Etching method and plasma processing apparatus

Abstract

In one exemplary embodiment of the present invention, an etching method includes: (a) a step for providing a substrate on a substrate support unit in a chamber, wherein the substrate comprises a first film that has a recess and a second film that is positioned on the first film, the first film contains a metal element and / or a non-metal element, and the second film has an opening that corresponds to the recess; (b) a step for modifying the side wall of the recess with a first plasma that is generated from a first processing gas; and (c) a step for forming a metal-containing deposit on the second film while etching the bottom of the recess with a second plasma that is generated from a second processing gas which is different from the first processing gas, the second processing gas containing a halogen-containing gas and a metal-containing gas.

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] In the manufacture of electronic devices, plasma etching is sometimes performed on a film to form recesses in the film. To form such recesses, a mask is formed on the film to be etched. A known example of such a mask is a resist mask. The resist mask is consumed during plasma etching of the film to be etched. Therefore, hard masks have been used. As a hard mask, a hard mask made of tungsten silicide (WSi) is known, as described in Patent Document 1.

[0003] Japanese Patent Application Laid-Open No. 2007-294836

[0004] The present disclosure provides techniques for etching films with high etch selectivity.

[0005] In one exemplary embodiment, an etching method includes: (a) providing a substrate on a substrate support in a chamber, the substrate comprising a first film having a recess and a second film on the first film, the first film including tungsten, and the second film having an opening corresponding to the recess; (b) modifying sidewalls of the recess with a first plasma generated from a first process gas, the first process gas including an oxygen-containing gas; and (c) forming a tungsten-containing deposit on the second film while etching a bottom of the recess with a second plasma generated from a second process gas different from the first process gas, the second process gas including a chlorine-containing gas and a tungsten-containing gas.

[0006] According to one exemplary embodiment, a technique is provided for etching a film with high etch selectivity.

[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 cross-sectional view of an exemplary substrate to which the method of FIG. 3 can be applied. FIG. 5 is a cross-sectional view illustrating a step of the 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 cross-sectional view illustrating a step of the 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 an example of the configuration of an inductively coupled plasma processing apparatus as an example of the plasma processing apparatus 1. Fig. 2 is a diagram for explaining an example of the configuration 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 example embodiment. The etching method MT1 shown in FIG. 3 (hereinafter referred to as "method MT1") can be performed by the plasma processing apparatus 1 according to the above embodiment. The method MT1 can be applied to a substrate W.

[0028] Figure 4 is a cross-sectional view of an example substrate to which the method of Figure 3 can be applied. As shown in Figure 4, in one embodiment, the substrate W includes a first film F1 and a second film F2 on the first film F1. The substrate W may further include a third film F3 below the first film F1. The substrate W may further include a base region UR below the third film F3.

[0029] The first film F1 includes a metal element and / or a non-metal element. The first film F1 may include only a metal element, only a non-metal element, or both a metal element and a non-metal element. The first film F1 may include a transition metal element. The first film F1 may include, as a metal element, at least one element selected from the group consisting of tungsten (W), molybdenum (Mo), titanium (Ti), tin (Sn), aluminum (Al), zirconium (Zr), hafnium (Hf), indium (In), ruthenium (Ru), gallium (Ga), and zinc (Zn). The first film F1 may include, as a non-metal element, at least one element selected from the group consisting of silicon (Si), carbon (C), nitrogen (N), oxygen (O), hydrogen (H), boron (B), and phosphorus (P). The first film F1 may be a silicon film. The first film F1 may include tungsten silicide (W). ｘ Si ｙ ), tungsten silicon nitride (W ｘ Si ｙ N ｚ ), tungsten silicon boron (W ｘ Si ｙ B ｚ ) and tungsten silicon carbon (W ｘ Si ｙ C ｚ Each of the composition ratios x, y, and z may be a real number greater than 0. The first film F1 may be a film for forming a hard mask.

