Etching method and plasma processing apparatus

Abstract

This technology provides a method for suppressing shape abnormalities during etching. [Solution] In one exemplary embodiment, the etching method includes: (a) providing a substrate on a substrate support in a chamber, the substrate comprising a metal-containing film and a mask on the metal-containing film; (b) etching the metal-containing film with a first plasma generated from a first processing gas containing a halogen-containing gas; (c) exhausting the first processing gas after (b) by increasing the opening of a pressure regulating valve for adjusting the pressure in the chamber from a first value to a second value and then maintaining it at the second value; (d) oxidizing the surface of the metal-containing film with a second plasma generated from a second processing gas containing an oxygen-containing gas; and (e) repeating (b) and (d).

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 plasma etching method for etching a film containing tungsten using plasma. In the etching process, a gas containing silicon, a gas containing halogen, and a gas containing carbon and oxygen are used. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2018-74006 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] This disclosure provides a technology that can suppress shape abnormalities during etching. [Means for solving the problem]

[0005] In one exemplary embodiment, the etching method includes: (a) providing a substrate on a substrate support in a chamber, the substrate comprising a metal-containing film and a mask on the metal-containing film; (b) etching the metal-containing film with a first plasma generated from a first processing gas containing a halogen-containing gas; (c) after (b), exhausting the first processing gas by increasing the opening of a pressure regulating valve for adjusting the pressure in the chamber from a first value to a second value and then maintaining it at the second value; (d) oxidizing the surface of the metal-containing film with a second plasma generated from a second processing gas containing an oxygen-containing gas; and (e) repeating (b) and (d). [Effects of the Invention]

[0006] According to one exemplary embodiment, a technique is provided that can suppress shape abnormalities during etching. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a diagram illustrating an example of the configuration of a plasma processing system. [Figure 2] Figure 2 is a diagram illustrating an example configuration of an inductively coupled plasma processing apparatus. [Figure 3] Figure 3 is a diagram illustrating a partial configuration example of the plasma processing apparatus shown in Figure 2. [Figure 4] Figure 4 shows an example of an exhaust system. [Figure 5] Figure 5 is a flowchart of an etching method according to one exemplary embodiment. [Figure 6] Figure 6 is a magnified view of a portion of a substrate to which the method in Figure 5 may be applied. [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 showing one step of an etching method according to one exemplary embodiment. [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 timing chart showing an example of the time variation of the opening and closing of the valve for supplying gas and the opening degree of the pressure regulating valve. [Figure 11] Figure 11 is a timing chart showing an example of the time evolution of the pressure inside the chamber, the opening of the pressure regulating valve, and the gas flow rate. [Figure 12] Figure 12 is a timing chart showing an example of the time evolution of the pressure inside the chamber, the opening of the pressure regulating valve, and the gas flow rate. [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 diagram illustrating an example configuration of a plasma processing system. In one embodiment, the plasma processing system includes a plasma processing apparatus 1 and a control unit 2. The plasma processing system is an example of a substrate processing system, and the plasma processing apparatus 1 is an example of a substrate processing apparatus. The plasma processing apparatus 1 includes a plasma processing chamber 10, a substrate support 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 (ECR) plasma, 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 the 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, some or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 is implemented, for example, by a computer 2a. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The functions implemented by the processing unit 2a1 described herein may be implemented in a circuit or processing circuitry, including a general-purpose processor, an application-specific processor, integrated circuits, ASICs (Application Specific Integrated Circuits), a CPU (Central Processing Unit), conventional circuitry, and / or a combination thereof, programmed to implement the functions described herein. A processor is considered a circuit or processing circuit, including transistors and other circuitry. A processor may be a programmed processor that executes a program stored in the storage unit 2a2. This program may be stored in the memory unit 2a2 in advance, or it may be retrieved via a medium when needed. The retrieved program is stored in the memory unit 2a2 and read from the memory 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 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).In the present disclosure, a circuit, unit, or means is hardware programmed to realize the described functions, or hardware configured to execute. The hardware may be any hardware described in the present disclosure, or any hardware known to be programmed or configured to realize the described functions. When the hardware is a processor regarded as a circuit type, the circuit, means, or unit is a combination of hardware and software used to constitute the hardware and / or the processor.

