JP2024064179A - Etching method and plasma processing apparatus - Google Patents

Abstract

[Problem] To provide an etching method and plasma processing apparatus that can obtain a high etching selectivity. [Solution] The etching method includes the steps of: (a) preparing a substrate, the substrate including a first region including a first material and a second region including a second material different from the first material; (b) forming a deposit on the substrate using a first plasma generated from a first process gas including carbon; and (c) after (b), etching the second region with a chemical species generated from the deposit on the second region using a second plasma generated from a second process gas different from the first process gas, at least one of the first process gas or the second process gas including a metal-containing gas. [Selected Figure] Figure 3

Description

An exemplary embodiment of the present disclosure relates to an etching method and a plasma processing apparatus.

Japanese Patent Application Laid-Open No. 2003-233633 discloses a method for etching an insulating film using plasma. In this method, etching _is performed while forming a conductive layer on the surface of the insulating film during etching. In the etching, plasma generated from a mixed gas of _WF6 and _C4F8 is used.

Japanese Patent Application Laid-Open No. 9-50984

This disclosure provides an etching method and plasma processing apparatus that can achieve a high etching selectivity ratio.

In one exemplary embodiment, the etching method includes: (a) preparing a substrate, the substrate including a first region including a first material and a second region including a second material different from the first material; (b) forming a deposit on the substrate using a first plasma generated from a first process gas including carbon; and (c) after (b), etching the second region with a chemical species generated from the deposit on the second region using a second plasma generated from a second process gas different from the first process gas, at least one of the first process gas or the second process gas including a metal-containing gas.

According to one exemplary embodiment, an etching method and a plasma processing apparatus are provided that provide a high etching selectivity ratio.

FIG. 1 is a schematic diagram of a plasma processing apparatus according to an exemplary embodiment. FIG. 2 is a schematic diagram of a plasma processing apparatus according to an exemplary embodiment. FIG. 3 is a flow chart of an etching method according to one exemplary embodiment. FIG. 4 is an enlarged cross-sectional view of a portion of an example substrate to which the method of FIG. 3 may be applied. FIG. 5 is a cross-sectional view illustrating a step of an etching method according to an exemplary embodiment. FIG. 6 is a cross-sectional view illustrating a step of an etching method according to an exemplary embodiment. FIG. 7 is a cross-sectional view illustrating a step of an etching method according to an exemplary embodiment. FIG. 8 is a graph showing an example of the relationship between the bias power and the etching characteristics. FIG. 9 is a graph showing an example of the relationship between the bias power and the etching characteristics.

Various exemplary embodiments will be described in detail below with reference to the drawings. Note that the same or equivalent parts in each drawing will be given the same reference numerals.

Figure 1 is a diagram for explaining an example of the configuration of a plasma processing system. In one embodiment, the plasma processing system includes a plasma processing device 1 and a control unit 2. The plasma processing system is an example of a substrate processing system, and the plasma processing device 1 is an example of a substrate processing device. The plasma processing device 1 includes a plasma processing chamber 10, a substrate support unit 11, and a plasma generation unit 12. The plasma processing chamber 10 has a plasma processing space. The plasma processing chamber 10 also has at least one gas supply port for supplying at least one processing gas to the plasma processing space, and at least one gas 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 unit 11 is disposed in the plasma processing space and has a substrate support surface for supporting a substrate.

The plasma generating unit 12 is configured to generate plasma from at least one processing gas supplied into the plasma processing space. The plasma formed in the plasma processing space may be capacitively coupled plasma (CCP), inductively coupled plasma (ICP), electron-cyclotron-resonance plasma (ECR plasma), helicon wave excited plasma (HWP), or surface wave plasma (SWP), etc. In addition, various types of plasma generating units may be used, including an alternating current (AC) plasma generating unit and a direct current (DC) plasma generating unit. In one embodiment, the AC signal (AC power) used in the AC plasma generating unit has a frequency in the range of 100 kHz to 10 GHz. Thus, the AC signal includes an RF (Radio Frequency) signal and a microwave signal. In one embodiment, the RF signal has a frequency in the range of 100 kHz to 150 MHz.

