Etching method and plasma processing apparatus

Abstract

To provide an etching method for efficiently forming a deposit on a shoulder part of a second region which is positioned at a lower side of a first region including an opening, and a plasma processing device.SOLUTION: An etching method MT includes a step ST1 of providing a substrate. The substrate comprises a first region including an opening and a second region which is positioned at a lower side of the first region. The second region includes a recess which is communicated to the opening. In a view in a direction vertical to a principal surface of the substrate, the second region includes a shoulder part which is positioned within the opening. The shoulder part includes an upper end of a sidewall of the recess, and the second region contains silicon and contains a material which is different from a material contained in the first region. The method also includes: a step ST3 of forming a deposit on the shoulder part by first plasma generated from a first process gas containing a gas containing carbon and oxygen; and a step ST4 of etching a bottom part of the recess with second plasma generated from a second process gas which is different from the first process gas.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] Exemplary embodiments of this disclosure relate to etching methods and plasma processing apparatus. [Background technology]

[0002] Patent Document 1 discloses a technique for etching the bottom of recesses in a substrate having a film containing recesses and a mask provided on the film. In Patent Document 1, deposits are selectively formed on the mask, and then the bottom of the recesses is etched. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-119918 [Overview of the project] [Problems that the invention aims to solve]

[0004] This disclosure provides a technique for efficiently forming deposits on the shoulder of a second region located below a first region having an opening. [Means for solving the problem]

[0005] In one exemplary embodiment, the etching method includes (a) providing a substrate, the substrate having a first region having an opening and a second region located below the first region, the second region including a recess communicating with the opening, and, viewed from a direction perpendicular to the main surface of the substrate, the second region including a shoulder located within the opening, the shoulder including the upper end of the side wall of the recess, and the second region including silicon and a material different from the material included in the first region; and (b) forming a deposit on the shoulder with a first plasma generated from a first processing gas including a gas containing carbon and oxygen; and (c) etching the bottom of the recess with a second plasma generated from a second processing gas different from the first processing gas. [Effects of the Invention]

[0006] According to one exemplary embodiment, a technique is provided for efficiently forming deposits on the shoulder of a second region located below a first region having an opening. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic diagram showing a plasma processing apparatus according to one exemplary embodiment. [Figure 2] Figure 2 is a schematic diagram showing a plasma processing apparatus according to one exemplary embodiment. [Figure 3] Figure 3 is a flowchart of an etching method according to one exemplary embodiment. [Figure 4] Figure 4 is a cross-sectional view of an example substrate to which the method in Figure 3 may be applied. [Figure 5] Figure 5 is a cross-sectional view showing one step of an etching method according to one exemplary embodiment. [Figure 6] Figure 6 is a cross-sectional view showing one step of an etching method according to one exemplary embodiment. [Figure 7] Figure 7 is a cross-sectional view showing one step of an etching method according to one exemplary embodiment. [Figure 8] Figure 8 is a cross-sectional view of a substrate relating to a modified example to which the method of Figure 3 may be applied. [Figure 9] Figure 9 is a cross-sectional view showing one step of an etching method according to one exemplary embodiment. [Figure 10] Figure 10 is a schematic diagram showing a substrate processing system according to one exemplary embodiment. [Modes for carrying out the invention]

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

[0009] Figure 1 is a schematic diagram showing a plasma processing apparatus according to one exemplary embodiment. In one embodiment, the plasma processing system includes a plasma processing apparatus 1 and a control unit 2. The plasma processing system is an example of a substrate processing system, and the plasma processing apparatus 1 is an example of a substrate processing apparatus. The plasma processing apparatus 1 includes a plasma processing chamber 10, a substrate support unit 11, and a plasma generation unit 12. The plasma processing chamber 10 has a plasma processing space. The plasma processing chamber 10 also has at least one gas supply port for supplying at least one processing gas to the plasma processing space, and at least one gas outlet for discharging gas from the plasma processing space. The gas supply port is connected to a gas supply unit 20, which will be described later, and the gas outlet is connected to an exhaust system 40, which will be described later. The substrate support unit 11 is located in the plasma processing space and has a substrate support surface for supporting a substrate.

[0010] The plasma generation unit 12 is configured to generate plasma from at least one processing gas supplied into the plasma processing space. The plasma formed in the plasma processing space may be a capacitively coupled plasma (CCP), an inductively coupled plasma (ICP), an electron-cyclotron-resonance plasma (ECR), a helicon wave-excited plasma (HWP), or a surface wave plasma (SWP), etc. Various types of plasma generation units, including an AC (Alternating Current) plasma generation unit and a DC (Direct Current) plasma generation unit, may also be used. In one embodiment, the AC signal (AC power) used in the AC plasma generation unit has a frequency in the range of 100 kHz to 10 GHz. Therefore, the AC signal includes an RF (Radio Frequency) signal and a microwave signal. In one embodiment, the RF signal has a frequency in the range of 100 kHz to 150 MHz.

[0011] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform various processes described herein. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to perform the various processes described herein. In one embodiment, part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The control unit 2 is implemented, for example, by a computer 2a. The processing unit 2a1 may be configured to perform various control operations by reading a program from the storage unit 2a2 and executing the read program. This program may be stored in the storage unit 2a2 in advance, or it may be obtained via a medium when needed. The obtained program is stored in the storage unit 2a2 and read from the storage unit 2a2 and executed by the processing unit 2a1. The medium may be various storage media readable by the computer 2a, or it may be a communication line connected to the communication interface 2a3. The processing unit 2a1 may be a CPU (Central Processing Unit). The memory unit 2a2 may include RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing device 1 via a communication line such as a LAN (Local Area Network).

[0012] The following describes an example configuration of a capacitively coupled plasma processing apparatus as an example of a plasma processing apparatus 1. Figure 2 is a schematic diagram showing a plasma processing apparatus according to one exemplary embodiment.

