Etching method and plasma treatment system

Abstract

To provide a technology to improve etching selectivity.SOLUTION: An etching method that is performed in a plasma processing device including a chamber includes a step (a) of providing a substrate having a film to be etched and a mask on the film to be etched into a chamber, the mask including at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, titanium, indium, gallium, and zinc, and a step (b) of etching the film to be etched using plasma generated from a processing gas containing hydrogen fluoride gas.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a method for etching a substrate on which a polysilicon mask is formed on a silicon-containing film. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2016-21546 [Overview of the project] [Problems that the invention aims to solve]

[0004] This disclosure provides a technique for improving the selectivity ratio of etching. [Means for solving the problem]

[0005] In one exemplary embodiment of the present disclosure, an etching method is provided which is performed in a plasma processing apparatus having a chamber, the method comprising: (a) providing a substrate having a film to be etched and a mask on the film to be etched into the chamber, wherein the mask comprises at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, titanium, indium, gallium, and zinc; and (b) etching the film to be etched using a plasma generated from a processing gas comprising hydrogen fluoride gas. [Effects of the Invention]

[0006] According to one exemplary embodiment of the present disclosure, a technique for improving the selectivity of etching can be provided. [Brief explanation of the drawing]

[0007] [Figure 1] It is a diagram schematically showing an exemplary plasma processing system. [Figure 2] It is a flowchart showing an example of this processing method. [Figure 3] It is a diagram showing an example of the cross-sectional structure of substrate W. [Figure 4] It is a diagram showing an example of the cross-sectional structure of substrate W at the end of step ST12. [Figure 5] It is a flowchart showing another example of this processing method. [Figure 6] It is a diagram showing an example of the cross-sectional structure of substrate W1. [Figure 7] It is a diagram showing the results of Experiment 1. [Figure 8] It is a plan view showing the shape of mask MK after etching.

Mode for Carrying Out the Invention

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

[0009] In one exemplary embodiment, an etching method is provided that is executed in a plasma processing apparatus having a chamber, the method including: (a) providing a substrate having an etching target film and a mask on the etching target film in the chamber, the mask including at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, titanium, indium, gallium, and zinc; and (b) etching the etching target film using plasma generated from a processing gas containing hydrogen fluoride gas.

[0010] In one exemplary embodiment, the mask includes a carbide or silicide of a metal.

[0011] In one exemplary embodiment, the mask includes at least one selected from the group consisting of Ru, WSi, TiN, Mo, and InGaZnO.

[0012] In one exemplary embodiment, the mask further comprises at least one selected from the group consisting of silicon, carbon, and nitrogen.

[0013] In one exemplary embodiment, the processing gas further comprises a phosphorus-containing gas.

[0014] In one exemplary embodiment, the phosphorus-containing gas comprises a phosphorus halide gas.

[0015] In one exemplary embodiment, the phosphorus-containing gas is a gas containing at least one of fluorine and chlorine.

[0016] In one exemplary embodiment, among the processing gases excluding the inert gas, the flow rate of hydrogen fluoride gas is the highest.

[0017] In one exemplary embodiment, the processing gas further comprises at least one gas selected from the group consisting of a tungsten-containing gas, a titanium-containing gas, and a molybdenum-containing gas.

[0018] In one exemplary embodiment, in the step (b), the temperature of the substrate support portion that supports the substrate is set to 0°C or lower.

[0019] In one exemplary embodiment, the film to be etched comprises at least one selected from the group consisting of a silicon oxide film, a silicon nitride film, a polysilicon film, and a laminated film containing at least two of these films.

[0020] In one exemplary embodiment, the film to be etched is a silicon-containing film, a carbon-containing film, or a metal oxide film.

[0021] In one exemplary embodiment, the film to be etched is a multilayer film comprising a silicon oxide film and a silicon nitride film, and step (b) includes (b1) a step of etching the silicon oxide film and (b2) a step of etching the silicon nitride film, wherein the temperature is controlled so that the temperature of the substrate in step (b2) is higher than the temperature of the substrate in step (b1).

[0022] In one exemplary embodiment, the temperature control includes at least one of the following controls: (I) controlling the duty cycle of a source RF signal supplied to the chamber to be greater in step (b2) than in step (b1); (II) controlling the duty cycle of a bias signal supplied to a substrate support that supports the substrate to be greater in step (b2) than in step (b1); (III) controlling the pressure of a heat transfer gas supplied between the substrate and the substrate support to be less in step (b2) than in step (b1); (IV) controlling the voltage supplied to the electrostatic chuck of the substrate support to be less in step (b2) than in step (b1); and (V) controlling the temperature of a heat transfer fluid supplied to a flow path within the substrate support to be higher in step (b2) than in step (b1).

[0023] In one exemplary embodiment, the temperature of the heat transfer fluid is the same in step (b1) and step (b2), and the temperature control includes at least one of the controls (I) to (IV).

[0024] In one exemplary embodiment, an etching method is provided which is performed in a plasma processing apparatus having a chamber, the method comprising: (a) providing a substrate having a film to be etched and a mask on the film to be etched into the chamber, wherein the mask comprises at least one selected from tungsten, molybdenum, ruthenium, titanium, indium, gallium, and zinc; and (b) etching the film to be etched using a plasma comprising HF species.

[0025] In one exemplary embodiment, the HF species is produced from at least one gas, such as hydrogen fluoride gas or hydrofluorocarbon gas.

[0026] In one exemplary embodiment, the HF species is produced from a hydrofluorocarbon gas having two or more carbon atoms.

[0027] In one exemplary embodiment, the HF species is produced from a mixed gas containing a hydrogen source and a fluorine source.

[0028] In one exemplary embodiment, a plasma processing system is provided comprising a plasma processing apparatus having a chamber and a control unit, wherein the control unit performs the following: (a) a control to provide a substrate having a film to be etched and a mask on the film to be etched into the chamber, wherein the mask includes at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, titanium, indium, gallium, and zinc; and (b) a control to etch the film to be etched using plasma generated from a processing gas containing hydrogen fluoride gas.

[0029] Hereinafter, each embodiment of this disclosure will be described in detail with reference to the drawings. In each drawing, the same or similar elements are denoted by the same reference numeral, and redundant explanations are omitted. Unless otherwise specified, positional relationships such as top, bottom, 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 actual ratios are not limited to those shown.

[0030] <Example of a plasma processing system configuration> The following describes an example of a plasma processing system configuration. Figure 1 is a diagram illustrating an example of a capacitively coupled plasma processing system configuration.

[0031] The plasma processing system includes a capacitively coupled plasma processing apparatus 1 and a control unit 2. The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply 30, and an exhaust system 40. The plasma processing apparatus 1 also includes a substrate support unit 11 and a gas introduction unit. The gas introduction unit is configured to introduce at least one processing gas into the plasma processing chamber 10. The gas introduction unit includes a shower head 13. The substrate support unit 11 is located inside the plasma processing chamber 10. The shower head 13 is located above the substrate support unit 11. In one embodiment, the shower head 13 constitutes 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 shower head 13, the side walls 10a of the plasma processing chamber 10, and the substrate support unit 11. The plasma processing chamber 10 has at least one gas supply port for supplying at least one processing gas to the plasma processing space 10s and at least one gas outlet for discharging gas from the plasma processing space. The plasma processing chamber 10 is grounded. The shower head 13 and the substrate support part 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0032] 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.

[0033] 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 placed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic electrode 1111b placed 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. Other members surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member, may also 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. Furthermore, at least one RF / DC electrode, coupled to the RF (Radio Frequency) power supply 31 and / or DC (Direct Current) power supply 32 described later, may be placed within the ceramic member 1111a. In this case, at least one RF / DC electrode functions as a lower electrode. When a bias RF signal and / or DC signal, described later, is supplied to 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 at least one RF / DC electrode may function as multiple lower electrodes. Also, the electrostatic electrode 1111b may function as a lower electrode. Therefore, the substrate support portion 11 includes at least one lower electrode.

[0034] 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.

[0035] 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.