The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to execute various steps described in this disclosure. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to execute various steps described herein. In one embodiment, a part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The control unit 2 is realized, for example, by a computer 2a. The processing unit 2a1 may be configured to perform various control operations by reading a program from the storage unit 2a2 and executing the read program. This program may be stored in the storage unit 2a2 in advance, or may be acquired via a medium when necessary. The acquired program is stored in the storage unit 2a2 and is read from the storage unit 2a2 by the processing unit 2a1 and executed. The medium may be various storage media readable by the computer 2a, or may be 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 RAM (Random Access Memory), a ROM (Read Only Memory), a HDD (Hard Disk Drive), a SSD (Solid State Drive), or a combination of these. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a LAN (Local Area Network).

Below, an example of the configuration of a capacitively coupled plasma processing apparatus is described as an example of the plasma processing apparatus 1. Figure 2 is a diagram for explaining an example of the configuration of a capacitively coupled plasma processing apparatus.

The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply 30, and an exhaust system 40. The plasma processing apparatus 1 also includes a substrate support unit 11 and a gas inlet unit. The gas inlet unit is configured to introduce at least one processing gas into the plasma processing chamber 10. The gas inlet unit includes a shower head 13. The substrate support unit 11 is disposed in the plasma processing chamber 10. The shower head 13 is disposed above the substrate support unit 11. In one embodiment, the shower head 13 constitutes at least a part of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the shower head 13, the sidewall 10a of the plasma processing chamber 10, and the substrate support unit 11. The plasma processing chamber 10 is grounded. The shower head 13 and the substrate support unit 11 are electrically insulated from the housing of the plasma processing chamber 10.

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 the 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.

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 may function as a lower electrode. The electrostatic chuck 1111 is disposed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic electrode 1111b disposed within the ceramic member 1111a. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Note that other members surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member, may have the annular region 111b. In this case, the ring assembly 112 may be disposed on the annular electrostatic chuck or the annular insulating member, or may be disposed on both the electrostatic chuck 1111 and the annular insulating member. Also, at least one RF/DC electrode coupled to an RF power source 31 and/or a DC power source 32 described later may be disposed in the ceramic member 1111a. In this case, the at least one RF/DC electrode functions as a lower electrode. When a bias RF signal and/or a DC signal described later is supplied to the at least one RF/DC electrode, the RF/DC electrode is also called a bias electrode. Note that the conductive member of the base 1110 and the at least one RF/DC electrode may function as multiple lower electrodes. Also, the electrostatic electrode 1111b may function as a lower electrode. Thus, the substrate support 11 includes at least one lower electrode.

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.

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 back surface of the substrate W and the central region 111a.

The shower head 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The shower head 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and multiple gas inlets 13c. The processing gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s from the multiple gas inlets 13c. The shower head 13 also includes at least one upper electrode. In addition to the shower head 13, the gas introduction unit may include one or more side gas injectors (SGIs) attached to one or more openings formed in the sidewall 10a.

The gas supply 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply 20 is configured to supply at least one process gas from a respective gas source 21 through a respective flow controller 22 to the showerhead 13. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, the gas supply 20 may include at least one flow modulation device that modulates or pulses the flow rate of the at least one process gas.

The power supply 30 includes an RF power supply 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power supply 31 is configured to supply at least one RF signal (RF power) to at least one lower electrode and/or at least one upper electrode. This causes a plasma to be formed from at least one processing gas supplied to the plasma processing space 10s. Thus, the RF power supply 31 can function as at least a part of the plasma generating unit 12. In addition, by supplying a bias RF signal to at least one lower electrode, a bias potential is generated on the substrate W, and ion components in the formed plasma can be attracted to the substrate W.

In one embodiment, the RF power supply 31 includes a first RF generating section 31a and a second RF generating section 31b. The first RF generating section 31a is coupled to at least one lower electrode and/or at least one upper electrode via at least one impedance matching circuit and 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 section 31a may be configured to generate multiple source RF signals having different frequencies. The generated one or more source RF signals are supplied to at least one lower electrode and/or at least one upper electrode.

The second RF generator 31b is coupled to at least one lower electrode via at least one impedance matching circuit and 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 lower frequency 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 provided to at least one lower electrode. Also, in various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

The power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generator 32a and a second DC generator 32b. In one embodiment, the first DC generator 32a is connected to at least one lower electrode and configured to generate a first DC signal. The generated first DC signal is applied to the at least one lower electrode. In one embodiment, the second DC generator 32b is connected to at least one upper electrode and configured to generate a second DC signal. The generated second DC signal is applied to the at least one upper electrode.