[0030] The second film F2 has an opening OP. The second film F2 may have a plurality of openings OP. The opening OP may have a hole pattern or a line pattern. The dimension (CD) of the opening OP may be 45 nm or less, or 28 nm or less. The second film F2 may be a mask. The second film F2 may contain a material different from the material of the first film F1. The second film F2 may contain at least one selected from the group consisting of a metal other than tungsten, silicon, and carbon. The second film F2 may contain at least one selected from the group consisting of a metal-containing film other than a tungsten-containing film, a silicon-containing film, and a carbon-containing film. The second film F2 may be a silicon oxide film, a silicon nitride film, or a silicon oxynitride film. The second film F2 may be a resist mask. The second film F2 may be a photoresist mask containing a metal such as tin. The second film F2 may be a resist mask for EUV exposure. The second film F2 may be a zirconium-containing film or a zirconium oxide-containing film. When the first film F1 is a silicon film, the second film F2 may be a metal-containing film, a carbon-containing film, a silicon nitride film, or a silicon oxynitride film. The second film F2 may have a sparse / dense pattern. The second film F2 may have a plurality of first openings OP arranged at a first pitch and having a first dimension, and a plurality of second openings OP arranged at a second pitch and having a second dimension. The second pitch is different from the first pitch. The second dimension is different from the first dimension. Here, "dimension" refers to the diameter (diameter) of the circle if the opening is circular, and at least one of the major axis and minor axis of the ellipse if the opening is elliptical. When the opening is elliptical, the comparison of the first dimension and the second dimension is performed by comparing the major axes or the minor axes.

[0031] The second film F2 may be formed by pattern reversal. For example, a fourth film is formed on the first film F1, and the fourth film is patterned by photolithography and etching. A fifth film is then formed on the patterned fourth film, and the openings in the fourth film are filled with the fifth film. The patterned fourth film is then removed by lift-off, and the remaining fifth film becomes the second film F2. Pattern reversal technology is described, for example, in Japanese Patent Application No. 2021-173638 filed on October 25, 2021. The entirety of Japanese Patent Application No. 2021-173638 is incorporated herein by reference.

[0032] The third film F3 may be a silicon-containing film or a nitride film. The silicon-containing film may be a silicon nitride film (SiN film) or a silicon carbonitride film (SiCN film). The third film F3 may be an etching stop layer.

[0033] The underlayer region UR may include at least one film for a memory device such as a DRAM or 3D-NAND.

[0034] Method MT1 will be described below with reference to FIGS. 3 to 7, taking as an example a case where method MT1 is applied to a substrate W using the plasma processing apparatus 1 of the above embodiment. Each of FIGS. 5 to 7 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 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.

[0035] As shown in FIG. 3 , the method MT1 may include steps ST1 to ST8. The steps ST1 to ST8 may be performed in order. The steps ST1 to ST8 may be performed in-situ or in-system. When the steps ST1 to ST8 are performed in-system, the chamber in which the step ST6 is performed may be different from the chamber in which the step ST4 is performed. The method MT1 may not include at least one of the steps ST1, ST2, ST5, ST7, and ST8. The step ST1 may be performed after the step ST8.

[0036] (Step ST1) In step ST1, the plasma processing chamber 10 is cleaned. A cleaning gas may be used in step ST1. The cleaning gas may contain fluorine, chlorine, or oxygen.

[0037] (Step ST2) In step ST2, the inner wall of the plasma processing chamber 10 is pre-coated. A pre-coating gas may be used in step ST2. The pre-coating gas may be silicon tetrachloride (SiCl ４ ) gas or aminosilane-based gas.

[0038] 5 is provided on the substrate support 11 in the plasma processing chamber 10. The first film F1 of the substrate W has a recess RS. The recess RS corresponds to the opening OP of the second film F2.

[0039] The recess RS may be formed by etching the first film F1 through the opening OP in the substrate W in FIG. 4 in the plasma processing chamber 10. The etching may be performed in the same manner as in step ST6. The recess RS may be provided in the first film F1 in advance before the substrate W is supplied into the plasma processing chamber 10.

