 is suppressed in step ST31 compared to when a high level electric bias is supplied to the substrate support 11. As a result, the etching selectivity of the second region R2 relative to the first region R1 can be improved.

[0097] Step ST31 of method MT4 may be performed in step ST3 of methods MT1 to MT3. That is, a first level electric bias may be supplied to the substrate support 11 in step ST3 of methods MT1 to MT3. In this case, step ST21 of method MT4 may be performed in step ST2 of method MT1. That is, a second level electric bias may be supplied to the substrate support 11 in step ST2 of method MT1.

[0098] 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.

[0099] Various exemplary embodiments included in the present disclosure are now described in [E1] to [E20] below.

[0100] [E1] A method of etching, comprising: (a) providing a substrate on a substrate support in a chamber, the substrate comprising a first region and a second region, the first region comprising a first material comprising at least one selected from the group consisting of silicon oxide and carbon, and the second region comprising a second material different from the first material; and (b) exposing the substrate to a first plasma generated from a first process gas comprising hydrogen fluoride without supplying an electrical bias to the substrate support.

[0101] According to the etching method [E1], in (b), etching of the first region is suppressed, and as a result, the etching selectivity of the second region relative to the first region can be improved.

[0102] [E2] The etching method according to [E1], wherein the first region is a region on the second region and has at least one opening.

[0103] [E3] The etching method according to [E1] or [E2], wherein in (b), the temperature of the substrate support part is 10 to 150°C.

[0104] [E4] The etching method according to any one of [E1] to [E3], further comprising the step of: (c) exposing the substrate to a second plasma generated from a second process gas different from the first process gas while supplying the electric bias to the substrate support; and etching the second region by repeating steps (b) and (c).

[0105] [E5] The etching method according to [E4], wherein the duration of (b) is shorter than the duration of (c).

[0106] [E6] The etching method according to any one of [E1] to [E5], wherein the duration of (b) is 0.1 to 100 seconds.

[0107] [E7] The etching method according to [E4] or any one of [E5] to [E6] citing [E4], wherein the duration of (c) is 0.1 to 100 seconds.

[0108] [E8] The etching method according to any one of [E1] to [E7], wherein in (b), high-frequency power is not supplied to the substrate support part.

[0109] [E9] The etching method according to any one of [E1] to [E8], wherein the second material includes at least one selected from the group consisting of silicon oxide, silicon nitride, silicon oxynitride, polysilicon, metal, and carbon.

[0110] [E10] The etching method according to [E4] or any one of [E5] to [E9] citing [E4], wherein the second process gas includes a fluorocarbon gas.

[0111] [E11] The etching method according to any one of [E1] to [E10], wherein the first process gas further contains an inert gas.

[0112] [E12] The etching method according to any one of [E1] to [E11], wherein the second material includes at least one selected from the group consisting of silicon nitride, silicon oxynitride, polysilicon, and metal.

[0113] [E13] The etching method according to any one of [E1] to [E12], wherein the second material includes at least one metal selected from the group consisting of tungsten, molybdenum, and titanium.

[0114] [E14] The etching method according to any one of [E1] to [E13], wherein the substrate further includes an underlying region, the first region and the second region are regions on the underlying region, at least a top portion of each of the first region and the second region is exposed, and the second region is adjacent to the first region.

[0115] [E15] The etching method according to [E14], wherein (a) comprises: (a1) a step of providing the substrate including the base region, an etching target film on the base region, and a mask on the etching target film, wherein the etching target film includes the second material and the mask includes at least one opening; (a2) a step of forming the second region by etching the etching target film through the at least one opening; and (a3) ​​a step of forming the first region by depositing the first material on a sidewall of the second region.

[0116] [E16] The etching method according to any one of [E1] to [E15], wherein in (b), the second region is etched selectively with respect to the first region.

[0117] [E17] An etching method comprising: (a) providing a substrate on a substrate support in a chamber, the substrate comprising a first region and a second region, the first region comprising a first material comprising at least one selected from the group consisting of silicon oxide and carbon, and the second region comprising a second material different from the first material; (b) exposing the substrate to a first plasma generated from a first process gas comprising hydrogen fluoride while applying no electrical bias or a first level of electrical bias to the substrate support; and (c) exposing the substrate to a second plasma generated from a second process gas, the second process gas being the same as or different from the first process gas, while applying a second level of electrical bias to the substrate support that is greater than the first level.

[0118] [E18] The etching method according to [E17], wherein the first region is a region on the second region and has at least one opening, and the second region is etched by repeating steps (b) and (c).

[0119] [E19] The etching method according to [E17], wherein the substrate further includes an underlying region, the first region and the second region are regions on the underlying region, at least a top portion of each of the first region and the second region is exposed, and the second region is adjacent to the first region, and in (b), the second region is selectively etched relative to the first region, and in (c), the underlying region is etched.