[0036] The showerhead 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The showerhead 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and a plurality of gas inlet ports 13c. The processing gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s through the plurality of gas inlet ports 13c. The showerhead 13 also includes at least one upper electrode. In addition to the showerhead 13, the gas introduction unit may also include one or more side gas injectors (SGIs) attached to one or more openings formed in the side wall 10a.

[0037] The gas supply unit 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply unit 20 is configured to supply at least one processing gas to the shower head 13 from a corresponding gas source 21 via a corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Furthermore, the gas supply unit 20 may include one or more flow modulation devices that modulate or pulse the flow rate of at least one processing gas.

[0038] The power supply 30 includes an RF power supply 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power supply 31 is configured to supply at least one RF signal (RF power) to at least one lower electrode and / or at least one upper electrode. This causes plasma to be formed from at least one processing gas supplied to the plasma processing space 10s. Thus, the RF power supply 31 can function as at least part of a plasma generation unit configured to generate plasma from one or more processing gases in the plasma processing chamber 10. In addition, by supplying a bias RF signal to at least one lower electrode, a bias potential is generated on the substrate W, and ionic components in the formed plasma can be drawn into the substrate W.

[0039] In one embodiment, the RF power supply 31 includes a first RF generation unit 31a and a second RF generation unit 31b. The first RF generation unit 31a is coupled to at least one lower electrode and / or at least one upper electrode via at least one impedance matching circuit and is configured to generate a source RF signal (source RF power) for plasma generation. In one embodiment, the source RF signal has a frequency in the range of 10 MHz to 150 MHz. In one embodiment, the first RF generation unit 31a may be configured to generate a plurality of source RF signals having different frequencies. One or more generated source RF signals are supplied to at least one lower electrode and / or at least one upper electrode.

[0040] The second RF generation unit 31b is coupled to at least one lower electrode via at least one impedance matching circuit and is configured to generate a bias RF signal (bias RF power). The frequency of the bias RF signal may be the same as or different from the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency lower than the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 100 kHz to 60 MHz. In one embodiment, the second RF generation unit 31b may be configured to generate a plurality of bias RF signals having different frequencies. One or more generated bias RF signals are supplied to at least one lower electrode. In various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0041] The power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generation unit 32a and a second DC generation unit 32b. In one embodiment, the first DC generation unit 32a is connected to at least one lower electrode and configured to generate a first DC signal. The generated first bias DC signal is applied to at least one lower electrode. In one embodiment, the second DC generation unit 32b is connected to at least one upper electrode and configured to generate a second DC signal. The generated second DC signal is applied to at least one upper electrode.

[0042] In various embodiments, at least one of the first and second DC signals may be pulsed. In this case, a sequence of voltage pulses is applied to at least one lower electrode and / or at least one upper electrode. The voltage pulses may have a rectangular, trapezoidal, triangular, or combination thereof pulse waveform. In one embodiment, a waveform generation unit for generating a sequence of voltage pulses from a DC signal is connected between the first DC generation unit 32a and at least one lower electrode. Thus, the first DC generation unit 32a and the waveform generation unit constitute a voltage pulse generation unit. When the second DC generation unit 32b and the waveform generation unit constitute a voltage pulse generation unit, the voltage pulse generation unit is connected to at least one upper electrode. The voltage pulses may have positive or negative polarity. The sequence of voltage pulses may also include one or more positive voltage pulses and one or more negative voltage pulses within one cycle. The first and second DC generation units 32a and 32b may be provided in addition to the RF power supply 31, and the first DC generation unit 32a may be provided in place of the second RF generation unit 31b.

[0043] The exhaust system 40 may be connected to, for example, a gas outlet 10e located at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure regulating valve regulates the pressure in the plasma processing space 10s. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0044] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform various processes described herein. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to perform the various processes described herein. In one embodiment, part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The control unit 2 is implemented, for example, by a computer 2a. The processing unit 2a1 may be configured to perform various control operations by reading a program from the storage unit 2a2 and executing the read program. This program may be stored in the storage unit 2a2 in advance, or it may be obtained via a medium when needed. The obtained program is stored in the storage unit 2a2 and read from the storage unit 2a2 and executed by the processing unit 2a1. The medium may be various storage media readable by the computer 2a, or it may be a communication line connected to the communication interface 2a3. The processing unit 2a1 may be a CPU (Central Processing Unit). The memory unit 2a2 may include RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing device 1 via a communication line such as a LAN (Local Area Network).

[0045] <An example of a plasma treatment method> Figure 2 is a flowchart showing an example of a plasma processing method (hereinafter also referred to as "this processing method") according to one exemplary embodiment. As shown in Figure 2, this processing method includes a step ST11 of providing a substrate and an etching step ST12. The processing in each step may be performed using the plasma processing system shown in Figure 1. In the following, the case in which the control unit 2 controls each part of the plasma processing apparatus 1 to perform this processing method on the substrate W will be described as an example.

[0046] (Step ST11: Provision of substrate) In step ST11, the substrate W is placed in the plasma processing space 10s of the plasma processing apparatus 1. The substrate W is placed in the central region 111a of the substrate support portion 11. The substrate W is then held in the substrate support portion 11 by the electrostatic chuck 1111.

[0047] Figure 3 shows an example of the cross-sectional structure of the substrate W provided in step ST11. The substrate W has a silicon-containing film SF as the film to be etched and a mask MK formed on the silicon-containing film SF. The silicon-containing film SF may be formed on a base film UF. The substrate W may be used in the manufacture of semiconductor devices. Semiconductor devices include, for example, semiconductor memory devices such as DRAM and 3D-NAND flash memory.

[0048] The underlayer film UF is, in one example, a silicon wafer or an organic film, dielectric film, metal film, semiconductor film, etc., formed on a silicon wafer. In one embodiment, the underlayer film UF may be an etching stop film. In one embodiment, the etching stop film contains at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, titanium, indium, gallium, and zinc. The etching stop film may, for example, contain carbides or silicides of tungsten, molybdenum, and titanium. The etching stop film may, for example, be a tungsten-containing film. The etching stop film may further contain tungsten and at least one selected from the group consisting of silicon, carbon, and nitrogen. In one example, the etching stop film contains at least one selected from the group consisting of WC (tungsten carbide), WSi (tungsten silicide), WSiN, and WSiC. The etching stop film may, for example, contain at least one selected from the group consisting of Ru, WSi, TiN, Mo, and InGaZnO. The underlayer film UF may be composed of multiple layers. When the underlayer film UF is composed of multiple layers, the etching stop film may be formed on the uppermost layer of the underlayer film UF. That is, the silicon-containing film SF may be formed in contact with the etching stop film.

[0049] The silicon-containing film SF is the film to be etched by this processing method. The silicon-containing film SF may be, for example, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, a silicon carbonitride film, a polycrystalline silicon film, or a carbon-containing silicon film. The silicon-containing film SF may be composed of multiple films stacked on top of each other. For example, the silicon-containing film SF may be composed of alternating layers of silicon oxide film and silicon nitride film. For example, the silicon-containing film SF may be composed of alternating layers of silicon oxide film and polycrystalline silicon film. For example, the silicon-containing film SF may be a multilayer film including silicon nitride film, silicon oxide film and polycrystalline silicon film. For example, the silicon-containing film SF may be composed of stacked layers of silicon oxide film and silicon carbonitride film. For example, the silicon-containing film SF may be a multilayer film including silicon oxide film, silicon nitride film and silicon carbonitride film. In one embodiment, the substrate W may have a carbon-containing film or a metal oxide film instead of the silicon-containing film SF. In this case, the carbon-containing film or metal oxide film is the film to be etched by this processing method. The film to be etched may contain impurities such as boron, nitrogen, and phosphorus.

[0050] The mask MK contains at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, titanium, indium, gallium, and zinc. The mask MK may, for example, contain carbides or silicides of tungsten, molybdenum, and titanium. The mask MK may, for example, be a tungsten-containing film. The mask MK may further contain tungsten and at least one selected from the group consisting of silicon, carbon, and nitrogen. In one example, the mask MK contains at least one selected from the group consisting of WC (tungsten carbide), WSi (tungsten silicide), WSiN, and WSiC. The mask MK may, for example, contain at least one selected from the group consisting of Ru, WSi, TiN, Mo, and InGaZnO. The mask MK may be a single-layer mask consisting of one layer, or a multilayer mask consisting of two or more layers.

