Etching method and etching apparatus

Abstract

The disclosed etching method comprises: (a) a step of providing a substrate having a base film, a silicon-containing film on the base film, and a mask on the silicon-containing film in a chamber; (b) a step of forming a recess by etching the silicon-containing film using a first plasma that is generated from a first processing gas that contains hydrogen fluoride gas and a tungsten-containing gas; and (c) a step of further etching the silicon-containing film using a second plasma that is generated from a second processing gas that contains hydrogen fluoride gas after the step (b), wherein the second processing gas does not contain a tungsten-containing gas or contains a tungsten-containing gas at a flow rate that is less than the flow rate of the tungsten-containing gas in the first processing gas.

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a technique for etching a film in a silicon-containing substrate using a mask containing amorphous carbon or an organic polymer. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2016-39310 [Overview of the project] [Problems that the invention aims to solve]

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

[0005] In one exemplary embodiment of the present disclosure, an etching method is provided that includes the steps of: (a) providing a substrate having a base film, a silicon-containing film on the base film, and a mask on the silicon-containing film into a chamber; (b) etching the silicon-containing film to form recesses using a first plasma generated from a first processing gas containing hydrogen fluoride gas and tungsten-containing gas; and (c) further etching the silicon-containing film after step (b) using a second plasma generated from a second processing gas containing hydrogen fluoride gas, wherein the second processing gas does not contain the tungsten-containing gas, or contains the tungsten-containing gas at a flow rate lower than that of the tungsten-containing gas in the first processing gas. [Effects of the Invention]

[0006] According to one exemplary embodiment of the present disclosure, a technique for improving an etching shape can be provided.

Brief Description of the Drawings

[0007] [Figure 1] It is a diagram for explaining a configuration example of a capacitively coupled plasma processing apparatus. [Figure 2] It is a flowchart showing an etching method according to the first embodiment. [Figure 3] It is a diagram showing an example of a cross-sectional structure of a substrate W. [Figure 4] It is a diagram showing an example of a cross-sectional structure of the substrate W at the end of step ST12. [Figure 5] It is a diagram showing an example of a cross-sectional structure of the substrate W at the end of step ST13. [Figure 6] It is an example of a timing chart when the underlayer film UF contains silicon. [Figure 7] It is another example of a timing chart when the underlayer film UF contains silicon. [Figure 8] It is an example of a timing chart when the underlayer film contains metal. [Figure 9] It is a flowchart showing an etching method according to the second embodiment. [Figure 10] It is a diagram showing the relationship between ion flux and ion energy. [Figure 11] It is a timing chart showing an example of a source RF signal and a bias RF signal. [Figure 12] It is a timing chart showing an example of a source RF signal and a bias DC signal. [Figure 13] It is a flowchart showing an etching method according to the third embodiment. [Figure 14] It is a diagram showing an example of a cross-sectional structure of the substrate W at the end of step ST32. [Figure 15] It is a diagram showing an example of a cross-sectional structure of the substrate W at the end of step ST33. [Figure 16]This is an example of a timing chart of the third embodiment.

Embodiments for Carrying Out the Invention

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

[0009] In one exemplary embodiment, a method of etching includes: (a) providing a substrate having a base film, a silicon-containing film on the base film, and a mask on the silicon-containing film in a chamber; (b) etching the silicon-containing film with a first plasma generated from a first processing gas including hydrogen fluoride gas and tungsten-containing gas to form a concave portion; and (c) after the step (b), further etching the silicon-containing film with a second plasma generated from a second processing gas including hydrogen fluoride gas, wherein the second processing gas does not contain tungsten-containing gas or contains tungsten-containing gas at a flow rate less than that of the tungsten-containing gas in the first processing gas.

[0010] In one exemplary embodiment, the tungsten-containing gas includes WF6.

[0011] In one exemplary embodiment, the first processing gas further includes a phosphorus-containing gas.

[0012] In one exemplary embodiment, the second processing gas does not contain a phosphorus-containing gas or contains a phosphorus-containing gas at a flow rate less than that of the phosphorus-containing gas in the first processing gas.

[0013] In one exemplary embodiment, the second processing gas further includes xenon gas.

[0014] In one exemplary embodiment, the first processing gas does not contain xenon gas or contains xenon gas at a flow rate less than that of the xenon gas in the second processing gas.

[0015] In one exemplary embodiment, step (b) is carried out until the substrate is exposed in the recess or until at least a portion of the substrate is exposed in the recess.

[0016] In one exemplary embodiment, step (b) is carried out until a portion of the underlying film is etched.

[0017] In one exemplary embodiment, the cycle including steps (b) and (c) is performed multiple times.

[0018] In one exemplary embodiment, step (b) etches the silicon-containing film while forming a first protrusion at a first position on the mask that reduces the width of the mask opening, and a second protrusion at a second position on the mask below the first position that reduces the width of the mask opening.

[0019] In one exemplary embodiment, in step (b), an inverse tapered recess is formed in the silicon-containing film, and in step (c), the shape of the recess is made rectangular.

[0020] In one exemplary embodiment, an etching method is provided that includes the steps of (a) providing a substrate having a base film, a silicon-containing film on the base film, and a mask on the silicon-containing film into a chamber; (b) etching the silicon-containing film using a first plasma generated from a first processing gas to form recesses; and (c) after step (b), further etching the silicon-containing film using a second plasma generated from a second processing gas, wherein the first processing gas comprises a single gas or mixed gas containing fluorine and hydrogen and a metal-containing gas, and the second processing gas comprises a single gas or mixed gas containing fluorine and hydrogen, and the second processing gas either does not contain a metal-containing gas or contains a metal-containing gas at a flow rate lower than that of the metal-containing gas in the first processing gas.

[0021] In one exemplary embodiment, the metal-containing gas includes at least one metal selected from the group consisting of tungsten, molybdenum, titanium, and ruthenium.

[0022] In one exemplary embodiment, the first processing gas further comprises a phosphorus-containing gas.

[0023] In one exemplary embodiment, the second process gas either does not contain phosphorus-containing gas or contains phosphorus-containing gas at a flow rate lower than that of the phosphorus-containing gas in the first process gas.

[0024] In one exemplary embodiment, the second processing gas further comprises a noble gas. The noble gas may include at least one selected from the group consisting of argon, krypton, xenon, and radon.

[0025] In one exemplary embodiment, the first process gas either does not contain the noble gas or contains the noble gas at a flow rate less than that of the noble gas in the second process gas.

[0026] In one exemplary embodiment, an etching apparatus is provided comprising a chamber, a substrate support within the chamber, a plasma generation unit, and a control unit configured to control the plasma generation unit, wherein the control unit is configured to perform the following steps: (a) providing a substrate having a base film, a silicon-containing film on the base film, and a mask on the silicon-containing film into the chamber; (b) etching the silicon-containing film to form recesses using a first plasma generated from a first processing gas containing hydrogen fluoride gas and tungsten-containing gas; and (c) further etching the silicon-containing film after step (b) using a second plasma generated from a second processing gas containing hydrogen fluoride gas, wherein the second processing gas either does not contain tungsten-containing gas or contains tungsten-containing gas at a flow rate lower than that of the tungsten-containing gas in the first processing gas.

[0027] 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 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 actual ratios are not limited to those shown.

[0028] <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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] The power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generation unit 32a and a second DC generation unit 32b. In one embodiment, the first DC generation unit 32a is connected to at least one lower electrode and configured to generate a first DC signal. The generated first DC signal is applied to at least one lower electrode as a first bias DC signal. 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.

[0040] 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.

[0041] 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.

[0042] 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).

[0043] <First Embodiment> Figure 2 is a flowchart of the etching method according to the first embodiment. As shown in Figure 2, the etching method includes a step ST11 for providing a substrate, a first etching step ST12, and a second etching step ST13. The processing in each of steps ST11 to ST13 may be performed using the plasma processing system shown in Figure 1. That is, the etching method according to the first embodiment may be performed using the plasma processing apparatus 1 as the etching apparatus. In the following, the etching method according to the first embodiment will be described using the case in which the control unit 2 controls each part of the plasma processing apparatus 1 to perform etching on the substrate W as an example.

[0044] (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.

[0045] Figure 3 shows an example of the cross-sectional structure of the substrate W. In step ST11, the substrate W shown in Figure 3 may be provided. The substrate W includes a silicon-containing film SF formed on a base film UF as the film to be etched. The substrate W may further have a mask MF on the silicon-containing film SF. 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.

[0046] The underlayer film UF may, in one example, be a silicon wafer, an organic film, a dielectric film, a metal film, or a semiconductor film formed on a silicon wafer. The underlayer film UF may consist of multiple stacked films. The underlayer film UF may contain silicon or a metal such as tungsten.

[0047] The silicon-containing film SF is the film to be etched. The silicon-containing film SF may include, in one example, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, a polycrystalline silicon film, or a carbon-containing silicon film. The silicon-containing film SF may consist of multiple stacked films. For example, the silicon-containing film SF may include alternately stacked silicon oxide films and silicon nitride films. Alternatively, for example, the silicon-containing film SF may include alternately stacked silicon oxide films and polycrystalline silicon films. Furthermore, for example, the silicon-containing film SF may be a stacked film containing a silicon nitride film, a silicon oxide film, and a polycrystalline silicon film.

