Etching method and plasma processing apparatus

Abstract

To provide a technique for suppressing shape abnormality of etching.SOLUTION: An etching method is provided. The method includes (a) preparing a substrate including an etching target film having a recess and a mask disposed on the etching target film and having an opening through which the recess is exposed, (b) forming a metal-containing film on a sidewall of the recess by using a first plasma generated from a first processing gas containing a metal-containing gas, the metal-containing gas containing at least one metal selected from a group consisting of ruthenium, tungsten, molybdenum and titanium, and (c) etching the etching target film in the recess by using a second plasma generated from a second processing gas containing a hydrogen fluoride gas.SELECTED DRAWING: Figure 4

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 technique for etching a silicon-containing film while suppressing bowing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-21546 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique for suppressing etching shape abnormalities. [Means for solving the problem]

[0005] In one exemplary embodiment of the present disclosure, there is provided an etching method performed in a plasma processing apparatus including a chamber, the etching method including: (a) preparing a substrate, the substrate including a film to be etched having a recess; and a mask having an opening exposing the recess and disposed on the film to be etched; (b) forming a metal-containing film on a sidewall of the recess using a first plasma formed from a first process gas including a metal-containing gas, the metal-containing gas including at least one metal selected from the group consisting of ruthenium, tungsten, molybdenum, and titanium; and (c) etching the film to be etched in the recess using a second plasma formed from a second process gas including hydrogen fluoride gas. [Effects of the Invention]

[0006] According to one exemplary embodiment of the present disclosure, a technique for suppressing etching shape abnormalities can be provided. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a plasma processing apparatus. [Figure 2] FIG. 1 is a diagram illustrating an example of the configuration of a capacitively coupled plasma processing apparatus. [Figure 3] FIG. 10 is a diagram for explaining an example of bowing. [Figure 4] 1 is a flowchart illustrating an example of the method. [Figure 5] 1 is a diagram showing an example of a cross-sectional structure of a substrate W provided in step ST11. FIG. [Figure 6] 10 is a diagram showing an example of a cross-sectional structure of the substrate W after processing in step ST12. FIG. [Figure 7] 10 is a diagram showing an example of a cross-sectional structure of the substrate W after being processed in step ST2. FIG. [Figure 8] FIG. 10 is a diagram showing an example of the cross-sectional structure of the substrate W being processed at step ST3. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, each embodiment of the present disclosure will be described.

[0009] In one exemplary embodiment, there is provided an etching method performed in a plasma processing apparatus including a chamber, the etching method including: (a) preparing a substrate, the substrate including a film to be etched having a recess; and a mask having an opening exposing the recess and disposed on the film to be etched; (b) forming a metal-containing film on a sidewall of the recess using a first plasma formed from a first process gas including a metal-containing gas, the metal-containing gas including at least one metal selected from the group consisting of ruthenium, tungsten, molybdenum, and titanium; and (c) etching the film to be etched in the recess using a second plasma formed from a second process gas including hydrogen fluoride gas.

[0010] In one exemplary embodiment, the second process gas further comprises a metal-containing gas, and in (c), a metal-containing film is formed on the sidewall of the recess and the target film is etched in the recess.

[0011] In one exemplary embodiment, a cycle comprising steps (b) and (c) is repeated multiple times.

[0012] In one exemplary embodiment, the second process gas further comprises a phosphorus-containing gas.

[0013] In one exemplary embodiment, in (c), the temperature of the substrate or a substrate support that supports the substrate is controlled to 0° C. or less.

[0014] In one exemplary embodiment, there is provided an etching method performed in a plasma processing apparatus having a chamber, the etching method including: (a) a step of preparing a substrate, the substrate including a film to be etched having a recess, and a mask having an opening exposing the recess and disposed on the film to be etched; and (b) a step of forming a metal-containing film on a sidewall of the recess and etching the film to be etched in the recess using plasma generated from a process gas including a metal-containing gas and hydrogen fluoride gas, the metal-containing gas including at least one metal selected from the group consisting of ruthenium, tungsten, molybdenum, and titanium.

[0015] In one exemplary embodiment, the process gas further comprises a phosphorus-containing gas.

[0016] In one exemplary embodiment, in (b), the temperature of the substrate or a substrate support that supports the substrate is controlled to 0° C. or less.

[0017] In one exemplary embodiment, the film to be etched is a silicon-containing film, a carbon-containing film, or a metal oxide film.

[0018] In one exemplary embodiment, the film to be etched includes at least one selected from the group consisting of a silicon oxide film, a silicon nitride film, a silicon oxynitride film, a silicon carbonitride film, and a polycrystalline silicon film, and a stacked film including at least two of these films.

[0019] In one exemplary embodiment, the mask comprises at least one metal selected from the group consisting of ruthenium, tungsten, molybdenum, titanium, indium, gallium, and zinc.

[0020] In one exemplary embodiment, the mask is a carbon-containing film.

[0021] In one exemplary embodiment, the substrate includes an etch stop film below the film to be etched, the etch stop film comprising at least one metal selected from the group consisting of ruthenium, tungsten, molybdenum, titanium, indium, gallium, and zinc.