In various embodiments, the first and second DC signals may be pulsed. In this case, a sequence of voltage pulses is applied to at least one lower electrode and/or at least one upper electrode. The voltage pulses may have a rectangular, trapezoidal, triangular, or combination thereof pulse waveform. In one embodiment, a waveform generator for generating a sequence of voltage pulses from the DC signal is connected between the first DC generator 32a and at least one lower electrode. Thus, the first DC generator 32a and the waveform generator constitute a voltage pulse generator. When the second DC generator 32b and the waveform generator constitute a voltage pulse generator, the voltage pulse generator is connected to at least one upper electrode. The voltage pulses may have a positive polarity or a negative polarity. Also, the sequence of voltage pulses may include one or more positive polarity voltage pulses and one or more negative polarity voltage pulses within one period. The first and second DC generating units 32a and 32b may be provided in addition to the RF power source 31, or the first DC generating unit 32a may be provided in place of the second RF generating unit 31b.

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 adjusted by the pressure regulating valve. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

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

Figure 4 is a partially enlarged 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 region R1 and a second region R2. The first region R1 may have at least one recess R1a. The first region R1 may have multiple recesses R1a. Each recess R1a may be a recess for forming a contact hole or a recess for forming a line pattern. The second region R2 may be present in the recess R1a or may be embedded in the recess R1a. The second region R2 may be provided to cover the first region R1.

The first region R1 includes a first material. The first material may include silicon and nitrogen. The first region R1 may include silicon nitride (SiN _x ). The first region R1 may be a region formed by, for example, CVD or the like, or may be a region obtained by nitriding silicon. The first region R1 may include a first portion including silicon nitride (SiN _x ) and a second portion including silicon carbide (SiC). In this case, the first portion has a recess R1a.

The second region R2 includes a second material. The second material is different from the first material. The second material may include silicon. The second material may include oxygen. The second region R2 may include silicon oxide (SiO _x ). The second region R2 may be a region formed by, for example, CVD or the like, or may be a region obtained by oxidizing silicon. The second region R2 may have a recess R2a. The recess R2a has a width larger than the width of the recess R1a.

The substrate W may include an underlying region UR and at least one raised region RA provided on the underlying region UR. The underlying region UR and the at least one raised region RA are covered by a first region R1. The underlying region UR may include silicon. A plurality of raised regions RA are located on the underlying region UR. Recesses R1a of the first region R1 are located between the plurality of raised regions RA. Each raised region RA may form a gate region of a transistor.

The substrate W may include a mask MK. The mask MK is provided on the second region R2. The mask MK may include metal or silicon. The mask MK may have an opening OP. The opening OP corresponds to the recess R2a of the second region R2.

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. Figs. 5 to 7 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 by the 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.

As shown in FIG. 3, method MT1 may include steps ST1, ST2, ST3, and ST4. Steps ST1 to ST4 may be performed in sequence. Method MT1 may not include step ST4.

(Step ST1)
In step ST1, a substrate W shown in Fig. 4 is prepared. The substrate W may be supported by a substrate support 11 in a plasma processing chamber 10. The substrate W may have the shape shown in Fig. 4 as a result of plasma etching, or may have the shape shown in Fig. 4 from the beginning when it is provided to the plasma processing chamber 10. In step ST1, the second region R2 may be provided so as to cover the first region R1. In step ST1, the second region R2 may be etched so that the upper surface of the first region R1 and the upper surface of the second region R2 are exposed.

(Step ST2)
In step ST2, as shown in Fig. 5, a deposit DP is formed on the substrate W using a first plasma PL1 generated from a first processing gas. The deposit DP may include a first deposit DP1 formed on the first region R1 and a second deposit DP2 formed on the second region R2. The first deposit DP1 may be thicker than the second deposit DP2. The deposit DP may be formed on the mask MK. At the end of step ST2, the supply of the first processing gas is stopped.

