Etching method and plasma processing apparatus

Abstract

To provide a substrate processing method and a plasma processing apparatus capable of suppressing shape abnormality of a recess of a substrate.SOLUTION: In the exemplary embodiment, the etching method MT1 may include a process ST1 configured to provide the substrate on the substrate support in the chamber. The substrate includes a first region including a first material, a second region formed under the first region and including a second material different from the first material, and a mask formed on the first region and including a first opening. The method further includes a process ST2 configured to form a second opening communicating with the first opening by etching the first region with a first plasma generated from a first processing gas containing a halogenated metallic gas and form a metal-containing deposit on a sidewall of the second opening, and a process ST3 configured to form a recess communicating with the second opening by etching the second region with a second plasma generated from a second processing gas different from the first processing gas in a state that the metal-containing deposit is formed on the sidewall of the second opening.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION Exemplary embodiments of the present disclosure relate to an etching method and a plasma processing apparatus. [Background technology]

[0002] Patent Document 1 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. Plasma generated from a mixed gas of WF6 and C4F8 is used for etching. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-50984 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides an etching method and a plasma processing apparatus that can suppress shape abnormalities in recesses. [Means for solving the problem]

[0005] In one exemplary embodiment, an etching method includes: (a) providing a substrate on a substrate support in a chamber, the substrate including a first region including a first material, a second region formed below the first region and including a second material different from the first material, and a resist film formed above the first region and including a first opening; (b) etching the first region with plasma generated from a first process gas including a metal halide gas to form a second opening communicating with the first opening, and forming a metal-containing deposit on a sidewall of the second opening; and (c) etching the second region with a second process gas different from the first process gas, while the metal-containing deposit is formed on the sidewall of the second opening, to form a recess communicating with the second opening. [Effects of the Invention]

[0006] According to one exemplary embodiment, irregular shapes of the recesses can be suppressed. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram schematically illustrating a plasma processing apparatus according to an exemplary embodiment. [Figure 2] FIG. 2 is a diagram schematically illustrating a plasma processing apparatus according to an exemplary embodiment. [Figure 3] FIG. 3 is a flow chart of an etching method according to one exemplary embodiment. [Figure 4] FIG. 4 is a cross-sectional view of an example substrate to which the method of FIG. 3 can be applied. [Figure 5] FIG. 5 is a cross-sectional view illustrating a step of an etching method according to one example embodiment. [Figure 6] FIG. 6 is a cross-sectional view illustrating a step of an etching method according to one example embodiment. [Figure 7] FIG. 7 is a cross-sectional view of an example substrate at the end of etching the second region. [Figure 8] FIG. 8 is an example of a timing chart of the source RF power and the bias RF power. DETAILED DESCRIPTION OF THE INVENTION

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

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

[0010] The plasma generating unit 12 is configured to generate plasma from at least one processing gas supplied into the plasma processing space. The plasma formed in the plasma processing space may be capacitively coupled plasma (CCP), inductively coupled plasma (ICP), electron-cyclotron-resonance plasma (ECR plasma), helicon wave plasma (HWP), or surface wave plasma (SWP). Various types of plasma generating units may be used, including alternating current (AC) plasma generating units and direct current (DC) plasma generating units. 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. Therefore, the AC signal includes a radio frequency (RF) 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 in this disclosure. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to perform various processes described herein. In one embodiment, part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The control unit 2 may be implemented by, for example, a computer 2a. The processing unit 2a1 may be configured to read a program from the storage unit 2a2 and execute the read program to perform various control operations. The program may be stored in the storage unit 2a2 in advance or may be acquired via a medium when needed. The acquired program is stored in the storage unit 2a2 and read from the storage unit 2a2 by the processing unit 2a1 for execution. The medium may be various storage media readable by the computer 2a or a communication line connected to the communication interface 2a3. The processing unit 2a1 may be a CPU (Central Processing Unit). The storage unit 2a2 may include a random access memory (RAM), a read only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a local area network (LAN).

[0012] The following describes a configuration example of a capacitively coupled plasma processing apparatus as an example of the plasma processing apparatus 1. Fig. 2 is a diagram for explaining a configuration example of a capacitively coupled plasma processing apparatus.