[0012] Hereinafter, a configuration example of an inductively coupled plasma processing apparatus as an example of the plasma processing apparatus 1 will be described. FIG. 2 is a diagram for explaining a configuration example of an inductively coupled plasma processing apparatus.

[0013] The inductively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply system 30, and an exhaust system 40. The plasma processing chamber 10 includes a dielectric window 101. Further, the plasma processing apparatus 1 includes a substrate support unit 11, a gas introduction unit, and an antenna 14. The substrate support unit 11 is disposed in the plasma processing chamber 10. The antenna 14 is disposed on or above the plasma processing chamber 10 (that is, on or above the dielectric window 101). The plasma processing chamber 10 has a plasma processing space 10s defined by the dielectric window 101, the side wall 102 of the plasma processing chamber 10, and the substrate support unit 11. The plasma processing chamber 10 is grounded.

[0014] The substrate support portion 11 includes a main body portion 111 and a ring assembly 112. The main body portion 111 has a central region 111a for supporting the substrate W and an annular region 111b for supporting the ring assembly 112. A wafer is an example of 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 placed on the central region 111a of the main body portion 111, and the ring assembly 112 is placed 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. Therefore, the central region 111a is also called the substrate support surface for supporting the substrate W, and the annular region 111b is also called the ring support surface for supporting the ring assembly 112.

[0015] In one embodiment, the main body 111 includes a base 1110 and an electrostatic chuck 1111. The base 1110 includes a conductive member. The conductive member of the base 1110 can function as a bias electrode. The electrostatic chuck 1111 is placed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic chuck electrode 1111b placed within the ceramic member 1111a. The electrostatic chuck electrode 1111b is also called a clamping electrode. In one embodiment, the electrostatic chuck electrode 1111b is electrically connected or coupled to a chuck power supply. The chuck power supply may be a DC power supply or an AC power supply. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Furthermore, other members surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member, may have an annular region 111b. In this case, the ring assembly 112 may be placed on the annular electrostatic chuck or the annular insulating member, or on both the electrostatic chuck 1111 and the annular insulating member. In addition, at least one bias electrode, electrically connected or coupled to the power supply 31 and / or power supply 32 described later, may be placed within the ceramic member 1111a. Furthermore, the conductive member of the base 1110 and the bias electrode in the ceramic member 1111a may function as multiple bias electrodes. Also, the electrostatic chuck electrode 1111b may function as a bias electrode. Therefore, the substrate support portion 11 includes at least one bias electrode.

[0016] The ring assembly 112 includes one or more annular members. In one embodiment, the one or more annular members include one or more edge rings and at least one covering ring. The edge rings are formed of a conductive or insulating material, and the covering rings are 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 gas introduction section is configured to introduce at least one processing gas from the gas supply section 20 into the plasma processing space 10s. In one embodiment, the gas introduction section includes a Center Gas Injector (CGI) 13. The Center Gas Injector 13 is located above the substrate support section 11 and is attached to a central opening formed in the dielectric window 101. The Center Gas Injector 13 has at least one gas supply port 13a, at least one gas flow path 13b, and at least one gas inlet 13c. The processing gas supplied to the gas supply port 13a passes through the gas flow path 13b and is introduced into the plasma processing space 10s from the gas inlet 13c. In addition to or instead of the Center Gas Injector 13, the gas introduction section may also include one or more Side Gas Injectors (SGIs) attached to one or more openings formed in the side wall 102.

[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 gas inlet 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 system 30 includes a power supply 31 that is electrically connected to or coupled to the plasma processing chamber 10. In one embodiment, the power supply 31 is electrically connected to or coupled to the plasma processing chamber 10 via at least one impedance matcher. The impedance matcher may be a mechanically controlled matcher or an electronically controlled matcher. The power supply 31 is configured to supply at least one RF signal (RF power) to at least one bias electrode and antenna 14. This generates plasma from at least one processing gas supplied to the plasma processing space 10s. Thus, the power supply 31 can function as at least part of the plasma generation unit 12. Furthermore, by supplying a bias RF signal to at least one bias electrode, a bias potential is generated on the substrate W, and ions in the formed plasma can be drawn into the substrate W.

[0021] The power supply 31 includes a first RF generation unit 31a and a second RF generation unit 31b. The first RF generation unit 31a is electrically connected to or coupled to the antenna 14 and is configured to generate a source RF signal (source RF power) to generate plasma in the plasma processing space 10s. In one embodiment, the first RF generation unit 31a is electrically connected to or coupled to the antenna 14 via at least one impedance matcher. 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 the antenna 14.