[0013] A capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power source 30, and an exhaust system 40. The plasma processing apparatus 1 further includes a substrate support 11 and a gas introduction unit. The gas introduction unit is configured to introduce at least one processing gas into the plasma processing chamber 10. The gas introduction unit includes a shower head 13. The substrate support 11 is disposed within the plasma processing chamber 10. The shower head 13 is disposed above the substrate support 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, a sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 is grounded. The shower head 13 and the substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0014] The substrate support 11 includes a main body portion 111 and a ring assembly 112. The main body portion 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 the substrate W. The annular region 111b of the main body portion 111 surrounds the central region 111a of the main body portion 111 in a plan view. The substrate W is disposed on the central region 111a of the main body portion 111, and the ring assembly 112 is disposed on the annular region 111b of the main body portion 111 so as to surround the substrate W on the central region 111a of the main body portion 111. Accordingly, the central region 111a is also referred to as a substrate support surface for supporting the substrate W, and the annular region 111b is also referred to as a ring support surface for supporting the ring assembly 112.

[0015] In one embodiment, the main body portion 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 in 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 another member 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. Further, 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 referred to as a bias electrode. Note that the conductive member of the base 1110 and the at least one RF / DC electrode may function as a plurality of lower electrodes. Further, the electrostatic electrode 1111b may function as a lower electrode. Accordingly, the substrate support portion 11 includes at least one lower electrode.

[0016] The ring assembly 112 includes one or more annular members. In one embodiment, the one or more annular members include one or more edge rings and at least one cover ring. The edge ring is formed of a conductive material or an insulating material, and the cover ring is formed of an insulating material.

[0017] The substrate support section 11 may also include a temperature control module configured to adjust at least one of the electrostatic chuck 1111, the ring assembly 112, and the substrate to a target temperature. The temperature control module may include a heater, a heat transfer medium, a flow path 1110a, or a combination thereof. A heat transfer fluid, such as brine or gas, flows through the flow path 1110a. In one embodiment, the flow path 1110a is formed within the base 1110, and one or more heaters are arranged within the ceramic member 1111a of the electrostatic chuck 1111. The substrate support section 11 may also include a heat transfer gas supply section configured to supply heat transfer gas to the gap between the back surface of the substrate W and the central region 111a.

[0018] The showerhead 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The showerhead 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and a plurality of gas inlet ports 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 through the plurality of gas inlet ports 13c. The showerhead 13 also includes at least one upper electrode. In addition to the showerhead 13, the gas introduction unit may also include one or more side gas injectors (SGIs) attached to one or more openings formed in the side wall 10a.

[0019] The gas supply unit 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply unit 20 is configured to supply at least one processing gas to the shower head 13 from a corresponding gas source 21 via a corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Furthermore, the gas supply unit 20 may include at least one flow modulation device that modulates or pulses the flow rate of at least one processing gas.

[0020] The power supply 30 includes an RF power supply 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power supply 31 is configured to supply at least one RF signal (RF power) to at least one lower electrode and / or at least one upper electrode. This causes plasma to be formed from at least one processing gas supplied to the plasma processing space 10s. Thus, the RF power supply 31 can function as at least part of the plasma generation unit 12. In addition, by supplying a bias RF signal to at least one lower electrode, a bias potential is generated on the substrate W, and ionic components in the formed plasma can be drawn into the substrate W.

[0021] In one embodiment, the RF power supply 31 includes a first RF generation unit 31a and a second RF generation unit 31b. The first RF generation unit 31a is coupled to at least one lower electrode and / or at least one upper electrode via at least one impedance matching circuit and is configured to generate a source RF signal (source RF power) for plasma generation. In one embodiment, the source RF signal has a frequency in the range of 10 MHz to 150 MHz. In one embodiment, the first RF generation unit 31a may be configured to generate a plurality of source RF signals having different frequencies. One or more generated source RF signals are supplied to at least one lower electrode and / or at least one upper electrode.

[0022] The second RF generation unit 31b is coupled to at least one lower electrode via at least one impedance matching circuit and is configured to generate a bias RF signal (bias RF power). The frequency of the bias RF signal may be the same as or different from the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency lower than the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 100 kHz to 60 MHz. In one embodiment, the second RF generation unit 31b may be configured to generate a plurality of bias RF signals having different frequencies. One or more generated bias RF signals are supplied to at least one lower electrode. In various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0023] The power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generation unit 32a and a second DC generation unit 32b. In one embodiment, the first DC generation unit 32a is connected to at least one lower electrode and configured to generate a first DC signal. The generated first DC signal is applied to at least one lower electrode. In one embodiment, the second DC generation unit 32b is connected to at least one upper electrode and configured to generate a second DC signal. The generated second DC signal is applied to at least one upper electrode.

[0024] In various embodiments, the first and second DC signals may be pulsed. In this case, a sequence of voltage pulses is applied to at least one lower electrode and / or at least one upper electrode. The voltage pulses may have a rectangular, trapezoidal, triangular, or a combination thereof pulse waveform. In one embodiment, a waveform generation unit for generating a sequence of voltage pulses from the DC signal is connected between the first DC generation unit 32a and at least one lower electrode. Thus, the first DC generation unit 32a and the waveform generation unit constitute a voltage pulse generation unit. When the second DC generation unit 32b and the waveform generation unit constitute a voltage pulse generation unit, the voltage pulse generation unit is connected to at least one upper electrode. The voltage pulses may have positive or negative polarity. The sequence of voltage pulses may also include one or more positive voltage pulses and one or more negative voltage pulses within one period. The first and second DC generation units 32a and 32b may be provided in addition to the RF power supply 31, and the first DC generation unit 32a may be provided in place of the second RF generation unit 31b.

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

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

[0027] Figure 4 is a cross-sectional view of an example substrate W to which Method MT may be applied. The substrate W has a first region R1 having an opening OP and a second region R2 located below the first region R1. The second region R2 includes a recess RS communicating with the opening OP. The recess RS comprises a bottom RSa and a side wall RSb. The opening OP and the recess RS may have a hole pattern or a line pattern.

[0028] The first region R1 may contain silicon (Si). The first region R1 may contain silicon and oxygen (O). The first region R1 may contain silicon oxide (SiO x ) may be included. x is a positive real number.

[0029] The second region R2 includes a shoulder portion RSd located within the opening OP when viewed from a direction perpendicular to the main surface of the substrate W. The direction perpendicular to the main surface of the substrate W may be perpendicular to the plane direction of the substrate W, the thickness direction of the substrate W, or the direction from the first region R1 to the second region R2. When viewed from a direction perpendicular to the main surface of the substrate W, the shoulder portion RSd may be exposed. The shoulder portion RSd includes the upper end RSc1 of the side wall RSb. The upper end RSc1 may coincide with the lower end of the side wall defining the opening OP.