[0048] Mask MF is a film that functions as a mask in etching the silicon-containing film SF. Mask MF may be, for example, a hard mask. Mask MF may also be a carbon-containing mask and / or a metal-containing mask. A carbon-containing mask may be formed from, for example, at least one selected from the group consisting of spin-on carbon, tungsten carbide, amorphous carbon, and boron carbide. A metal-containing mask may be formed from, for example, at least one selected from the group consisting of titanium nitride, titanium oxide, and tungsten. A tungsten-containing mask may be formed from, for example, tungsten silicide (WSi) and / or tungsten carbide (WC). Mask MF may also be a boron-containing mask formed from, for example, silicon boride, boron nitride, or boron carbide.

[0049] As shown in Figure 3, the mask MF defines at least one opening OP on the silicon-containing film SF. The opening OP is a space on the silicon-containing film SF that is surrounded by the sidewalls of the mask MF. That is, the upper surface of the silicon-containing film SF has a region covered by the mask MF and a region exposed at the bottom of the opening OP.

[0050] 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 MF 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.

[0051] Each film constituting the substrate W (underlayment film UF, silicon-containing film SF, mask MF) may be formed by CVD, ALD, spin coating, etc. The opening OP may be formed by etching the mask MF. The mask MF may also be formed by lithography. Each of the above films may be flat or may have irregularities. Furthermore, the substrate W may have other films beneath the underlayment film UF, and the laminated film of silicon-containing film SF and underlayment film UF may function as a multilayer mask. That is, the laminated film of silicon-containing film SF and underlayment film UF may be used as a multilayer mask to etch the other films.

[0052] 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 MF to form an aperture OP may be performed in the plasma processing chamber 10. That is, the etching of the aperture 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 device or external 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.

[0053] 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, 20°C or lower, 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 and the heater temperature to their respective set temperatures, or to temperatures different from their respective set temperatures. The timing at which the heat transfer fluid begins to flow through the channel 1110a may be before, after, or simultaneously with the time when the substrate W is placed 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.

[0054] (Process ST12: First etching) In step ST12, the silicon-containing film SF is etched using plasma generated from the first processing gas. First, the first processing gas is supplied from the gas supply unit 20 into the plasma processing space 10s. The first processing gas contains hydrogen fluoride (HF) gas. The HF gas functions as an etchant. During the processing in step ST12, the temperature of the substrate support unit 11 is maintained at the set temperature adjusted in step ST11.

[0055] 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 difference between the plasma and the substrate W. The bias potential difference attracts active species such as ions and radicals in the plasma to the substrate W. As a result, the silicon-containing film SF is etched, and a recess is formed in the silicon-containing film SF based on the shape of the opening OP of the mask MF. The first etching may be performed until before the underlying film UF is exposed (e.g., immediately before), or until at least a part of the underlying film UF is exposed. That is, step ST12 may be terminated before the underlying film UF of the substrate W is exposed (e.g., immediately before), or at the timing when at least a part of the underlying film UF is exposed.

[0056] 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 process 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. Note that Figure 4 shows a state where the underlying film UF is not exposed at the end of process ST12. That is, process ST12 may be stopped with the silicon-containing film SF remaining between the underlying film UF and the bottom of the recess RC, and process ST13 may be started in this state and performed for a period that includes the time when the underlying film UF is exposed. Alternatively, at least a portion of the underlying film UF may be exposed in the recess RC at the end of process ST12. Furthermore, the cycle including processes ST12 and ST13 may be performed multiple times until the underlying film UF is exposed or until a portion of the underlying film UF is etched.

[0057] In step ST12, the source RF signal may have a frequency in the range of 10 MHz to 150 MHz. For example, the source RF signal may have a frequency of 40 MHz or higher or 60 MHz or higher. Also 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 (e.g., a sequence of voltage pulses) supplied from the DC generation unit 32a. Both the source RF signal and the bias signal may be continuous waves or pulsed waves, and one of the source RF signal and the bias signal may be a continuous wave and the other a pulsed wave. If both the source RF signal and the bias signal are pulsed waves, the periods of both pulsed waves may be synchronized. The duty cycle of the pulsed wave may be set as appropriate, for example, 1 to 80% or 5 to 50%. The duty cycle is the proportion of the period in the pulsed wave's cycle that is characterized by a high power or voltage level. Furthermore, when using a bias DC signal, each voltage pulse in the sequence 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.

[0058] In step ST12, the HF gas contained in the first process gas may have the highest flow rate (partial pressure) among the first process gas (or, if the first process gas contains an inert gas, all other gases in the first process gas excluding the 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 relative to the total flow rate of the first process gas (or, if the first process gas contains an inert gas, the total flow rate of all gases in the first process gas excluding the inert gas). The flow rate of the HF gas may be less than 100% by volume, 99.5% or less by volume, 98% or less by volume, or 96% or less relative to the total flow rate of the first process gas. For example, the flow rate of the HF gas is adjusted to be 70% or more by volume and 96% or less relative to the total flow rate of the first process gas.

[0059] The first processing gas may further include at least one selected from the group consisting of carbon-containing gases, oxygen-containing gases, and phosphorus-containing gases.

[0060] The carbon-containing gas may be, for example, either or both of a fluorocarbon gas and a hydrofluorocarbon gas. For 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. For 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 10 The 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.

[0061] The oxygen-containing gas may be at least one gas selected from the group consisting of, for example, O2, CO, CO2, H2O, and H2O2. In one example, the oxygen-containing gas may be at least one gas selected from the group consisting of, for example, O2, CO, CO2, and H2O2, other than H2O. The flow rate of the oxygen-containing gas may be adjusted according to the flow rate of the carbon-containing gas.

[0062] The phosphorus-containing gas is a gas containing phosphorus-containing molecules. The phosphorus-containing molecules may be oxides such as phosphorus pentoxide (P4O 10 10), phosphorus octoxide (P4O8), phosphorus hexoxide (P4O6), etc. Phosphorus pentoxide may sometimes be called diphosphorus pentoxide (P2O5). The phosphorus-containing molecules may be halides (phosphorus halides) 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 molecules may contain fluorine as a halogen element, such as phosphorus fluoride, etc. Alternatively, the phosphorus-containing molecules may contain a halogen element other than fluorine as a halogen element. The phosphorus-containing molecules may be phosphoryl halides such as phosphoryl fluoride (POF3), phosphoryl chloride (POCl3), and phosphoryl bromide (POBr3). The phosphorus-containing molecules may be phosphine (PH3), calcium phosphide (such as Ca3P2), phosphoric acid (H3PO4), sodium phosphate (Na3PO4), hexafluorophosphoric acid (HPF6), etc. The phosphorus-containing molecules may be fluorophosphines (H g PF h ). Here, the sum of g and h is 3 or 5. Examples of fluorophosphines include HPF2 and H2PF3. The treatment gas may contain, as at least one phosphorus-containing molecule, one or more of the above phosphorus-containing molecules. For example, the treatment gas may contain, as at least one phosphorus-containing molecule, at least one of PF3, PCl3, PF5, PCl5, POCl3, PH3, PBr3, or PBr5. When each phosphorus-containing molecule contained in the treatment gas is liquid or solid, each phosphorus-containing molecule may be vaporized by heating or the like and supplied into the plasma treatment space within 10 s.

[0063] The phosphorus-containing gas is PCl a F b (where a is an integer of 1 or more, b is an integer of 0 or more, and a + b is an integer of 5 or less) 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.

[0064] PCl a 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.

[0065] 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.

[0066] Phosphorus-containing gases are PCl c F d C e H f The gas may be one in which c, d, e, and f are integers of 1 or more. The phosphorus-containing gas may also be a gas containing P (phosphorus), F (fluorine), and halogens other than F (fluorine) (e.g., 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.

[0067] Phosphine-based gases may be used as the phosphorus-containing gas. Examples of phosphine-based gases include phosphine (PH3), compounds in which at least one hydrogen atom of phosphine is substituted with a suitable substituent, and phosphine acid derivatives.

[0068] The substituents that substitute for the hydrogen atoms of phosphine are not particularly limited and include, for example, 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. Examples include chlorine atoms, methyl groups, and hydroxymethyl groups.

[0069] Examples of phosphinic acid derivatives include phosphinic acid (H3O2P), alkylphosphinic acid (PHO(OH)R), and dialkylphosphinic acid (PO(OH)R2).

[0070] 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.

[0071] The flow rate of phosphorus-containing gas included in the first process gas may be 20% or less by volume, 10% or less by volume, and 5% or less by volume of the total flow rate of the first process gas excluding the flow rate of the inert gas.