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

[0023] The power supply system 30 may also include a power supply 32 that is electrically connected to or coupled to the plasma processing chamber 10. The power supply 32 includes a voltage generation unit 32a. In one embodiment, the voltage generation unit 32a is electrically connected to or coupled to at least one bias electrode and configured to generate a voltage signal. The generated voltage signal is applied to at least one bias electrode.

[0024] In various embodiments, the voltage signal may be pulsed. In this case, the voltage generation unit 32a functions as a voltage pulse generation unit configured to generate a sequence of voltage pulses. Thus, the sequence of voltage pulses is applied to at least one bias electrode. In one embodiment, the sequence of voltage pulses has multiple cycles, each cycle including a burst of voltage pulses in a first period and a constant reference voltage in a second period. That is, the burst of voltage pulses is repeated in the sequence of voltage pulses. The absolute value of the voltage level of the voltage pulse is greater than the absolute value of the voltage level of the reference voltage. The voltage pulse may have an arbitrary waveform having a rectangular, trapezoidal, triangular, or a combination thereof, and the arbitrary waveform may change over time. The voltage pulse may have positive or negative polarity. Furthermore, the sequence of voltage pulses may include one or more positive voltage pulses and one or more negative voltage pulses within one cycle. Note that the voltage generation unit 32a may be provided in addition to the power supply 31, or it may be provided in place of the second RF generation unit 31b.

[0025] The antenna 14 includes one or more coils. In one embodiment, the antenna 14 may include an outer coil and an inner coil arranged coaxially. In this case, the power supply 31 may be connected to both the outer coil and the inner coil, or to either the outer coil or the inner coil. In the former case, the same RF generation unit may be connected to both the outer coil and the inner coil, or separate RF generation units may be connected to the outer coil and the inner coil separately.

[0026] The exhaust system 40 may be connected to, for example, a gas outlet 10e located at the bottom of the plasma processing chamber 10. The gas outlet 10e may be positioned at the bottom of the plasma processing chamber 10 so as to surround the main body 111 of the substrate support 11. The exhaust system 40 may also 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.

[0027] Figure 3 is a diagram illustrating a partial configuration example of the plasma processing apparatus shown in Figure 2. As shown in Figure 3, the gas supply unit 20 may include a plurality of gas sources 21, a plurality of flow controllers 22, and a flow splitter 23. A first gas source 21 may be connected to the flow splitter 23 via a first flow controller 22. A second gas source 21 may be connected to the flow splitter 23 via a second flow controller 22. A first processing gas contained in the first gas source 21 reaches the flow splitter 23 through the first flow controller 22. A second processing gas contained in the second gas source 21 reaches the flow splitter 23 through the second flow controller 22.

[0028] The gas introduction section of the plasma processing apparatus 1 may include a side gas injection section 113 in addition to the central gas injection section 13. The side gas injection section 113 is attached to the side wall 102 of the plasma processing chamber 10. A valve V1 may be installed in the gas supply pipe between the central gas injection section 13 and the gas supply section 20. Valve V1 may be located between the central gas injection section 13 and the flow splitter 23. A valve V2 may be installed in the gas supply pipe between the side gas injection section 113 and the gas supply section 20. Valve V2 may be located between the side gas injection section 113 and the flow splitter 23. By opening and closing valves V1 and V2, the supply of processing gas flowing through the gas supply pipe can be started or stopped.

[0029] Figure 4 shows an example of an exhaust system. As shown in Figure 4, the exhaust system 40 may include an exhaust chamber 41, a vacuum pump 42, and a pressure regulating valve 43. The exhaust chamber 41 may be connected to a gas outlet 10e. The exhaust chamber 41 may communicate with the plasma processing chamber 10. The vacuum pump 42 may be connected to a gas exhaust port 41a located at the bottom of the exhaust chamber 41. The pressure regulating valve 43 can adjust the amount of gas discharged from the gas exhaust port 41a by raising and lowering a support pin 44 that supports the pressure regulating valve 43. The pressure regulating valve 43 may be an automatic pressure control (APC). The support pin 44 is movable up and down through the bottom of the exhaust chamber 41. When the support pin 44 rises, a gap 45 is formed between the pressure regulating valve 43 and the bottom of the exhaust chamber 41. The distance of the gap 45 corresponds to the opening degree of the pressure regulating valve 43. By adjusting the opening of the pressure regulating valve 43, the processing gas in the exhaust chamber 41 and the plasma processing chamber 10 can be exhausted.