[0030] The recess RS may have an inner diameter smaller than the inner diameter of the opening OP. The recess RS may have the same inner diameter as the opening OP at the upper end RSc1 of the side wall RSb. The recess RS may have an inner diameter smaller than the inner diameter of the opening OP at a position RSc2 below the upper end RSc1. The shoulder RSd may include position RSc2. The shoulder RSd may be formed such that the inner diameter of the recess RS gradually narrows from the upper end RSc1 of the side wall RSb towards position RSc2. Alternatively, the recess RS may have an inner diameter smaller than the inner diameter of the opening OP at the upper end RSc1.

[0031] The second region R2 contains silicon and a material different from the material contained in the first region R1. The second region R2 may contain silicon and nitrogen (N). The second region R2 contains silicon nitride (SiN x) may be included. x is a positive real number.

[0032] The substrate W may further comprise a mask MK having an aperture MOP. The mask MK is located on a first region R1. The aperture MOP of the mask MK communicates with an aperture OP of the first region R1. The mask MK may contain a carbon-containing film or a metal-containing film. The carbon-containing film may include an amorphous carbon film. The metal-containing film may contain at least one selected from the group consisting of tungsten silide (WSi), tungsten carbide (WC), and titanium nitride (TiN).

[0033] The substrate W may further comprise a base film UR. The base film UR is located beneath the second region R2. The base film UR may contain materials different from those contained in the first region R1 and the second region R2. The base film UR may contain silicon.

[0034] The substrate W may further comprise a plurality of protrusions GA. The plurality of protrusions GA are arranged between the second region R2 and the underlying film UR. The plurality of protrusions GA may be arranged along the upper surface of the underlying film UR. The plurality of protrusions GA may be covered by the second region R2. The bottom RSa of the recess RS may be arranged between adjacent plurality of protrusions GA. The plurality of protrusions GA may be arranged away from the recess RS. Each protrusion GA may form the gate region of a transistor.

[0035] The following describes method MT, taking as an example the case where method MT is applied to the substrate W using the plasma processing apparatus 1 of the above embodiment, with reference to Figures 4 to 7. Each of Figures 4 to 7 is a cross-sectional view showing one step of an etching method according to one exemplary embodiment. When the plasma processing apparatus 1 is used, method MT can be executed in the plasma processing apparatus 1 by the control unit 2 controlling each part of the plasma processing apparatus 1. In method MT, as shown in Figure 2, the substrate W on the substrate support part 11 arranged in the plasma processing chamber 10 is processed.

[0036] As shown in Figure 3, Method MT may include steps ST1 to ST5. Steps ST1 to ST5 may be performed in order. Step ST4 may be performed in the same plasma processing chamber 10 as step ST3. Method MT does not have to include at least one of steps ST2 and ST5. As will be described in detail later, in step ST3, a first plasma generated from a first processing gas is used, and in step ST4, a second plasma generated from a second processing gas is used.

[0037] (Process ST1) In step ST1, the substrate W shown in Figure 4 is provided. The substrate W can be supported by the substrate support 11 within the plasma processing chamber 10.

[0038] The substrate W may be provided in a state in which the first region R1 has been etched by etching in the SAC (Self-Align Contact) process. The etching in the SAC process may be carried out using a plasma processing apparatus 1. The etching in the SAC process may be carried out in the same plasma processing chamber 10 as steps ST1 to ST5.

[0039] Figure 5 shows a cross-sectional view of the substrate W before etching in the SAC process. As shown in Figure 5, before etching in the SAC process, the first region R1 may be located within the opening OP and recess RS shown in Figure 4. In the etching process in the SAC process, the first region R1 located within the opening OP and recess RS may be etched by a third plasma generated from a third processing gas different from the first and second processing gases. The opening OP may be formed and the recess RS exposed by etching the first region R1 through the opening MOP of the mask MK. In the etching process in the SAC process, the opening OP and recess RS may be formed so that they do not come into contact with the protrusion GA. In the substrate W after etching in the SAC process, the shoulder portion RSd may be exposed, as shown in Figure 4.

[0040] The third processing gas may contain a fluorine-containing gas. The fluorine-containing gas is a fluorocarbon gas (C x F y (gas) and hydrofluorocarbon gas (C x H y F z The third treatment gas may include at least one selected from the group consisting of (gas). x, y, and z are positive integers. The fluorocarbon gas may include at least one selected from the group consisting of methane gas (CF4 gas), hexafluoropropene gas (C3F6 gas), octafluoropropane gas (C3F8 gas), octafluorocyclobutane gas (C4F8 gas), and hexafluoro-1,3-butadiene gas (C4F6 gas). The hydrofluorocarbon gas may include at least one selected from the group consisting of difluoromethane gas (CH2F2 gas), trifluoromethane gas (CHF3 gas), and fluoromethane gas (CH3F gas). The third treatment gas may further include an oxygen-containing gas. The oxygen-containing gas may include oxygen gas. The third treatment gas may further include a noble gas.

[0041] (Process ST2) In step ST2, the substrate W may be cleaned. In step ST2, residue generated by etching the first region R1 may be removed. In step ST2, the substrate W may also be cleaned with cleaning plasma generated from a cleaning gas in the plasma processing chamber 10. The cleaning gas may contain an oxygen-containing gas. The cleaning gas may also contain a mixed gas containing nitrogen gas and hydrogen gas.

[0042] (Process ST3) In step ST3, as shown in Figure 6, a deposit DP is formed on the shoulder RSd of the second region R2 by a first plasma generated from the first processing gas. The deposit DP may contain carbon. Figure 6 shows a cross-sectional view of the substrate W in step ST3. In step ST3, the deposit DP is preferentially formed on the shoulder RSd. This allows the bottom RSa of the recess RS to be etched while protecting the shoulder RSd in step ST4, which follows step ST3. Figures 6, 7, and 9 highlight the locations where the deposit DP is formed. The thickness of the deposit DP in Figures 6, 7, and 9 may differ from the actual thickness.