[0051] As shown in Figure 3, the mask MK defines at least one opening OP on the silicon-containing film SF. The opening OP is a space on the silicon-containing film SF surrounded by the side walls of the mask MK. That is, the upper surface of the silicon-containing film SF has a region covered by the mask MK and a region exposed at the bottom of the opening OP.

[0052] The opening OP may have any shape when viewed in plan view of the substrate W, that is, when the substrate W is viewed from top to bottom in Figure 3. 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, and the multiple side walls may define multiple openings OP. Each of the multiple openings OP may have a linear shape and be arranged at regular intervals to form a line and space pattern. Alternatively, each of the multiple openings OP may have a hole shape and form an array pattern.

[0053] Each film constituting the substrate (underlayment film UF, silicon-containing film SF, or mask MK) may be formed by CVD, ALD, spin coating, etc. Mask MK may be formed by lithography. The opening OP of mask MK may be formed by etching mask MK. Each film may be a flat film or a film with irregularities. The substrate W may further have other films beneath the underlayment film UF. In this case, recesses corresponding to the opening OP may be formed in the silicon-containing film SF and the underlayment film UF and used as masks for etching the other films.

[0054] At least part of the process for forming each film on the substrate W may be performed within the space of the plasma processing chamber 10. For example, the step of etching the mask MK to form an opening OP may be performed in the plasma processing chamber 10. That is, the etching of the opening OP and the silicon-containing film SF, described later, may be performed consecutively within the same chamber. Alternatively, after all or part of each film on the substrate W has been formed in an external apparatus or chamber of the plasma processing apparatus 1, the substrate W may be brought into the plasma processing space 10s of the plasma processing apparatus 1 and placed in the central region 111a of the substrate support section 11 to provide the substrate W.

[0055] After the substrate W is placed in the central region 111a of the substrate support section 11, the temperature of the substrate support section 11 is adjusted to a set temperature by the temperature control module. The set temperature may be, for example, 0°C or lower, -10°C or lower, -20°C or lower, -30°C or lower, -40°C or lower, -50°C or lower, -60°C or lower, or -70°C or lower. In one example, adjusting or maintaining the temperature of the substrate support section 11 includes setting the temperature of the heat transfer fluid flowing through the channel 1110a or the heater temperature to the set temperature, or to a temperature different from the set temperature. The timing at which the heat transfer fluid begins to flow through the channel 1110a may be before, after, or simultaneously with the placement of the substrate W on the substrate support section 11. Furthermore, the temperature of the substrate support section 11 may be adjusted to the set temperature before process ST11. That is, the substrate W may be placed on the substrate support section 11 after the temperature of the substrate support section 11 has been adjusted to the set temperature.

[0056] (Step ST12: Etching) In step ST12, the silicon-containing film SF is etched using plasma generated from the processing gas. First, the processing gas is supplied from the gas supply unit 20 into the plasma processing space 10s. During the processing in step ST12, the gases contained in the processing gas and the flow rates (partial pressures) of each gas may or may not be changed. For example, if the silicon-containing film SF is composed of a laminated film made up of different types of silicon-containing films, the composition of the processing gas and the flow rates (partial pressures) of each gas may be changed as the etching progresses or depending on the type of film being etched. During the processing in step ST12, the temperature of the substrate support unit 11 may be maintained at the set temperature adjusted in step ST11, or it may be changed as the etching progresses or depending on the type of film being etched.

[0057] 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 processing gas in the plasma processing space 10s. A bias signal is also supplied to the lower electrode of the substrate support 11, generating a bias potential between the plasma and the substrate W. The bias potential attracts active species such as ions and radicals in the plasma to the substrate W. As a result, the portion of the silicon-containing film SF that is not covered by the mask MK (the portion exposed at the opening OP) is etched.

[0058] In step ST12, the bias signal may be a bias RF signal supplied from the second RF generation unit 31b. Alternatively, the bias signal may be a bias DC signal supplied from the DC generation unit 32a. Both the source RF signal and the bias signal may be continuous waves or pulsed waves, or one may be a continuous wave and the other a pulsed wave. When both the source RF signal and the bias signal are pulsed waves, the periods of both pulsed waves may or may not be synchronized. The duty cycle of the source RF signal and / or bias signal pulsed wave may be set as appropriate, for example, 1 to 80%, or 5 to 50%. The duty cycle is the proportion of the pulse wave period that is occupied by a high power or voltage level. When a bias DC signal is used as the bias signal, the pulsed wave may have a rectangular, trapezoidal, triangular, or a combination thereof waveform. The polarity of the bias DC signal may be negative or positive, as long as the potential of the substrate W is set to create a potential difference between the plasma and the substrate to attract ions.

[0059] In step ST12, the HF gas contained in the process gas may have the highest flow rate (partial pressure) among the process gases (or all gases except the inert gas if the process gas includes an inert gas). For example, the flow rate of the HF gas may be 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 95% or more of the total flow rate of the process gases (or the flow rate of all gases except the inert gas if the process gas includes an inert gas; the same applies hereinafter in this specification). The flow rate of the HF gas may be less than 100% of the total flow rate of the process gases, 99.5% or less, 98% or less, or 96% or less. For example, the flow rate of the HF gas is adjusted to be 70% or more and 96% or less of the total flow rate of the process gases.

[0060] The processing gas may further contain phosphorus-containing gas. Phosphorus-containing gas is a gas containing phosphorus-containing molecules. Phosphorus-containing molecules include tetraphosphorus decoxide (P4O). 10), tetraphosphorus octoxide (P4O8), tetraphosphorus hexoxide (P4O6), and other oxides may be used. Tetraphosphorus decoxide is sometimes called diphosphorus pentoxide (P2O5). The phosphorus-containing molecule may also be a halide (phosphorus halogen) such as phosphorus trifluoride (PF3), phosphorus pentafluoride (PF5), phosphorus trichloride (PCl3), phosphorus pentachloride (PCl5), phosphorus tribromide (PBr3), phosphorus pentabromide (PBr5), and phosphorus iodide (PI3). That is, the phosphorus-containing molecule may contain fluorine as a halogen element, such as phosphorus fluoride. Alternatively, the phosphorus-containing molecule may contain halogen elements other than fluorine as a halogen element. The phosphorus-containing molecule may be a phosphoryl halogen such as phosphoryl fluoride (POF3), phosphoryl chloride (POCl3), and phosphoryl bromide (POBr3). Phosphorus-containing molecules may include phosphine (PH3), calcium phosphide (Ca3P2, etc.), phosphoric acid (H3PO4), sodium phosphate (Na3PO4), hexafluorophosphate (HPF6), etc. Phosphorus-containing molecules may include fluorophosphines (H g PF h ) may be the case. Here, the sum of g and h is 3 or 5. Examples of fluorophosphines include HPF2 and H2PF3. The processing gas may contain at least one phosphorus-containing molecule, which is one or more of the phosphorus-containing molecules listed above. For example, the processing gas may contain at least one of PF3, PCl3, PF5, PCl5, POCl3, PH3, PBr3, or PBr5, which is at least one phosphorus-containing molecule. If each phosphorus-containing molecule contained in the processing gas is a liquid or solid, each phosphorus-containing molecule may be vaporized by heating or the like and supplied into the plasma processing space 10s.

[0061] Phosphorus-containing gases are PCl a F b (a is an integer greater than or equal to 1, b is an integer greater than or equal to 0, and a+b is an integer less than or equal to 5) Gas or PC c H d F e (d and e are integers between 1 and 5, and c is an integer between 0 and 9) The gas may be such.

[0062] PCla F b The gas may be at least one gas selected from the group consisting of, for example, PClF2 gas, PCl2F gas, and PCl2F3 gas.