[0030] The exhaust system 40 may further include a pressure gauge 46 for measuring the pressure in the exhaust chamber 41 and the plasma processing chamber 10. The pressure gauge 46 may be mounted on the side wall of the exhaust chamber 41.

[0031] Figure 5 is a flowchart of an etching method according to one exemplary embodiment. The etching method MT1 shown in Figure 5 (hereinafter referred to as "method MT1") can be performed by the plasma processing apparatus 1 of the above embodiment. Method MT1 can be applied to the substrate W.

[0032] Figure 6 is a cross-sectional view of an example substrate to which the method of Figure 5 may be applied. As shown in Figure 6, in one embodiment, the substrate W comprises a metal-containing film MF and a mask MK on the metal-containing film MF. The substrate W may further comprise a substrate region UR beneath the metal-containing film MF. The mask MK has at least one opening OP. The opening OP may have a hole pattern or a line pattern.

[0033] The mask MK may be a carbon-containing film or a silicon-containing film.

[0034] The metal-containing film MF may contain a metal element and a non-metal element. The metal-containing film MF may contain, as the metal element, at least one transition metal element selected from the group consisting of tungsten, titanium, molybdenum, hafnium, zirconium, and ruthenium. The metal-containing film MF may contain, as the non-metal element, at least one of silicon, carbon, nitrogen, oxygen, hydrogen, boron, and phosphorus. The metal-containing film MF may contain at least one tungsten compound selected from the group consisting of tungsten silicide (W x Si y ), tungsten silicon nitride (W x Si y N z ), tungsten silicon boron (W x Si y B z ), and tungsten silicon carbon (W x Si y C z ). Each of the composition ratios x, y, and z may be a real number greater than 0. The metal-containing film MF may be a film for forming a hard mask.

[0035] The underlying region UR may include a silicon substrate.

[0036] Hereinafter, regarding the method MT1, taking the case where the method MT1 is applied to the substrate W using the plasma processing apparatus 1 of the above embodiment as an example, it will be described with reference to FIGS. 3 to 9. Each of FIGS. 7 to 9 is a cross-sectional view showing one step of an etching method according to an exemplary embodiment. When the plasma processing apparatus 1 is used, the method MT1 can be executed in the plasma processing apparatus 1 by controlling each part of the plasma processing apparatus 1 by the control unit 2. In the method MT1, as shown in FIG. 2, the substrate W on the substrate support portion 11 disposed in the plasma processing chamber 10 is processed.

[0037] As shown in Figure 5, Method MT1 may include steps ST1 to ST6. Steps ST1 to ST6 may be performed in order. Steps ST1 to ST6 may be performed in-situ (in the same chamber) or in-system (in a system capable of transporting substrates under reduced pressure between different chambers). Method MT1 does not necessarily include step ST5.

[0038] (Process ST1) In step ST1, the substrate W shown in Figure 6 is provided. The substrate W may be provided on a substrate support 11 located inside the plasma processing chamber 10.

[0039] (Process ST2) In step ST2, as shown in Figure 7, the metal-containing film MF is etched by a first plasma PL1 generated from a first processing gas containing a halogen-containing gas. Recesses RS corresponding to the openings OP of the mask MK may be formed in the metal-containing film MF. The first processing gas may be introduced into the plasma processing chamber 10 from a first gas injection unit (e.g., a central gas injection unit 13).

[0040] The halogen-containing gas in step ST2 may include a chlorine-containing gas or a fluorine-containing gas. An example of a chlorine-containing gas is chlorine (Cl2) gas. Examples of fluorine-containing gases are CF4 gas and NF3 gas. The first treatment gas in step ST2 may further include a hydrocarbon gas. An example of a hydrocarbon gas is methane (CH4) gas. The first treatment gas in step ST2 may further include an inert gas. Examples of inert gases are noble gases and nitrogen gas.

[0041] The processing time for step ST2 may be 10 seconds or less.

[0042] In step ST2, if the measured pressure inside the plasma processing chamber 10 is above a target value for a predetermined period, the supply of a source signal for generating the first plasma PL1 may be started. This allows etching to begin only after the pressure inside the plasma processing chamber 10 has stabilized.