[0043] As shown in Figure 6, in step ST3, deposits DP may be formed not only on the shoulder RSd but also on the first region R1 or the mask MK. In step ST3, deposits DP may be formed on the bottom RSa of the recess RS. The thickness of the deposits DP formed on the shoulder RSd may be greater than the thickness of the deposits DP formed on the bottom RSa. The thickness of the deposits DP formed on the first region R1 or the mask MK may be greater than the thickness of the deposits DP formed on the shoulder RSd. If the thickness of the deposits DP on the bottom RSa is small, etching of the bottom RSa can be promoted in step ST4. As an index for evaluating the deposition of deposits DP, the ratio of the thickness of the deposits DP on the shoulder RSd to the thickness of the deposits DP on the bottom RSa (thickness of deposits DP on the shoulder RSd / thickness of deposits DP on the bottom RSa; hereinafter also referred to as the "M / B ratio") may be used. The M / B ratio may be 3 or greater. Another indicator for evaluating the deposition of sediment DP may be the ratio of the thickness of sediment DP on the bottom RSa to the thickness of sediment DP on the mask MK (thickness of sediment DP on bottom RSa / thickness of sediment DP on mask MK; hereinafter also referred to as the "B / T ratio"). The B / T ratio may be 0.3 or less (30% or less).

[0044] The first processing gas contains carbon and oxygen. The gas containing carbon and oxygen may include at least one selected from the group consisting of carbon monoxide (CO), carbon dioxide (CO2), and carbonyl sulfide (COS). The first processing gas may further contain a hydrogen-containing gas. The first processing gas may further contain a gas containing carbon and hydrogen. The gas containing carbon and hydrogen is hydrocarbon gas (C x H y gas), wherein x and y are positive integers. The hydrocarbon gas may be CH4. The first processing gas may be a hydrofluorocarbon gas. The hydrofluorocarbon gas may be CH3F gas. The first processing gas may further contain a noble gas. The noble gas may be argon gas (Ar gas).

[0045] In the first processing gas, the flow rate of the gas containing carbon and oxygen may be greater than the flow rate of the gas containing carbon and hydrogen. In the first processing gas, the flow rate of the gas containing carbon and oxygen may be 3 times or more the flow rate of the gas containing carbon and hydrogen. In the first processing gas, the flow rate of the gas containing carbon and oxygen may be 10 times or less the flow rate of the gas containing carbon and hydrogen. The flow rate of the gas containing carbon and oxygen may be not less than 50 sccm and not more than 120 sccm. The flow rate of the gas containing carbon and oxygen may be not less than 80 sccm and not more than 100 sccm. The flow rate of the gas containing carbon and hydrogen may be not less than 5 sccm and not more than 30 sccm. The flow rate of the gas containing carbon and hydrogen may be not less than 10 sccm and not more than 20 sccm.

[0046] (Step ST4) In step ST4, the bottom RSa of the recess RS is etched by a second plasma generated from a second processing gas different from the first processing gas. Figure 7 shows a cross-sectional view of the substrate W in step ST4. As shown in Figure 7, in step ST4, the bottom RSa may reach the underlying film UF. In step ST4, the deposits DP on the shoulder RSd and the deposits DP on the mask MK may be etched. In step ST4, the thickness of the deposits DP on the shoulder RSd and the deposits DP on the mask MK may be reduced. In step ST4, along with the etching of the bottom RSa, the deposits DP on the bottom RSa may be completely removed.

[0047] The second process gas may contain a hydrogen-containing gas and a fluorine-containing gas. The hydrogen-containing gas may include hydrogen gas. An example of a fluorine-containing gas included in the second process gas may be the same as an example of a fluorine-containing gas included in the third process gas. In the second process gas, the flow rate of the hydrogen-containing gas may be greater than the flow rate of the fluorine-containing gas. The second process gas does not have to contain an oxygen-containing gas.

[0048] (Process ST5) In step ST5, steps ST2 and ST3 may be repeated. By repeating steps ST2 and ST3, the bottom RSa can be etched while replenishing the deposit DP on the shoulder RSd, as shown in Figure 7. In step ST5, the substrate W may be cleaned before step ST3. That is, if one cycle consists of performing steps ST3 and ST4 once each, the next cycle may be started after removing the deposit DP by cleaning the substrate W. The cleaning of the substrate W in step ST5 may be performed in the same way as in step ST2.

[0049] According to method MT, in step ST3, deposits DP are preferentially formed on the shoulder portion RSd of the second region R2. This makes it possible to etch the bottom portion RSa of the recess RS while protecting the shoulder portion RSd in step ST4.

[0050] In step ST3, the first processing gas may further contain a hydrogen-containing gas. In this case, the etching resistance of the deposit DP can be improved. This reduces the reduction in the thickness of the deposit DP in step ST4. As a result, it is possible to suppress the abrasion of the shoulder RSd and the mask MK.

[0051] In step ST3, the first processing gas may further contain a gas containing carbon and hydrogen. In this case, the thickness of the deposit DP deposited on the shoulder RSd can be increased. This allows the remaining thickness of the deposit DP deposited on the shoulder RSd after step ST4 to be increased.

[0052] In step ST3, the first treatment gas may contain a noble gas. In this case, the thickness of the deposit DP can be adjusted by adjusting the flow rate of the noble gas.

[0053] In step ST3, deposits DP may be formed on the first region R1 or mask MK. In this case, the erosion of the first region R1 or mask MK in step ST4 can be suppressed.

[0054] Method MT may further include step ST5, which repeats steps ST3 and ST4. In this case, even if the deposit DP is removed by etching in step ST4, the deposit DP can be repeatedly added and deposited.

[0055] Method MT may include a step ST2 for cleaning the substrate W between steps ST1 and ST3. In this case, occlusion of the opening MOP, opening OP, or recess RS can be suppressed in step ST3.

[0056] In method MT, the substrate W may be cleaned in step ST5 before step ST3. In this case, in step ST3 after cleaning the substrate W, occlusion of the opening MOP, opening OP, or recess RS can be suppressed.