[0072] The first processing gas may further contain a tungsten-containing gas (W-containing gas). The tungsten-containing gas may be a gas containing tungsten and 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 one or more of the following: gases containing tungsten and fluorine, such as tungsten difluoride (WF2) gas, tungsten tetrafluoride (WF4) gas, tungsten pentafluoride (WF5) gas, tungsten hexafluoride (WF6) gas, or gases containing tungsten and chlorine, such as tungsten dichloride (WCl2) gas, tungsten tetrachloride (WCl4) gas, tungsten pentachloride (WCl5) gas, and tungsten hexachloride (WCl6) gas. Among these, the tungsten-containing gas may be at least one of WF6 gas and WCl6 gas. The first processing gas may contain a titanium-containing gas or a molybdenum-containing gas in place of or in addition to the tungsten-containing gas. That is, the first processing gas may contain at least one metal-containing gas. The metal-containing gas may contain at least one metal selected from the group consisting of tungsten, molybdenum, titanium, and ruthenium.

[0073] The first processing gas may further contain halogen-containing gases. The first processing gas may further contain halogen-containing gases other than fluorine, i.e., fluorine-free halogen-containing gases and / or fluorine-containing halogen-containing gases. 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. In one 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 another 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 yet another example, the halogen-containing gas other than fluorine is Cl2 gas or HBr gas. Furthermore, the fluorine-containing halogen-containing gas may also include NF3 gas (nitrogen trifluoride gas) and / or SF6 gas (sulfur hexafluoride gas).

[0074] The first processing gas may further contain an inert gas. The inert gas may be, for example, a noble gas such as Ar gas, He gas, Ne gas, Kr gas, Xe gas, Rn gas, and / or nitrogen gas.

[0075] Furthermore, the first processing gas may contain a gas capable of generating hydrogen fluoride species (HF species) in the first 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] The gas capable of producing HF species may be a single gas or a mixed gas containing fluorine and hydrogen. A single gas containing fluorine and hydrogen may be, for example, a hydrofluorocarbon gas. The hydrofluorocarbon gas 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 10 It 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] The hydrogen source in a mixed gas containing fluorine and hydrogen 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] (Process ST13: Second etching) The second etching step ST13 is performed following the first etching step ST12. The second etching step ST13 may be started before the recessed RC reaches the underlying film UF. That is, step ST13 may be started while the silicon-containing film SF remains between the underlying film UF and the bottom of the recessed RC, and may be performed for a period that includes when the underlying film UF is exposed. Alternatively, the second etching step ST13 may be started when at least a portion of the underlying film UF is exposed in the recess. The switch from step ST12 to step ST13 may be based on at least one of the depth of the recessed RC, the aspect ratio of the recessed RC, and the etching time.

[0079] In step ST13, first, a second processing gas is supplied from the gas supply unit 20 into the plasma processing space 10s. In step ST13, similar to step ST12, a source RF signal is supplied to the lower electrode of the substrate support unit 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 unit 11, and a second plasma is generated from the second processing gas in the plasma processing space 10s. Also in step ST13, a bias signal is supplied to the lower electrode of the substrate support unit 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, and these active species further etch the silicon-containing film SF. Step ST13 is performed until the underlying film UF is exposed, or until at least a portion of the underlying film UF is etched in the depth direction. 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 described later.

[0080] Figure 5 shows an example of the cross-sectional structure of the substrate W at the end of process ST13. As shown in Figure 5, in the substrate W after processing in process ST13, the bottom of the recessed RC reaches the underlying film UF, and the underlying film UF is exposed. At this time, a part of the underlying film UF may be etched in the depth direction. The aspect ratio of the recessed 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.

[0081] In step ST13, the second processing gas may contain the same type of gas as the first processing gas, or it may contain a different type of gas. The second processing gas may, for example, contain HF gas. The second processing gas may further contain, for example, at least one selected from the group consisting of carbon-containing gas, oxygen-containing gas, and phosphorus-containing gas as described above. The second processing gas may further contain, for example, tungsten-containing gas, titanium-containing gas, molybdenum-containing gas, inert gas, and halogen-containing gas as described above. The second processing gas may, like the first processing gas, contain a gas capable of generating HF species in the second plasma, instead of some or all of the HF gas.

[0082] In step ST13, the source RF signal may have a frequency in the range of 10 MHz to 150 MHz. For example, the source RF signal may have a frequency of 40 MHz or higher or 60 MHz or higher. Also in step ST13, 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 (e.g., a sequence of voltage pulses) supplied from the DC generation unit 32a. Both the source RF signal and the bias signal may be continuous waves or pulsed waves, and one of the source RF signal and the bias signal may be a continuous wave and the other a pulsed wave. If both the source RF signal and the bias signal are pulsed waves, the periods of both pulsed waves may be synchronized. The duty cycle of the pulsed wave may be set as appropriate, for example, 1 to 80% or 5 to 50%. The duty cycle is the proportion of the period in the pulsed wave's cycle that is characterized by a high power or voltage level. Furthermore, when using a bias DC signal, each voltage pulse in the sequence may have a rectangular, trapezoidal, triangular, or a combination thereof waveform. The polarity of each voltage pulse in 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. Note that the source RF signal and / or bias signal may be supplied continuously from process ST12. Alternatively, the supply of the source RF signal and / or bias signal may be stopped at the end of process ST12 and restarted at the beginning of process ST13.

[0083] When starting process ST13, the etching conditions (recipe 2) are changed from the processing conditions (recipe 1) in process ST12. That is, in process ST13, the etching of the silicon-containing film SF is performed using a different recipe than in process ST12. Changing the recipe may include using a second processing gas different from the first processing gas, and / or performing temperature control to increase the temperature of the substrate W compared to process ST12. For example, the processing conditions (recipe 2) in process ST13 may be conditions that improve the selectivity ratio of the silicon-containing film SF to the underlayment film UF compared to the processing conditions (recipe 1) in process ST12. In this case, the processing conditions (recipe 2) in process ST13 may be selected according to the type of film of the underlayment film UF. For example, the processing conditions may be different depending on whether the underlayment film UF contains silicon or metal. Changing the recipe may also include reducing the process pressure (pressure inside the chamber during processing). That is, in process ST13, the pressure inside the plasma processing space 10s may be reduced compared to process ST12. For example, the pressure in the plasma processing space 10s in process ST13 may be reduced by 30% or more compared to process ST12.

[0084] Figure 6 is an example of a timing chart when the undercoat UF contains silicon. In the example shown in Figure 6, the composition of the processing gas differs between process ST12 and process ST13. In Figure 6, the horizontal axis represents time. The vertical axis represents the flow rates of HF gas, carbon-containing gas, and oxygen-containing gas contained in the processing gas (first or second processing gas), and the density of fluorine species in the plasma (first or second plasma). "QL1," "QL2," and "QL3" represent flow rates that are smaller than or zero than the flow rates shown by "QH1," "QH2," and "QH3," respectively. Also, "DL" represents the density of fluorine species in the plasma that is smaller than the density of fluorine species in the plasma shown by "DH." In Figure 6, "carbon-containing gas" refers to either or both fluorocarbon gas and hydrofluorocarbon gas. When the carbon-containing gas is both fluorocarbon gas and hydrofluorocarbon gas, the flow rate of the carbon-containing gas is the sum of the flow rates of the fluorocarbon gas and hydrofluorocarbon gas. Furthermore, "fluorine species" are active species of fluorine that have been separated from fluorine-containing gases in the processed gas (e.g., HF gas, fluorocarbon gas, hydrofluorocarbon gas, NF3 gas, or SF6 gas, etc.).

[0085] As shown in Figure 6, when the undercoat UF contains silicon, the flow rate (partial pressure) of HF gas may be reduced and the flow rates (partial pressure) of carbon-containing gas (fluorocarbon gas and / or hydrofluorocarbon gas) and oxygen-containing gas may be increased when switching from process ST12 to process ST13. In one example, when switching from process ST12 to process ST13, the processing gas (second processing gas) may contain 50% or more by volume of carbon-containing gas and oxygen-containing gas relative to the total flow rate of the second processing gas excluding the flow rate of inert gas. In addition, the number of carbon atoms in the fluorocarbon gas and / or hydrofluorocarbon gas contained in the second processing gas may be 2 or more.

[0086] As etching progresses in step ST13, the underlying film UF is exposed. If the underlying film UF contains silicon, the fluorine species in the plasma also act as etchants for the underlying film UF. In the example timing chart shown in Figure 6, the density of fluorine species in the second plasma generated in step ST13 is lower than the density of fluorine species in the first plasma generated in step ST12. Therefore, etching of the underlying film UF is suppressed. In other words, the selectivity of etching the silicon-containing film SF against the underlying film UF can be improved.

[0087] Figure 7 shows another example of a timing chart when the undercoat UF contains silicon. Figure 7 shows an example of controlling the temperature of the substrate W in step ST13 to be higher than the temperature of the substrate W in step ST12. In Figure 7, the horizontal axis represents time. The vertical axis represents the signal level (power of the source RF signal and / or the level of the bias signal (absolute value of the voltage level of the power or voltage pulse of the bias RF signal)), the DC voltage supplied to the electrostatic chuck 1111 (ESC voltage), the pressure of the heat transfer gas (e.g., He) supplied to the gap between the electrostatic chuck 1111 and the back surface of the substrate W, the heater temperature and / or the temperature of the heat transfer fluid flowing through the channel 1110a (temperature control module temperature), and the temperature of the substrate W. In Figure 7, "WL" indicates a signal level lower than the signal level indicated by "WH". "VL" indicates an ESC voltage lower than the ESC voltage indicated by "VH". "PL" indicates a heat transfer gas pressure lower than the heat transfer gas pressure indicated by "PH". "TL1" and "TL2" indicate temperatures lower than those indicated by "TH1" and "TH2," respectively.