[0040] (Process ST4) In process ST4, as shown in FIG. 6 , the sidewall RSa of the recess RS is modified by a first plasma PL1 generated from the first processing gas. As a result, a modified region MR can be formed on the sidewall RSa of the recess RS. The modified region MR can also be formed on the bottom RSb of the recess RS. The modified region MR may be formed by a reaction of chemical species in the first plasma PL1 with the first film F1. The modified region MR can suppress etching of the sidewall RSa of the recess RS in process ST6.

[0041] The first process gas in step ST4 may include at least one selected from the group consisting of an oxygen-containing gas, a carbon-containing gas, and a nitrogen-containing gas. The oxygen-containing gas may be ozone (O ３ ) gas, hydrogen peroxide (H ２ O ２ ) Gas, H ２ O gas, oxygen (O ２ ) gas, carbon monoxide (CO) gas, and carbon dioxide (CO ２ The carbon-containing gas may include at least one selected from the group consisting of a fluorocarbon gas and a hydrofluorocarbon gas. The nitrogen-containing gas may include nitrogen (N ２ ) gas and ammonia (NH ３ ) gases.

[0042] In step ST4, an electric bias does not have to be supplied to the substrate support portion 11.

[0043] (Step ST5) In step ST5, the internal space of the plasma processing chamber 10 is purged. The purging may be performed by supplying a noble gas into the plasma processing chamber 10. In step ST5, an electric bias may not be supplied to the substrate support 11.

[0044] 7, in step ST6, a second plasma PL2 generated from the second process gas is used to etch the bottom RSb of the recess RS while forming a metal-containing deposit DP on the second film F2. The thickness of the metal-containing deposit DP formed on the top surface of the second film F2 may be greater than the thickness of the metal-containing deposit DP formed on the sidewall defining the opening OP of the second film F2.

[0045] The second process gas used in step ST6 is different from the first process gas used in step ST4. The second process gas includes a halogen-containing gas and a metal-containing gas. The second process gas may further include a noble gas. An example of a noble gas is argon gas. The second process gas may not include carbon or fluorine.

[0046] The halogen-containing gas may be a chlorine-containing gas. The chlorine-containing gas may be chlorine (Cl ２ ) gas and hydrogen chloride (HCl) gas.

[0047] The metal-containing gas may contain a halogen. The metal-containing gas may contain the same metal element as the metal element contained in the first film F1. The metal-containing gas may be a tungsten-containing gas. The tungsten-containing gas may be tungsten hexafluoride (WF ６ The metal-containing gas may be a metal halide gas. An example of a metal halide gas is TiCl. ４ Gas, SnCl ４ Gas, WF ６ Gas, WCl ６ Gas, AlCl ３ Gas, ZrCl ４ Gas, MoF ６ Gas and MoCl ６ Includes gas.

[0048] The ratio of the flow rate of the metal-containing gas to the total flow rate of the second process gas may be 10% by volume or less, or may be 5% by volume or less.

[0049] The metal-containing deposit DP may contain the same metal as that contained in the metal-containing gas of the second process gas. The metal-containing deposit DP may be formed by a reaction between chemical species in the second plasma PL2 and the second film F2. The metal-containing deposit DP may be a metal oxide. An example of a metal oxide is tungsten(VI) oxide (WO ３ ) is included.

[0050] In step ST6, an electric bias may be supplied to the substrate support 11. The processing time of step ST6 may be longer than the processing time of step ST4. The plasma processing chamber in which step ST6 is performed may be the same as or different from the plasma processing chamber in which step ST4 is performed.

[0051] In step ST6, the source RF signal for plasma generation may be pulsed. Step ST6 may include a first period and a second period. In the first period, the source RF signal for plasma generation is supplied at a first level. In the second period, the source RF signal for plasma generation is not supplied, or the source RF signal for plasma generation is supplied at a second level lower than the first level. The first period and the second period may be alternately repeated. The total time (period) of the first period and the second period may be 1 second or less.

[0052] (Step ST7) In step ST7, the internal space of the plasma processing chamber 10 is purged. Step ST7 may be performed in the same manner as step ST5.