[0120] [E20] A plasma processing apparatus comprising: a chamber; a substrate support for supporting a substrate in the chamber, the substrate including a first region and a second region, the first region including a first material including at least one selected from the group consisting of silicon oxide and carbon, and the second region including a second material different from the first material; a gas supply unit configured to supply a first process gas including hydrogen fluoride into the chamber; a plasma generation unit configured to generate a first plasma from the first process gas in the chamber; and a controller, wherein the controller is configured to control the gas supply unit and the plasma generation unit to perform the following step: (b) exposing the substrate to the first plasma without supplying an electric bias to the substrate support unit.

[0121] 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.

[0122] 1...plasma processing apparatus, 2...control section, 10...plasma processing chamber, 11...substrate support section, 12...plasma generation section, 20...gas supply section, PL1...first plasma, R1...first region, R2...second region, W...substrate.

Claims

1. A method of etching comprising: (a) providing a substrate on a substrate support in a chamber, the substrate comprising a first region and a second region, the first region comprising a first material comprising at least one selected from the group consisting of silicon oxide and carbon, and the second region comprising a second material different from the first material; and (b) exposing the substrate to a first plasma generated from a first process gas comprising hydrogen fluoride without supplying an electrical bias to the substrate support.

2. The etching method of claim 1, wherein the first region is a region above the second region and has at least one opening.

3. The etching method according to claim 1, wherein in (b), the temperature of the substrate support is 10 to 150°C.

4. The etching method of claim 2, further comprising the step of: (c) exposing the substrate to a second plasma generated from a second process gas different from the first process gas while supplying the electrical bias to the substrate support; and etching the second region by repeating steps (b) and (c).

5. The etching method of claim 4, wherein the duration of (b) is less than the duration of (c).

6. The etching method according to claim 4 or 5, wherein the duration of (b) is 0.1 to 100 seconds.

7. The etching method according to claim 4 or 5, wherein the duration of (c) is 0.1 to 100 seconds.

8. The etching method according to claim 4 or 5, wherein in (b), no high-frequency power is supplied to the substrate support.

9. The etching method according to claim 4 or 5, wherein the second material includes at least one selected from the group consisting of silicon oxide, silicon nitride, silicon oxynitride, polysilicon, metal and carbon.

10. The etching method according to claim 4 or 5, wherein the second process gas comprises a fluorocarbon gas.

11. The etching method according to claim 4 or 5, wherein the first process gas further comprises an inert gas.

12. The etching method of claim 2, wherein the second material comprises at least one selected from the group consisting of silicon nitride, silicon oxynitride, polysilicon, and a metal.

13. The etching method of claim 2, wherein the second material comprises at least one metal selected from the group consisting of tungsten, molybdenum, and titanium.

14. The etching method of claim 1, wherein the substrate further includes an underlying region, the first region and the second region are regions on the underlying region, at least a top portion of each of the first region and the second region is exposed, and the second region is adjacent to the first region.

15. The etching method of claim 14, wherein (a) comprises: (a1) providing the substrate including an underlying region, a film to be etched on the underlying region, and a mask on the film to be etched, the film to be etched including the second material, and the mask including at least one opening; (a2) forming the second region by etching the film to be etched through the at least one opening; and (a3) ​​forming the first region by depositing the first material on a sidewall of the second region.

16. The etching method according to claim 14 or 15, wherein in (b), the second region is etched selectively with respect to the first region.

17. A method of etching comprising: (a) providing a substrate on a substrate support in a chamber, the substrate comprising a first region and a second region, the first region comprising a first material comprising at least one selected from the group consisting of silicon oxide and carbon, and the second region comprising a second material different from the first material; (b) exposing the substrate to a first plasma generated from a first process gas comprising hydrogen fluoride while providing no electrical bias or a first level of electrical bias to the substrate support; and (c) exposing the substrate to a second plasma generated from a second process gas, the same as or different from the first process gas, while providing a second level of electrical bias to the substrate support that is greater than the first level.

18. The etching method according to claim 17, wherein the first region is a region on the second region and has at least one opening, and the second region is etched by repeating steps (b) and (c).

19. The etching method of claim 17, wherein the substrate further includes an underlying region, the first region and the second region are regions on the underlying region, at least a top portion of each of the first region and the second region is exposed, and the second region is adjacent to the first region, (b) etching the second region selectively with respect to the first region, and (c) etching the underlying region.

20. A plasma processing apparatus comprising: a chamber; a substrate support for supporting a substrate in the chamber, the substrate comprising a first region and a second region, the first region comprising a first material comprising at least one selected from the group consisting of silicon oxide and carbon, and the second region comprising a second material different from the first material; a gas supply unit configured to supply a first process gas comprising hydrogen fluoride into the chamber; a plasma generation unit configured to generate a first plasma from the first process gas in the chamber; and a control unit, wherein the control unit is configured to control the gas supply unit and the plasma generation unit to perform the following step: (b) exposing the substrate to the first plasma without supplying an electrical bias to the substrate support unit.

Images