The first process gas includes carbon. The first process gas may include fluorine. The first process gas may include at least one of fluorocarbon ( _{CxFy )} gas or hydrofluorocarbon ( _{CxHyFz )} gas. Each of x, y, and _z is a natural number. Examples of fluorocarbon gas include _CF4 gas, _C3F6 gas, _C3F8 gas _{, C4F8} gas, and _C4F6 gas. Examples of _{hydrofluorocarbon} gas include _{CH2F2 gas} , _CHF3 gas _, and _{CH3F gas} .

The first process gas may not include a metal-containing gas, or may further include a metal-containing gas. The metal-containing gas may include at least one element selected from the group consisting of tungsten and molybdenum. The metal-containing gas may include at least one selected from the group consisting of a tungsten halide gas and a molybdenum halide gas. The tungsten halide gas may include at least one selected from the group consisting of a tungsten hexafluoride (WF ₆ ) gas, a tungsten hexabromide (WBr ₆ ) gas, a tungsten hexachloride (WCl ₆ ) gas, and a WF ₅ Cl gas. The molybdenum halide gas may include at least one selected from the group consisting of a molybdenum hexafluoride (MoF ₆ ) gas and a molybdenum hexachloride (MoCl ₆ ) gas.

The first process gas may further include an oxygen-containing gas. Examples of the oxygen-containing gas include oxygen gas and carbon dioxide (CO ₂ ) gas. The first process gas may further include a noble gas. Examples of the noble gas include argon gas, helium gas, xenon gas, and neon gas. The first process gas may further include a nitrogen-containing gas. Examples of the nitrogen-containing gas include nitrogen gas.

The deposit DP may contain carbon. The deposit DP may contain fluorine. The carbon and fluorine originate from the first processing gas. The deposit DP may further contain a metal and a halogen. The metal and halogen originate from a metal-containing gas contained in the first processing gas. The deposit DP may contain a metal-containing layer on the substrate W and a carbon-containing layer on the metal-containing layer. The metal-containing layer is more likely to be formed on the first region R1 than on the second region R2. The metal-containing layer may further contain a halogen. The carbon-containing layer further contains fluorine. Since the carbon-containing layer is less likely to be formed on the metal-containing layer, deposition of an excessive carbon-containing layer can be suppressed.

The processing time of step ST2 may be longer than 0 seconds, and may be less than 5 seconds, or may be less than 3 seconds.

In step ST2, bias power does not need to be applied to the substrate support portion 11.

A transition step may be performed between steps ST2 and ST3. In the transition step, the substrate W is processed using plasma generated from a processing gas containing a noble gas.

(Step ST3)
In step ST3, as shown in FIG. 6, the second region R2 is etched by chemical species generated from the second deposit DP2 on the second region R2 using a second plasma PL2 generated from the second processing gas. The chemical species may be generated by ions in the second plasma PL2 colliding with the second deposit DP2. The chemical species may include a halogen. In step ST3, the second deposit DP2 on the second region R2 may be removed. In step ST3, the thickness of the first deposit DP1 on the first region R1 may be reduced. At the end of step ST3, the supply of the second processing gas is stopped.

The second process gas in step ST3 is different from the first process gas in step ST2. The second process gas may include a noble gas. Examples of noble gases include argon gas, helium gas, xenon gas, and neon gas. The second process gas may not include a metal-containing gas, or may further include a metal-containing gas. Examples of metal-containing gases that may be included in the second process gas are the same as the examples of metal-containing gases that may be included in the first process gas. The second process gas may not include carbon.

The processing time of step ST3 may be longer than the processing time of step ST2. The processing time of step ST3 may be longer than 0 seconds, and may be 5 seconds or less, or 3 seconds or less.

In step ST3, bias power may be applied to the substrate support 11. The bias power may be 50 W or more, 75 W or more, or 100 W or more. The bias power may be 250 W or less, 200 W or less, or 150 W or less.

The above-mentioned transition process may be performed between step ST3 and step ST4.

(Step ST4)
In step ST4, steps ST2 and ST3 are repeated. The number of times (the number of cycles) of each of steps ST2 and ST3 may be 10 or more, or 100 or less. When step ST4 is not performed, the number of cycles is 1. In step ST4, the above-mentioned transition step may be performed between steps ST2 and ST3. The step ST4 can increase the amount of etching in the second region R2. By etching the second region R2, a contact hole HL can be formed as shown in FIG. 7. The contact hole HL corresponds to the recess R1a of the first region R1. In this way, steps ST1 to ST4 may be performed in the etching of a self-aligned contact (SAC) structure. At the end of step ST4, the first deposit DP1 may remain on the first region R1. In this case, the etching of the first region R1 in step ST4 is suppressed. The remaining first deposit DP1 can be removed by cleaning after step ST4. At the end of step ST4, the first deposit DP1 may not be present on the first region R1.