[0022] In one exemplary embodiment, there is provided a plasma processing apparatus including a chamber and a controller, the controller being configured to: (a) prepare a substrate in the chamber, the substrate including a film to be etched having a recess, and a mask disposed on the film to be etched, the mask having an opening exposing the recess; (b) form a metal-containing film on a sidewall of the recess using a first plasma formed in the chamber from a first process gas including a metal-containing gas, the metal-containing gas including at least one metal selected from the group consisting of ruthenium, tungsten, molybdenum, and titanium; and (c) etch the film to be etched in the recess using a second plasma formed in the chamber from a second process gas including hydrogen fluoride gas.

[0023] Hereinafter, each embodiment of the present disclosure will be described in detail with reference to the drawings. In each drawing, the same or similar elements are designated by the same reference numerals, and redundant explanations will be omitted. Unless otherwise specified, the positional relationships, such as up, down, left, and right, will be described based on the positional relationships shown in the drawings. The dimensional ratios in the drawings do not represent actual ratios, and the actual ratios are not limited to the ratios shown in the drawings.

[0024] <Configuration example of plasma processing system> 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.

[0025] 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.

[0026] 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).

[0027] <Configuration example of a capacitively coupled plasma processing apparatus> 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] <An example from Boeing> Bowing is known as one of the shape abnormalities that occur in plasma etching. Bowing is a phenomenon in which the opening dimensions of a portion of the sidewall of a recess formed by etching become larger than the opening dimensions of the top of the recess. The portion where bowing occurs has a barrel-like shape in cross section, for example. Bowing is thought to occur when part of the sidewall of the recess is removed by ions that recoil from a mask or the like.

[0042] 3 is a diagram illustrating an example of bowing. FIG. 3 shows an example of a cross-sectional structure in which a recess RC is formed by etching an etching target film EF of a substrate W through a mask MK having an opening OP. In this example, a barrel-shaped bow in cross section occurs on the upper side (low aspect region) of the recess RC when the bottom BT of the recess RC reaches the base film UF. The opening dimension of the recess RC where the bowing occurs is larger than the opening dimension of the middle to lower side of the recess RC (medium aspect region to high aspect region). Note that bowing may occur not only on the upper side of the recess RC but also on the middle to lower side of the recess RC.

[0043] An etching method according to an exemplary embodiment of the present disclosure (hereinafter also referred to as "the method") can suppress such bowing. Hereinafter, the method will be described with reference to the drawings.

[0044] <An example of this method> 4 is a flowchart showing an example of the method. The method includes step ST1 of preparing a substrate, step ST2 of forming a metal-containing film in a recess, and step ST3 of etching the recess. Step ST1 includes step ST11 of providing a substrate W and step ST12 of etching the substrate W to form a recess. In one embodiment, the processes in each step may be performed in a plasma processing apparatus 1 (see FIGS. 1 and 2). In the following example, the method is performed by a control unit 2 controlling each unit of a capacitively coupled plasma processing apparatus 1 (see FIG. 2).

[0045] (Step ST1: Preparation of the substrate) In step ST1, a substrate having a recess is prepared. First, in step ST11, the substrate W is provided in the plasma processing space 10s of the plasma processing apparatus 1. Then, in step ST12, a recess is formed in the substrate W.

[0046] In step ST11, the substrate W is placed in the central region 111a of the substrate support 11 and held on the substrate support 11 by an electrostatic chuck 1111. FIG. 5 is a diagram showing an example of the cross-sectional structure of the substrate W provided in step ST11. As shown in FIG. 5, the substrate W includes an etching target film EF and a mask MK placed on the etching target film EF. In one embodiment, the etching target film EF may be formed on an underlayer film UF. The substrate W may be used in the manufacture of semiconductor devices. The semiconductor devices include, for example, semiconductor memory devices such as DRAMs and 3D-NAND flash memories.

[0047] In one embodiment, the underlayer UF is a silicon wafer, an organic film, a dielectric film, a metal film, a semiconductor film, or the like formed on a silicon wafer. In one embodiment, the underlayer UF may include an etch-stop film. In one embodiment, the etch-stop film includes at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, titanium, indium, gallium, and zinc. The etch-stop film may include, for example, a carbide or silicide of the above metal. The etch-stop film may be, for example, a tungsten-containing film. The etch-stop film may further include tungsten and at least one selected from the group consisting of silicon, carbon, and nitrogen. In one example, the etch-stop film includes at least one selected from the group consisting of tungsten carbide, tungsten silicide, WSiN, and WSiC. The etch-stop film may include, for example, at least one selected from the group consisting of ruthenium, tungsten silicide, titanium nitride, molybdenum, and InGaZnO.

[0048] In one embodiment, the base film UF may be configured by stacking multiple films. When the base film UF is configured by multiple films, the etching stop film may be formed on the top layer of the base film UF. In other words, the etching stop film may be disposed so as to contact the etching target film EF.

[0049] The etching target film EF is a film that is to be etched by the present method. The etching target film EF may be composed of a single film, or may be composed of a plurality of films stacked together.