[0013] The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply 20, a power supply 30, and an exhaust system 40. The plasma processing apparatus 1 also includes a substrate support 11 and a gas inlet. The gas inlet is configured to introduce at least one process gas into the plasma processing chamber 10. The gas inlet includes a showerhead 13. The substrate support 11 is disposed within the plasma processing chamber 10. The showerhead 13 is disposed above the substrate support 11. In one embodiment, the showerhead 13 forms at least a portion of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the showerhead 13, a sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 is grounded. The showerhead 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 111 and a ring assembly 112. The main body 111 has a central region 111a for supporting a substrate W and an annular region 111b for supporting the ring assembly 112. A wafer is an example of a substrate W. The annular region 111b of the main body 111 surrounds the central region 111a of the main body 111 in a plan view. The substrate W is disposed on the central region 111a of the main body 111, and the ring assembly 112 is disposed on the annular region 111b of the main body 111 so as to surround the substrate W on the central region 111a of the main body 111. Therefore, the central region 111a is also called a substrate support surface for supporting the substrate W, and the annular region 111b is also called a ring support surface for supporting the ring assembly 112.

[0015] In one embodiment, the main body 111 includes a base 1110 and an electrostatic chuck 1111. The base 1110 includes a conductive member. The conductive member of the base 1110 can function as a 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 the annular region 111b may also be provided by another member surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member. In this case, the ring assembly 112 may be disposed on the annular electrostatic chuck or the annular insulating member, or may be disposed on both the electrostatic chuck 1111 and the annular insulating member. Furthermore, at least one RF / DC electrode coupled to an RF power supply 31 and / or a DC power supply 32, which will be described later, may be disposed within the ceramic member 1111a. In this case, the at least one RF / DC electrode functions as a lower electrode. When a bias RF signal and / or a DC signal, which will be 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. Alternatively, the electrostatic electrode 1111b may function as a lower electrode. Therefore, the substrate support 11 includes at least one lower electrode.

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

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

[0018] The 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 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 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 sidewall 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 process gas from a corresponding gas source 21 to the showerhead 13 via a corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, the gas supply unit 20 may include at least one flow modulation device that modulates or pulses the flow rate of the at least one process gas.

[0020] The power supply 30 includes an RF power supply 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power supply 31 is configured to supply at least one RF signal (RF power) to at least one lower electrode and / or at least one upper electrode. This generates a plasma from at least one processing gas supplied to the plasma processing space 10s. Therefore, the RF power supply 31 can function as at least a part of the plasma generation unit 12. Furthermore, by supplying a bias RF signal to the 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.

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

[0022] The second RF generating unit 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 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 generating unit 31b may be configured to generate multiple bias RF signals having different frequencies. The generated one or more bias RF signals are supplied to at least one 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 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.

[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 combination thereof. 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 either positive or negative polarity. Furthermore, the sequence of voltage pulses may include one or more positive voltage pulses and one or more negative voltage pulses within one period. The first and second DC generating units 32a and 32b may be provided in addition to the RF power supply 31, or the first DC generating unit 32a may be provided instead of the second RF generating unit 31b.

[0025] 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 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] 3 is a flowchart of an etching method according to one exemplary embodiment. The etching method MT1 shown in FIG. 3 (hereinafter referred to as "method MT1") can be performed by the plasma processing apparatus 1 according to the above embodiment. The method MT1 can be applied to a substrate W.

[0027] Figure 4 is a cross-sectional view of an example substrate to which the method of Figure 3 can be applied. As shown in Figure 4, in one embodiment, the substrate W includes a first region R1, a second region R2, and a mask MK.

[0028] The first region R1 includes a first material. The first material may include at least one of silicon or metal. The first material may include at least one selected from the group consisting of polysilicon, silicon oxide, silicon nitride, silicon oxynitride, and silicon carbide. The first region R1 may be a SOG (Spin on Glass) film.

[0029] The second region R2 is formed below the first region R1. In the thickness direction of the substrate W, the first region R1 is formed above the second region R2. The second region R2 includes a second material different from the first material. The second material may include carbon. The second material may include amorphous carbon. The second region R2 may be a carbon-containing film such as a SOC (Spin on Carbon) film.