The above method MT1 can increase the etching selectivity of the second region R2 relative to the first region R1.

When the first process gas in step ST2 shown in FIG. 5 contains a metal-containing gas, the mechanism by which the etching selectivity ratio increases is presumed to be as follows, but is not limited to this.

The first deposit DP1 formed on the first region R1 in step ST2 contains metal derived from the metal-containing gas contained in the first processing gas. In this case, the etching rate of the first deposit DP1 in step ST3 is smaller than when the first deposit DP1 does not contain metal. Furthermore, the second deposit DP2 formed on the second region R2 in step ST2 may contain halogen. The halogen contained in the second deposit DP2 contributes to the etching of the second region R2 in step ST3. Therefore, the etching rate of the second region R2 in step ST3 is increased. Therefore, the etching selectivity of the second region R2 relative to the first region R1 can be increased.

According to the above method MT1, since the etching rate of the first deposit DP1 in the step ST3 is small, the first region R1 can be protected even if the first deposit DP1 is thin. It is possible to suppress clogging of the recess R1a caused by the excess first deposit DP1. If the first deposit DP1 is thin, the excess first deposit DP1 is less likely to protrude into the recess R1a. Therefore, it is possible to suppress a part of the second region R2 from being etched due to the excess first deposit DP1 located on the second region R2. Therefore, it is possible to improve the etching permeability. The smaller the area of the second region R2 that remains unetched in the recess R1a, the higher the etching permeability. When the first processing gas in the step ST2 contains an oxygen-containing gas, the first deposit DP1 is less likely to remain on the second region R2, so the etching permeability can be further improved.

When the second process gas in step ST3 shown in FIG. 6 contains a metal-containing gas, the mechanism by which the etching selectivity ratio increases is presumed to be as follows, but is not limited to this.

In step ST3, the metal-containing gas contained in the second processing gas forms a metal deposit on the first deposit DP1 formed on the first region R1 in step ST2. Therefore, the first deposit DP1 in step ST3 contains a metal. In this case, the etching rate of the first deposit DP1 in step ST3 is smaller than when the first deposit DP1 does not contain a metal. Furthermore, in step ST3, when the metal-containing gas contained in the second processing gas contains a halogen, the halogen contributes to etching the second region R2. Therefore, the etching rate of the second region R2 in step ST3 is increased. Therefore, the etching selectivity ratio of the second region R2 to the first region R1 can be increased.

According to the above method MT1, since the etching rate of the first deposit DP1 in step ST3 is small, the first region R1 can be protected even if the first deposit DP1 is thin. It is possible to suppress clogging of the recess R1a caused by excess first deposit DP1. If the first deposit DP1 is thin, the excess first deposit DP1 is less likely to protrude into the recess R1a. Therefore, it is possible to suppress a portion of the second region R2 from being etched due to the first deposit DP1 located on the second region R2. Therefore, it is possible to improve the etching permeability. When the first processing gas in step ST2 contains an oxygen-containing gas, the first deposit DP1 is less likely to remain on the second region R2, so the etching permeability can be further improved.

Various experiments conducted to evaluate method MT1 are described below. The experiments described below are not intended to limit the scope of this disclosure.

(First Experiment)
In the first experiment, a substrate W including a first region R1 including silicon nitride (SiN _x ) and a second region R2 including silicon oxide (SiO _x ) was prepared. The substrate W did not have a pattern. Then, the process ST2 to the process ST4 were performed on the substrate W using the plasma processing apparatus 1.

In step ST2, a first plasma PL1 was generated from a first processing gas. A deposit was formed on the substrate W by using the first plasma PL1. The first processing gas was a mixed gas of tungsten hexafluoride (WF ₆ ) gas, C ₄ F ₆ gas, argon (Ar) gas, and oxygen (O ₂ ) gas. No bias power was applied to the substrate support 11 in step ST2.