[0050] In one embodiment, the etching target film EF is a silicon-containing film. The silicon-containing film is, for example, a silicon oxide film, a silicon nitride film, a silicon carbonitride film, a polycrystalline silicon film, or a laminated film including two or more of these films. For example, the silicon-containing film may be formed by alternately laminating silicon oxide films and silicon nitride films. For example, the silicon-containing film may be formed by alternately laminating silicon oxide films and polycrystalline silicon films. For example, the silicon-containing film may be a laminated film including a silicon nitride film, a silicon oxide film, and a polycrystalline silicon film.

[0051] In one embodiment, the film to be etched EF is a carbon-containing film, and in one example, the carbon-containing film is an amorphous carbon film.

[0052] In one embodiment, the film to be etched EF is a metal oxide film, for example, a zinc oxide film or a tin oxide film.

[0053] The mask MK has a pattern to be transferred to the etching target film EF by etching. The mask MK may be a single-layer mask consisting of one layer, or may be a multi-layer mask consisting of two or more layers. As shown in FIG. 5, a sidewall SS1 of the mask MK defines at least one opening OP on the etching target film EF. The opening OP is a space above the etching target film EF and is surrounded by the sidewall SS1 of the mask MK. That is, the upper surface of the etching target film EF has an area covered by the mask MK and an area exposed at the bottom of the opening OP.

[0054] The openings OP may have any shape when viewed from above the substrate W, i.e., when the substrate W is viewed from top to bottom in FIG. 5. The shape may be, for example, a circle, an ellipse, a rectangle, a line, or a combination of one or more of these. The mask MK may have multiple side walls that define multiple openings OP. The multiple openings OP may each have a linear shape and be arranged at regular intervals to form a line-and-space pattern. Alternatively, the multiple openings OP may each have a hole shape and form an array pattern.

[0055] The mask MK may be appropriately selected depending on the etching target film EF. In one embodiment, the mask MK is made of a material whose etching rate with respect to the plasma formed in step ST12 or step ST3 is lower than that of the etching target film EF.

[0056] In one embodiment, the mask MK is a carbon-containing mask or a metal-containing mask. The carbon-containing mask may be, for example, an amorphous carbon (ACL) film, a spin-on carbon (SOC) film, or a photoresist film. The ACL film may be doped with elements such as boron, arsenic, tungsten, or xenon. The metal-containing mask may be, for example, a metal-containing film containing the same type of metal as the etching stop film described above.

[0057] The base film UF, etching target film EF, and mask MK may each be formed by any method. For example, the base film UF, etching target film EF, and mask MK may be formed by a CVD method, an ALD method, a PVD method, a spin coating method, or the like. The mask MK may be formed by, for example, lithography. The opening OP in the mask MK may be formed by etching the mask MK. The base film UF, etching target film EF, and mask MK may each be a flat film or a film having an uneven surface. The substrate W may further include another film below the base film UF. In this case, recesses having shapes corresponding to the openings OP may be formed in the etching target film EF and base film UF and used as masks for etching the other film.

[0058] At least a part of the process for forming the base film UF, the etching target film EF, and the mask MK on the substrate W may be performed in the plasma processing space 10s as part of step ST11. For example, when the opening OP in the mask MK is formed by etching, the etching in step ST11 and the etching in step ST12 may be performed consecutively in the plasma processing space 10s. In one embodiment, the substrate W may be provided in the plasma processing space 10s after all or part of the substrate W is formed in an apparatus or chamber external to the plasma processing apparatus 1.

[0059] In one embodiment, after the substrate W is provided in the central region 111a of the substrate support 11, the substrate support 11 is controlled to a given temperature by a temperature control module. In one example, controlling the temperature of the substrate support 11 to a given temperature includes setting the temperature of the heat transfer fluid flowing through the flow path 1110a or the heater temperature to a given temperature, or to a temperature different from the given temperature. The timing at which the heat transfer fluid starts flowing through the flow path 1110a may be before, after, or simultaneously with the substrate W being placed on the substrate support 11. The temperature of the substrate support 11 may be controlled to a given temperature before step ST1. That is, the substrate W may be provided to the substrate support 11 after the temperature of the substrate support 11 is controlled to a given temperature. In one embodiment, the given temperature is 0°C or less, -10°C or less, -20°C or less, -30°C or less, -40°C or less, -50°C, -60°C or less, or -70°C or less. In one embodiment, the given temperature is -100°C or higher.

[0060] In one embodiment, the substrate W may be controlled to a given temperature instead of controlling the substrate support 11 to a given temperature. Controlling the temperature of the substrate W to a given temperature includes setting the temperature of the substrate support 11, the temperature of the heat transfer fluid flowing through the flow path 1110a, and / or the heater temperature to a given temperature or to a temperature different from the given temperature.

[0061] In step ST12, recesses are formed in the etching target film EF. First, a processing gas is supplied from the gas supply unit 20 into the plasma processing space 10s. The processing gas may be selected so that the etching target film EF can be etched with a sufficient selectivity relative to the mask MK. The processing gas may be the same as or different from the second processing gas used in the etching in step ST3, which will be described later.