[0030] The mask MK is formed on the first region R1. The mask MK is formed on the opposite side of the first region R1 from the second region R2 in the thickness direction of the substrate W. The mask MK includes at least one first opening OP1. The mask MK may have a plurality of first openings OP1. The first opening OP1 may have a hole pattern or a line pattern. The dimension (CD: Critical Dimension) of the first opening OP1 may be 100 nm or less, 50 nm or less, or 30 nm or less. The mask MK may include a resist. The mask MK may be a photoresist film or a photoresist film for EUV exposure.

[0031] The substrate W may further include a base region UR. The base region UR may be formed below the second region R2. The base region UR may include a first base region UR1 and a second base region UR2. The first base region UR1 and the second base region UR2 are arranged in order. The first base region UR1 and the second base region UR2 are formed on the opposite side of the second region R2 from the first region R1 in the thickness direction of the substrate W. The first base region UR1 and the second base region UR2 may be stacked films.

[0032] The second underlying region UR2 may contain a material different from the material contained in the first underlying region UR1. The first underlying region UR1 and the second underlying region UR2 may contain silicon and nitrogen, or may contain silicon and oxygen. The first underlying region UR1 and the second underlying region UR2 may contain silicon nitride (SiN x ), or silicon oxide (SiO x The first underlying region UR1 and the second underlying region UR2 may be an SOC (Spin on Carbon) film or a carbon-containing film.

[0033] 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 and 6 are cross-sectional views showing a step of an etching method according to one exemplary embodiment. FIG. 7 is a cross-sectional view of an example substrate at the end of etching of the second region. When the plasma processing apparatus 1 is used, method MT1 can be performed in the plasma processing apparatus 1 by controlling each part of the plasma processing apparatus 1 with 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.

[0034] 3, the method MT1 may include steps ST1 to ST3, which may be performed in sequence.

[0035] (Process ST1) 4 is provided on a substrate support 11 in a plasma processing chamber 10. The substrate W can be supported by the substrate support 11 in the plasma processing chamber 10.

[0036] (Process ST2) 5, in step ST2, the first region R1 is etched by a first plasma PM1 generated from the first process gas. This allows a second opening OP2 communicating with the first opening OP1 of the mask MK to be formed in the first region R1. The second opening OP2 may be formed to penetrate the first region R1 in the thickness direction of the substrate W. When step ST2 is completed, the top surface of the second region R2 may be exposed at the bottom OPa of the second opening OP2.

[0037] The first process gas in step ST2 contains a metal halide gas. The first process gas may further contain at least one selected from the group consisting of a gas containing carbon and fluorine, and a nitrogen-containing gas. The first process gas may further contain a hydrogen-containing gas.

[0038] The metal halide gas may contain at least one selected from the group consisting of tungsten, titanium, molybdenum, vanadium, platinum, hafnium, niobium, tantalum, and rhenium. The metal halide gas may contain fluorine. The metal halide gas may contain at least one selected from the group consisting of tungsten hexafluoride (WF6) gas, tungsten hexabromide (WBr6) gas, tungsten hexachloride (WCl6) gas, WF5Cl gas, titanium tetrachloride (TiCl4) gas, molybdenum pentafluoride (MoF5) gas, vanadium hexafluoride (VF6) gas, platinum hexafluoride (PtF6) gas, hafnium tetrafluoride (HfF4) gas, and niobium pentafluoride (NbF5) gas.

[0039] Gases containing carbon and fluorine are called fluorocarbons (C x F y ) gases and hydrofluorocarbons (C x H y F z ) gases. Examples of fluorocarbon gases include CF4 gas, C3F6 gas, C3F8 gas, C4F8 gas, and C4F6 gas. Examples of hydrofluorocarbon gases include CH2F2 gas, CHF3 gas, and CH3F gas.

[0040] The nitrogen-containing gas may include nitrogen (N2) gas.

[0041] The hydrogen-containing gas may include at least one selected from the group consisting of hydrogen (H2) gas, monosilane (SiH4) gas, and ammonia (NH3) gas.