[0088] As shown in Figure 7, if the undercoat UF contains silicon, (I) the signal level of the source RF signal and / or the signal level of the bias signal may be increased when switching from process ST12 to process ST13. Increasing the signal level may include increasing the effective value of the signal level (e.g., power), increasing the signal supply time, and increasing the duty cycle of the signal. This increases the heat input to the substrate W, causing the temperature of the substrate W to rise.

[0089] As shown in Figure 7, when switching from process ST12 to process ST13, (II) the DC voltage (ESC voltage) supplied to the electrostatic chuck 1111 may be reduced to decrease the suction force of the electrostatic chuck 1111. Also, (III) the heat transfer gas (e.g., He) pressure between the electrostatic chuck 1111 and the back surface of the substrate W may be reduced. Also, (IV) the heater temperature and / or the temperature of the heat transfer fluid flowing through the channel 1110a may be increased. In any case, the temperature of the substrate W will rise. Note that one or more of the above temperature control methods (I) to (IV) may be combined. The difference between the temperature of the substrate W in process ST12 (TL2) and the temperature of the substrate W in process ST13 (TH2) may be, for example, 30°C or more. In one example, the temperature of the substrate W in process ST12 (TL2) may be -40°C and the temperature of the substrate W in process ST13 (TH2) may be 0°C.

[0090] As etching progresses in step ST13, the underlying film UF is exposed. In the example timing chart shown in Figure 7, the temperature of the substrate W in step ST13 is higher than the temperature of the substrate W in step ST12. Therefore, the amount of etchant (e.g., fluorine species in the plasma) adsorbed onto the underlying film UF decreases. This suppresses etching of the underlying film UF, and the selectivity of etching the silicon-containing film SF onto the underlying film UF may improve.

[0091] Furthermore, when switching from process ST12 to process ST13, both a change in the configuration of the processing gas (for example, the change in the configuration of the processing gas as described with reference to Figure 6) and a control to increase the temperature of the substrate W (for example, the control as described with reference to Figure 7) may be performed.

[0092] Figure 8 is an example of a timing chart when the undercoat UF contains metal. Figure 8 shows an example where the composition of the processing gas differs between process ST12 and process ST13. In Figure 8, the horizontal axis represents time. The vertical axis represents the flow rates of HF gas, carbon-containing gas, and NF3 / SF6 gas contained in the processing gas (first or second processing gas), and the density of fluorine species in the plasma (first or second plasma). "QH1" and "QH2" represent flow rates greater than 0, respectively. "QL4" represents a flow rate that is less than or zero than the flow rate shown in "QH4". "DL" represents a density of fluorine species in the plasma that is less than the density of fluorine species in the plasma shown in "DH". In Figure 8, "carbon-containing gas" refers to either or both fluorocarbon gas and hydrofluorocarbon gas. When the carbon-containing gas is both fluorocarbon gas and hydrofluorocarbon gas, the flow rate of the carbon-containing gas is the sum of the flow rates of the fluorocarbon gas and hydrofluorocarbon gas. Furthermore, in Figure 8, "NF3 / SF6 gas" refers to either NF3 gas or SF6 gas, or both. When "NF3 / SF6 gas" refers to both NF3 gas and SF6 gas, the flow rate of NF3 / SF6 gas is the sum of the individual flow rates of NF3 gas and SF6 gas. Note that NF3 gas and SF6 gas are examples of carbon-free fluorine sources that can be used in addition to HF gas, as described above.

[0093] As shown in Figure 8, if the undercoat UF contains metal, the flow rate (partial pressure) of fluorine-containing gases other than hydrogen fluoride, such as NF3 gas and / or SF6 gas, may be reduced when switching from process ST12 to process ST13. In addition, the flow rate (partial pressure) of HF gas may also be reduced.

[0094] As etching progresses in step ST13, the underlying film UF is exposed. If the underlying film UF contains metal, fluorine species in the plasma can react with the metal and etch the underlying film UF. In the example timing chart shown in Figure 8, the density of fluorine species in the second plasma generated in step ST13 is lower than the density of fluorine species in the first plasma generated in step ST12. Therefore, etching of the underlying film UF is suppressed. In other words, the selectivity of etching the silicon-containing film SF against the underlying film UF can be improved.

[0095] If the substrate film UF contains metal, further control to increase the temperature of the substrate W may be performed in step ST13. The control to increase the temperature of the substrate W may be performed by combining one or more of the temperature control methods (I) to (IV) described above with reference to Figure 7. This promotes the volatilization of by-products containing metal in the substrate film UF and suppresses the generation of residue containing the metal. In addition to or instead of this, a gas highly reactive with the metal in the substrate film UF may be added as a second processing gas. For example, if the substrate film UF contains tungsten, CO gas may be added as the second processing gas. The CO gas reacts with W scattered from the substrate film UF during step ST13 to produce volatile W(CO)6. This suppresses the generation of residue containing the metal (W) in the substrate film UF. In addition to or instead of CO gas, the second processing gas may include a chlorine-containing gas such as Cl2 gas, SiCl4 gas, or BCl3 gas.

[0096] According to the etching method of the first embodiment, in step ST13, etching of the silicon-containing film SF is performed under different processing conditions (recipe) than in step ST12. This makes it possible to select the optimal recipe according to the progress of etching, i.e., the depth of the recessed RC. For example, in areas where the depth of the recessed RC is shallow, a recipe that increases the etching rate of the silicon-containing film SF can be selected, and in areas where the recessed RC is deep and the underlying film UF is exposed, a recipe that increases the etching selectivity ratio of the silicon-containing film SF to the underlying film UF can be selected.

[0097] <Second Embodiment> Figure 9 is a flowchart of the etching method according to the second embodiment. As shown in Figure 9, the etching method according to the second embodiment includes a step ST21 of providing a substrate, a step ST22 of generating plasma, and an etching step ST23. Each of the processes in steps ST21 to ST23 may be performed using the plasma processing system shown in Figure 1. That is, the etching method according to the second embodiment may be performed using the plasma processing apparatus 1 as the etching apparatus. In the following, the etching method according to the second embodiment will be described using the case in which the control unit 2 controls each part of the plasma processing apparatus 1 to perform etching on the substrate W as an example.

[0098] (Step ST21: Provision of substrate) In step ST21, the substrate W is provided into the plasma processing space 10s of the plasma processing apparatus 1. The substrate W is provided into 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. The substrate W provided in step ST21 may be the same as the substrate W described in relation to the first embodiment (see Figure 3).

[0099] In the second embodiment, after the substrate W is placed in the central region 111a of the substrate support 11, the temperature of the substrate support 11 is adjusted to a set temperature by the temperature control module, similar to the first embodiment. The set temperature may be, for example, 20°C or lower, 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. The temperature of the substrate support 11 may be adjusted to the set temperature before step ST21. Furthermore, during processing in steps ST22 and ST23, the temperature of the substrate support 11 may be maintained at the set temperature adjusted in step ST21.

[0100] (Process ST22: Plasma generation) In step ST22, plasma is generated from the processing gas. First, the processing gas is supplied from the gas supply unit 20 into the plasma processing space 10s. The processing gas may be the same gas as the first processing gas and / or second processing gas described in the first embodiment.

[0101] In step ST22, a source RF signal is then 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.

[0102] Figure 10 shows the relationship between ion flux and ion energy. As shown in Figure 10, the higher the frequency of the source RF signal, the lower the ion energy. Also, the higher the frequency of the source RF signal, the greater the ion flux and the higher the electron density. For example, when using a source RF signal with a frequency of 40 MHz (RF40), a source RF signal with a frequency of 60 MHz (RF60), and a source RF signal with a frequency of 100 MHz (RF100), the following relationships hold for ion energy and ion flux. Ion energy: RF40 > RF60 > RF100 Ion flux: RF40 <RF60<RF100

[0103] In step ST22, the frequency of the source RF signal is selected so that a high-density plasma is generated with low ion energy. Such frequencies may vary depending on the plasma generation method of the plasma processing apparatus. For example, in the plasma processing apparatus 1, if the source RF signal is supplied to the upper electrode and the bias signal is supplied to the lower electrode, the frequency of the source RF signal may be 40 MHz or higher. Also, for example, if the plasma processing apparatus 1 supplies both the source RF signal and the bias signal to the lower electrode, the frequency of the source RF signal supplied to the lower electrode of the substrate support section 11 may be 60 MHz or higher. Furthermore, the frequency of the source RF signal may be 150 MHz or less, or 100 MHz or less.

[0104] Furthermore, in step ST22, a bias signal is supplied to the lower electrode of the substrate support 11. This generates a bias potential difference between the plasma and the substrate W. The bias potential difference attracts active species such as ions and radicals in the plasma to the substrate W. The bias signal may be a bias RF signal supplied from the second RF generation unit 31b. The bias signal may also be a bias DC signal (e.g., a sequence of voltage pulses) supplied from the DC generation unit 32a.