[0053] (Step ST8) In step ST8, a cycle including steps ST4 to ST7 is repeated. In each cycle, steps ST4 to ST7 are performed in order. Each cycle may not include step ST5, and may not include step ST7. The cycle may be repeated until the bottom RSb of the recess RS reaches the third film F3. At the end of step ST8, the depth of the recess RS may be 200 nm or more, the dimension of the recess RS may be 45 nm or less, and the aspect ratio of the recess RS may be 15 or more.

[0054] In steps ST4 to ST8, the temperature of the substrate support part 11 may be 0°C or higher, room temperature (e.g., 20°C) or higher, 50°C or higher, 60°C or higher, or 200°C or lower.

[0055] After step ST8, the metal-containing deposit DP may be removed using, for example, diluted hydrofluoric acid (DHF).

[0056] In the method MT1, steps ST4 and ST6 may be performed simultaneously. In this case, steps ST5, ST7, and ST8 are not performed. In the step in which steps ST4 and ST6 are performed simultaneously, a plasma generated from a process gas containing a first process gas and a second process gas is used to modify the sidewall RSa of the recess RS and etch the bottom RSb of the recess RS, while forming a metal-containing deposit DP on the second film F2.

[0057] According to the above-described plasma processing apparatus 1 and method MT1, in step ST6, the metal-containing deposit DP suppresses etching of the second film F2. Therefore, the etching selectivity of the first film F1 relative to the second film F2 can be improved. Furthermore, in step ST6, the modified region MR suppresses etching of the sidewall RSa of the recess RS of the first film F1. Therefore, the first film F1 can be etched while suppressing shape abnormalities (bowing) of the sidewall RSa of the recess RS. Furthermore, in step ST6, when the metal-containing gas contains a halogen, the etching rate of the first film F1 can be improved.

[0058] The method MT1 may be applied to a substrate W including a first film F1 that is a silicon film and a second film F2 that is a carbon-containing film or a silicon oxide film. In this case, the recess RS formed in the first film F1 may be a TSV (through silicon via).

[0059] Various experiments performed to evaluate Method MT1 are described below, but the experiments described below are not intended to limit the present disclosure.

[0060] (First Experiment) In the first experiment, a substrate having a WSiN film and a mask on the WSiN film was prepared. The mask was a silicon oxide film with an opening. This substrate was placed on a substrate support in a plasma processing chamber of a plasma processing apparatus. Next, the WSiN film was etched using plasma to form recesses in the WSiN film. Next, O ２ The sidewalls of the recesses were modified by plasma generated from the gas (step ST4). In step ST4, no bias power was applied to the substrate support. Next, Ar gas was supplied into the plasma processing chamber to purge the internal space of the plasma processing chamber (step ST5). Next, Cl ２ Gas, WF ６ The bottom of the recess was etched by plasma generated from a process gas containing Ar gas, and a tungsten-containing deposit was formed on the mask (step ST6). In step ST6, bias power was applied to the substrate support. In step ST6, the WF ６ The gas flow rate ratio was 0.6% by volume. Next, Ar gas was supplied into the plasma processing chamber to purge the internal space of the plasma processing chamber (step ST7). A cycle including steps ST4 to ST7 was repeated to form deep recesses in the WSiN film. The final depth of the recesses was approximately 340 nm.

[0061] (Second Experiment) In step ST6, WF ６ The experiment was carried out in the same manner as in the first experiment, except that the gas flow rate ratio was set to 1.2% by volume.

[0062] (Third Experiment) In step ST6, WF ６ The experiment was carried out in the same manner as in the first experiment, except that the gas flow rate ratio was set to 1.7% by volume.

[0063] (Etching Rate) The depth of the recesses was measured by observing the cross sections of the substrates obtained in Experiments 1 to 3. The etching rate of the WSiN film was calculated from the depth of the recesses.

[0064] In the first experiment, the etching rate of the WSiN film was 0.9 nm / sec. In the second experiment, the etching rate of the WSiN film was 1.2 nm / sec. In the third experiment, the etching rate of the WSiN film was 1.2 nm / sec. From these results, it can be seen that WF ６ It can be seen that the etching rate of the WSiN film increases as the gas flow rate ratio increases.