[0042] In step ST2, the flow rate of the metal halide gas may be lower than the flow rate of the carbon- and fluorine-containing gas or the flow rate of the nitrogen-containing gas. The flow rate of the nitrogen-containing gas may be higher than the flow rate of the carbon- and fluorine-containing gas or lower than the flow rate of the carbon- and fluorine-containing gas. The flow rate of the hydrogen-containing gas may be lower than the flow rates of the carbon- and fluorine-containing gas and the nitrogen-containing gas. The flow rate of the metal halide gas may be lower than the flow rate of the hydrogen-containing gas. The flow rate of the metal halide gas may be 20 sccm or less, 10 sccm or less, or 0.5 sccm or more.

[0043] In step ST2, the temperature of the substrate support 11 may be 10° C. or higher, or 30° C. or lower. In step ST2, the pressure in the plasma processing chamber 10 may be 1.33 Pa (10 mTorr) or higher, or 6.65 Pa (50 mTorr) or lower.

[0044] In step ST2, a metal-containing deposit DS is formed on the sidewall OPb of the second opening OP2. The metal-containing deposit DS is derived from a metal halide gas. The metal-containing deposit DS contains, for example, tungsten and may further contain fluorine. In step ST2, the first region R1 is etched while protecting the sidewall OPb of the second opening OP2 with the metal-containing deposit DS. This suppresses lateral etching of the sidewall OPb. In addition, the etching selectivity of the first region R1 relative to the mask MK is improved. As shown in FIG. 5, in step ST2, the metal-containing deposit DS may be further formed on the side and top surfaces of the mask MK. A metal-containing deposit DS may be formed on the sidewall OPb of the second opening OP2, following the metal-containing deposit DS formed on the sidewall of the mask MK.

[0045] In step ST2, the amount of deposition of the metal-containing deposit DS can vary depending on the flow rate of the metal halide gas. This can change the dimensions of the second opening OP2 at the end of step ST2. An example of the relationship between the flow rate of the metal halide gas and the dimensions of the second opening OP2 is described below, but this is not necessarily limited to this example. For example, WF6 gas is used as the metal halide gas. When the flow rate of WF6 gas is 1 sccm, the dimensions of the bottom OPa of the second opening OP2 are smaller than when the flow rate of WF6 gas is 0 sccm, and the ratio between the dimensions of the top edge of the second opening OP2 and the dimensions of the bottom OPa can approach 1. This is presumably because the metal-containing deposit DS is formed on the sidewall OPb, improving the verticality of the sidewall OPb. Furthermore, when the flow rate of WF6 gas is 1 sccm, the height of the mask MK can be higher than when the flow rate of WF6 gas is 0 sccm. This is presumably because the amount of etching of the mask MK is reduced due to the formation of the metal-containing deposit DS on the side and top surfaces of the mask MK.

[0046] When the flow rate of WF6 gas is greater than 1 sccm, the dimensions of the bottom OPa of the second opening OP2 may be larger, and the ratio between the upper end dimension of the second opening OP2 and the dimension of the bottom OPa may be larger, compared to when the flow rate of WF6 gas is 1 sccm. Furthermore, when the flow rate of WF6 gas is greater than 1 sccm, the height of the mask MK may be smaller, compared to when the flow rate of WF6 gas is 1 sccm. This is presumably due to an increased amount of etching of the mask MK by WF6 gas.

[0047] (Process ST3) In step ST3, as shown in FIG. 6, the second region R2 is etched with a second plasma PM2 generated from the second process gas while the metal-containing deposit DS is formed on the sidewall OPb of the second opening OP2. This allows a recess RS1 communicating with the second opening OP2 to be formed in the second region R2. The recess RS1 may be an opening or may be formed to penetrate the second region R2 in the thickness direction of the substrate W. As shown in FIG. 7, when step ST3 is completed, the upper surface of the second base region UR2 may be exposed at the bottom RSa of the recess RS1. Furthermore, when step ST3 is completed, the mask MK may be removed or may remain.