[0105] In step ST22, the source RF signal and the bias signal may each be a continuous wave or a pulsed wave. Alternatively, in step ST22, one of the source RF signal and the bias signal may be a continuous wave and the other a pulsed wave. If both the source RF signal and the bias signal are pulsed waves, the periods of both pulsed waves may be synchronized. The duty cycle of the pulsed wave may be set as appropriate, for example, 1 to 80% or 5 to 50%. The duty cycle is the proportion of the pulsed wave period in which the power or voltage level is high. When a bias DC signal is used, each voltage pulse in the sequence may have a rectangular, trapezoidal, triangular, or a combination thereof waveform. The polarity of each voltage pulse in 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.

[0106] Figure 11 is a timing chart showing an example of a source RF signal and a bias RF signal. Figure 11 is an example where both the source RF signal and the bias RF signal are pulse waves. The horizontal axis in Figure 11 represents time. In one example, the source RF signal has a frequency between 40 MHz and 100 MHz. The source RF signal is supplied to the lower electrode of the substrate support 11 and / or the upper electrode of the shower head 13 during a first period and a second period alternating with the first period. The source RF signal has a first level (power level) during the first period and a second level (power level) during the second period. In Figure 11, the first level is a power level lower than the second level or is 0W.

[0107] The bias RF signal is supplied to the lower electrode of the substrate support 11 during a third period and a fourth period alternating with the third period. In one example, the bias RF signal has a frequency between 400 kHz and 13.56 MHz. The bias RF signal has a third level (power level) during the third period and a fourth level (power level) during the fourth period. In Figure 11, the third level is a power level lower than the fourth level or 0W. As shown in Figure 11, the second period and the fourth period may coincide (synchronize). Note that some or all of the second period and the fourth period do not have to overlap.

[0108] Figure 12 is a timing chart showing an example of a source RF signal and a bias DC signal. Figure 12 is an example where both the source RF signal and the bias DC signal are pulse waves. The horizontal axis in Figure 12 represents time. The source RF signal shown in Figure 12 is the same as the source RF signal in the example shown in Figure 11. The bias DC signal is supplied to the lower electrode of the substrate support 11 during the fifth period and the sixth period, which alternates with the fifth period. The bias DC signal has a fifth level (voltage level) during the fifth period and a sixth level (voltage level) during the sixth period. In Figure 12, the absolute value of the fifth level is less than the absolute value of the sixth level or is 0V. As shown in Figure 12, the second period and the sixth period may coincide (synchronize). Note that some or all of the second period and the sixth period do not have to overlap with each other.

[0109] In step ST22, a second bias signal may be supplied to the upper electrode. The second bias signal may be a second DC signal supplied from the second DC generation unit 32b and / or a bias RF signal supplied from the second RF generation unit 31b. The second bias signal may be a continuous wave or a pulsed wave. In this case, positive ions present in the plasma processing space 10s are attracted to the upper electrode and collide with it, resulting in the emission of secondary electrons from the upper electrode. The emitted secondary electrons can modify the mask MF and improve the etching resistance of the mask MF. In addition, the irradiation of secondary electrons neutralizes the charged state of the substrate W, thereby increasing the straight-line propagation of ions into the recesses of the silicon-containing film SF formed by etching. Furthermore, if the upper electrode is made of a silicon-containing material, silicon is emitted from the upper electrode along with the secondary electrons due to the collision of positive ions. The emitted silicon combines with oxygen in the plasma to form a silicon oxide compound. The silicon oxide compound can be deposited on the mask MF and function as a protective film. As explained above, supplying a second bias signal to the upper electrode can produce effects such as improved selectivity, suppression of etching shape abnormalities, and improved etching rate.

[0110] (Process ST23: Etching) In step ST23, the silicon-containing film SF is etched by plasma generated in the plasma processing space 10s, and recesses are formed in the silicon-containing film SF based on the shape of the opening OP of the mask MF. Etching is terminated when the depth of the recesses formed by etching reaches a given depth, or when the etching time reaches a given time.

[0111] In the etching method according to the second embodiment, in step ST22, the frequency of the source RF signal is set to 40 MHz or higher. When the frequency of the source RF signal is 40 MHz or higher, even if the power level of the source RF signal and / or the level of the bias signal (power level of the bias RF signal or voltage level of the bias DC signal) is increased to increase the electron density of the plasma, the increase in ion energy is suppressed. That is, by setting the frequency of the source RF signal to 40 MHz or higher, it becomes possible to control the electron density of the generated plasma independently of the ion energy. Therefore, in step ST22, it is possible to generate a higher density plasma compared to when the frequency is lower than 40 MHz while suppressing the increase in the ion energy of the plasma. As a result, in etching in step ST23, the density of the etchant (HF type) increases and the heat input to the substrate W is suppressed. As a result, in etching in step ST23, the adsorption of the etchant (HF type) can also be promoted. Furthermore, in etching in step ST23, the increase in ion energy is suppressed, which can also reduce damage to the mask MF. Therefore, according to the etching method of the second embodiment, the etching rate of the silicon-containing film SF can be improved, and the selectivity ratio of etching of the silicon-containing film SF relative to the mask MF can be improved.

[0112] <Third Embodiment> Figure 13 is a flowchart of the etching method according to the third embodiment. Similar to the first embodiment, the etching method according to the third embodiment includes a step ST31 for providing a substrate, a first etching step ST32, and a second etching step ST33. The processing in each of steps ST31 to ST33 may be performed using the plasma processing system shown in Figure 1. That is, the etching method according to the third embodiment may be performed using the plasma processing apparatus 1 as the etching apparatus. In the following, the etching method according to the third embodiment will be described using the case in which the control unit 2 controls each part of the plasma processing apparatus 1 to perform etching on the substrate W as an example. Note that in the third embodiment, the explanation of parts that overlap with the first or second embodiment will be omitted or simplified.

[0113] (Step ST31: Provision of substrate) In step ST31, the substrate W is provided into the plasma processing space 10s of the plasma processing apparatus 1. The substrate W is provided into 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. The substrate W provided in step ST31 may be the same as the substrate W described in relation to the first embodiment (see Figure 3).

[0114] In the third embodiment, after the substrate W is placed in the central region 111a of the substrate support 11, the temperature of the substrate support 11 is adjusted to a set temperature by the temperature control module. The set temperature may be, for example, 20°C or lower, 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 11 includes setting the temperature of the heat transfer fluid flowing through the channel 1110a and the heater temperature to their respective set temperatures, or to temperatures different from their respective set temperatures. The timing at which the heat transfer fluid begins to flow through the channel 1110a may be before or after the time when the substrate W is placed on the substrate support 11, or it may be at the same time. Furthermore, the temperature of the substrate support 11 may be adjusted to the set temperature before step ST31. That is, the substrate W may be placed on the substrate support 11 after the temperature of the substrate support 11 has been adjusted to the set temperature.

[0115] (Process ST32: First etching process) In step ST32, the silicon-containing film SF is etched using plasma generated from the first processing gas. First, the first processing gas is supplied from the gas supply unit 20 into the plasma processing space 10s. The first processing gas includes HF gas and W-containing gas.

[0116] 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 difference between the plasma and the substrate W. The bias potential difference attracts active species such as ions and radicals in the plasma to the substrate W. As a result, the silicon-containing film SF is etched, and a recess is formed in the silicon-containing film SF based on the shape of the opening OP of the mask MF. The first etching may be performed until before the underlying film UF is exposed (e.g., immediately before), or until at least a portion of the underlying film UF is exposed. That is, step ST32 may be terminated before the underlying film UF of the substrate W is exposed (e.g., immediately before), or at the timing when at least a portion of the underlying film UF is exposed.

[0117] Figure 14 shows an example of the cross-sectional structure of the substrate W at the end of process ST32. As shown in Figure 14, the processing in process ST32 etches the portion of the silicon-containing film SF exposed at the opening OP in the depth direction (from top to bottom in Figure 14), forming a recess RC. Note that Figure 14 shows the state at the end of process ST32 where the underlying film UF is not exposed. That is, process ST32 may be stopped with the silicon-containing film SF remaining between the underlying film UF and the bottom of the recess RC, and process ST33 may be started in this state and carried out for a period that includes the time when the underlying film UF is exposed. Alternatively, at least a portion of the underlying film UF may be exposed in the recess RC at the end of process ST32.

[0118] When the silicon-containing film SF is etched, a first protrusion CV1 is formed on the side wall of the mask MF at a first position on the mask MF near the upper end of the opening OP. The first protrusion reduces the width of the opening OP on the mask MF. It is thought that the first protrusion CV1 is formed by deposit components contained in the first processing gas and / or reaction byproducts generated by etching adhering to the first position. The first protrusion CV1 may be formed from a carbon-containing material derived from a carbon-containing gas, as described later.