[0057] Figure 8 is a cross-sectional view of a modified substrate W1 to which method MT may be applied. Substrate W1 may have the same configuration as substrate W, except as follows: In substrate W1, a second region R2 may have a plurality of recesses RS communicating with a single opening OP. The second region R2 may include an intermediate region RS21. The intermediate region RS21 may be formed between a plurality of adjacent recesses RS. The intermediate region RS21 may cover a projection GA. When viewed from a direction perpendicular to the main surface of substrate W1, the intermediate region RS21 may be located within the opening OP. The intermediate region RS21 may have a plurality of shoulders RSd. The plurality of shoulders RSd include first and second shoulders RSd. The first shoulder RSd includes the upper end RSc1 of the side wall RSb of the first recess RS among the plurality of recesses RS. The second shoulder RSd includes the upper end RSc1 of the side wall RSb of the second recess RS among the plurality of recesses RS. The intermediate region RS21 has an upper surface RS21a that extends between the first shoulder portion RSd and the second shoulder portion RSd. The first region R1 does not necessarily have to be formed on the intermediate region RS21. That is, the upper surface RS21a of the intermediate region RS21 may be exposed.

[0058] Figure 9 is a cross-sectional view showing one step of the etching method when method MT is applied to substrate W1. Figure 9 is a cross-sectional view of substrate W1 in step ST3. The deposit DP may be formed on the shoulder portion RSd. The deposit DP may be formed on the mask MK. The deposit DP may be formed on the bottom portion RSa of the recess RS. Furthermore, for substrate W1, the deposit DP may be formed on the upper surface RS21a of the intermediate region RS21. The deposit DP may be formed continuously from the shoulder portion RSd to the upper surface RS21a of the intermediate region RS21.

[0059] When method MT is applied to substrate W1, in step ST3, deposits DP are preferentially formed on the shoulder portion RSd of the second region R2 and on the upper surface RS21a of the intermediate region RS21. This makes it possible to etch the bottom portion RSa of the recess RS while protecting the shoulder portion RSd and the upper surface RS21a of the intermediate region RS21 in step ST4.

[0060] Figure 10 is a schematic diagram showing a substrate processing system PS according to one exemplary embodiment. As shown in Figure 10, the substrate processing system PS is a system capable of performing various processes such as plasma processing on a substrate W or substrate W1. Method MT can be applied to the substrate W or substrate W1 using the substrate processing system PS.

[0061] The substrate processing system PS includes vacuum transport modules TM1, TM2, process modules PM1 to PM12, load lock modules LL1, LL2, atmospheric transport module LM, aligner AN, storage SR, etc.

[0062] Vacuum transport modules TM1 and TM2 each have a roughly rectangular shape in plan view. Process modules PM1 to PM6 are connected to two opposing sides of vacuum transport module TM1. Of the other two opposing sides of vacuum transport module TM1, load lock modules LL1 and LL2 are connected to one side, and a path (not shown) for connecting to vacuum transport module TM2 is connected to the other side. The side of vacuum transport module TM1 to which load lock modules LL1 and LL2 are connected is angled according to the two load lock modules LL1 and LL2. Process modules PM7 to PM12 are connected to two opposing sides of vacuum transport module TM2. Of the other two opposing sides of vacuum transport module TM2, a path (not shown) for connecting to vacuum transport module TM1 is connected to one side. Vacuum transport modules TM1 and TM2 have vacuum chambers with a vacuum atmosphere, and vacuum transport robots TR1 and TR2 are located inside them, respectively.

[0063] The vacuum transport robots TR1 and TR2 are configured to rotate, extend, and move up and down freely. The vacuum transport robots TR1 and TR2 transport objects based on operation instructions output by the control unit CU, which will be described later. For example, the vacuum transport robot TR1 holds the object to be transported with forks FK11 and FK12 located at its tip and transports the object between load lock modules LL1 and LL2, process modules PM1 to PM6 and a path (not shown). For example, the vacuum transport robot TR2 holds the object to be transported with forks FK21 and FK22 located at its tip and transports the object between process modules PM7 to PM12 and a path (not shown). The forks are also called picks or end effectors.

[0064] The transported objects include the substrate W and consumable parts. The consumable parts are components that are replaceably installed within process modules PM1 to PM12 and are consumed as various processes such as plasma processing are performed within process modules PM1 to PM12. The consumable parts include, for example, the components that make up the ring assembly 112 and the shower head 13, which will be described later.

[0065] Process modules PM1 to PM12 have a processing chamber and a stage (mounting platform) located inside. After the substrate W is placed on the stage, process modules PM1 to PM12 reduce the pressure inside, introduce a processing gas, apply R power to generate plasma, and perform plasma treatment on the substrate with the plasma. The vacuum transport modules TM1 and TM2 and process modules PM1 to PM12 are separated by a gate valve G1 that can be opened and closed.

[0066] Load lock modules LL1 and LL2 are positioned between the vacuum transport module TM1 and the atmospheric transport module LM. Load lock modules LL1 and LL2 have a variable internal pressure chamber that can be switched between vacuum and atmospheric pressure. Load lock modules LL1 and LL2 have a stage located inside. When transporting a substrate W from the atmospheric transport module LM to the vacuum transport module TM1, load lock modules LL1 and LL2 maintain an internal pressure of atmospheric pressure to receive the substrate W from the atmospheric transport module LM, then reduce the internal pressure to transport the substrate W into the vacuum transport module TM1. When transporting a substrate W from the vacuum transport module TM1 to the atmospheric transport module LM, load lock modules LL1 and LL2 maintain an internal pressure of vacuum to receive the substrate W from the vacuum transport module TM1, then increase the internal pressure to atmospheric pressure to transport the substrate into the atmospheric transport module LM. Load lock modules LL1 and LL2 and the vacuum transport module TM1 are separated by a gate valve G2 that can be opened and closed. The load lock modules LL1 and LL2 and the atmospheric transport module LM are separated by a gate valve G3 that can be opened and closed.

[0067] The atmospheric transport module LM is positioned opposite the vacuum transport module TM1. The atmospheric transport module LM may be, for example, an EFEM (Equipment Front End Module). The atmospheric transport module LM is rectangular in shape, equipped with an FFU (Fan Filter Unit), and is an atmospheric transport chamber maintained at atmospheric pressure. Two load lock modules LL1 and LL2 are connected to one side of the atmospheric transport module LM along its longitudinal direction. Load ports LP1 to LP4 are connected to the other side of the atmospheric transport module LM along its longitudinal direction. Containers C that contain multiple (e.g., 25) substrates W are placed on the load ports LP1 to LP4. Container C may be, for example, a FOUP (Front-Opening Unified Pod). An atmospheric transport robot TR3 for transporting objects is located inside the atmospheric transport module LM.