In step ST3, a second plasma PL2 was generated from the second processing gas. The second region R2 was etched using the second plasma PL2. The second processing gas was argon gas. The bias power applied to the substrate support 11 in step ST3 was 200 W.

In step ST4, steps ST2 and ST3 were repeated so that steps ST2 and ST3 were performed 30 times. A transition step was performed between steps ST2 and ST3. In the transition step, the substrate W was processed using plasma generated from argon gas.

(Second Experiment)
In the second experiment, the same method as in the first experiment was carried out, except that oxygen gas was removed from the first process gas.

(Third Experiment)
In the third experiment, the same method as in the first experiment was carried out, except that the tungsten hexafluoride gas was removed from the first process gas.

(First Experimental Results)
A TEM image of a cross section of the substrate W on which the method was performed in the first to third experiments was observed. From the TEM image, the etching amount of the first region R1 and the etching amount of the second region R2 were measured, and the etching selectivity ratio of the second region R2 to the first region R1 was calculated. In the first experiment, the etching amount of the first region R1 was 3.1 nm, and the etching amount of the second region R2 was 13.4 nm. Thus, in the first experiment, the etching selectivity ratio was 4.3. In the second experiment, the etching amount of the first region R1 was 2.2 nm, and the etching amount of the second region R2 was 12.3 nm. Thus, in the second experiment, the etching selectivity ratio was 5.6. In the third experiment, the etching amount of the first region R1 was 3.7 nm, and the etching amount of the second region R2 was 7.6 nm. Thus, in the third experiment, the etching selectivity ratio was 2.1. In the first and second experiments, the etching rate in the first region R1 was smaller, the etching rate in the second region R2 was larger, and the etching selectivity was larger than in the third experiment.

(Fourth Experiment)
In the fourth experiment, a substrate W having the pattern shown in FIG. 4 was used, and the same method as the first experiment was carried out, except that the number of times that the process ST2 and the process ST3 were carried out was 65.

(Fifth Experiment)
In the fifth experiment, the same method as the fourth experiment was carried out, except that the flow rate of the oxygen gas contained in the first process gas was increased.

(Sixth Experiment)
In the sixth experiment, the same method as in the fourth experiment was carried out, except that the tungsten hexafluoride gas was removed from the first process gas.

(Results of the second experiment)
In the fourth to sixth experiments, a TEM image of a cross section of the substrate W on which the method was performed was observed. From the TEM image, the etching amount of the first region R1 and the etching amount of the second region R2 were measured, and the etching selectivity ratio of the second region R2 to the first region R1 was calculated. In the fourth experiment, the etching amount of the first region R1 was 6.4 nm, and the etching amount of the second region R2 was 53.4 nm. Thus, in the fourth experiment, the etching selectivity ratio was 8.3. In the fifth experiment, the etching amount of the first region R1 was 6.5 nm, and the etching amount of the second region R2 was 53.9 nm. Thus, in the fifth experiment, the etching selectivity ratio was 8.3. In the sixth experiment, the etching amount of the first region R1 was 5.9 nm, and the etching amount of the second region R2 was 26.8 nm. Thus, in the sixth experiment, the etching selectivity ratio was 4.5. In the fourth and fifth experiments, the etching rate of the second region R2 was larger than in the sixth experiment, and the etching selectivity ratio was larger.

The upper surface of the substrate W on which the method was performed in the fourth to sixth experiments was observed. The etching performance was confirmed in the recess R1a. In the fourth and fifth experiments, the etching performance was higher than in the sixth experiment. In the fifth experiment, the etching performance was higher than in the fourth experiment.

(Experiment 7)
In the seventh experiment, the same method as in the fourth experiment was carried out, except that a substrate W with a different pattern was used.

(Experiment 8)
In the eighth experiment, the same method as in the seventh experiment was carried out, except that the bias power in step ST3 was set to 175 W.

(9th Experiment)
In the ninth experiment, the same method as in the seventh experiment was carried out, except that the bias power in step ST3 was set to 150 W.

(Experiment 10)
In the tenth experiment, the same method as in the seventh experiment was carried out, except that the bias power in step ST3 was set to 125 W.

(Experiment 11)
In the twelfth experiment, the same method as in the seventh experiment was carried out, except that the bias power in step ST3 was set to 100 W.