[0119] Furthermore, as described above, since the first processing gas contains a W-containing gas in addition to the HF gas, a second protrusion CV2 is formed at a second position on the side wall of the mask MF, in addition to the first protrusion CV1, which reduces the width of the opening OP. The second position is lower than the first position. The second protrusion CV2 is formed from a W-containing substance (or metal-containing substance) derived from the W-containing gas (or metal-containing gas). The second protrusion CV2 suppresses the incidence of ions on the side wall of the recess RC and the incidence of ions on the bottom of the recess RC. Therefore, according to this embodiment, the phenomenon of horizontal etching (boeing) of the silicon-containing film SF is suppressed. On the other hand, the shape of the recess RC (shape in the vertical cross-section) becomes tapered towards the bottom (reverse taper).

[0120] Furthermore, if the first protrusion CV1 is formed from a carbon-containing material and the second protrusion CV2 is formed from a W-containing material (or a metal-containing material), in step ST32, the amounts of hydrogen species and fluorine species in the first plasma may be adjusted so that the second protrusion CV2 is formed below the first protrusion CV1. For this purpose, the flow rate of the hydrogen source gas, which is the source of hydrogen species, and the flow rate of the fluorine source gas, which is the source of fluorine species, may be adjusted in the first processing gas. Fluorine species reduce the amount of W-containing material (or metal-containing material) near the upper end of the opening OP of the mask MF. Hydrogen species reduce the amount of fluorine species. Therefore, as the ratio of the amount of fluorine species to the amount of hydrogen species increases, the second position becomes lower. Thus, by adjusting the amounts of fluorine species and hydrogen species, it is possible to adjust the second position in which the second protrusion CV2 is formed.

[0121] In step ST32, the HF gas contained in the first process gas may have the largest flow rate among the first process gas (or, if the first process gas contains an inert gas, all gases in the first process gas excluding the inert gas). The flow rate of the HF gas may be adjusted to the same range as the flow rate of the HF gas in the first embodiment.

[0122] In step ST32, the tungsten-containing gas (W-containing gas) included in the first processing gas may be a gas containing tungsten and 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 W-containing gas may be one or more of the following: gases containing tungsten and fluorine, such as tungsten difluoride (WF2) gas, tungsten tetrafluoride (WF4) gas, tungsten pentafluoride (WF5) gas, and tungsten hexafluoride (WF6) gas; and gases containing tungsten and chlorine, such as tungsten dichloride (WCl2) gas, tungsten tetrachloride (WCl4) gas, tungsten pentachloride (WCl5) gas, and tungsten hexachloride (WCl6) gas. Among these, the W-containing gas may be at least one of WF6 gas and WCl6 gas. The first treatment gas may contain one or more of the following in place of or in addition to the W-containing gas: molybdenum-containing gas, titanium-containing gas, and ruthenium-containing gas. In other words, the first processing gas may contain at least one metal-containing gas selected from the group consisting of tungsten-containing gas, molybdenum-containing gas, titanium-containing gas, and ruthenium-containing gas. To put it another way, the first processing gas may contain at least one metal-containing gas. The at least one metal-containing gas may contain at least one metal selected from the group consisting of tungsten, molybdenum, titanium, and ruthenium.

[0123] The first process gas may further contain a phosphorus-containing gas. The first process gas may further contain a carbon-containing gas. The first process gas may further contain an oxygen-containing gas. The first process gas may further contain a halogen-containing gas. The first process gas may contain halogen-containing gases other than fluorine, i.e., fluorine-free halogen-containing gases and / or fluorine-containing halogen-containing gases. In one example, the first process gas contains HF gas and W-containing gas, in addition to phosphorus-containing gas, carbon-containing gas, and halogen-containing gas. The phosphorus-containing gas, carbon-containing gas, oxygen-containing gas, and halogen-containing gas that the first process gas may contain may be the gases listed in the description of the first embodiment.

[0124] As described above, the first processing gas may further contain a halogen-containing gas, similar to the first processing gas in the first embodiment. In one example, the halogen-containing gas may include NF3 gas. The first processing gas may also contain one or more other halogen-containing gases in place of or in addition to NF3 gas. The first processing gas may also further contain Cl2 gas and HBr gas in place of or in addition to NF3 gas.

[0125] The first processing gas may contain no noble gas, or may contain noble gas at a flow rate less than that of the noble gas in the second processing gas described later. The first processing gas may contain a first noble gas and / or a second noble gas as the noble gas. The first noble gas includes at least one noble gas selected from the group consisting of krypton (Kr), xenon (Xe), and radon (Rn). The second noble gas includes at least one noble gas selected from the group consisting of Ar, Ne, and He.

[0126] The first processing gas may contain a gas capable of generating hydrogen fluoride species (HF species) in the first plasma, instead of some or all of the HF gas. The HF species includes at least one of hydrogen fluoride gas, radicals, and ions. The gas capable of generating HF species may be a single gas or mixed gas containing fluorine and hydrogen. As the single gas or mixed gas containing fluorine and hydrogen, the gases listed in the description of the first embodiment above can be used.

[0127] (Process ST33: Second etching process) Step ST33 is performed following step ST32. In one example, step ST33 may be started before the recessed RC reaches the underlying film UF. That is, step ST33 may be started with the silicon-containing film SF remaining between the underlying film UF and the bottom of the recessed RC. Alternatively, step ST33 may be started when at least a portion of the underlying film UF is exposed to the recessed RC. The switch from step ST32 to step ST33 may be based on at least one of the depth of the recessed RC, the aspect ratio of the recessed RC, and the etching time.

[0128] In step ST33, first, a second processing gas is supplied from the gas supply unit 20 into the plasma processing space 10s. In step ST33, similar to step ST12, a source RF signal is supplied to the lower electrode of the substrate support unit 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 unit 11, and a second plasma is generated from the second processing gas in the plasma processing space 10s. Also in step ST33, a bias signal is supplied to the lower electrode of the substrate support unit 11, generating a bias potential difference between the plasma and the substrate W. Due to the bias potential difference, active species such as ions and radicals in the plasma are attracted to the substrate W, and the silicon-containing film SF is further etched by these active species. Step ST33 is performed until the underlying film UF is exposed, or until a part of the underlying film UF is etched in the depth direction. During the processing in steps ST32 and ST33, the temperature of the substrate support unit 11 may be maintained at the set temperature adjusted in step ST31, or it may be changed.

[0129] Figure 15 shows an example of the cross-sectional structure of the substrate W during processing in step ST33. As shown in Figure 15, in the substrate W after processing in step ST33, the bottom of the recess RC reaches the underlying film UF, and the underlying film UF is exposed in the recess RC. At this time, a part of the underlying film UF may be etched in the depth direction. In step ST33, the plasma generated from the second processing gas can enlarge the opening width at the bottom of the recess RC, making the shape of the recess RC (shape in the vertical cross-section) rectangular. In this state, the aspect ratio of the recess RC may be, for example, 20 or more, and may be 30 or more, 40 or more, 50 or more, or 100 or more.

[0130] In step ST33, the HF gas contained in the second process gas may have the largest flow rate (partial pressure) among the second process gas (or all gases in the second process gas excluding the inert gas if the second process gas contains an inert gas). The flow rate of the HF gas may be adjusted to the same range as the flow rate of the HF gas in the first embodiment.

[0131] The second process gas may contain at least one noble gas. The second process gas may contain the first noble gas and / or the second noble gas as described above. The second process gas may also contain nitrogen gas.

[0132] The second process gas may contain a halogen-containing gas, similar to the first process gas. The second process gas may also contain a carbon-containing gas, similar to the first process gas.

[0133] The second process gas may either not contain W-containing gas (or metal-containing gas), or it may contain W-containing gas at a flow rate lower than that of W-containing gas (or metal-containing gas) in the first process gas. In one example, the second process gas does not contain W-containing gas (or metal-containing gas). If the second process gas contains W-containing gas (or metal-containing gas), the W-containing gas (or metal-containing gas) may be any of the W-containing gases (or metal-containing gases) described above.

[0134] The second process gas may either not contain phosphorus-containing gas, or it may contain phosphorus-containing gas at a flow rate lower than that of the phosphorus-containing gas in the first process gas. In one example, the second process gas does not contain phosphorus-containing gas. If the second process gas contains phosphorus-containing gas, the phosphorus-containing gas may be any of the phosphorus-containing gases described above.

[0135] Figure 16 is an example of a timing chart for the third embodiment. 16 In this graph, the horizontal axis represents time. The vertical axis represents the flow rates of HF gas, W-containing gas, the first noble gas, and phosphorus-containing gas contained in the processed gas (first processed gas or second processed gas). "QH1", "QH2", "QH3", and "QH4" are flow rates greater than 0. "QL1", "QL2", "QL3", and "QL4" are flow rates smaller than "QH1", "QH2", "QH3", and "QH4", or are zero, respectively.

[0136] As shown in Figure 16, when switching from process ST32 to process ST33, the flow rate (partial pressure) of the W-containing gas (or metal-containing gas) and / or the flow rate of the phosphorus-containing gas may be reduced, and the flow rate (partial pressure) of the first noble gas may be increased.