[0048] The second process gas is a gas different from the first process gas. The second process gas may contain at least one of an oxygen-containing gas, a hydrogen-containing gas, or a nitrogen-containing gas. The oxygen-containing gas may contain oxygen (O2) gas. The nitrogen-containing gas may contain nitrogen (N2) gas. The hydrogen-containing gas may contain at least one selected from the group consisting of hydrogen (H2) gas, monosilane (SiH4) gas, and ammonia (NH3) gas. When the second process gas contains both a hydrogen-containing gas and a nitrogen-containing gas, the flow rate of the hydrogen-containing gas may be the same as or different from the flow rate of the nitrogen-containing gas. The flow rate of the hydrogen-containing gas may be higher or lower than the flow rate of the nitrogen-containing gas.

[0049] The second process gas may not contain a carbon-containing gas. The second process gas may not contain a metal halide gas. In step ST3, a metal-containing deposit DS may not be formed on the sidewall RSb of the recess RS1.

[0050] In step ST3, the temperature of the substrate support 11 may be 10°C or higher or 30°C or lower. The temperature of the substrate support 11 in step ST3 may be equal to the temperature of the substrate support 11 in step ST2. In step ST3, the pressure in the plasma processing chamber 10 may be 1.33 kPa (10 Torr) or higher or 6.65 kPa (50 Torr) or lower. The pressure in the plasma processing chamber 10 in step ST3 may be equal to or higher than the pressure in the plasma processing chamber 10 in step ST2.

[0051] As shown in FIG. 7, in step ST3, when etching of the second region R2 is completed, a metal-containing deposit DS may remain on the sidewall OPb of the second opening OP2. That is, the metal-containing deposit DS may remain on the sidewall OPb without being removed until etching of the second region R2 is completed. The thickness of the metal-containing deposit DS on the sidewall OPb when etching of the second region R2 is completed may be thinner than the thickness of the metal-containing deposit DS on the sidewall OPb when etching of the first region R1 is completed (see, for example, FIG. 6). The remaining metal-containing deposit DS suppresses etching of the first region R1, thereby suppressing lateral etching of the sidewall RSb of the recess RS1. In addition, the etching selectivity of the second region RS2 relative to the first region R1 is improved.

[0052] FIG. 8 is an example of a timing chart of source RF power and bias RF power. The upper part of FIG. 8 is an example of a timing chart of source RF power WS. The lower part of FIG. 8 is an example of a timing chart of bias RF power WB. FIG. 8 corresponds to steps ST2 and ST3 in method MT1. The horizontal axis of FIG. 8 represents time. The vertical axis of FIG. 8 represents the power levels of source RF power WS and bias RF power WB.

[0053] In step ST2, the source RF power WS may have a first power level PL1 and a second power level PL2 lower than the first power level PL1. The first power level PL1 and the second power level PL2 may be alternately repeated. The second power level PL2 may be 50% or less of the first power level PL1. While the source RF power WS has the first power level PL1, generation of the first plasma PM1 may be promoted. While the source RF power WS has the second power level PL2, generation of the first plasma PM1 may be stopped, or plasma having a lower plasma density than the first plasma PM1 may be generated.

[0054] The source RF power WS may have a third power level PL3 in step ST3. The third power level PL3, which is the maximum value of the source RF power WS for generating the second plasma PM2 in step ST3, is greater than the first power level PL1, which is the maximum value of the source RF power WS for generating the first plasma PM1 in step ST2. The third power level PL3 may be five or more times, or ten or more times, the first power level PL1. The source RF power WS may continuously have the third power level PL3 throughout step ST3. As a result, the total energy amount of the source RF power WS supplied in step ST3 may be greater than the total energy amount of the source RF power WS supplied in step ST2.

[0055] In step ST2, the bias RF power WB may have a fourth power level PL4 and a fifth power level PL5 lower than the fourth power level PL4. The fourth power level PL4 and the fifth power level PL5 may be alternately repeated. The fourth power level PL4 may be equal to the first power level PL1. The fourth power level PL4 may be higher than the second power level PL2. The fifth power level PL5 may be a state in which the bias RF power WB is off (0 W). While the bias RF power WB has the fourth power level PL4, a bias potential generated in the substrate W by the bias RF power WB supplied to the substrate support 11 may attract ion components in the first plasma PM1 to the substrate W. While the bias RF power WB has the fifth power level PL5, the attraction of ion components in the first plasma PM1 to the substrate W may be stopped.