[0063] PC c H d F e The gas may be at least one gas selected from the group consisting of, for example, PF2CH3 gas, PF(CH3)2 gas, PH2CF3 gas, PH(CF3)2 gas, PCH3(CF3)2 gas, PH2F gas, and PF3(CH3)2 gas.

[0064] The phosphorus-containing gas may be PCl c F d C e H f (where c, d, e, and f are each an integer of 1 or more). The phosphorus-containing gas may also be a gas containing a halogen other than P (phosphorus), F (fluorine), and F (fluorine) (for example, Cl, Br, or I) in its molecular structure, a gas containing P (phosphorus), F (fluorine), C (carbon), and H (hydrogen) in its molecular structure, or a gas containing P (phosphorus), F (fluorine), and H (hydrogen) in its molecular structure.

[0065] The phosphorus-containing gas may use a phosphine-based gas. Examples of the phosphine-based gas include phosphine (PH3), a compound in which at least one hydrogen atom of phosphine is substituted with an appropriate substituent, and a phosphinic acid derivative.

[0066] The substituent for substituting the hydrogen atom of phosphine is not particularly limited, and examples include halogen atoms such as fluorine atoms and chlorine atoms; alkyl groups such as methyl groups, ethyl groups, and propyl groups; and hydroxyalkyl groups such as hydroxymethyl groups, hydroxyethyl groups, and hydroxypropyl groups. In one example, chlorine atoms, methyl groups, and hydroxymethyl groups are included.

[0067] Examples of phosphinic acid derivatives include phosphinic acid (H3O2P), alkylphosphinic acid (PHO(OH)R), and dialkylphosphinic acid (PO(OH)R2).

[0068] As the phosphine gas, at least one gas selected from the group consisting of PCH3Cl2 (dichloro(methyl)phosphine) gas, P(CH3)2Cl (chloro(dimethyl)phosphine) gas, P(HOCH2)Cl2 (dichloro(hydroxylmethyl)phosphine) gas, P(HOCH2)2Cl (chloro(dihydroxylmethyl)phosphine) gas, P(HOCH2)(CH3)2 (dimethyl(hydroxylmethyl)phosphine) gas, P(HOCH2)2(CH3) (methyl(dihydroxylmethyl)phosphine) gas, P(HOCH2)3 (tris(hydroxylmethyl)phosphine) gas, H3O2P (phosphinic acid) gas, PHO(OH)(CH3)(methylphosphine) gas, and PO(OH)(CH3)2 (dimethylphosphine) gas may be used.

[0069] The flow rate of phosphorus-containing gas included in the process gas may be 20% or less by volume, 10% or less by volume, or 5% or less by volume, of the total flow rate of the process gas.

[0070] The processing gas may further contain a tungsten-containing gas. The tungsten-containing gas may be a gas containing tungsten and a halogen, for example, WF x Cl yThe gas is a gas (where x and y are integers between 0 and 6, and the sum of x and y is between 2 and 6). Specifically, the tungsten-containing gas may be a gas containing tungsten and fluorine, such as tungsten difluoride (WF2) gas, tungsten tetrafluoride (WF4) gas, tungsten pentafluoride (WF5) gas, tungsten hexafluoride (WF6) gas, or a gas containing tungsten and chlorine, such as tungsten dichloride (WCl2) gas, tungsten tetrachloride (WCl4) gas, tungsten pentachloride (WCl5) gas, or tungsten hexachloride (WCl6) gas. Among these, at least one of WF6 gas and WCl6 gas may be used. The flow rate of the tungsten-containing gas may be 5% by volume or less of the total flow rate of the treatment gas. The treatment gas may contain at least one of titanium-containing gas and molybdenum-containing gas in place of or in addition to the tungsten-containing gas.

[0071] The processing gas may further contain a carbon-containing gas. The carbon-containing gas may be, for example, either or both of a fluorocarbon gas and a hydrofluorocarbon gas. In one example, the fluorocarbon gas may be 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. In one example, the hydrofluorocarbon gas may be 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, C5H2F 10The carbon-containing gas may be at least one selected from the group consisting of gas and C5H3F7 gas. The carbon-containing gas may also be a linear type having unsaturated bonds. For example, the linear carbon-containing gas having unsaturated bonds may be at least one selected from the group consisting of 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-tetrafluoroethane-1-one), CHF2COF (difluoroacetic acid fluoride) gas, and COF2 (carbonyl fluoride) gas.

[0072] The processing gas may further contain an oxygen-containing gas. The oxygen-containing gas may be, for example, at least one gas selected from the group consisting of O2, CO, CO2, H2O, and H2O2. In one example, the oxygen-containing gas may be an oxygen-containing gas other than H2O, for example, at least one gas selected from the group consisting of O2, CO, CO2, and H2O2. The flow rate of the oxygen-containing gas may be adjusted according to the flow rate of the carbon-containing gas.

[0073] The processing gas may further contain halogen-containing gases other than fluorine. The halogen-containing gases other than fluorine may be chlorine-containing gases, bromine-containing gases and / or iodine-containing gases. 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. In one example, the halogen-containing gas other than fluorine may be at least one selected from the group consisting of Cl2 gas, Br2 gas, and HBr gas. In another example, the halogen-containing gas other than fluorine is either Cl2 gas or HBr gas.

[0074] The processing gas may further contain 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.

[0075] Furthermore, the processing gas may include a gas capable of generating hydrogen fluoride species (HF species) in the plasma, instead of some or all of the HF gas. The HF species includes at least one of hydrogen fluoride gas, radicals, and ions.

[0076] Gases capable of producing HF species may be, for example, hydrofluorocarbon gases. Hydrofluorocarbon gases may have 2 or more carbon atoms, 3 or more, or 4 or more. Examples of hydrofluorocarbon gases include CH2F2 gas, C3H2F4 gas, C3H2F6 gas, C3H3F5 gas, C4H2F6 gas, C4H5F5 gas, C4H2F8 gas, C5H2F6 gas, and C5H2F 10It is at least one selected from the group consisting of gases and C5H3F7 gas. Hydrofluorocarbon gases, for example, are at least one selected from the group consisting of CH2F2 gas, C3H2F4 gas, C3H2F6 gas and C4H2F6 gas.

[0077] A gas capable of producing HF species may be, for example, a mixed gas containing a hydrogen source and a fluorine source. The hydrogen source may be at least one selected from the group consisting of, for example, H2 gas, NH3 gas, H2O gas, H2O2 gas, and hydrocarbon gases (CH4 gas, C3H6 gas, etc.). The fluorine source may be a fluorine-containing gas that does not contain carbon, such as NF3 gas, SF6 gas, WF6 gas, or XeF2 gas. Alternatively, the fluorine source may be a fluorine-containing gas that contains carbon, such as fluorocarbon gas and hydrofluorocarbon gas. The fluorocarbon gas may be at least one selected from the group consisting of, for example, CF4 gas, C2F2 gas, C2F4 gas, C3F6 gas, C3F8 gas, C4F6 gas, C4F8 gas, and C5F8 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 (such as C3H2F4 gas, C3H2F6 gas, C4H2F6 gas, etc.).

[0078] Etching in step ST12 forms recesses in the silicon-containing film SF based on the shape of the opening OP of the mask MK. When a given stop condition is met, etching in step ST12 is stopped, and the process ends. The stop condition may be set based on, for example, the etching time or the depth of the recesses.

[0079] Figure 4 shows an example of the cross-sectional structure of the substrate W at the end of process ST12. As shown in Figure 4, the processing in process ST12 etches the portion of the silicon-containing film SF exposed at the opening OP in the depth direction (from top to bottom in Figure 4), forming a recess RC. Figure 4 shows an example where the bottom of the recess RC reaches the underlying film UF, exposing the underlying film UF, due to etching in process ST12. The aspect ratio of the recess RC in this state may be, for example, 20 or more, and may be 30 or more, 40 or more, 50 or more, or 100 or more.