[0137] In the etching method according to the third embodiment, in step ST32, the silicon-containing film SF is etched with a first processing gas containing HF gas and W-containing gas (or metal-containing gas). In step ST33, the silicon-containing film SF is further etched with a second processing gas containing HF gas. In step ST32, the formation of a second protrusion CV2 on the side wall of the mask MF suppresses bowing of the silicon-containing film SF. Although the shape of the recess RC formed in step ST32 (shape in the longitudinal section) is inversely tapered, the opening width at the bottom of the recess RC can be enlarged in step ST33 to make the shape of the recess RC rectangular. The enlargement of the opening width at the bottom of the recess RC in step ST33 is achieved, in part, by using a second processing gas in which the flow rate of W-containing gas (or metal-containing gas) is reduced or set to zero.

[0138] In the above description, the case where the process switches from step ST32 to step ST33 before the recessed RC reaches the underlying film UF, or when at least a portion of the underlying film UF is exposed, was explained. However, in the third embodiment, the timing of switching from step ST32 to step ST33 is not limited to this. For example, the process may switch from step ST32 to step ST33 after the recessed RC reaches the underlying film UF and a portion of the underlying film UF has been etched. Alternatively, for example, the cycle including steps ST32 and ST33 may be performed multiple times until the underlying film UF is exposed or a portion of the underlying film UF is etched.

[0139] As described above, in the third embodiment, the first processing gas may further contain phosphorus-containing gas. The second processing gas may either not contain phosphorus-containing gas or contain phosphorus-containing gas at a flow rate lower than that of the phosphorus-containing gas in the first processing gas. The phosphorus-containing gas increases the etching rate of the silicon-containing film SF at the bottom of the recessed RC and suppresses lateral etching of the side walls defining the recessed RC. Therefore, when the first processing gas contains phosphorus-containing gas, the etching rate of the silicon-containing film SF can be increased, and bowing can be suppressed. Also, when the second processing gas does not contain phosphorus-containing gas or contains phosphorus-containing gas at a flow rate lower than that of the phosphorus-containing gas in the first processing gas, it is possible to increase the width of the bottom of the recessed RC, i.e., the width of the bottom of the recessed RC in the vicinity of (or directly above) the base film UF. As described above, step ST32 may be stopped with the silicon-containing film SF remaining between the base film UF and the bottom of the recessed RC, and step ST33 may be started in this state.

[0140] In a third embodiment, the second processing gas may further contain the first noble gas described above (e.g., xenon gas). In this case, the first processing gas may not contain the first noble gas, or may contain the first noble gas at a flow rate lower than that of the first noble gas in the second processing gas. In this case, the first and second processing gases may further contain a halogen-containing gas. The halogen-containing gas may include NF3 gas. The halogen-containing gas may further contain one or more other halogen-containing gases such as Cl2 gas and / or HBr gas. By using a second processing gas containing the first noble gas, it is possible to increase the width of the bottom of the recessed RC, for example, the width of the recessed RC in the vicinity of (or directly above) the undercoat UF.

[0141] In a third embodiment, the first process gas may further contain a halogen-containing gas including NF3 gas. The halogen-containing gas may further contain one or more other halogen-containing gases, such as Cl2 gas and / or HBr gas, in addition to NF3 gas. The second process gas may also contain a halogen-containing gas, similar to the first process gas. The second process gas may not contain NF3 gas, or may contain NF3 gas at a flow rate lower than that of NF3 gas in the first process gas. The second process gas may further contain an oxygen-containing gas (e.g., O2 gas) and a noble gas. The first process gas may not contain the noble gas, or may contain the noble gas at a flow rate lower than that of the noble gas in the second process gas. In this case, the noble gas in each of the first and second process gases may be a first noble gas (e.g., xenon gas), a second noble gas (e.g., argon gas), or both the first and second noble gases may be included. In this case as well, it is possible to increase the width of the bottom of the recessed RC, for example, the width of the recessed RC in the vicinity of (or directly above) the underlying film UF.

[0142] The embodiments described above are for illustrative purposes only and are not intended to limit the scope of the disclosure. The embodiments described above can be modified in various ways without departing from the scope and spirit of the disclosure. For example, the first embodiment to Such etching methods may be used in combination with the etching method according to the second embodiment and / or the etching method according to the third embodiment. Furthermore, the etching method according to the second embodiment may be used in combination with the etching method according to the third embodiment. In addition, for example, the etching methods according to each embodiment 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 microwave plasma.

[0143] Furthermore, in the various embodiments described above, a metal-containing gas, such as the W-containing gas described above, was included in the processing gas (for example, the first processing gas) as a metal supply source. However, the metal supply source may be an upper electrode formed from a metal-containing material and / or an edge ring made of a metal-containing material. That is, the metal-containing material released from the upper electrode and / or edge ring in the first etching step may form the second protrusion CV2.

[0144] Furthermore, in the etching methods according to the various embodiments described above, the first and second processing gases do not necessarily contain metal-containing gases such as the W-containing gas described above. Also, in the etching methods according to the various embodiments described above, a metal supply source does not necessarily have to be used.

[0145] Furthermore, in the etching methods according to the various embodiments described above, the film to be etched may be a film other than the silicon-containing film SF.

[0146] Embodiments of this disclosure further include the following embodiments:

[0147] (Note 1) An etching method performed in a plasma processing apparatus having a chamber, (a) A step of providing a substrate having a base film and a silicon-containing film on the base film into a chamber, (b) A step of etching the silicon-containing film using a first plasma generated from a first processing gas containing hydrogen fluoride gas to form a recess, wherein the etching is carried out until the underlying film is exposed in the recess or until at least a portion of the underlying film is exposed in the recess, (c) A step of further etching the silicon-containing film in the recess under conditions different from those of step (b), Etching methods including [specific methods].

[0148] (Note 2) The etching method according to Appendix 1, wherein in step (c) above, a second plasma is generated using a second processing gas different from the first processing gas.

[0149] (Note 3) The etching method according to Appendix 2, wherein the second plasma has a fluorine species density lower than the fluorine species density in the first plasma.

[0150] (Note 4) The etching method according to Appendix 2 or Appendix 3, wherein the undercoat contains silicon, and the second processing gas contains 50% or more by volume of fluorocarbon gas or hydrofluorocarbon gas and oxygen-containing gas relative to the total flow rate of the second processing gas excluding the flow rate of the inert gas.

[0151] (Note 5) The etching method according to Appendix 4, wherein the fluorocarbon gas or hydrofluorocarbon gas contained in the second processing gas has two or more carbon atoms.

[0152] (Note 6) The etching method according to Appendix 2 or Appendix 3, wherein the undercoat contains a metal, the first processing gas further contains a fluorine-containing gas other than hydrogen fluoride, and the second processing gas either does not contain the fluorine-containing gas or contains the fluorine-containing gas at a partial pressure lower than the partial pressure of the fluorine-containing gas in the first processing gas.

[0153] (Note 7) The etching method according to Appendix 6, wherein the fluorine-containing gas is at least one of NF3 gas and SF6 gas.

[0154] (Note 8) The etching method according to Appendix 6 or Appendix 7, wherein the second processing gas further comprises at least one of CO gas and a chlorine-containing gas.

[0155] (Note 9) The etching method according to any one of the appendices 1 to 8, wherein in step (c), temperature control is performed so that the temperature of the substrate becomes higher than the temperature of the substrate in step (b).

[0156] (Note 10) The etching method according to Appendix 9, wherein the temperature control includes one or more of the following: (I) increasing the power of the source RF signal or bias signal supplied to the chamber; (II) decreasing the suction force of the substrate support portion that supports the substrate; (III) decreasing the pressure of the heat transfer gas supplied to the gap between the substrate and the substrate support portion; and (IV) raising the set temperature of the substrate support portion to a higher temperature than the set temperature in step (b).

[0157] (Note 11) The etching method according to Appendix 9 or Appendix 10, wherein the temperature control includes controlling the temperature of the substrate to be 30°C or higher than the temperature of the substrate in step (b).

[0158] (Note 12) The etching method according to any one of the appendices 1 to 11, wherein in step (c), pressure control is performed so that the pressure in the chamber is lower than the pressure in the chamber in step (b).

[0159] (Note 13) The etching method according to Appendix 12, wherein the pressure control includes controlling the pressure in the chamber to be 30% or more lower than the pressure in the chamber in step (b).

[0160] (Note 14) The etching method according to any one of the appendices 1 to 13, wherein the first processing gas further comprises a phosphorus-containing gas.

[0161] (Note 15) The etching method according to any one of the appendices 1 to 14, wherein the first processing gas comprises at least one of a carbon-containing gas and an oxygen-containing gas.

[0162] (Note 16) The etching method according to any one of Appendix 1 to Appendix 15, wherein in step (b) above, the temperature of the substrate support portion supporting the substrate is controlled to 20°C or less.

[0163] (Note 17) The etching method according to any one of Appendix 1 to Appendix 16, wherein the source RF signal supplied to the chamber has a frequency of 40 MHz or higher.

[0164] (Note 18) An etching method performed in a plasma processing apparatus having a chamber, (a) A step of providing a substrate having a base film and a silicon-containing film on the base film into a chamber, (b) A step of etching the silicon-containing film using a plasma containing HF species to form a recess, wherein the etching is carried out until the underlying film is exposed in the recess or until at least a portion of the underlying film is exposed in the recess, (c) An etching method comprising the step of further etching the silicon-containing film in the recess under conditions different from those of step (b).