[0062] In one embodiment, the process gas may include a fluorine-containing gas. Examples of the fluorine-containing gas include hydrogen fluoride (HF) gas, a fluorocarbon gas, or a hydrofluorocarbon gas. In one embodiment, the process gas may further include one or more gases selected from the group consisting of a phosphorus-containing gas, a carbon-containing gas, an oxygen-containing gas, a halogen-containing gas other than fluorine, and an inert gas. The types of gases constituting the process gas and the flow rates (partial pressures) of each gas may be constant during the process in step ST12 or may be changed as the etching progresses.

[0063] Next, a source RF signal is supplied to the lower electrode of the substrate support 11 and / or the upper electrode of the shower head 13. This generates a high-frequency electric field between the shower head 13 and the substrate support 11, and plasma is generated from the processing gas in the plasma processing space 10s. In one embodiment, a bias signal may be supplied to the lower electrode of the substrate support 11. This attracts active species such as ions and radicals in the plasma to the substrate W, etching the target film EF and forming recesses. The bias signal may be a bias RF signal supplied from the second RF generator 31b. The bias signal may also be a bias DC signal supplied from the DC generator 32a.

[0064] In one embodiment, during the processing in step ST12, the temperature of the substrate support 11 or the substrate W may be controlled to a given temperature set in step ST11.

[0065] 6 is a diagram showing an example of the cross-sectional structure of the substrate W after processing in step ST12. As shown in Fig. 6, by the processing in step ST12, the portion of the etching target film EF exposed at the opening OP is etched in the depth direction (from top to bottom in Fig. 6), forming a recess RC. The recess RC is a space defined by the sidewall SS2 and bottom BT of the etching target film EF.

[0066] In one embodiment, step ST12 may be terminated based on the dimensions (depth, opening dimension, aspect ratio) of the recess RC and / or the etching time. In one embodiment, step ST12 may be terminated at a timing before bowing occurs in the recess RC. In one embodiment, the depth D1 of the recess RC after step ST12 may be 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, 5% or less, 3% or less, or 1% or less of the final etching depth (e.g., the depth D2 to the underlayer UF).

[0067] As described above, in step ST1, the substrate W including the etching target film EF having the recesses RC and the mask MK having the openings OP is prepared on the substrate support part 11 of the plasma processing chamber 10. Note that the substrate W may be prepared by forming the recesses RC in the substrate W in an apparatus or chamber external to the plasma processing apparatus 1, and then providing the substrate W on the substrate support part 11 of the plasma processing apparatus 1.

[0068] (Step ST2: Formation of metal-containing film) In step ST2, a metal-containing film is formed in the recess RC of the etching target film EF.

[0069] First, a first process gas containing a metal-containing gas is supplied from the gas supply unit 20 into the plasma processing space 10s. The metal-containing gas contains at least one metal selected from the group consisting of ruthenium, tungsten, molybdenum, and titanium (hereinafter also referred to as "metal M"). In one embodiment, the metal-containing gas contains ruthenium and a halogen. For example, the metal-containing gas may be RuO3 gas, RuO4 gas, RuF5 gas, or RuF6 gas. In one embodiment, the metal-containing gas may be a gas containing tungsten, molybdenum, or titanium and a halogen. For example, the metal-containing gas may be WF2 gas, WF4 gas, WF5 gas, WF6 gas, WCl2 gas, WCl4 gas, WCl5 gas, WCl6 gas, MoF4 gas, MoCl6 gas, or TiCl4 gas. In one embodiment, the first process gas further contains an inert gas. The inert gas may be, for example, a noble gas such as Ar gas, He gas, or Kr gas, or nitrogen gas.

[0070] Next, a source RF signal is supplied to the lower electrode of the substrate support 11 and / or the upper electrode of the shower head 13. This generates a high-frequency electric field between the shower head 13 and the substrate support 11, and a first plasma is generated from the first process gas in the plasma processing space 10s. At this time, a bias signal does not need to be supplied to the lower electrode of the substrate support 11. Alternatively, a bias signal may be supplied to the lower electrode of the substrate support 11. In this case, the level (power level or voltage level) of the bias signal may be lower than the level of the bias signal supplied to the substrate support 11 in step ST12 or step ST3. The bias signal may be a bias RF signal or a bias DC signal.

[0071] In one embodiment, during processing in step ST2, the temperature of the substrate support 11 or the substrate W may be controlled to the same temperature as the given temperature set in step ST11, or may be controlled to a different temperature (e.g., a temperature higher than the given temperature).

[0072] FIG. 7 is a diagram showing an example of the cross-sectional structure of the substrate W after processing at step ST2. As shown in FIG. 7, a metal-containing film MF is formed in the recess RC by the processing at step ST2. The metal-containing film MF is a film containing a metal M derived from the first processing gas. In one embodiment, the metal-containing film MF is continuously formed from the top TP1 of the mask MK to the sidewall SS1 of the mask MK and the sidewall SS2 of the etching target film EF. In one embodiment, the metal-containing film MF may be formed on the entire sidewall SS2 of the etching target film EF, or may be formed on a portion (e.g., the upper portion) of the sidewall SS2. In one embodiment, the metal-containing film MF may be formed on the sidewall SS2 from the top of the recess RC toward the bottom BT in a bottom-down manner. The metal-containing film MF may provide protection for the sidewall SS2 on which the metal-containing film MF is formed during etching of the recess RC in step ST3.