(Third Experimental Results)
A TEM image of a cross section of the substrate W on which the method was performed in the seventh to eleventh experiments was observed. From the TEM image, the etching rate of the second region R2 and the etching selectivity of the second region R2 with respect to the first region R1 were calculated. The results are shown in FIG.

Figure 8 is a graph showing an example of the relationship between bias power and etching characteristics. The vertical axis of the graph shows the etching rate [nm/cycle] or the etching selectivity ratio. The etching rate [nm/cycle] is the amount of etching of the second region R2 etched in one cycle including steps ST2 and ST3. The horizontal axis of the graph shows the bias power [W]. In the graph, REF shows the etching rate and the etching selectivity ratio when neither the first processing gas nor the second processing gas contains tungsten hexafluoride gas. As shown in Figure 8, in the seventh to eleventh experiments, the etching rate and the etching selectivity of the second region R2 were larger than when neither the first processing gas nor the second processing gas contains tungsten hexafluoride gas. Furthermore, it can be seen from Figure 8 that the etching rate of the second region R2 increases as the bias power increases. It can be seen that the etching selectivity ratio is maximum when the bias power is 150 W.

(Experiment 12)
In the twelfth experiment, the same method as the ninth experiment was performed, except that the tungsten hexafluoride gas was removed from the first process gas in the step ST2 and the tungsten hexafluoride gas was added to the second process gas in the step ST3. The bias power in the step ST3 was 150 W.

(13th Experiment)
In the thirteenth experiment, the same method as in the twelfth experiment was carried out, except that the bias power in step ST3 was set to 100 W.

(Experiment 14)
In the fourteenth experiment, the same method as in the twelfth experiment was carried out, except that the bias power in step ST3 was set to 75 W.

(Results of the fourth experiment)
A TEM image of a cross section of the substrate W on which the method was performed in the twelfth to fourteenth experiments was observed. From the TEM image, the etching rate of the second region R2 and the etching selectivity of the second region R2 with respect to the first region R1 were calculated. The results are shown in FIG. 9.

Figure 9 is a graph showing an example of the relationship between bias power and etching characteristics. The vertical and horizontal axes of the graph in Figure 9 are the same as those of the graph in Figure 8. In the graph, REF indicates the etching rate and etching selectivity when neither the first processing gas nor the second processing gas contains tungsten hexafluoride gas. As shown in Figure 9, in the 12th to 14th experiments, the etching selectivity was higher than when neither the first processing gas nor the second processing gas contains tungsten hexafluoride gas. Furthermore, it can be seen from Figure 8 that the etching rate of the second region R2 increases as the bias power increases. It can be seen that the etching selectivity is maximum when the bias power is 100 W.

The upper surface of the substrate W on which the method was performed in the 12th to 14th experiments was observed. The etching permeability was confirmed in the recess R1a. In the 12th to 14th experiments, the etching permeability was higher than when neither the first processing gas nor the second processing gas contained tungsten hexafluoride gas.

Although various exemplary embodiments have been described above, various additions, omissions, substitutions, and modifications may be made without being limited to the exemplary embodiments described above. In addition, elements in different embodiments may be combined to form other embodiments.

For example, the substrate W may include a first region R1 and a second region R2 having an opening on the first region R1. The first region R1 may include at least one selected from the group consisting of a carbon-containing film and a metal-containing film. The second region R2 may be a laminate film including a silicon oxide film and a silicon nitride film.

Various exemplary embodiments included in this disclosure are described below in [E1] to [E11].

[E1]
(a) providing a substrate, the substrate including a first region including a first material and a second region including a second material different from the first material;
(b) forming a deposit on the substrate using a first plasma generated from a first process gas comprising carbon;
(c) after (b), etching the second region with a chemical species generated from the deposit on the second region using a second plasma generated from a second process gas different from the first process gas;
Including,
11. The etching method, wherein at least one of the first process gas or the second process gas comprises a metal-containing gas.

The first process gas may contain a metal-containing gas and the second process gas may not contain a metal-containing gas, the second process gas may contain a metal-containing gas and the first process gas may not contain a metal-containing gas, or both the first process gas and the second process gas may contain a metal-containing gas.

The above etching method [E1] can increase the etching selectivity of the second region relative to the first region.

[E2]
The etching method according to [E1], wherein the second material includes silicon.