[0080] According to this processing method, the mask MK of the substrate W contains at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, titanium, indium, gallium, and zinc. These metals have high etching resistance to plasma containing HF species generated in the etching process ST12. Therefore, when etching the silicon-containing film SF using plasma containing HF species in process ST12, etching of the mask MK can be suppressed. This improves the selectivity ratio of etching of the silicon-containing film SF to the mask MK. The same applies when the substrate W has a carbon-containing film or a metal oxide film instead of the silicon-containing film SF (when the film to be etched is a carbon-containing film or a metal oxide film). In other words, according to this processing method, the selectivity ratio of the film to be etched to the mask MK can be improved. Furthermore, when the substrate W has an etching stop film containing the above metal as an underlayment film UF, etching of the underlayment film UF in process ST12 can be suppressed.

[0081] Figure 5 is a flowchart showing another example of this processing method. This example comprises a step ST21 of providing a substrate W1, a first etching step ST22, and a second etching step ST23. In this example, the first etching step ST22 and the second etching step ST23 are performed under different conditions.

[0082] For example, when manufacturing semiconductor memory devices such as DRAM, temperature control may be performed so that the temperature of the substrate W1 is different in process ST22 and process ST23. The following explanation will focus on this point, and explanations of points similar to those in the flowchart shown in Figure 2 will be omitted.

[0083] Figure 6 shows an example of the cross-sectional structure of the substrate W1 provided in process ST21. The substrate W1 has a silicon-containing film SF and a mask MK stacked in that order on a base film UF. The silicon-containing film SF consists of a second silicon-containing film SF2 and a first silicon-containing film SF1 formed on the second silicon-containing film.

[0084] The first silicon-containing film SF1 and the second silicon-containing film SF2 are different types of films. For example, the first silicon-containing film SF1 may be a silicon nitride film, and the second silicon-containing film SF2 may be a silicon oxide film. Alternatively, for example, the first silicon-containing film SF1 may be a silicon carbonitride film, and the second silicon-containing film SF2 may be a silicon oxide film.

[0085] In this example, after providing the substrate W1 to the substrate support 11, the first silicon-containing film SF1 is etched in the first etching step ST22 using a processing gas containing hydrogen fluoride gas. Then, the second silicon-containing film SF2 is etched in the second etching step ST23 using a processing gas containing hydrogen fluoride gas. The composition of the processing gases used in steps ST22 and ST23, and the flow rates (partial pressures) of each gas, may be the same or different.

[0086] In this example, the temperature of the substrate W1 is controlled in step ST22 to reach a first temperature, and in step ST23 to reach a second temperature different from the first temperature. The first and second temperatures may be set appropriately depending on the material of the first silicon-containing film SF1 and the material of the second silicon-containing film SF2. For example, if the first silicon-containing film SF1 is a silicon nitride film and the second silicon-containing film SF2 is a silicon oxide film, the second temperature may be controlled to be lower than the first temperature. In this case, the first temperature may be controlled to be between -20°C and 30°C, and the second temperature may be controlled to be between -70°C and -30°C. The temperature difference between the first and second temperatures may be between 10°C and 50°C, or between 20°C and 40°C. By controlling the first and second temperatures in this way, the etching rate of the silicon oxide film can be increased. This is because silicon oxide films promote the adsorption of etchants (hydrogen fluoride species) at lower temperatures compared to silicon nitride films.

[0087] Temperature control may be performed, for example, in steps ST22 and ST23, by one or more of the following controls (I) to (V): (I) changing the duty cycle of the source RF signal supplied to the upper and / or lower electrodes of the plasma processing chamber 10; (II) changing the duty cycle of the bias signal (bias RF signal or bias DC signal) supplied to the lower electrode; (III) changing the pressure of the heat transfer gas (e.g., He) between the electrostatic chuck 1111 and the back surface of the substrate W1; (IV) changing the voltage (adsorption voltage) supplied to the electrostatic chuck 1111; (V) changing the temperature of the heat transfer fluid flowing through the channel 1110a.

[0088] When the duty cycle of the signals in (I) and (II) above, or the temperature of the heat transfer fluid in (IV) above, increases, the amount of heat input to the substrate W1 increases, causing the temperature of the substrate W1 to rise. Also, when the pressure of the heat transfer gas in (III) above, or the adsorption voltage in (IV) above decreases, the amount of heat absorbed by the substrate W (amount of heat transferred to the substrate support part 11) is suppressed, causing the temperature of the substrate W1 to rise. For example, in order to make the temperature of the substrate W1 in process ST23 higher than the temperature of the substrate W1 in process ST22, one or more of the following controls can be performed in process ST23: (I) Increase the duty cycle of the source RF signal. (II) Increase the duty cycle of the bias signal. (III) Decrease the pressure of the heat transfer gas. (IV) Decrease the adsorption voltage. (V) Increase the temperature of the heat transfer fluid. These temperature controls may be selected based on their responsiveness (the time it takes for the temperature of the substrate W1 to actually change). For example, if the responsiveness of temperature control (V) is lower than that of the other controls, temperature control (V) may be omitted (while keeping the temperature of the heat transfer fluid constant), and the other controls (I) to (IV) may be performed instead.

[0089] Furthermore, the temperature control of the substrate W1 in processes ST22 and ST23 is not limited to the above temperature control, as long as the heat input and / or heat absorption to the substrate W1 can be adjusted. For example, the temperature of the substrate W1 may be controlled by increasing or decreasing the power or voltage of the source RF signal or bias signal. Alternatively, temperature control may be performed by maintaining a constant temperature setting in the temperature control module.

[0090] In this example, the first silicon-containing film SF1 and the second silicon-containing film SF2 can each be etched in a temperature range where the adsorption of the etchant (HF species) is more effectively promoted. This can improve the etching rate of the silicon-containing film SF. On the other hand, as described above, the mask MK has high etching resistance to plasma containing HF species, and etching of the mask MK is suppressed. Therefore, in this example, the selectivity ratio of etching of the silicon-containing film SF to the mask MK can be improved.

[0091] In this example, the conditions changed between process ST22 and process ST23 are not limited to the temperature of the substrate W1. For example, in the manufacturing of semiconductor memory devices such as 3D-NAND, control may be performed to change the partial pressure of the gas contained in the processing gas between process ST23 and process ST22. For example, if the processing gas contains phosphorus-containing gas, the partial pressure of the phosphorus-containing gas may be changed between process ST22 and process ST23, and the partial pressure of the phosphorus-containing gas in process ST23 may be controlled to be lower than the partial pressure of the phosphorus-containing gas in process ST22. For example, if the processing gas contains at least one metal-containing gas selected from the group consisting of tungsten-containing gas, titanium-containing gas, ruthenium-containing gas, and molybdenum-containing gas, the partial pressure of the metal-containing gas may be changed between process ST22 and process ST23, and the partial pressure of the metal-containing gas in process ST23 may be controlled to be lower than the partial pressure of the metal-containing gas in process ST22. For example, if the processing gas contains carbon-containing gas, the partial pressure of the carbon-containing gas may be changed between steps ST22 and ST23, and the partial pressure of the carbon-containing gas in step ST23 may be controlled to be lower than the partial pressure of the carbon-containing gas in step ST22. In each example, steps ST22 and ST23 may be repeated. Also, depending on the aspect ratio of the recessed RC, the conditions may be changed stepwise or continuously from those of step ST22 to those of step ST23.

[0092] Each of the above embodiments can be modified in various ways. In one embodiment, this processing method may be carried out using a plasma processing apparatus that uses any plasma source other than the capacitively coupled plasma processing apparatus 1, such as an inductively coupled plasma or a microwave plasma.