[0073] (Process ST3) In step ST3, the recess RC in the etching target film EF is etched. First, a second processing gas containing HF gas is supplied from the gas supply unit 20 into the plasma processing space 10s.

[0074] In one embodiment, HF gas may have the highest flow rate (partial pressure) of the second process gas, excluding the inert gas. For example, the flow rate of HF gas may be 50% by volume or more, 60% by volume or more, 70% by volume or more, 80% by volume or more, 90% by volume or more, or 95% by volume or more of the total flow rate of the second process gas (if the second process gas includes an inert gas, the flow rate of all gases excluding the inert gas). The flow rate of HF gas may be less than 100% by volume, 99.5% by volume or less, 98% by volume or less, or 96% by volume or less of the total flow rate of the second process gas. For example, the flow rate of HF gas is 70% by volume or more and 96% by volume or less of the total flow rate of the second process gas.

[0075] In one embodiment, the second process gas further comprises one or more gases selected from the group consisting of a phosphorus-containing gas, a carbon-containing gas, an oxygen-containing gas, a halogen-containing gas other than fluorine, and an inert gas.

[0076] In one embodiment, the phosphorus-containing gas is a halogenated phosphorus gas. The halogenated phosphorus gas may be, for example, a phosphorus fluoride gas containing fluorine as a halogen element, such as PF3 gas or PF5 gas. In one embodiment, the halogenated phosphorus gas may be a phosphorus chloride gas containing chlorine as a halogen element, such as PCl3 gas or PCl5 gas. In one embodiment, the halogenated phosphorus gas may be a gas containing bromine or iodine as a halogen element, such as PBr3 gas, PBr5 gas, or PI3 gas. In one embodiment, the halogenated phosphorus gas may be a gas containing two or more halogen elements, such as PClF2 gas, PCl2F gas, or PCl2F3 gas. In one embodiment, the halogenated phosphorus gas may be a phosphorus oxyfluoride gas or a phosphorus oxychloride gas. For example, the halogenated phosphorus gas may be POF3 gas, POCl3 gas, POF2Cl2 gas, POFCl2 gas, or POF2Cl gas. In one embodiment, the flow rate of the phosphorus-containing gas contained in the second process gas is 20% by volume or less, 10% by volume or less, or 5% by volume or less of the total flow rate of the second process gas.

[0077] In one embodiment, the carbon-containing gas is a fluorocarbon gas and / or a hydrofluorocarbon gas. The fluorocarbon gas may be, for example, at least one selected from the group consisting of CF4 gas, C2F2 gas, C2F4 gas, C3F6 gas, C3F8 gas, C4F6 gas, C4F8 gas, and C5F8 gas. The hydrofluorocarbon gas may be, for example, CHF3 gas, CH2F2 gas, CH3F gas, C2HF5 gas, C2H2F4 gas, C2H3F3 gas, C2H4F2 gas, C3HF7 gas, C3H2F2 gas, C3H2F4 gas, C3H2F6 gas, C3H3F5 gas, C4H2F6 gas, C4H5F5 gas, C4H2F8 gas, C5H2F6 gas, and C5H2F. 10The carbon-containing gas may be at least one selected from the group consisting of C5H3F7 gas and C5H3F7 gas. In one embodiment, the carbon-containing gas is a linear gas having an unsaturated bond. Examples of such gases include C3F6 (hexafluoropropene) gas, C4F8 (octafluoro-1-butene, octafluoro-2-butene) gas, C3H2F4 (1,3,3,3-tetrafluoropropene) gas, C4H2F6 (trans-1,1,1,4,4,4-hexafluoro-2-butene) gas, C4F8O (pentafluoroethyl trifluorovinyl ether) gas, CF3COF gas (1,2,2,2-tetrafluoroethan-1-one), CHF2COF (difluoroacetic acid fluoride) gas, and COF2 (carbonyl fluoride) gas.

[0078] In one embodiment, the oxygen-containing gas is, for example, at least one gas selected from the group consisting of O, CO, CO, H, O, and H, O. In one example, the oxygen-containing gas is an oxygen-containing gas other than H, for example, at least one gas selected from the group consisting of O, CO, CO, and H, O. The flow rate of the oxygen-containing gas may be adjusted depending on the flow rate of other gases (e.g., carbon-containing gas) contained in the second process gas.