[0043] (Process ST3) In step ST3, as shown in Figure 4, the opening of the pressure regulating valve 43 for adjusting the pressure in the plasma processing chamber 10 is increased from a first value to a second value, and then maintained at the second value to exhaust the first processing gas. As a result, the first processing gas remaining in the plasma processing chamber 10 in step ST2 can be removed.

[0044] The processing time for process ST3 may be shorter than the processing time for process ST2, or shorter than the processing time for process ST4, which will be described later. The processing time for process ST3 may be 1 second or less, or 0.5 seconds or less. The processing time for process ST3 may be greater than 0 seconds.

[0045] In step ST3, an inert gas does not necessarily have to be supplied into the plasma processing chamber 10. In step ST3, the first processing gas from step ST2 may be supplied, or the second processing gas from step ST4 described later may be supplied.

[0046] The opening degree of the pressure regulating valve 43 in process ST3 may be greater than the opening degree of the pressure regulating valve 43 in process ST2. The opening degree of the pressure regulating valve 43 in process ST2 may be greater than the opening degree of the pressure regulating valve 43 in process ST4, which will be described later.

[0047] (Process ST4) In step ST4, as shown in Figure 8, the surface of the metal-containing film MF is oxidized by a second plasma PL2 generated from a second processing gas containing oxygen. As a result, a metal oxide layer OX may be formed on the surface of the metal-containing film MF. The metal oxide layer OX may be formed on the side surface of the recess RS of the metal-containing film MF, or on the bottom surface of the recess RS of the metal-containing film MF. The second processing gas may be introduced into the plasma processing chamber 10 from a second gas injection port (e.g., a side gas injection port 113). In step ST4, the opening of the pressure regulating valve 43 may be reduced from the second value in step ST3 to the fifth value.

[0048] An example of an oxygen-containing gas in process ST4 is oxygen (O2) gas.

[0049] The pressure inside the plasma processing chamber 10 in step ST4 may be higher than the pressure inside the plasma processing chamber 10 in step ST2.

[0050] The processing time for process ST4 may be shorter than the processing time for process ST2. The processing time for process ST4 may be 10 seconds or less.

[0051] In step ST4, if the measured pressure inside the plasma processing chamber 10 is above a target value for a predetermined period, the supply of a source signal for generating the second plasma PL2 may be started. This allows oxidation to begin only after the pressure inside the plasma processing chamber 10 has stabilized.

[0052] (Process ST5) In step ST5, as shown in Figure 4, the second processing gas may be exhausted by increasing the opening of the pressure regulating valve 43 for adjusting the pressure in the plasma processing chamber 10 from a third value to a fourth value and then maintaining it at the fourth value. As a result, the second processing gas remaining in the plasma processing chamber 10 in step ST4 can be removed. Step ST5 may be performed in the same manner as step ST3.

[0053] The processing time for process ST5 may be shorter than the processing time for process ST4, or shorter than the processing time for process ST2. The processing time for process ST5 may be 1 second or less, or 0.5 seconds or less. The processing time for process ST5 may be greater than 0 seconds.

[0054] In step ST5, an inert gas does not necessarily have to be supplied into the plasma processing chamber 10. In step ST5, the second processing gas from step ST4 may be supplied, or the first processing gas from step ST2 may be supplied.

[0055] The opening degree of the pressure regulating valve 43 in process ST5 may be greater than the opening degree of the pressure regulating valve 43 in process ST4.

[0056] (Process ST6) In process ST6, processes ST2 and ST4 are repeated. In process ST6, a cycle CY including processes ST2 and ST4 may be repeated. Cycle CY may further include process ST3, or further include process ST5. Process ST6 may terminate when the number of cycles CY reaches a predetermined threshold, or when a predetermined time is reached. Alternatively, as shown in Figure 9, process ST6 may terminate when the bottom surface of the recess RS reaches the substrate area UR.

[0057] In steps ST2 to ST6, the temperature of the substrate support portion 11 may be 100°C or higher, 140°C or higher, or 170°C or lower.