[0093] In one embodiment, during etching of the film to be etched (silicon-containing film SF, carbon-containing film, metal oxide film, etc.), a declocking gas may be supplied from the gas supply unit 20 into the plasma processing space 10s. The declocking gas is a gas that contributes to suppressing the blocking of the opening of the mask MK. In one embodiment, the declocking gas may include at least one gas selected from hydrogen, nitrogen, oxygen, halogens, and noble gases. In one embodiment, the declocking gas may be a gas that reacts with phosphorus to produce volatile compounds. In one embodiment, the declocking gas may be at least one gas selected from the group consisting of H2 gas, HBr gas, CB2F2 gas, Cl2 gas, BCl3 gas, SiCl gas, CO gas, CF4 gas, CH4 gas, CH2F2 gas, C3H2F4 gas, N2 gas, NF3 gas, and O2 gas. Active species in the plasma generated from these gases can react with phosphorus to produce volatile compounds. This can suppress the formation of phosphorus-containing deposits on the sidewalls of the mask MK during etching, thereby preventing the opening OP from becoming blocked. In one embodiment, the declocking gas may be a gas from which the etching of the mask MK by the plasma generated is less likely to proceed. Examples of such declocking gases include H2 gas, CF4 gas, CH2F2 gas, or C3H2F4 gas. In one embodiment, the declocking gas may be a gas that does not contain sulfur (S).

[0094] In one embodiment, the declocking gas may be supplied to the plasma processing space 10s as part of the etching process gas. For example, the declocking gas may be included as the process gas used in steps ST12, ST22, and ST23. In this case, the flow rate of the declocking gas included in the process gas may be constant during etching, or it may increase or decrease as etching progresses. In one example, the process gas may include the declocking gas during a certain period of etching, but not during another period of etching. In another example, the process gas may include a first flow rate of declocking gas during a certain period of etching, and a second flow rate of declocking gas smaller than the first flow rate during another period of etching.

[0095] In one embodiment, the declocking gas may be supplied to the plasma processing space 10s separately from the etching processing gas. For example, the etching step of this processing method may include a first step of etching the film to be etched by generating a first plasma from a processing gas containing phosphorus and halogen, and a second step of removing phosphorus-containing deposits formed on the sidewalls of the mask by generating a second plasma from the declocking gas. In one embodiment, the first and second steps may be repeated multiple times.

[0096] The following describes Experiment 1, which was conducted to evaluate this processing method. This disclosure is not limited in any way by Experiment 1 described below.

[0097] In Experiment 1, the etching resistance of various films to plasma generated from a processing gas containing HF gas was evaluated using the plasma processing apparatus 1. Specifically, substrates on which each of the films to be evaluated was formed were provided to the substrate support section 11, plasma was generated from the processing gas to etch the films, and the etching rate was measured. During the etching process, the temperature of the substrate support section 11 was set to -70°C.

[0098] Figure 7 shows the results of Experiment 1. In Figure 7, the horizontal axis represents the various films evaluated in Experiment 1, with "ACL" being amorphous carbon film, "B" being boron film, "BSi" being boron-doped silicon film, "Poly" being polysilicon film, "TiN" being titanium nitride film, "W" being tungsten film, and "WC" being tungsten carbide film. The vertical axis (ER) represents the etching rate [nm / min] of each film. "Gas A" is the etching rate when plasma is generated using processing gas A, which consists of HF gas, fluorocarbon gas, and oxygen gas. "Gas B" is the etching rate when plasma is generated using processing gas B, which consists of HF gas.

[0099] As shown in Figure 7, when plasma was generated from processing gas A, the tungsten film and tungsten carbide film exhibited lower etching rates and higher etching resistance compared to other films. Furthermore, when plasma was generated from processing gas B, the titanium nitride film, tungsten film, and tungsten carbide film also exhibited lower etching rates and higher etching resistance compared to other films. This indicates that a mask MK containing tungsten or tungsten carbide can improve the selectivity ratio compared to masks such as amorphous carbon films when etching silicon-containing films SF using processing gas A or B. Additionally, a mask MK containing titanium nitride can improve the selectivity ratio compared to masks such as amorphous carbon when etching silicon-containing films SF using processing gas B.

[0100] <Examples> Next, examples of this processing method will be described. This disclosure is not limited in any way by the following examples.

[0101] (Example 1) In Example 1, the substrate W was etched using the plasma processing apparatus 1 along the flow chart described in Figure 2. A tungsten silicide film having a perforated opening pattern was used as the mask MK. A laminated film consisting of a silicon oxide film and a silicon nitride film formed on the silicon oxide film was used as the silicon-containing film SF. In step ST12, first, the silicon nitride film was etched using plasma generated from a processing gas consisting of HF gas, C4F8 gas, and oxygen gas. Next, the silicon oxide film was etched using plasma generated from a processing gas consisting of HF gas. In step ST12, the temperature of the substrate support portion 11 was set to -70°C.

[0102] (Example 2) Example 2 is the same as Example 1, except that in step ST12, the silicon oxide film was etched using plasma generated from a processing gas consisting of HF gas and phosphorus-containing gas. The flow rate of the phosphorus-containing gas was 2 volume percent of the total flow rate of the processing gas.

[0103] Table 1 shows the etching results for Example 1 and Example 2. In Table 1, "Selectivity Ratio to Mask" is the selectivity ratio of the silicon-containing film SF to the mask MK. "MK ER" and "SF ER" are the etching rates of the mask MK and the silicon-containing film SF, respectively.

[0104] [Table 1]

[0105] As shown in Table 1, in both Example 1 and Example 2, the etching rate of the mask MK was suppressed, and the selectivity ratio to the mask was good. In Example 2, i.e., when a phosphorus-containing gas was included as the processing gas, the etching rate of the mask MK was further suppressed compared to Example 1, and the etching rate of the silicon-containing film SF was even higher. Therefore, Example 2 showed an even greater improvement in the selectivity ratio to the mask compared to Example 1. In addition, no shape abnormalities of the openings OP or recesses RC due to etching were observed in either Example 1 or Example 2.

[0106] Figure 8 is a plan view showing the shape of the mask MK after etching. As shown in Figure 8, in Example 2, the opening shape of the mask MK after etching was closer to a perfect circle compared to Example 1, and shape abnormalities due to etching were more suppressed.

[0107] (Example 3) In Example 3, the substrate W was etched using the plasma processing system 1 along the flow chart described in Figure 2. A tungsten silicide film having a perforated opening pattern was used as the mask MK. A laminated film in which silicon nitride and silicon oxide films were alternately stacked was used as the silicon-containing film SF. In step ST12, etching was performed using plasma generated from a processing gas consisting of HF gas and phosphorus-containing gas. During the etching process in step ST12, the temperature of the substrate support portion 11 was set to -20°C. The flow rate of the phosphorus-containing gas was 3 volume% of the total flow rate of the processing gas.

[0108] In Reference Example 1, a substrate in which the mask MK of Example 3 was replaced with an amorphous carbon mask was etched under the same conditions as in Example 3.

[0109] Table 2 shows the etching results for Example 3 and Reference Example 1. In Table 2, "Selectivity Ratio to Mask" is the selectivity ratio of the silicon-containing film SF to the mask MK or amorphous carbon mask. "MK ER" is the etching rate of the mask MK or amorphous carbon mask. "SF ER" is the etching rate of the silicon-containing film SF. "Boeing CD" is the maximum opening width of the recess RC formed in the silicon-containing film SF by etching. "TB Bias" is the difference between the maximum opening width of the recess RC and the opening width at the top of the recess RC (the boundary portion with the mask MK or amorphous carbon mask).

[0110] [Table 2]

[0111] As shown in Table 2, in Example 3, the etching rate of the silicon-containing film SF was high, but the etching rate of the mask MK was kept low, resulting in a significantly higher selectivity ratio to the mask. In contrast, in Reference Example 1, although the etching rate of the silicon-containing film SF was similar to that of Example 3, the etching rate of the amorphous carbon mask was also high, and the selectivity ratio to the mask was about one-quarter of that of Example 3. Furthermore, in Example 3, both the Boeing CD and TB bias were kept low, and Boeing was suppressed. In contrast, in Reference Example 1, both the Boeing CD and TB bias were high, and Boeing was not suppressed.

[0112] (Example 4) In Example 4, the substrate W was etched using the plasma processing system 1 along the flow chart described in Figure 2. A tungsten silicide film having a perforated opening pattern was used as the mask MK. A laminated film in which silicon nitride and silicon oxide films were alternately stacked was used as the silicon-containing film SF. In step ST12, etching was performed using plasma generated from a processing gas consisting of HF gas and phosphorus-containing gas. During the etching process, the temperature of the substrate support portion 11 was set to -50°C.