[0079] In one embodiment, the halogen-containing gas other than fluorine may be a chlorine-containing gas, a bromine-containing gas, and / or an iodine-containing gas. For example, the chlorine-containing gas may be at least one gas selected from the group consisting of Cl2, SiCl2, SiCl4, CCl4, SiH2Cl2, Si2Cl6, CHCl3, SO2Cl2, BCl3, PCl3, PCl5, and POCl3. For example, the bromine-containing gas may be at least one gas selected from the group consisting of Br2, HBr, CBr2F2, C2F5Br, PBr3, PBr5, POBr3, and BBr3. For example, the iodine-containing gas may be at least one gas selected from the group consisting of HI, CF3I, C2F5I, C3F7I, IF5, IF7, I2, and PI3. For example, the halogen-containing gas other than fluorine may be at least one gas selected from the group consisting of Cl2 gas, Br2 gas, and HBr gas. In one example, the halogen-containing gas other than fluorine is Cl2 gas or HBr gas.

[0080] In one embodiment, the inert gas is a noble gas such as Ar gas, He gas, Kr gas, etc., and / or nitrogen gas.

[0081] In one embodiment, the second process gas may include a gas capable of generating hydrogen fluoride species (HF species) in plasma instead of a part or all of the HF gas. The HF species include at least one of hydrogen fluoride gas, radicals, and ions.

[0082] The gas capable of generating HF species may be, for example, a hydrofluorocarbon gas. The hydrofluorocarbon gas may have two or more, three or more, or four or more carbon atoms. Examples of the hydrofluorocarbon gas include CH2F2 gas, C3H2F4 gas, C3H2F6 gas, C3H3F5 gas, C4H2F6 gas, C4H5F5 gas, C4H2F8 gas, C5H2F6 gas, and C5H2F 10 The hydrofluorocarbon gas is at least one selected from the group consisting of CH2F2 gas, C3H2F4 gas, C3H2F6 gas, and C4H2F6 gas.

[0083] The gas capable of generating HF species may be, for example, a mixed gas containing a hydrogen source and a fluorine source. The hydrogen source may be, for example, at least one selected from the group consisting of H gas, NH gas, H O gas, H O gas, and hydrocarbon gas (CH gas, C H gas, etc.). The fluorine source may be, for example, a fluorine-containing gas that does not contain carbon, such as NF gas, SF gas, WF gas, or XeF gas. The fluorine source may also be a fluorine-containing gas that contains carbon, such as a fluorocarbon gas or a hydrofluorocarbon gas. For example, the fluorocarbon gas may be at least one selected from the group consisting of CF gas, C F gas, C F gas, C F gas, C F gas, C F gas, C F gas, C F gas, and C F gas. The hydrofluorocarbon gas may be, for example, at least one selected from the group consisting of CHF3 gas, CH2F2 gas, CH3F gas, C2HF5 gas, and hydrofluorocarbon gases containing three or more C atoms (C3H2F4 gas, C3H2F6 gas, C4H2F6 gas, etc.).

[0084] In one embodiment, the type and flow rate (partial pressure) of the gas constituting the second process gas may be constant during the process in step ST3, or may be changed as the etching progresses.

[0085] Next, a source RF signal is supplied to the lower electrode of the substrate support 11 and / or the upper electrode of the shower head 13. This generates a high-frequency electric field between the shower head 13 and the substrate support 11, and a second plasma is generated from the second process gas in the plasma processing space 10s. In one embodiment, a bias signal may be supplied to the lower electrode of the substrate support 11. This attracts active species such as ions and radicals in the second plasma to the substrate W, further etching the recess RC in the etching target film EF in the depth direction. The bias signal may be a bias RF signal supplied from the second RF generator 31b. The bias signal may also be a bias DC signal supplied from the DC generator 32a.

[0086] In one embodiment, during the processing in step ST3, the temperature of the substrate support 11 or the substrate W may be controlled to a given temperature set in step ST11.

[0087] FIG. 8 is a diagram showing an example of the cross-sectional structure of the substrate W during processing at step ST3. As shown in FIG. 8, the recess RC is further etched in the depth direction by the processing at step ST3. As described above, a metal-containing film MF containing a metal M (ruthenium, tungsten, molybdenum, and / or titanium) is formed on the sidewall SS2 of the recess RC in step ST2. The metal-containing film MF containing the metal M has low reactivity with the activated species of hydrogen fluoride in the second plasma. The metal-containing film MF has higher etching resistance to the second plasma than the etching target film EF. The metal-containing film MF functions as a protective film for the sidewall SS2 during etching at step ST3. This can prevent the sidewall SS2 in the portion where the metal-containing film is formed from being etched in the width direction (the left-right direction in FIG. 8 ) and expanding, causing bowing. Note that if the metal-containing film MF is also formed on the mask MK, the metal-containing film MF also functions as a protective film for the mask MK. This can improve the etching selectivity of the etching target film EF relative to the etching of the mask MK.

[0088] When a predetermined stopping condition is satisfied, the etching in step ST3 is stopped, and the method ends. The stopping condition may be, for example, the etching time or the depth of the recess RC. The aspect ratio of the recess RC at the end of the etching may be, for example, 20 or more, 30 or more, 40 or more, 50 or more, or 100 or more.

[0089] According to this method, the occurrence of bowing in the recess RC of the etching target film EF during the etching in step ST3 can be suppressed, that is, the occurrence of shape abnormalities due to etching can be suppressed.