[0058] Figure 10 is a timing chart showing an example of the time variation of valve opening and closing and pressure regulating valve opening in the gas supply section. Valve V1 shown in Figure 3 may be a valve for supplying the first processing gas in process ST2. Valve V2 may be a valve for supplying the second processing gas in process ST4. As shown in Figure 10, in the first period P1, valve V1 is open while valve V2 is closed. The first period P1 corresponds to process ST2. In the second period P2, valve V1 transitions from an open state to a partially open state (partially closed state), while valve V2 transitions from a closed state to a partially open state (partially closed state). The second period P2 is the period that follows the first period P1. The second period P2 corresponds to process ST3. In the third period P3, valve V1 transitions from a partially open state (partially closed state) to a closed state and maintains the closed state, while valve V2 transitions from a partially open state (partially closed state) to an open state and maintains the open state. The third period P3 is the period that follows the second period P2. The third period P3 corresponds to process ST4.

[0059] During the first period P1, the opening degree of the pressure regulating valve 43 is a first value VOP1. During the second period P2, the opening degree of the pressure regulating valve 43 increases from the first value VOP1 to the second value VOP2, and is then maintained at the second value VOP2. The second value VOP2 is greater than the first value VOP1. During the third period P3, the opening degree of the pressure regulating valve 43 decreases from the second value VOP2 to the fifth value VOP5, and is then maintained at the fifth value VOP5. The fifth value VOP5 may be less than the second value VOP2 and less than the first value VOP1.

[0060] Figure 11 is a timing chart showing an example of the time evolution of the pressure in the chamber, the opening of the pressure regulating valve, and the gas flow rate. In Figure 11, Cl2 represents the flow rate of chlorine gas, and O2 represents the flow rate of oxygen gas. PR represents the pressure in the plasma processing chamber 10. VOP represents the opening of the pressure regulating valve 43. In the first period P1, chlorine gas is supplied while oxygen gas is not. The opening of the pressure regulating valve 43 is the first value. In the second period P2, the flow rate of chlorine gas decreases while the flow rate of oxygen gas increases. The opening of the pressure regulating valve 43 increases from the first value to the second value and is then maintained at the second value. In the third period P3, chlorine gas is not supplied while oxygen gas is supplied. The opening of the pressure regulating valve 43 decreases from the second value to the fifth value and is then maintained at the fifth value. As a result, in the third period P3, the pressure in the plasma processing chamber 10 increases.

[0061] Figure 12 is a timing chart showing an example of the time evolution of the pressure in the chamber, the opening of the pressure regulating valve, and the gas flow rate. In Figure 12, Cl2 represents the flow rate of chlorine gas, and O2 represents the flow rate of oxygen gas. PR represents the pressure in the plasma processing chamber 10. VOP represents the opening of the pressure regulating valve 43. In the third period P3, chlorine gas is not supplied, while oxygen gas is supplied. The opening of the pressure regulating valve 43 is the third value. The third value may be the same as the fifth value. In the fourth period P4, the flow rate of chlorine gas increases, while the flow rate of oxygen gas decreases. The opening of the pressure regulating valve 43 increases from the third value to the fourth value and is then maintained at the fourth value. The fourth value may be the same as the first value. The fourth period P4 is the period that follows the third period P3. The fourth period P4 corresponds to process ST5. After the fourth period P4, the first period P1 to the fourth period P4 may be repeated.

[0062] According to the plasma processing apparatus 1 and method MT1 described above, since the first processing gas is exhausted in step ST3, etching of the metal-containing film MF by the first processing gas remaining in the plasma processing chamber 10 can be suppressed in step ST4. Therefore, shape abnormalities in etching can be suppressed. For example, shape abnormalities (bowing) on ​​the side walls of recesses RS can be suppressed. Alternatively, the expansion of CD at the upper end of recesses RS can be suppressed. Furthermore, since the second processing gas is exhausted in step ST5, oxidation of the metal-containing film MF by the second processing gas remaining in the plasma processing chamber 10 can be suppressed in step ST2 following step ST5.

[0063] From the above description, it will be understood that the various embodiments of this disclosure are described herein for illustrative purposes and can be modified in various ways without departing from the scope and spirit of this disclosure. Accordingly, the various embodiments disclosed herein are not intended to limit the scope and spirit, and the true scope and spirit are shown by the appended claims.

[0064] Herein, various exemplary embodiments included in this disclosure are described in [E1] to [E17] below.