[0068] The atmospheric transport robot TR3 is configured to move along the longitudinal direction of the atmospheric transport module LM, and is also configured to rotate, extend and retract, and move up and down. The atmospheric transport robot TR3 transports objects based on operation instructions output by the control unit CU, which will be described later. For example, the atmospheric transport robot TR3 holds the object to be transported with the fork FK31 located at its tip and transports the object between the load ports LP1 to LP4, load lock modules LL1 and LL2, aligner AN, and storage SR.

[0069] The aligner AN is connected to one side of the atmospheric transport module LM along its short direction. However, the aligner AN may also be connected to a side of the atmospheric transport module LM along its long direction. Furthermore, the aligner AN may be installed inside the atmospheric transport module LM. The aligner AN includes a support base, an optical sensor (neither of which are shown), etc. In this context, the aligner is a device that detects the position of the object to be transported.

[0070] The support base is a rotatable base with a vertically extending axis, and is configured to support the substrate W on it. The support base is rotated by a drive unit (not shown). The drive unit is controlled by a control unit CU, which will be described later. When the support base rotates due to the power from the drive unit, the substrate placed on the support base also rotates.

[0071] The optical sensor detects the edges of the substrate while it is rotating. From the edge detection results, the optical sensor detects the amount of deviation in the angular position of the substrate's notch (or another marker) relative to a reference angular position, and the amount of deviation in the substrate's center position relative to the reference position. The optical sensor outputs the amount of deviation in the notch's angular position and the amount of deviation in the substrate's center position to the control unit CU, which will be described later. Based on the amount of deviation in the notch's angular position, the control unit CU calculates the amount of rotation of the rotating support base to correct the notch's angular position to the reference angular position. The control unit CU controls the drive device (not shown) to rotate the rotating support base by this amount of rotation. This corrects the notch's angular position to the reference angular position. In addition, the control unit CU controls the position of the fork FK31 of the air transport robot TR3 when receiving the substrate W from the aligner AN, based on the amount of deviation in the center position of the substrate W, so that the center position of the substrate coincides with a predetermined position on the fork FK31 of the air transport robot TR3.

[0072] The storage SR is connected to the longitudinal side of the atmospheric transport module LM. However, the storage SR may also be connected to the short side of the atmospheric transport module LM. Alternatively, the storage SR may be located inside the atmospheric transport module LM. The storage SR contains the objects to be transported.

[0073] The substrate processing system PS is equipped with a control unit CU. The control unit CU may be, for example, a computer. The control unit CU includes a CPU (central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), auxiliary storage device, etc. The CPU operates based on a program stored in the ROM or auxiliary storage device and controls each part of the substrate processing system PS. For example, the control unit CU outputs operation instructions to the vacuum transport robots TR1, TR2, the atmospheric transport robot TR3, etc. The operation instructions include instructions for aligning the forks FK11, FK12, FK21, FK22, FK31 that transport the object to be transported with the transport location of the object to be transported.

[0074] In method MT, step ST3 may be carried out in a first chamber. In that case, step ST4 may be carried out in a second chamber different from the first chamber. An example of the first chamber is any of the process modules PM1 to PM12. An example of the second chamber is any of the process modules PM1 to PM12, excluding the process module corresponding to the first chamber. In method MT, steps ST1 to ST5 may each be carried out in different chambers. For example, step ST1 may be carried out in process module PM1. Step ST2 may be carried out in process module PM2. Step ST3 may be carried out in process module PM3. Step ST4 may be carried out in process module PM4. Step ST5 may be carried out in process module PM5. After one step is completed, the substrate W or substrate W1 may be transported to another process module by the vacuum transport module TM1.

[0075] Although various exemplary embodiments have been described above, the invention is not limited to the exemplary embodiments described above, and various additions, omissions, substitutions, and modifications may be made. Furthermore, it is possible to combine elements from different embodiments to form other embodiments.

[0076] The following describes the first to eleventh experiments conducted to evaluate process ST3 in method MT. The experiments described below are not limiting to this disclosure.

[0077] (Experiment 1) In the first experiment, a substrate having the same structure as the substrate shown in Figure 4 was prepared. The first region R1 is a silicon oxide film. The second region R2 is a silicon nitride film. Next, a deposit DP was formed on the shoulder RSd of the second region R2 by the first plasma generated from the first processing gas (step ST3). The first processing gas is a mixture of H2 gas, CO gas, and Ar gas. The flow rate of CO gas is 7.5 times that of H2 gas. The processing time for step ST3 is 60 seconds. Before performing step ST3, the first to fifth experiments were conducted with the deposit DP already deposited on the bottom RSa of the recess RS. In the subsequent experiments, from the second to the eleventh experiment, the conditions were the same as in the first experiment, except for the first processing gas and the processing time of step ST3.

[0078] (Second experiment) The first processing gas is a mixture of COS gas, CO gas, and Ar gas. The flow rate of CO gas is 23 times that of COS gas. The processing time for step ST3 is 60 seconds.

[0079] (Third experiment) The first treatment gas is a mixture of CH4 gas, CO gas, and Ar gas. The flow rate of CO gas is 4.5 times that of CH4 gas. The processing time for step ST3 is 30 seconds.

[0080] (Fourth experiment) The first treatment gas is a mixture of CH4 gas, CO gas, and Ar gas. The flow rate of CO gas is 9.0 times that of CH4 gas. The processing time for step ST3 is 60 seconds. (Experiment 5) The first processing gas is a mixture of CH3F gas and Ar gas. The processing time for step ST3 is 30 seconds.

[0081] (Experimental results from Experiment 1 to Experiment 5) In each of the first to fifth experiments, the cross-section of the substrate was observed. In the cross-section, the change in the thickness of the deposit DP on the mask MK, the thickness of the deposit DP on the shoulder RSd, and the thickness of the deposit DP on the bottom RSa of the recess RS was measured before and after process ST3.