[0090] <Modification> This method may be modified in various ways without departing from the scope and spirit of the present disclosure.

[0091] In one embodiment, in this method, step ST2 and step ST3 may be repeated. That is, step ST2 and step ST3 constitute one cycle, and this cycle may be repeated multiple times. In this case, the formation of the metal-containing film MF on the sidewall SS2 of the recess RC and the etching of the recess RC in the depth direction are alternately repeated. This can further suppress bowing.

[0092] In one embodiment, the second process gas used in step ST3 may further contain a metal-containing gas containing a metal M. In this case, in step ST3, the formation of the metal-containing film MF on the sidewall SS2 of the recess RC and the etching of the recess RC in the depth direction proceed simultaneously, which can further suppress bowing.

[0093] In one embodiment, in this method, after performing step ST11, step ST3 may be performed without performing step ST2, and the second process gas used in step ST3 may contain a metal-containing gas containing the metal M. In this case, in step ST3, the formation of the metal-containing film MF on the sidewall SS2 of the recess RC and the etching of the recess RC in the depth direction proceed simultaneously. This can suppress bowing.

[0094] In one embodiment, step ST1 may further include a step of forming a carbon-containing film on the sidewall SS2 of the recess RC after forming the recess RC in step ST12. The carbon-containing film may be formed by various methods, such as a plasma CVD method, a thermal CVD method, or an ALD method. The metal M (ruthenium, tungsten, molybdenum, and / or titanium) tends to deposit easily in the carbon-containing film. By forming the carbon-containing film on the sidewall SS2 of the recess RC in advance, the formation of the metal-containing film MF on the sidewall SS2 of the recess RC can be promoted in step ST2 or step ST3 according to the above-described modification.

[0095] Embodiments of the present disclosure further include the following aspects.

[0096] (Appendix 1) An etching method performed in a plasma processing apparatus including a chamber, comprising: (a) preparing a substrate, the substrate including a film to be etched having a recess, and a mask disposed on the film to be etched, the mask having an opening exposing the recess; (b) forming a metal-containing film on a sidewall of the recess using a first plasma formed from a first process gas including a metal-containing gas, the metal-containing gas including at least one metal selected from the group consisting of ruthenium, tungsten, molybdenum, and titanium; (c) etching the etching target film in the recess using a second plasma formed from a second process gas containing hydrogen fluoride gas.

[0097] (Appendix 2) The etching method according to claim 1, wherein the second process gas further contains the metal-containing gas, and in (c), a metal-containing film is formed on a side wall of the recess and the etching target film is etched in the recess.

[0098] (Appendix 3) 3. The etching method according to claim 1, wherein a cycle including the steps (b) and (c) is repeated multiple times.

[0099] (Appendix 4) 4. The etching method according to claim 1, wherein the second process gas further contains a phosphorus-containing gas.

[0100] (Appendix 5) 5. The etching method according to claim 1, wherein in (c), the temperature of the substrate or a substrate support part that supports the substrate is controlled to 0° C. or lower.

[0101] (Appendix 6) An etching method performed in a plasma processing apparatus including a chamber, comprising: (a) preparing a substrate, the substrate including a film to be etched having a recess, and a mask disposed on the film to be etched, the mask having an opening exposing the recess; (b) forming a metal-containing film on a sidewall of the recess and etching the film to be etched in the recess using plasma generated from a process gas containing a metal-containing gas and hydrogen fluoride gas, wherein the metal-containing gas contains at least one metal selected from the group consisting of ruthenium, tungsten, molybdenum, and titanium.

[0102] (Appendix 7) 7. The etching method of claim 6, wherein the process gas further comprises a phosphorus-containing gas.

[0103] (Appendix 8) 8. The etching method according to claim 6, wherein in (b), the temperature of the substrate or a substrate support part that supports the substrate is controlled to 0° C. or lower.

[0104] (Appendix 9) 9. The etching method according to claim 1, wherein the film to be etched is a silicon-containing film, a carbon-containing film, or a metal oxide film.

[0105] (Appendix 10) 10. The etching method according to any one of claims 1 to 9, wherein the film to be etched includes at least one selected from the group consisting of a silicon oxide film, a silicon nitride film, a silicon oxynitride film, a silicon carbonitride film, a polycrystalline silicon film, and a stacked film including at least two of these films.

[0106] (Appendix 11) 11. The etching method of claim 1, wherein the mask comprises at least one metal selected from the group consisting of ruthenium, tungsten, molybdenum, titanium, indium, gallium, and zinc.

[0107] (Appendix 12) 12. The etching method of claim 1, wherein the mask is a carbon-containing film.

[0108] (Appendix 13) 13. The etching method according to any one of claims 1 to 12, wherein the substrate includes an etching stop film below the film to be etched, and the etching stop film contains at least one metal selected from the group consisting of ruthenium, tungsten, molybdenum, titanium, indium, gallium, and zinc.