[0065] (Fourth Experiment) An experiment was carried out in the same manner as in the second experiment, except that the cycle was repeated until the final depth of the recesses reached about 300 nm.

[0066] (Fifth Experiment) In step ST6, WF ６ CF instead of gas ４ Except for using gas, the experiment was carried out in the same manner as in Experiment 4. The final depth of the recesses was about 300 nm.

[0067] (Etching Selectivity) The depth of the recess and the thickness of the mask were measured by observing the cross sections of the substrates obtained in Experiments 4 and 5. The etching selectivity of the WSiN film to the mask was calculated from the depth of the recess and the thickness of the mask.

[0068] In the fourth experiment, the etching selectivity was about 3. In the fifth experiment, the etching selectivity was about 2. From these results, it was found that WF ６ It can be seen that the use of gas improves the etching selectivity of the WSiN film relative to the mask.

[0069] (Surface Analysis) As in Experiments 1 to 4, a tungsten-containing deposit was formed on a silicon oxide film by plasma. The resulting tungsten-containing deposit was analyzed by X-ray photoelectron spectroscopy (XPS). The results showed that the tungsten-containing deposit was WO ３ It was found to contain.

[0070] (Plasma Measurement) As in the first to fourth experiments, a tungsten-containing deposit was formed on a silicon oxide film by plasma. The emission intensities of W and F in the plasma were measured by inductively coupled plasma optical emission spectroscopy (ICP-OES). ６It was found that the emission intensities of W and F increased as the gas flow rate ratio increased. Furthermore, it was found that the correlation coefficient between the emission intensities of W and F and the etching rate of the WSiN film was larger than the correlation coefficient between the emission intensities of W and F and the etching rate of the silicon oxide film. From these results, it was found that WF ６ It is presumed that the F radicals generated from the gas increase the etching rate of the WSiN film.

[0071] 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.

[0072] Various exemplary embodiments included in the present disclosure are now described in [E1] to [E21] below.

[0073] [E1] An etching method comprising: (a) providing a substrate on a substrate support in a chamber, the substrate comprising a first film having a recess and a second film on the first film, the first film including tungsten, and the second film having an opening corresponding to the recess; (b) modifying sidewalls of the recess with a first plasma generated from a first process gas, the first process gas including an oxygen-containing gas; and (c) forming a tungsten-containing deposit on the second film while etching a bottom of the recess with a second plasma generated from a second process gas different from the first process gas, the second process gas including a chlorine-containing gas and a tungsten-containing gas.

[0074] [E2] The etching method according to [E1], further comprising the step of: (d) purging the internal space of the chamber between (b) and (c).

[0075] [E3] The etching method according to [E1] or [E2], further comprising the step of: (e) repeating a cycle including the steps (b) and (c).

[0076] [E4] The etching method according to [E1], wherein (b) and (c) are carried out simultaneously.

[0077] [E5] The etching method according to any one of [E1] to [E4], wherein the second film contains at least one selected from the group consisting of metals other than tungsten, silicon, and carbon.

[0078] [E6] The etching method according to any one of [E1] to [E5], wherein the chlorine-containing gas includes at least one selected from the group consisting of chlorine gas and hydrogen chloride gas.

[0079] [E7] The etching method according to any one of [E1] to [E6], wherein the tungsten-containing gas contains a halogen.

[0080] [E8] The etching method according to any one of [E1] to [E7], wherein a ratio of a flow rate of the tungsten-containing gas to a total flow rate of the second process gas is 10% by volume or less.

[0081] [E9] The etching method according to any one of [E1] to [E8], wherein the second process gas further contains a noble gas.

[0082] [E10] The oxygen-containing gas is ozone gas, hydrogen peroxide gas, H ２ The etching method according to any one of [E1] to [E9], comprising at least one selected from the group consisting of O gas, oxygen gas, carbon monoxide gas, and carbon dioxide gas.