[0082] In the first experiment, the change in the thickness of the sediment DP on the mask MK (hereinafter referred to as "change on mask MK") was +10.4 nm. The change in the thickness of the sediment DP on the shoulder RSd (hereinafter referred to as "change on shoulder RSd") was +0.5 nm. The change in the thickness of the sediment DP on the bottom RSa (hereinafter referred to as "change on bottom RSa") was -2.7 nm. Here, the reason why the thickness of the sediment DP on bottom RSa decreased is assumed to be because the first treatment gas contained H2 gas, which cleaned the sediment DP. In the second experiment, the change on mask MK was +11.9 nm, the change on shoulder RSd was +2.2 nm, and the change on bottom RSa was +2.0 nm. In the third experiment, the change on mask MK was +11.5 nm, the change on shoulder RSd was +2.6 nm, and the change on bottom RSa was +1.2 nm. In the fourth experiment, the change on the mask MK was +19.0 nm, the change on the shoulder RSd was +4.6 nm, and the change on the bottom RSa was +1.2 nm. In the fifth experiment, the change on the mask MK was +3.4 nm, the change on the shoulder RSd was +3.0 nm, and the change on the bottom RSa was +2.5 nm.

[0083] Of the first to fifth experiments, the ratio of the thickness of the sediment DP on the shoulder RSd to the thickness of the sediment DP on the bottom RSa (M / B ratio) was highest in the fourth experiment. In the fourth experiment, the M / B ratio was 3.1 (+4.6 nm / +1.2 nm).

[0084] (Experiments 6-10) In the subsequent experiments, from the 6th to the 10th, the first treatment gas was a mixture of CH4 gas, CO gas, and Ar gas. The processing time for step ST3 was 60 seconds. The experiments were conducted by changing only the flow rate of the CH4 gas.

[0085] (Experiment 6) The flow rate of CO gas is 7.5 times that of CH4 gas.

[0086] (Experiment 7) The flow rate of CO gas is three times that of CH4 gas.

[0087] (Experiment 8) The flow rate of CO gas is 2.1 times that of CH4 gas.

[0088] (Experiment 9) The flow rate of CO gas is 1 times that of CH4 gas.

[0089] (Experiment 10) The flow rate of CO gas is 0.3 times that of CH4 gas.

[0090] (Experimental results from Experiment 6 to Experiment 10) In each of the 6th to 10th experiments, the change in the thickness of the sediment DP on the mask MK and the thickness of the sediment DP on the bottom RSa of the recess RS before and after process ST3 was measured. Then, the ratio of the thickness of the sediment DP on the bottom RSa to the thickness of the sediment DP on the mask MK (B / T ratio) was calculated. In the 6th experiment, the B / T ratio was 29%. In the 7th experiment, the B / T ratio was 33%. In the 8th experiment, the B / T ratio was 36%. In the 9th experiment, the B / T ratio was 58%. In the 10th experiment, the B / T ratio was 94%. It was found that the B / T ratio decreased as the flow rate ratio of CH4 gas decreased.

[0091] (Experiment 1, Experiment 3, Experiment 5, and Experiment 11) In addition to the first, third, and fifth experiments, an eleventh experiment was conducted to evaluate whether the performance of the sediment DP on the mask MK changed depending on the type of treatment gas used in the first experiment. In the eleventh experiment, the first treatment gas was a mixture of CO gas and Ar gas. The treatment time for step ST3 was 60 seconds.

[0092] (Experimental results from Experiment 1, Experiment 3, Experiment 5, and Experiment 11) In the first, third, fifth, and eleventh experiments, we observed whether or not the openings OP were blocked after step ST3. Furthermore, after step ST3, we performed etching in step ST4 to evaluate the etching resistance of the deposits DP on the mask MK. Etching resistance can be evaluated, for example, by the amount of decrease in the thickness of the deposits DP on the mask MK before and after step ST4. A smaller decrease indicates higher etching resistance. In the fifth experiment, the openings OP were blocked. The etching resistance was evaluated as high. In the first experiment, the openings OP were not blocked. The etching resistance was evaluated as lower than the result of the fifth experiment. In the third experiment, the openings OP were not blocked. The etching resistance was evaluated as equivalent to the result of the fifth experiment. In the eleventh experiment, the openings OP were not blocked. The etching resistance was evaluated as the lowest. From the above results, it was found that when the first processing gas was a mixture of H2 gas and CO gas (experiment 1), a mixture of CH4 gas and CO gas (experiment 3), and CO gas (experiment 11), the opening OP was not blocked. Furthermore, it was found that when the first processing gas contained a hydrogen-containing gas (experiments 1, 3, and 5), the etching resistance of the deposits DP on the mask MK was higher compared to when the first processing gas did not contain a hydrogen-containing gas (experiment 11).

[0093] Herein, various exemplary embodiments included in this disclosure are described in [E1] to [E20] below.

[0094] [E1] (a) The process of providing a substrate, The substrate has a first region having an opening and a second region located below the first region, the second region including a recess communicating with the opening. Viewed from a direction perpendicular to the main surface of the substrate, the second region includes a shoulder located within the opening, and the shoulder includes the upper end of the side wall of the recess. The second region includes silicon and a material different from the material included in the first region, and the process is as follows: (b) A step of forming a deposit on the shoulder portion with a first plasma generated from a first processing gas containing carbon and oxygen, (c) A step of etching the bottom of the recess with a second plasma generated from a second processing gas different from the first processing gas, Etching methods including

[0095] [E2] The etching method according to [E1], wherein the first processing gas further comprises a hydrogen-containing gas.

[0096] [E3] The etching method according to [E1] or [E2], wherein the first processing gas further comprises a gas containing carbon and hydrogen.

[0097] [E4] The etching method according to [E3], wherein the carbon and hydrogen-containing gas is a hydrocarbon gas.

[0098] [E5] The etching method according to [E1] or [E4], wherein, in (b) above, the flow rate of the gas containing carbon and oxygen is greater than the flow rate of the gas containing carbon and hydrogen.

[0099] [E6] The etching method according to any one of [E3] to [E5], wherein, in (b) above, the flow rate of the gas containing carbon and oxygen is three times or more the flow rate of the gas containing carbon and hydrogen.

[0100] [E7] The etching method according to [E6], wherein, in (b) above, the flow rate of the gas containing carbon and oxygen is 10 times or less the flow rate of the gas containing carbon and hydrogen.

[0101] [E8] The etching method according to any one of [E1] to [E7], wherein the carbon and oxygen-containing gas comprises at least one selected from the group consisting of CO, CO2, and COS.

[0102] [E9] The etching method according to any one of [E1] to [E8], wherein the first processing gas further comprises a noble gas.