[0113] (Examples 5-11) Examples 5 to 11 were performed under the same conditions as Example 4, except that the gases shown in Table 3 were added to the processing gas, and the substrate W had the same configuration as in Example 4.

[0114] Table 3 shows the etching results for Examples 4 to 11. In Table 3, "Added Gas" refers to the gas added to the processing gas. "Selectivity Ratio to Mask" is the selectivity ratio of the silicon-containing film SF to the mask MK. "Necking CD" is the minimum opening width of the opening OP of the mask MK.

[0115] [Table 3]

[0116] As shown in Table 3, all examples showed good selectivity against the mask. Furthermore, in Examples 5-10, where H2 gas, CH4 gas, C3H2F4 gas, CF4 gas, NF3 gas, or O2 gas was added as an additive gas to the processing gas, necking CD was larger and mask MK opening blockage was suppressed compared to Example 4. In Examples 5-7, where H2 gas, CH4 gas, and C3H2F4 gas were added as processing gases, the selectivity against the mask was comparable to that of Example 4. In Example 11, where COS gas was added as a processing gas, the selectivity against the mask was lower and necking CD was smaller compared to Example 4.

[0117] (Example 12) In Example 12, the substrate W was etched using the plasma processing system 1 along the flow chart described in Figure 2. A ruthenium film having a perforated opening pattern was used as the mask MK. A silicon oxide film was used as the silicon-containing film SF. In step ST12, etching was performed for 30 seconds using plasma generated from a processing gas consisting of HF gas. During the etching process, the temperature of the substrate support portion 11 was set to -70°C.

[0118] (Example 13) In Example 13, a substrate W with the same configuration as in Example 12 was etched under the same conditions as in Example 12, except that the processing gas further contained a phosphorus-containing gas.

[0119] Table 4 shows the etching results for Examples 12 and 13. "Selectivity Ratio to Mask" is the selectivity ratio of the silicon-containing film SF to the mask MK. "MK ER" is the etching rate of the mask MK. "SF ER" is the etching rate of the silicon-containing film SF. "Boeing CD" is the maximum opening width of the recess RC formed in the silicon-containing film SF by etching.

[0120] [Table 4]

[0121] As shown in Table 4, in Example 12, the mask MK (ruthenium film) was hardly etched during the etching of the silicon-containing film SF. As a result, the selectivity ratio to the mask was sufficiently large. It is thought that the etching of the silicon-containing film SF was promoted by the HF species in the plasma, while the mask MK, which is made of ruthenium film, had high resistance to these HF species and was hardly etched. This tendency was even more pronounced in Example 13 than in Example 12. That is, in Example 13, the etching rate of the silicon-containing film SF was even higher than in Example 12, while the etching rate of the mask MK was even lower. As a result, the selectivity ratio to the mask was significantly larger. Compared to Example 12, Boeing CD was also improved in Example 13.

[0122] Embodiments of this disclosure further include the following embodiments:

[0123] (Note 1) An etching method performed in a plasma processing apparatus having a chamber, (a) A step of providing a substrate having a film to be etched and a mask on the film to be etched into a chamber, wherein the mask comprises at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, titanium, indium, gallium, and zinc, (b) An etching method comprising the step of etching the film to be etched using plasma generated from a processing gas containing hydrogen fluoride gas.

[0124] (Note 2) The etching method according to Appendix 1, wherein the mask comprises a carbide or silicide of the metal.

[0125] (Note 3) The etching method according to Appendix 1, wherein the mask comprises at least one selected from the group consisting of Ru, WSi, TiN, Mo, and InGaZnO.

[0126] (Note 4) The etching method according to Appendix 3, wherein the mask further comprises at least one selected from the group consisting of silicon, carbon, and nitrogen.

[0127] (Note 5) The etching method according to any one of Appendix 1 to Appendix 4, wherein the processing gas further comprises a phosphorus-containing gas.

[0128] (Note 6) The etching method described in Appendix 5, wherein the phosphorus-containing gas includes halogenated phosphorus gas.

[0129] (Note 7) The etching method according to Appendix 5 or Appendix 6, wherein the phosphorus-containing gas is a gas containing at least one of fluorine and chlorine.

[0130] (Note 8) The etching method described in any one of Appendix 1 to Appendix 7, wherein the processing gas, excluding the inert gas, has the highest flow rate of the hydrogen fluoride gas.

[0131] (Note 9) The etching method according to any one of the appendices 1 to 8, wherein the processing gas further comprises at least one gas selected from the group consisting of tungsten-containing gas, titanium-containing gas, and molybdenum-containing gas.

[0132] (Note 10) The etching method according to any one of Appendix 1 to Appendix 9, wherein in step (b) above, the temperature of the substrate support portion that supports the substrate is set to 0°C or lower.

[0133] (Note 11) The etching method according to any one of the appendices 1 to 10, wherein the etching target film includes at least one selected from the group consisting of a silicon oxide film, a silicon nitride film, a polysilicon film, and a multilayer film comprising at least two of these films.

[0134] (Note 12) The etching method according to any one of Appendix 1 to Appendix 10, wherein the film to be etched is a silicon-containing film, a carbon-containing film, or a metal oxide film.

[0135] (Note 13) The film to be etched is a multilayer film comprising a silicon oxide film and a silicon nitride film, and step (b) comprises (b1) a step of etching the silicon oxide film and (b2) a step of etching the silicon nitride film. The etching method according to any one of Appendix 1 to Appendix 10, wherein the temperature of the substrate in step (b2) is controlled to be higher than the temperature of the substrate in step (b1).

[0136] (Note 14) The aforementioned temperature control is, (I) Control such that the duty cycle of the source RF signal supplied to the chamber is greater in step (b2) than in step (b1), (II) Control such that the duty cycle of the bias signal supplied to the substrate support portion supporting the substrate is greater in step (b2) than in step (b1), (III) Control such that the pressure of the heat transfer gas supplied between the substrate and the substrate support is lower in step (b2) than in step (b1), (IV) Control such that the voltage supplied to the electrostatic chuck of the substrate support is smaller in step (b2) than in step (b1), and (V) The etching method according to Appendix 13, comprising at least one control of the control such that the temperature of the heat transfer fluid supplied to the flow path in the substrate support is higher in step (b2) than in step (b1).

[0137] (Note 15) The etching method according to Appendix 14, wherein the temperature of the heat transfer fluid is the same in step (b1) and step (b2), and the temperature control includes at least one of the controls described in (I) to (IV).

[0138] (Note 16) An etching method performed in a plasma processing apparatus having a chamber, (a) A step of providing a substrate having a film to be etched and a mask on the film to be etched into a chamber, wherein the mask includes at least one selected from tungsten, molybdenum, ruthenium, titanium, indium, gallium, and zinc, (b) An etching method comprising the step of etching the film to be etched using plasma containing HF species.

[0139] (Note 17) The etching method according to Appendix 16, wherein the HF species is generated from at least one gas, such as hydrogen fluoride gas or hydrofluorocarbon gas.

[0140] (Note 18) The etching method described in Appendix 16, wherein the HF species is produced from a hydrofluorocarbon gas having two or more carbon atoms.

[0141] (Note 19) The etching method described in Appendix 16, wherein the aforementioned HF species is produced from a mixed gas containing a hydrogen source and a fluorine source.

[0142] (Note 20) A plasma processing apparatus comprising a chamber and a control unit, The control unit, (a) A control for providing a substrate having a film to be etched and a mask on the film to be etched into a chamber, wherein the mask includes at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, titanium, indium, gallium, and zinc, (b) A plasma processing system that performs control for etching the target film using plasma generated from a processing gas containing hydrogen fluoride gas.

[0143] (Note 21) The aforementioned mask is an etching method according to any one of the appendices 1 to 19, comprising tungsten.

[0144] (Note 22) The etching method according to any one of Appendix 1 to Appendix 19, wherein the film to be etched is a silicon-containing film.