[0109] (Appendix 14) A plasma processing apparatus including a chamber and a control unit, The control unit (a) providing a substrate in a chamber, the substrate including a film to be etched having a recess; and a mask disposed on the film to be etched, the mask having an opening exposing the recess; (b) forming a metal-containing film on a sidewall of the recessed portion in the chamber using a first plasma formed from a first process gas including a metal-containing gas, the metal-containing gas including at least one metal selected from the group consisting of ruthenium, tungsten, molybdenum, and titanium; (c) controlling, in the chamber, to etch the etching target film in the recess using a second plasma formed from a second process gas containing hydrogen fluoride gas.

[0110] (Appendix 15) A plasma processing apparatus including a chamber and a control unit, The control unit (a) preparing a substrate, the substrate including a film to be etched having a recess; and a mask disposed on the film to be etched, the mask having an opening exposing the recess; (b) forming a metal-containing film on a side wall of the recess and etching the film to be etched in the recess by using plasma generated from a process gas containing a metal-containing gas and hydrogen fluoride gas, wherein the metal-containing gas contains at least one metal selected from the group consisting of ruthenium, tungsten, molybdenum, and titanium.

[0111] The above embodiments are described for the purpose of explanation and are not intended to limit the scope of the present disclosure. Various modifications can be made to the above embodiments without departing from the scope and spirit of the present disclosure. For example, some components in one embodiment can be added to other embodiments. Also, some components in one embodiment can be replaced with corresponding components in other embodiments. [Explanation of symbols]

[0112] REFERENCE SIGNS LIST 1: plasma processing apparatus, 2: control unit, 10: plasma processing chamber, 10s: plasma processing space, 11: substrate support unit, 13: shower head, 20: gas supply unit, 31a: first RF generation unit, 31b: second RF generation unit, 32a: first DC generation unit, EF: film to be etched, MK: mask, OP: opening, RC: recess, UF: base film, W: substrate

Claims

1. An etching method performed in a plasma processing apparatus including a chamber, comprising: (a) preparing a substrate, the substrate including a film to be etched having a recess, and a mask disposed on the film to be etched, the mask having an opening exposing the recess; (b) forming a metal-containing film on a sidewall of the recess using a first plasma formed from a first process gas including a metal-containing gas, the metal-containing gas including at least one metal selected from the group consisting of ruthenium, tungsten, molybdenum, and titanium; (c) forming a metal-containing film on a sidewall of the recessed portion and etching the etching target film in the recessed portion by using a second plasma formed from the metal-containing gas and a second process gas containing hydrogen fluoride gas, Etching method.

2. The etching method according to claim 1 , wherein a cycle including the steps (b) and (c) is repeated a plurality of times.

3. The etching method of claim 1 , wherein the second process gas further comprises a phosphorus-containing gas.

4. 2. The etching method according to claim 1, wherein in (c), the temperature of the substrate or a substrate support part that supports the substrate is controlled to 0° C. or lower.

5. An etching method performed in a plasma processing apparatus including a chamber, comprising: (a) preparing a substrate, the substrate including a film to be etched having a recess, and a mask disposed on the film to be etched, the mask having an opening exposing the recess; (b) forming a metal-containing film on a sidewall of the recess and etching the film to be etched in the recess using plasma generated from a process gas containing a metal-containing gas and hydrogen fluoride gas, wherein the metal-containing gas contains at least one metal selected from the group consisting of ruthenium, tungsten, molybdenum, and titanium.

6. The etching method of claim 5 , wherein the process gas further comprises a phosphorus-containing gas.

7. 6. The etching method according to claim 5, wherein in (b), the temperature of the substrate or a substrate support part that supports the substrate is controlled to 0° C. or lower.

8. 8. The etching method according to claim 1, wherein the film to be etched is a silicon-containing film, a carbon-containing film, or a metal oxide film.

9. 8. The etching method according to claim 1, wherein the film to be etched includes at least one selected from the group consisting of a silicon oxide film, a silicon nitride film, a silicon oxynitride film, a silicon carbonitride film, a polycrystalline silicon film, and a stacked film including at least two of these films.

10. 8. The etching method according to claim 1, wherein the mask contains at least one metal selected from the group consisting of ruthenium, tungsten, molybdenum, titanium, indium, gallium, and zinc.

11. The etching method according to claim 1 , wherein the mask is a carbon-containing film.

12. 8. The etching method according to claim 1, wherein the substrate includes an etching stop film below the film to be etched, and the etching stop film contains at least one metal selected from the group consisting of ruthenium, tungsten, molybdenum, titanium, indium, gallium, and zinc.

13. A plasma processing apparatus including a chamber and a control unit, The control unit (a) providing a substrate in a chamber, the substrate including a film to be etched having a recess; and a mask disposed on the film to be etched, the mask having an opening exposing the recess; (b) forming a metal-containing film on a sidewall of the recess in the chamber using a first plasma formed from a first process gas including a metal-containing gas, the metal-containing gas including at least one metal selected from the group consisting of ruthenium, tungsten, molybdenum, and titanium; (c) controlling, in the chamber, a second plasma formed from the metal-containing gas and a second process gas containing hydrogen fluoride gas to form a metal-containing film on a sidewall of the recess and to etch the etching target film in the recess.

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