[0103] [E10] The etching method according to any one of [E1] to [E9], wherein the second processing gas comprises a hydrogen-containing gas and a fluorine-containing gas.

[0104] [E11] In (b) above, the etching method according to any one of [E1] to [E10] wherein the deposit is formed on the first region.

[0105] [E12] (d) The etching method according to any one of [E1] to [E11], further comprising the step of repeating (b) and (c).

[0106] [E13] The etching method according to [E12], wherein, in (d) above, the substrate is cleaned before (b).

[0107] [E14] (e) The etching method according to any one of [E1] to [E13], further comprising the step of cleaning the substrate between (a) and (b).

[0108] [E15] The etching method according to any one of [E1] to [E14], wherein (a) comprises the step of etching the first region provided in the opening and the recess with a third plasma generated from a third processing gas different from the first processing gas and the second processing gas.

[0109] [E16] The etching method according to [E15], wherein the second processing gas does not contain an oxygen-containing gas.

[0110] [E17] The etching method according to [E16], wherein the third processing gas comprises an oxygen-containing gas.

[0111] [E18] The etching method described in any one of [E1] to [E17], wherein (b) and (c) are performed in the same chamber.

[0112] [E19] The etching method according to any one of [E1] to [E18], wherein (b) is performed in a first chamber, and (c) is performed in a second chamber different from the first chamber.

[0113] [E20] A plasma processing apparatus, Chamber and, A substrate support portion for supporting the substrate within the chamber, A gas supply unit configured to supply a first processing gas containing carbon and oxygen and a second processing gas different from the first processing gas into the chamber, A plasma generation unit configured to generate a first plasma from the first processing gas and a second plasma from the second processing gas, Control unit and Equipped with, The aforementioned substrate is It has a first region having an opening and a second region located below the first region, the second region including a recess communicating with the opening, Viewed from a direction perpendicular to the main surface of the substrate, the second region includes a shoulder located within the opening, and the shoulder includes the upper end of the side wall of the recess. The second region includes silicon and also includes a material different from the material included in the first region. The control unit, The first plasma creates a deposit on the shoulder portion, A plasma processing apparatus configured to control the gas supply unit and the plasma generation unit so as to etch the bottom of the recess with the second plasma. [Explanation of Symbols]

[0114] 1...Plasma processing apparatus, 10...Plasma processing chamber, 11...Substrate support section, 12...Plasma generation section, 2...Control section, 20...Gas supply section, DP...Deposit, MT...Etching method, OP...Opening, R1...First region, R2...Second region, RS...Recess, RSa...Bottom, RSb...Side wall, RSc1...Upper end, RSd...Shoulder, W...Substrate.

Claims

1. (a) A process of providing a substrate, The substrate has a first region having an opening and a second region located below the first region, the second region including a recess communicating with the opening. Viewed from a direction perpendicular to the main surface of the substrate, the second region includes a shoulder portion located within the opening, and the shoulder portion includes the upper end of the side wall of the recess. The second region includes silicon and a material different from the material included in the first region, and the process is as follows: (b) A step of forming a deposit on the shoulder portion with a first plasma generated from a first processing gas containing carbon and oxygen, (c) Etching the second region at the bottom of the recess with a second plasma generated from a second processing gas different from the first processing gas, Etching methods including

2. The etching method according to claim 1, wherein the first processing gas further comprises a hydrogen-containing gas.

3. The etching method according to claim 1 or 2, wherein the first processing gas further comprises a gas containing carbon and hydrogen.

4. The etching method according to claim 3, wherein the gas containing carbon and hydrogen is a hydrocarbon gas.

5. The etching method according to claim 3, wherein, in (b) above, the flow rate of the gas containing carbon and oxygen is greater than the flow rate of the gas containing carbon and hydrogen.

6. The etching method according to claim 3, wherein, in (b) above, the flow rate of the gas containing carbon and oxygen is three times or more the flow rate of the gas containing carbon and hydrogen.

7. The etching method according to claim 6, wherein in (b) above, the flow rate of the gas containing carbon and oxygen is 10 times or less the flow rate of the gas containing carbon and hydrogen.

8. The aforementioned gas containing carbon and oxygen is CO, CO ２ The etching method according to claim 1 or 2, comprising at least one selected from the group consisting of , and COS.

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

10. The etching method according to claim 1 or 2, wherein the second processing gas includes a hydrogen-containing gas and a fluorine-containing gas.

11. The etching method according to claim 1 or 2, wherein the deposit is formed on the first region in (b).

12. (d) The etching method according to claim 1 or 2, further comprising the step of repeating (b) and (c).

13. The etching method according to claim 12, wherein in (d) above, the substrate is cleaned before (b).

14. (e) The etching method according to claim 1 or 2, further comprising the step of cleaning the substrate between (a) and (b).

15. The etching method according to claim 1 or 2, wherein (a) comprises etching the first region provided in the opening and the recess with a third plasma generated from a third processing gas different from the first processing gas and the second processing gas.

16. The etching method according to claim 15, wherein the second processing gas does not contain an oxygen-containing gas.

17. The etching method according to claim 16, wherein the third processing gas includes an oxygen-containing gas.

18. The etching method according to claim 1 or 2, wherein (b) and (c) are performed in the same chamber.

19. The etching method according to claim 1 or 2, wherein (b) is performed in a first chamber, and (c) is performed in a second chamber different from the first chamber.

20. A plasma processing apparatus, Chamber and, A substrate support portion for supporting the substrate within the chamber, A gas supply unit configured to supply a first processing gas containing carbon and oxygen and a second processing gas different from the first processing gas into the chamber, A plasma generation unit configured to generate a first plasma from the first processing gas and a second plasma from the second processing gas, Control unit and Equipped with, The aforementioned substrate is It has a first region having an opening and a second region located below the first region, the second region including a recess communicating with the opening, Viewed from a direction perpendicular to the main surface of the substrate, the second region includes a shoulder portion located within the opening, and the shoulder portion includes the upper end of the side wall of the recess. The second region includes silicon and also includes a material different from the material included in the first region. The control unit, The first plasma forms deposits on the shoulder portion, A plasma processing apparatus configured to control the gas supply unit and the plasma generation unit so that the second plasma etches the second region at the bottom of the recess.

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