[0065] [E1] (a) A step of providing a substrate on a substrate support portion in a chamber, wherein the substrate comprises a metal-containing film and a mask on the metal-containing film, (b) A step of etching the metal-containing film with a first plasma generated from a first processing gas containing a halogen-containing gas, (c) After (b) above, the first process gas is exhausted by increasing the opening of a pressure regulating valve for adjusting the pressure in the chamber from a first value to a second value and then maintaining it at the second value. (d) A step of oxidizing the surface of the metal-containing film with a second plasma generated from a second processing gas containing an oxygen-containing gas, (e) A step of repeating (b) and (c), (e) After (b) above, a step of exhausting the first process gas by adjusting the opening of a pressure regulating valve for adjusting the pressure in the chamber, Etching methods including

[0066] [E2] (f) The etching method according to [E1], further comprising the step of exhausting the second processing gas by increasing the opening of the pressure regulating valve from a third value to a fourth value and then maintaining it at the fourth value, after (d).

[0067] [E3] The etching method according to [E2], wherein the cycle including (b) and (d) further includes (c) and (f).

[0068] [E4] The etching method according to any one of [E1] to [E3], wherein the processing time of (c) is shorter than the processing time of (d).

[0069] [E5] The etching method according to any one of [E1] to [E4], wherein the processing time for (c) is 1 second or less.

[0070] [E6] The etching method according to any one of [E1] to [E5], wherein, in (d) above, the opening degree of the pressure regulating valve decreases from the second value to the fifth value.

[0071] [E7] The etching method according to [E6], wherein the fifth value is smaller than the first value.

[0072] [E8] The etching method according to any one of [E1] to [E7], wherein the opening degree of the pressure regulating valve in (c) is greater than the opening degree of the pressure regulating valve in (b).

[0073] [E9] The etching method according to any one of [E1] to [E8], wherein the metal-containing film comprises at least one tungsten compound selected from the group consisting of tungsten silicide, tungsten silicon nitride, tungsten silicon boron, and tungsten silicon carbon.

[0074] [E10] The etching method according to any one of [E1] to [E9], wherein the pressure in the chamber in (d) is higher than the pressure in the chamber in (b).

[0075] [E11] The etching method according to any one of [E1] to [E10], wherein the first processing gas further comprises a hydrocarbon gas.

[0076] [E12] The etching method according to any one of [E1] to [E11], wherein the halogen-containing gas includes chlorine gas.

[0077] [E13] The aforementioned oxygen-containing gas is an etching method according to any one of [E1] to [E12], which includes oxygen gas.

[0078] [E14] The etching method according to any one of [E1] to [E13], wherein, in (b) above, when the measured pressure in the chamber is equal to or greater than a target value for a predetermined period of time, the supply of a source signal for generating the first plasma is started.

[0079] [E15] The etching method according to any one of [E1] to [E14], wherein, in (d) above, if the measured pressure in the chamber is equal to or greater than a target value for a predetermined period of time, the supply of a source signal for generating the second plasma is started.

[0080] [E16] Chamber and, A substrate support portion for supporting a substrate within the chamber, wherein the substrate comprises a metal-containing film and a mask on the metal-containing film, A gas supply unit configured to supply a first processing gas and a second processing gas into the chamber, wherein the first processing gas contains a halogen-containing gas and the second processing gas contains an oxygen-containing gas, A plasma generation unit configured to generate a first plasma and a second plasma from the first processing gas and the second processing gas within the chamber, A pressure regulating valve for adjusting the pressure inside the chamber, Control unit and Equipped with, The control unit is configured to control the gas supply unit, the plasma generation unit, and the pressure regulating valve to execute the etching method, and the etching method is (b) A step of etching the metal-containing film with the first plasma, (c) After (b) above, the first process gas is exhausted by increasing the opening of the pressure regulating valve from a first value to a second value and then maintaining it at the second value, (d) A step of oxidizing the surface of the metal-containing film with the second plasma, (e) A step of repeating (b) and (d), A plasma processing apparatus, including a plasma treatment device.

[0081] [E17] A first gas injection unit configured to introduce the first processing gas from the gas supply unit into the chamber, A second gas injection unit configured to introduce the second processing gas from the gas supply unit into the chamber, Furthermore, In (b) above, the first processing gas is introduced into the chamber from the first gas injection unit. In (d) above, the second processing gas is introduced into the chamber from the second gas injection unit, the plasma processing apparatus according to [E16]. [Explanation of Symbols]

[0082] 1...Plasma processing apparatus, 2...Control unit, 10...Plasma processing chamber, 11...Substrate support unit, 12...Plasma generation unit, 20...Gas supply unit, 43...Pressure regulating valve, MF...Metal-containing film, MK...Mask, PL1...First plasma, PL2...Second plasma, W...Substrate.