[E3]
the first material includes silicon nitride;
The etching method according to [E2], wherein the second material includes silicon oxide.

[E4]
The etching method according to any one of [E1] to [E2], wherein the metal-containing gas contains at least one element selected from the group consisting of tungsten and molybdenum.

[E5]
The etching method according to [E4], wherein the metal-containing gas contains at least one selected from the group consisting of a halide tungsten gas and a halide molybdenum gas.

[E6]
(d) the etching method according to any one of [E1] to [E5], further comprising the step of repeating (b) and (c) after (c).

[E7]
The etching method according to any one of [E1] to [E6], wherein the second process gas contains a noble gas.

[E8]
The etching method according to any one of [E1] to [E7], wherein the first process gas contains the metal-containing gas.

In this case, in (b), a metal deposit is formed on the substrate. In (c), chemical species generated from the metal deposit on the second region promotes etching of the second region.

[E9]
The etching method according to any one of [E1] to [E8], wherein the second process gas contains the metal-containing gas.

In this case, in (c), the chemical species generated from the metal-containing gas promotes etching of the second region.

[E10]
The etching method according to any one of [E1] to [E9], wherein the first region has a recess, and the second region is present within the recess.

[E11]
A chamber;
a substrate support for supporting a substrate within the chamber, the substrate including a first region including a first material and a second region including a second material different from the first material;
a gas supply configured to supply a first process gas and a second process gas different from the first process gas into the chamber, the first process gas comprising carbon and at least one of the first process gas or the second process gas comprising a metal-containing gas;
a plasma generating unit configured to generate a first plasma and a second plasma from the first process gas and the second process gas in the chamber, respectively;
A control unit;
Equipped with
The control unit is
forming a deposit on the substrate using the first plasma;
A plasma processing apparatus configured to control the gas supply unit and the plasma generation unit so as to use the second plasma to etch the second region with chemical species generated from the deposit on the second region after the deposit is formed.

From the foregoing, it will be understood that the 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.

1...plasma processing apparatus, 2...control section, 10...plasma processing chamber, 11...substrate support section, 12...plasma generation section, 20...gas supply section, DP...deposit, PL1...first plasma, PL2...second plasma, R1...first region, R2...second region, W...substrate.

Claims (11)

(a) providing a substrate, the substrate including a first region including a first material and a second region including a second material different from the first material;
(b) forming a deposit on the substrate using a first plasma generated from a first process gas comprising carbon;
(c) after (b), etching the second region with a chemical species generated from the deposit on the second region using a second plasma generated from a second process gas different from the first process gas;
Including,
11. The etching method, wherein at least one of the first process gas or the second process gas comprises a metal-containing gas. The etching method of claim 1, wherein the second material includes silicon. the first material includes silicon nitride;
The etching method of claim 2 , wherein the second material comprises silicon oxide. The etching method according to claim 1 or 2, wherein the metal-containing gas contains at least one element selected from the group consisting of tungsten and molybdenum. The etching method according to claim 4, wherein the metal-containing gas includes at least one selected from the group consisting of a tungsten halide gas and a molybdenum halide gas. The etching method according to claim 1 or 2, further comprising the step of repeating steps (b) and (c) after step (c). The etching method according to claim 1 or 2, wherein the second process gas includes a noble gas. The etching method according to claim 1 or 2, wherein the first process gas includes the metal-containing gas. The etching method according to claim 1 or 2, wherein the second process gas includes the metal-containing gas. The etching method according to claim 1 or 2, wherein the first region has a recess and the second region is present within the recess. A chamber;
a substrate support for supporting a substrate within the chamber, the substrate including a first region including a first material and a second region including a second material different from the first material;
a gas supply configured to supply a first process gas and a second process gas different from the first process gas into the chamber, the first process gas comprising carbon and at least one of the first process gas or the second process gas comprising a metal-containing gas;
a plasma generating unit configured to generate a first plasma and a second plasma from the first process gas and the second process gas in the chamber, respectively;
A control unit;
Equipped with
The control unit is
forming a deposit on the substrate using the first plasma;
A plasma processing apparatus configured to control the gas supply unit and the plasma generation unit so as to use the second plasma to etch the second region with chemical species generated from the deposit on the second region after the deposit is formed.

Images