[0056] The bias RF power WB may have a sixth power level PL6 in process ST3. The sixth power level PL6, which is the maximum value of the bias RF power WB supplied to the substrate support 11 in process ST3, is higher than the fourth power level PL4, which is the maximum value of the bias RF power WB supplied to the substrate support 11 in process ST2. The sixth power level PL6 may be 1.1 times or more, or may be 2 times or less, the third power level PL3. The bias RF power WB may have the sixth power level PL6 continuously throughout process ST3. As a result, the total energy amount of the bias RF power WB supplied in process ST3 may be higher than the total energy amount of the bias RF power WB supplied in process ST2.

[0057] In step ST2, one cycle including a first period T1 to a third period T3 may be repeated. In the first period T1, the source RF power WS may be a first power level PL1, and the bias RF power WB may be a fifth power level PL5. In the second period T2, the source RF power WS may be a second power level PL2, and the bias RF power WB may be a fifth power level PL5. In the third period T3, the source RF power WS may be a second power level PL2, and the bias RF power WB may be a fourth power level PL4. The length of the first period T1 may be longer than the lengths of the second period T2 and the third period T3. In the example of FIG. 8, the proportion of the first period T1 in one cycle is 50%, the proportion of the second period T2 is 20%, and the proportion of the third period T3 is 30%.

[0058] According to the method MT1, the second region R2 is etched while the sidewall OPb of the second opening OP2 is protected by the metal-containing deposit DS, thereby suppressing lateral etching of the sidewall RSb of the recess RS1 formed in the second region R2. This suppresses shape abnormalities of the recess RS1. Furthermore, the etching selectivity of the second region R2 relative to the first region R1 is improved. This accelerates etching of the second region R2.

[0059] In step ST3, when etching of the second region R2 is completed, metal-containing deposits DS may remain on the sidewalls OPb of the second openings OP2. In this case, lateral expansion of the sidewalls RSb of the recesses RS1 formed in the second region R2 can be suppressed until etching of the second region R2 is completed. This further suppresses shape abnormalities of the recesses RS1.

[0060] In step ST2, the flow rate of the metal halide gas may be lower than the flow rate of the gas containing carbon and fluorine or the flow rate of the nitrogen-containing gas. In this case, by reducing the flow rate of the metal halide gas, etching of the sidewall OPb of the second opening OP2 can be further suppressed.

[0061] The maximum value of the source RF power WS for generating the second plasma PM2 in step ST3 may be greater than the maximum value of the source RF power WS for generating the first plasma PM1 in step ST2. The maximum value of the bias RF power WB supplied to the substrate support member 11 in step ST3 may be greater than the maximum value of the bias RF power WB supplied to the substrate support member 11 in step ST2. By making the maximum values ​​of the source RF power WS and the bias RF power WB in step ST3 greater than those in step ST2, it is possible to improve the etching rate and suppress abnormal shape of the recessed portion RS1 at the same time.

[0062] Various experiments performed to evaluate Method MT1 are described below, but the experiments described below are not intended to limit the present disclosure.

[0063] (First experiment) 4 was prepared. The substrate W included a first region R1 and a second region R2. Then, the plasma processing apparatus 1 was used to perform steps ST2 and ST3 on the substrate W.

[0064] In step ST2, a first plasma PM1 was generated in the plasma processing chamber 10 from a process gas containing WF6 gas, N2 gas, C4F8 gas, and CF4 gas, and the first region R1 was etched by the first plasma PM1. The flow rate of the WF6 gas was 1 sccm, which was lower than the flow rates of the other gases. In step ST3, a second plasma PM2 was generated in the plasma processing chamber 10 from a process gas containing H2 gas and N2 gas, and the second region R2 was etched by the second plasma PM2.

[0065] (Second experiment) The second experiment was carried out in the same manner as the first experiment, except that WF6 gas was not used in step ST2.

[0066] (First experiment results) In each of the first and second experiments, the cross section of the resulting substrate was observed, and the height of the first region R1, the dimensions of the upper end of the recess RS1, and the dimensions of the bottom of the recess RS1 were measured. The height of the first region R1 in the first experiment was higher than the height of the first region R1 in the second experiment. The dimensions of the upper end of the recess RS1 in the first experiment were smaller than the dimensions of the upper end of the recess RS1 in the second experiment. The dimensions of the bottom of the recess RS1 in the first experiment were smaller than the dimensions of the bottom of the recess RS1 in the second experiment. It can be seen that the WF6 gas contained in the process gas forms a metal-containing deposit DS, suppressing lateral etching of the sidewall RSb of the recess RS1. Furthermore, it can be seen that the amount of etching of the first region R1 formed under the mask MK was reduced.