Claims

1. (a) A step of providing a substrate on a substrate support portion in a chamber, wherein the substrate comprises a metal-containing film and a mask on the metal-containing film, (b) A step of etching the metal-containing film with a first plasma generated from a first processing gas containing a halogen-containing gas, (c) After (b) above, the first process gas is exhausted by increasing the opening of a pressure regulating valve for adjusting the pressure in the chamber from a first value to a second value and then maintaining it at the second value. (d) A step of oxidizing the surface of the metal-containing film with a second plasma generated from a second processing gas containing an oxygen-containing gas, (e) A step of repeating (b) and (d), Etching methods including

2. (f) The etching method according to claim 1, further comprising the step of exhausting the second processing gas by increasing the opening of the pressure regulating valve from a third value to a fourth value after (d), and then maintaining it at the fourth value.

3. The etching method according to claim 2, wherein the cycle including (b) and (d) further includes (c) and (f).

4. The etching method according to any one of claims 1 to 3, wherein the processing time of (c) is shorter than the processing time of (d).

5. The etching method according to any one of claims 1 to 3, wherein the processing time of (c) is 1 second or less.

6. The etching method according to any one of claims 1 to 3, wherein, in (d) above, the opening degree of the pressure regulating valve decreases from the second value to the fifth value.

7. The etching method according to claim 6, wherein the fifth value is smaller than the first value.

8. The etching method according to any one of claims 1 to 3, wherein the opening degree of the pressure regulating valve in (c) is greater than the opening degree of the pressure regulating valve in (b).

9. The etching method according to any one of claims 1 to 3, wherein the metal-containing film comprises at least one tungsten compound selected from the group consisting of tungsten silicide, tungsten silicon nitride, tungsten silicon boron, and tungsten silicon carbon.

10. The etching method according to any one of claims 1 to 3, wherein the pressure in the chamber in (d) is higher than the pressure in the chamber in (b).

11. The etching method according to any one of claims 1 to 3, wherein the first processing gas further comprises a hydrocarbon gas.

12. The etching method according to any one of claims 1 to 3, wherein the halogen-containing gas includes chlorine gas.

13. The etching method according to any one of claims 1 to 3, wherein the oxygen-containing gas includes oxygen gas.

14. The etching method according to any one of claims 1 to 3, wherein, in (b) above, if the measured pressure in the chamber is equal to or greater than a target value for a predetermined period of time, the supply of a source signal for generating the first plasma is started.

15. The etching method according to any one of claims 1 to 3, wherein, in (d) above, if the measured pressure in the chamber is equal to or greater than a target value for a predetermined period of time, the supply of a source signal for generating the second plasma is started.

16. Chamber and, A substrate support portion for supporting a substrate within the chamber, wherein the substrate comprises a metal-containing film and a mask on the metal-containing film, A gas supply unit configured to supply a first processing gas and a second processing gas into the chamber, wherein the first processing gas contains a halogen-containing gas and the second processing gas contains an oxygen-containing gas, A plasma generation unit configured to generate a first plasma and a second plasma from the first processing gas and the second processing gas within the chamber, A pressure regulating valve for adjusting the pressure inside the chamber, Control unit and Equipped with, The control unit is configured to control the gas supply unit, the plasma generation unit, and the pressure regulating valve to execute the etching method, and the etching method is (b) A step of etching the metal-containing film with the first plasma, (c) After (b) above, the first process gas is exhausted by increasing the opening of the pressure regulating valve from a first value to a second value and then maintaining it at the second value. (d) A step of oxidizing the surface of the metal-containing film with the second plasma, (e) A step of repeating (b) and (d), A plasma processing apparatus, including a plasma treatment device.

17. A first gas injection unit configured to introduce the first processing gas from the gas supply unit into the chamber, A second gas injection unit is configured to introduce the second processing gas from the gas supply unit into the chamber, Furthermore, In (b) above, the first processing gas is introduced into the chamber from the first gas injection unit. The plasma processing apparatus according to claim 16, wherein, in (d) above, the second processing gas is introduced into the chamber from the second gas injection unit.

Images