[0145] (Note 23) The etching method according to claim 22, wherein the silicon-containing film is a multilayer film comprising a silicon oxide film and a silicon nitride film.

[0146] (Note 24) A device manufacturing method performed in a plasma processing apparatus having a chamber, (a) A step of providing a substrate having a film to be etched and a mask on the film to be etched into a chamber, wherein the mask comprises at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, titanium, indium, gallium, and zinc, (b) A device manufacturing method comprising the step of etching the film to be etched using plasma generated from a processing gas containing hydrogen fluoride gas.

[0147] (Note 25) A computer in a plasma processing system comprising a plasma processing apparatus having a chamber and a control unit, (a) A control for providing a substrate having a film to be etched and a mask on the film to be etched into a chamber, wherein the mask includes at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, titanium, indium, gallium, and zinc, (b) A program that controls and executes the etching of the target film using plasma generated from a processing gas containing hydrogen fluoride gas.

[0148] (Note 26) A storage medium containing the program described in Appendix 25.

[0149] (Note 27) An etching method performed in a plasma processing apparatus having a chamber, (a) A step of providing a substrate having a film to be etched and a mask on the film to be etched into a chamber, wherein the mask includes at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, and titanium, indium, gallium, and zinc, (b) A step of etching the film to be etched by supplying a plasma generated from a processing gas containing a first gas containing phosphorus and halogens and a second gas that reacts with phosphorus to produce volatile compounds to the substrate, Etching methods, including

[0150] (Note 28) An etching method performed in a plasma processing apparatus having a chamber, (a) A step of providing a substrate having a film to be etched and a mask on the film to be etched into a chamber, wherein the mask has side walls defining an opening on the film to be etched and comprises at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, and titanium, indium, gallium, and zinc, (b) A step of etching the film to be etched by supplying a first plasma generated from a first gas containing phosphorus and halogen to the substrate, wherein a phosphorus-containing deposit is formed on the side wall of the mask, (c) An etching method comprising the step of removing the phosphorus-containing deposit by supplying a second plasma generated from a second gas containing at least one gas selected from the group consisting of hydrogen, nitrogen, oxygen, halogens, and noble gases to the substrate.

[0151] (Note 29) The etching method described in Appendix 28, wherein (b) and (c) are repeated alternately.

[0152] (Note 30) The etching method according to any one of the appendices 27 to 29, wherein the first gas includes hydrogen fluoride gas.

[0153] (Note 31) The etching method according to any one of appendices 27 to 29, wherein the second gas is a hydrogen-containing gas.

[0154] (Note 32) The etching method according to Appendix 31, wherein the hydrogen-containing gas comprises at least one gas selected from the group consisting of H2 gas, CH4 gas, CH2F2 gas, and C3H2F4 gas.

[0155] (Note 33) The etching method according to any one of appendices 27 to 29, wherein the second gas is a nitrogen-containing gas.

[0156] (Note 34) The etching method according to Appendix 33, wherein the nitrogen-containing gas is at least one of N2 gas and NF3 gas.

[0157] (Note 35) The etching method described in any one of Appendix 27 to Appendix 29, wherein the second gas is sulfur-free.

[0158] (Note 36) An etching method performed in a plasma processing apparatus having a chamber, (a) A step of providing a substrate having an etching stop film, a film to be etched on the etching stop film, and a mask on the film to be etched into a chamber, wherein the etching stop film comprises at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, titanium, indium, gallium, and zinc, (b) An etching method comprising the step of etching the film to be etched using plasma generated from a processing gas containing hydrogen fluoride gas.

[0159] (Note 37) The etching method according to Appendix 36, wherein the etching stop film comprises at least one selected from the group consisting of Ru, WSi, TiN, Mo, and InGaZnO.

[0160] The embodiments described above are for illustrative purposes only and are not intended to limit the scope of this disclosure. The embodiments described above can be modified in various ways without departing from the scope and spirit of this disclosure. For example, some components of one embodiment can be added to other embodiments, or some components of one embodiment can be replaced with corresponding components of other embodiments. [Explanation of symbols]

[0161] 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, SF...Silicon-containing film, MK...Mask, OP...Opening, RC...Recess, UF...Undercoat, W, W1...Substrate

Claims

1. 1. An etching method performed in a plasma processing apparatus having a chamber, comprising: (a) providing a substrate having a film to be etched in a chamber and a mask on the film to be etched, the mask comprising at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, titanium, indium, gallium, and zinc; (b) etching the film to be etched using plasma generated from a process gas containing hydrogen fluoride gas.

2. The etching method of claim 1 , wherein the mask comprises a carbide or silicide of the metal.

3. 2. The etching method of claim 1, wherein the mask comprises at least one selected from the group consisting of Ru, WSi, TiN, Mo, and InGaZnO.

4. The etching method according to claim 3 , wherein the mask further contains at least one selected from the group consisting of silicon, carbon and nitrogen.

5. The etching method according to claim 1 , wherein the process gas further comprises a phosphorus-containing gas.

6. The etching method according to claim 5 , wherein the phosphorus-containing gas includes a halogenated phosphorus gas.

7. 6. The etching method according to claim 5, wherein the phosphorus-containing gas is a gas containing at least one of fluorine and chlorine.

8. 5. The etching method according to claim 1, wherein the process gas has a largest flow rate of the hydrogen fluoride gas, except for an inert gas.

9. 4. The etching method according to claim 1, wherein the process gas further contains at least one gas selected from the group consisting of a tungsten-containing gas, a titanium-containing gas, and a molybdenum-containing gas.

10. The etching method of claim 5, wherein the processing gas further comprises an oxygen-containing gas.

11. 5. The etching method according to claim 1, wherein in the step (b), a temperature of a substrate support part that supports the substrate is set to 0[deg.] C. or lower.

12. 5. 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 polysilicon film, and a laminated film including at least two of these films.

13. 5. 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.

14. the etching target film is a laminated film including a silicon oxide film and a silicon nitride film, and the step (b) includes: (b1) a step of etching the silicon oxide film; and (b2) a step of etching the silicon nitride film; 5. The etching method according to claim 1, wherein temperature control is performed so that a temperature of the substrate in the step (b2) is higher than a temperature of the substrate in the step (b1).

15. The temperature control is (I) control such that the duty ratio of a source RF signal supplied to the chamber is larger in the step (b2) than in the step (b1); (II) controlling a duty ratio of a bias signal supplied to a substrate support part supporting the substrate to be larger in the step (b2) than in the step (b1); (III) controlling the pressure of the heat transfer gas supplied between the substrate and the substrate support to be lower in the step (b2) than in the step (b1); (IV) controlling the voltage supplied to the electrostatic chuck of the substrate support part to be smaller in the step (b2) than in the step (b1); and 15. The etching method according to claim 14, further comprising at least one control of (V) controlling the temperature of the heat transfer fluid supplied to the flow path in the substrate support to be higher in the step (b2) than in the step (b1).

16. 16. The etching method according to claim 15, wherein a temperature of the heat transfer fluid is the same in the step (b1) and the step (b2), and the temperature control includes at least one of the controls (I) to (IV).

17. 1. An etching method performed in a plasma processing apparatus having a chamber, comprising: (a) providing a substrate having a film to be etched and a mask on the film to be etched in a chamber, the mask comprising at least one selected from tungsten, molybdenum, ruthenium, titanium, indium, gallium, and zinc; (b) etching the film to be etched using a plasma containing an HF species.

18. 20. The etching method of claim 17, wherein the HF species is generated from at least one of hydrogen fluoride gas or a hydrofluorocarbon gas.

19. 20. The etching method of claim 17, wherein the HF species is generated from a hydrofluorocarbon gas having two or more carbon atoms.

20. 20. The etching method of claim 17, wherein the HF species is generated from a gas mixture comprising a hydrogen source and a fluorine source.

21. A plasma processing apparatus having a chamber and a control unit, The control unit is (a) providing a substrate having a film to be etched and a mask on the film to be etched in a chamber, the mask comprising at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, titanium, indium, gallium, and zinc; (b) controlling etching of the target film using plasma generated from a process gas containing hydrogen fluoride gas.

Images