[0083] [E11] The etching method according to any one of [E1] to [E10], wherein in (c), the temperature of the substrate support part is 0° C. or higher.

[0084] [E12] The etching method according to any one of [E1] to [E11], wherein in (c), the thickness of the tungsten-containing deposit formed on the top surface of the second film is greater than the thickness of the tungsten-containing deposit formed on a sidewall that defines the opening in the second film.

[0085] [E13] The etching method according to any one of [E1] to [E12], wherein (c) includes: (c1) a period in which a source RF signal for plasma generation is supplied at a first level; and (c2) a period in which the source RF signal for plasma generation is not supplied or the source RF signal for plasma generation is supplied at a second level lower than the first level.

[0086] [E14] An etching method comprising the steps of: (a) providing a substrate on a substrate support in a chamber, the substrate comprising a first film having a recess and a second film on the first film, the first film including a metal element and / or a non-metal element, and the second film including an opening corresponding to the recess; (b) modifying a sidewall of the recess with a first plasma generated from a first process gas; and (c) forming a metal-containing deposit on the second film while etching a bottom of the recess with a second plasma generated from a second process gas different from the first process gas, the second process gas including a halogen-containing gas and a metal-containing gas.

[0087] [E15] The etching method according to [E14], wherein the metal element includes at least one selected from the group consisting of tungsten, molybdenum, titanium, tin, aluminum, zirconium, hafnium, indium, ruthenium, gallium, and zinc.

[0088] [E16] The etching method according to [E14], wherein the first film is a silicon film, and the second film is a metal-containing film, a carbon-containing film, a silicon nitride film, or a silicon oxynitride film.

[0089] [E17] The etching method according to [E14] or [E15], wherein the first film contains a metal element and a non-metal element, and the non-metal element contains at least one selected from the group consisting of silicon, carbon, nitrogen, oxygen, hydrogen, boron, and phosphorus.

[0090] [E18] The etching method according to any one of [E14] to [E17], wherein the metal-containing gas contains a halogen.

[0091] [E19] The etching method according to any one of [E14] to [E18], wherein the metal-containing gas contains the same metal element as the metal element contained in the first film.

[0092] [E20] The etching method according to any one of [E14] to [E19], wherein the first process gas contains an oxygen-containing gas.

[0093] a chamber; a substrate support for supporting a substrate in the chamber, the substrate comprising a first film having a recess and a second film on the first film, the first film including tungsten, and the second film having an opening corresponding to the recess; a gas supply unit configured to supply a first process gas and a second process gas into the chamber, respectively, the first process gas including an oxygen-containing gas and the second process gas different from the first process gas, the second process gas including a chlorine-containing gas and a tungsten-containing gas; a plasma generation unit configured to generate a first plasma and a second plasma from the first process gas and the second process gas, respectively; and a controller, wherein the controller is configured to control the gas supply unit and the plasma generation unit to perform an etching method, the etching method comprising: modifying a sidewall of the recess with the first plasma; and forming a tungsten-containing deposit on the second film while etching a bottom of the recess with the second plasma.

[0094] 1...plasma processing apparatus, 2...control unit, 10...plasma processing chamber, 11...substrate support unit, 12...plasma generation unit, 20...gas supply unit, DP...metal-containing deposit, F1...first film, F2...second film, OP...opening, PL1...first plasma, PL2...second plasma, RS...recess, RSa...side wall, RSb...bottom, W...substrate.

Claims

1. An etching method comprising: (a) providing a substrate on a substrate support in a chamber, the substrate comprising a first film having a recess and a second film on the first film, the first film including tungsten, and the second film having an opening corresponding to the recess; (b) modifying sidewalls of the recess with a first plasma generated from a first process gas, the first process gas including an oxygen-containing gas; and (c) forming a tungsten-containing deposit on the second film while etching a bottom of the recess with a second plasma generated from a second process gas different from the first process gas, the second process gas including a chlorine-containing gas and a tungsten-containing gas.

2. The etching method according to claim 1, further comprising the step of: (d) purging the interior space of the chamber between (b) and (c).