[0067] Although various exemplary embodiments have been described above, the present invention is not limited to the above-described exemplary embodiments, and various additions, omissions, substitutions, and modifications may be made. Furthermore, elements in different embodiments may be combined to form other embodiments.

[0068] Various exemplary embodiments included in the present disclosure are now described in [E1] to [E16] below.

[0069] [E1] (a) providing a substrate on a substrate support in a chamber, the substrate including a first region comprising a first material, a second region formed below the first region and comprising a second material different from the first material, and a mask formed above the first region and including a first opening; (b) etching the first region with a first plasma generated from a first process gas containing a metal halide gas to form a second opening communicating with the first opening, and forming a metal-containing deposit on a sidewall of the second opening; (c) etching the second region with a second plasma generated from a second process gas different from the first process gas while the metal-containing deposit is formed on the side wall of the second opening, to form a recess communicating with the second opening;

[0070] [E2] The etching method according to [E1], wherein in (c), the metal-containing deposit remains on the side wall of the second opening when etching of the second region is completed.

[0071] [E3] The etching method according to [E1] or [E2], wherein the metal halide gas contains at least one selected from the group consisting of tungsten, titanium, molybdenum, vanadium, platinum, hafnium, niobium, tantalum, and rhenium.

[0072] [E4] The etching method according to [E3], wherein the metal halide gas includes at least one selected from the group consisting of tungsten hexafluoride gas, tungsten hexabromide gas, tungsten hexachloride gas, WF5Cl gas, titanium tetrachloride gas, molybdenum pentafluoride gas, vanadium hexafluoride gas, platinum hexafluoride gas, hafnium tetrafluoride gas, and niobium pentafluoride gas.

[0073] [E5] The etching method according to any one of [E1] to [E4], wherein the first process gas further contains at least one selected from the group consisting of a gas containing carbon and fluorine, and a nitrogen-containing gas.

[0074] [E6] The etching method according to [E5], wherein in (b), the flow rate of the metal halide gas is lower than the flow rate of the gas containing carbon and fluorine or the flow rate of the nitrogen-containing gas.

[0075] [E7] The etching method according to any one of [E1] to [E6], wherein the second process gas contains at least one of a hydrogen-containing gas and a nitrogen-containing gas.

[0076] [E8] The etching method according to any one of [E1] to [E7], wherein the second process gas does not contain a carbon-containing gas.

[0077] [E9] The etching method according to any one of [E1] to [E8], wherein the first material includes at least one of silicon and metal.

[0078] [E10] The etching method according to any one of [E1] to [E9], wherein the second material contains carbon.

[0079] [E11] The etching method according to any one of [E1] to [E10], wherein the mask includes a resist.

[0080] [E12] The etching method according to any one of [E1] to [E11], wherein the maximum value of the source RF power for generating the first plasma in (c) is greater than the maximum value of the source RF power for generating the second plasma in (b).

[0081] [E13] The etching method according to any one of [E1] to [E12], wherein the maximum value of the bias RF power supplied to the substrate support part in (c) is greater than the maximum value of the bias RF power supplied to the substrate support part in (b).

[0082] [E14] The etching method according to any one of [E1] to [E13], wherein the pressure inside the chamber in (c) is equal to or higher than the pressure inside the chamber in (b).

[0083] [E15] The etching method according to any one of [E1] to [E14], wherein the temperature of the substrate support part in (c) is equal to the temperature of the substrate support part in (b).

[0084] [E16] a chamber; a substrate support for supporting a substrate in the chamber, the substrate including: a first region including a first material; a second region formed below the first region and including a second material different from the first material; and a mask formed above the first region and including a first opening; a gas supply unit configured to supply into the chamber a first process gas including a metal halide gas and a second process gas different from the first process gas; a plasma generating unit configured to generate a first plasma and a second plasma from the first processing gas and the second processing gas, respectively, in the chamber; A control unit; Equipped with The control unit etching the first region with the first plasma to form a second opening communicating with the first opening, while forming a metal-containing deposit on a sidewall of the second opening; a plasma processing apparatus configured to control the gas supply unit and the plasma generation unit so as to etch the second region with the second plasma to form a recess communicating with the second opening, while the metal-containing deposit is formed on the side wall of the second opening. [Explanation of symbols]

[0085] 1...plasma processing apparatus, 2...controller, 10...plasma processing chamber, 11...substrate support, 12...plasma generation unit, 20...gas supply unit, DS...metal-containing deposit, MK...mask, OP1...first opening, OP2...second opening, OPb...sidewall of second opening, PM1...first plasma, PM2...second plasma, R1...first region, R2...second region, RS1...recess, W...substrate.

Claims

1. (a) providing a substrate on a substrate support in a chamber, the substrate including a first region comprising a first material, a second region formed below the first region and comprising a second material different from the first material, and a mask formed over the first region, the mask including a first opening; (b) etching the first region with a first plasma generated from a first process gas including a metal halide gas to form a second opening communicating with the first opening, and forming a metal-containing deposit on a sidewall of the second opening; (c) etching the second region with a second plasma generated from a second process gas different from the first process gas, while the metal-containing deposit is formed on the side wall of the second opening, to form a recess communicating with the second opening; An etching method comprising:

2. 2. The etching method according to claim 1, wherein in (c), the metal-containing deposit remains on a sidewall of the second opening when etching of the second region is completed.

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

4. The metal halide gas may be tungsten hexafluoride gas, tungsten hexabromide gas, tungsten hexachloride gas, WF ５ 3. The etching method according to claim 1, wherein the gas contains at least one selected from the group consisting of Cl gas, titanium tetrachloride gas, molybdenum pentafluoride gas, vanadium hexafluoride gas, platinum hexafluoride gas, hafnium tetrafluoride gas, and niobium pentafluoride gas.

5. 3. The etching method according to claim 1, wherein the first process gas further contains at least one selected from the group consisting of a gas containing carbon and fluorine, and a nitrogen-containing gas.

6. 6. The etching method according to claim 5, wherein in (b), the flow rate of the metal halide gas is lower than the flow rate of the gas containing carbon and fluorine or the flow rate of the nitrogen-containing gas.

7. 3. The etching method according to claim 1, wherein the second process gas contains at least one of a hydrogen-containing gas and a nitrogen-containing gas.

8. 3. The etching method according to claim 1, wherein the second process gas does not contain a carbon-containing gas.

9. The etching method according to claim 1 , wherein the first material includes at least one of silicon and a metal.

10. The etching method according to claim 1 , wherein the second material includes carbon.

11. The etching method according to claim 1 , wherein the mask includes a resist.

12. 3. The etching method according to claim 1, wherein a maximum value of source RF power for generating the first plasma in (c) is greater than a maximum value of source RF power for generating the second plasma in (b).

13. 3. The etching method according to claim 1, wherein a maximum value of the bias RF power supplied to the substrate support part in (c) is greater than a maximum value of the bias RF power supplied to the substrate support part in (b).

14. 3. The etching method according to claim 1, wherein the pressure in the chamber in (c) is equal to or higher than the pressure in the chamber in (b).

15. 3. The etching method according to claim 1, wherein the temperature of the substrate support part in (c) is equal to the temperature of the substrate support part in (b).

16. a chamber; a substrate support for supporting a substrate in the chamber, the substrate including: a first region including a first material; a second region formed below the first region including a second material different from the first material; and a mask formed above the first region, the mask including a first opening; a gas supply configured to supply into the chamber a first process gas including a metal halide gas and a second process gas different from the first process 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, respectively, in the chamber; A control unit; Equipped with The control unit etching the first region with the first plasma to form a second opening communicating with the first opening, while forming a metal-containing deposit on a sidewall of the second opening; a second plasma etching unit that etches the second region and forms a recess that communicates with the second opening, the second plasma etching the second region with the metal-containing deposit formed on the side wall of the second opening, the second plasma etching the second region and forming a recess that communicates with the second opening.

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