3. The etching method according to claim 1 or 2, further comprising the step of: (e) repeating a cycle including steps (b) and (c).

4. The etching method according to claim 1, wherein steps (b) and (c) are carried out simultaneously.

5. The etching method according to claim 1 or 2, wherein the second film contains at least one selected from the group consisting of metals other than tungsten, silicon, and carbon.

6. The etching method according to claim 1 or 2, wherein the chlorine-containing gas includes at least one selected from the group consisting of chlorine gas and hydrogen chloride gas.

7. The etching method according to claim 1 or 2, wherein the tungsten-containing gas contains a halogen.

8. The etching method according to claim 1 or 2, wherein the ratio of the flow rate of the tungsten-containing gas to the total flow rate of the second process gas is 10% by volume or less.

9. The etching method according to claim 1 or 2, wherein the second process gas further comprises a noble gas.

10. The oxygen-containing gas is ozone gas, hydrogen peroxide gas, H ２ 3. The etching method according to claim 1, wherein the gas contains at least one selected from the group consisting of O gas, oxygen gas, carbon monoxide gas, and carbon dioxide gas.

11. The etching method according to claim 1 or 2, wherein in step (c), the temperature of the substrate support is 0° C. or higher.

12. The etching method of claim 1 or 2, wherein in (c), the thickness of the tungsten-containing deposit formed on the top surface of the second film is greater than the thickness of the tungsten-containing deposit formed on the sidewalls that define the opening in the second film.

13. The etching method according to claim 1 or 2, wherein (c) includes: (c1) a period in which a source RF signal for plasma generation is supplied at a first level; and (c2) a period in which a source RF signal for plasma generation is not supplied or a source RF signal for plasma generation is supplied at a second level lower than the first level.

14. An etching method comprising: (a) providing a substrate on a substrate support in a chamber, the substrate comprising a first film having a recess and a second film on the first film, the first film including a metal element and / or a non-metal element, and the second film having an opening corresponding to the recess; (b) modifying a sidewall of the recess with a first plasma generated from a first process gas; and (c) forming a metal-containing deposit on the second film while etching a bottom of the recess with a second plasma generated from a second process gas different from the first process gas, the second process gas including a halogen-containing gas and a metal-containing gas.

15. The etching method according to claim 14, wherein the metal element includes at least one selected from the group consisting of tungsten, molybdenum, titanium, tin, aluminum, zirconium, hafnium, indium, ruthenium, gallium, and zinc.

16. The etching method according to claim 14, wherein the first film is a silicon film, and the second film is a metal-containing film, a carbon-containing film, a silicon nitride film, or a silicon oxynitride film.

17. The etching method according to claim 14 or 15, wherein the first film contains a metal element and a non-metal element, and the non-metal element contains at least one element selected from the group consisting of silicon, carbon, nitrogen, oxygen, hydrogen, boron, and phosphorus.

18. The etching method according to claim 14 or 15, wherein the metal-containing gas contains a halogen.

19. The etching method according to claim 14 or 15, wherein the metal-containing gas contains the same metal element as the metal element contained in the first film.

20. The etching method according to claim 14 or 15, wherein the first process gas includes an oxygen-containing gas.

21. A plasma processing apparatus comprising: a chamber; a substrate support for supporting a substrate in the chamber, the substrate comprising a first film having a recess and a second film on the first film, the first film including tungsten, and the second film having an opening corresponding to the recess; a gas supply unit configured to supply a first process gas and a second process gas into the chamber, respectively, the first process gas including an oxygen-containing gas and the second process gas different from the first process gas, the second process gas including a chlorine-containing gas and a tungsten-containing gas; a plasma generation unit configured to generate a first plasma and a second plasma from the first process gas and the second process gas, respectively; and a controller, wherein the controller is configured to control the gas supply unit and the plasma generation unit to perform an etching method, the etching method comprising: modifying a sidewall of the recess with the first plasma; and forming a tungsten-containing deposit on the second film while etching a bottom of the recess with the second plasma.

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