[0165] (Note 19) The etching method according to Appendix 18, wherein the HF species is generated from at least one gas, such as hydrogen fluoride gas or hydrofluorocarbon gas.

[0166] (Note 20) The etching method described in Appendix 18 or Appendix 19, wherein the HF species is produced from a hydrofluorocarbon gas having two or more carbon atoms.

[0167] (Note 21) The etching method described in Appendix 18, wherein the aforementioned HF species is produced from a mixed gas containing a hydrogen source and a fluorine source.

[0168] (Note 22) A plasma processing apparatus comprising a chamber and a control unit, The control unit, (a) Control to provide a substrate having a base film and a silicon-containing film on the base film into the chamber, (b) A control for etching the silicon-containing film to form a recess using a first plasma generated from a first processing gas containing hydrogen fluoride gas, wherein the etching is performed until the underlying film is exposed in the recess or until at least a portion of the underlying film is exposed in the recess, (c) Control to further etch the silicon-containing film in the recess under conditions different from those in the control described in (b), A plasma processing system configured to perform the following actions.

[0169] (Note 23) A device manufacturing method performed in a plasma processing apparatus having a chamber, (a) A step of providing a substrate having a base film and a silicon-containing film on the base film into a chamber, (b) A step of etching the silicon-containing film using a first plasma generated from a first processing gas containing hydrogen fluoride gas to form a recess, wherein the etching is carried out until the underlying film is exposed in the recess or until at least a portion of the underlying film is exposed in the recess, (c) A step of further etching the silicon-containing film in the recess under conditions different from those of step (b), A device manufacturing method including the following.

[0170] (Note 24) A computer in a plasma processing system comprising a plasma processing apparatus having a chamber and a control unit, (a) Control to provide a substrate having a base film and a silicon-containing film on the base film to the chamber, (b) A control for etching the silicon-containing film to form a recess using a first plasma generated from a first processing gas containing hydrogen fluoride gas, wherein the etching is performed until the underlying film is exposed in the recess or until at least a portion of the underlying film is exposed in the recess, (c) Control to further etch the silicon-containing film in the recess under conditions different from the control in (b), A program that executes the command.

[0171] (Note 25) Note 2 4 A storage medium containing the program described above.

[0172] (Note 26) An etching method performed in a plasma processing apparatus having a chamber, (a) A step of providing a substrate having a silicon-containing film into a chamber, (b) A step of supplying a processing gas containing hydrogen fluoride gas into the chamber and supplying an RF signal having a frequency of 40 MHz or higher to the chamber to generate plasma from the processing gas, (c) An etching method comprising the step of etching the silicon-containing film using the plasma.

[0173] (Note 27) An etching method performed in a plasma processing apparatus having a chamber, (a) A step of providing a substrate having a silicon-containing film into a chamber, (b) A step of supplying a processing gas into the chamber and supplying an RF signal having a frequency of 40 MHz or higher to the chamber to generate a plasma containing HF species from the processing gas, (c) An etching method comprising the step of etching the silicon-containing film using the plasma.

[0174] (Note 28) A plasma processing apparatus having a chamber and a control unit are provided, The control unit, (a) Control for providing a substrate having a silicon-containing film into the chamber, (b) A control system that supplies a processing gas containing hydrogen fluoride gas into the chamber and supplies an RF signal having a frequency of 40 MHz or higher to the chamber to generate plasma from the processing gas, (c) Control for etching the silicon-containing film using the plasma, A plasma processing system configured to perform the following actions.

[0175] (Note 29) A device manufacturing method performed in a plasma processing apparatus having a chamber, (a) A step of providing a substrate having a silicon-containing film into a chamber, (b) A step of supplying a processing gas containing hydrogen fluoride gas into the chamber and supplying an RF signal having a frequency of 40 MHz or higher to the chamber to generate plasma from the processing gas, (c) A device manufacturing method comprising the step of etching the silicon-containing film using the plasma.

[0176] (Note 30) A computer in a plasma processing system comprising a plasma processing apparatus having a chamber and a control unit, (a) Control for providing a substrate having a silicon-containing film into the chamber, (b) A control system that supplies a processing gas containing hydrogen fluoride gas into the chamber and supplies an RF signal having a frequency of 40 MHz or higher to the chamber to generate plasma from the processing gas, (c) Control for etching the silicon-containing film using the plasma, A program that executes the command.

[0177] (Note 31) A storage medium containing the program described in Appendix 30.

[0178] (Note A1) (a) A step of providing a substrate having a base film, a silicon-containing film on the base film, and a mask on the silicon-containing film into a chamber, (b) A step of etching the silicon-containing film to form recesses using a first plasma generated from a first processing gas containing hydrogen fluoride gas and tungsten-containing gas, (c) After step (b), a step of further etching the silicon-containing film using a second plasma generated from a second processing gas containing hydrogen fluoride gas, Includes, The second processing gas either does not contain the tungsten-containing gas, or contains the tungsten-containing gas at a flow rate lower than that of the tungsten-containing gas in the first processing gas. Etching method.

[0179] (Appendix A2) The etching method described in Appendix A1, wherein the tungsten-containing gas includes WF6.

[0180] (Note A3) The etching method according to Appendix A1 or Appendix A2, wherein the first processing gas further comprises a phosphorus-containing gas.

[0181] (Note A4) The second processing gas either does not contain phosphorus-containing gas, or contains phosphorus-containing gas at a flow rate lower than that of the phosphorus-containing gas in the first processing gas, as per Appendix A. 3 The etching method described below.

[0182] (Note A5) The etching of the silicon-containing film in step (b) above is stopped while the silicon-containing film remains between the undercoat and the bottom of the recess. The etching of the silicon-containing film in step (c) above is started in the above state and carried out over a period including the time when the underlying film is exposed. Etching method as described in Appendix A4.

[0183] (Note A6) The etching method described in any one of the appendices A1 to A5, wherein the second processing gas further comprises xenon gas.

[0184] (Note A7) The first processing gas is xeno hmm The etching method described in Appendix A6, wherein the gas is either not included or the xenon gas is included at a flow rate less than that of the xenon gas in the second processing gas.

[0185] (Note A8) The etching method described in Appendix A7, wherein each of the first and second processing gases contains nitrogen trifluoride gas.

[0186] (Note A9) The first processing gas includes nitrogen trifluoride gas. The second processing gas either does not contain nitrogen trifluoride gas, or contains nitrogen trifluoride gas at a flow rate lower than that of the nitrogen trifluoride gas in the first processing gas. The second processing gas further contains an oxygen-containing gas and a noble gas. The first processing gas either does not contain a noble gas, or contains a noble gas at a flow rate lower than that of the noble gas in the second processing gas. Etching method as described in A4 or A5.

[0187] (Note A10) The etching method according to any one of the appendices A1 to A9, wherein step (b) is performed until the underlying film is exposed in the recess or until at least a portion of the underlying film is exposed in the recess.

[0188] (Note A11) The etching method described in any one of the appendices A1 to A9, wherein step (b) is performed until a portion of the undercoat is etched.

[0189] (Note A12) The etching method described in any one of the appendices A1 to A9, wherein the cycle including the step in (b) and the step in (c) is performed multiple times.

[0190] (Note A13) The etching method according to any one of the appendices A1 to A12, wherein step (b) above involves etching the silicon-containing film while forming a first protrusion at a first position on the mask that reduces the width of the opening of the mask, and forming a second protrusion at a second position on the mask below the first position that reduces the width of the opening of the mask.

[0191] (Note A14) The first processing gas further contains a carbon-containing gas which is the source of the first protrusion. The tungsten-containing gas in the first processing gas is the source of the second protrusion. In step (b) above, the amounts of hydrogen species and fluorine species in the first plasma are adjusted so that the second protrusion is formed below the first protrusion. The etching method described in Appendix A13.

[0192] (Note A15) In step (b) above, a reverse tapered recess is formed in the silicon-containing film. In step (c) above, the shape of the recess is made rectangular. The etching method described in any one of the appendices A1 to A14.

[0193] (Note A16) (a) A step of providing a substrate having a base film, a silicon-containing film on the base film, and a mask on the silicon-containing film into a chamber, (b) A step of etching the silicon-containing film using a first plasma generated from a first processing gas to form a recess, (c) After step (b), a step of further etching the silicon-containing film using a second plasma generated from a second processing gas, Includes, The first processing gas comprises a single gas or mixed gas containing fluorine and hydrogen, and a metal-containing gas. The second processing gas includes a single gas or mixed gas containing fluorine and hydrogen, The second processing gas either does not contain the metal-containing gas, or contains the metal-containing gas at a flow rate lower than that of the metal-containing gas in the first processing gas. Etching method.

[0194] (Note A17) The etching method according to Appendix A16, wherein the metal-containing gas comprises at least one metal selected from the group consisting of tungsten, molybdenum, titanium, and ruthenium.

[0195] (Note A18) The etching method according to Appendix A16 or Appendix A17, wherein the first processing gas further comprises a phosphorus-containing gas.

[0196] (Note A19) The etching method according to Appendix A18, wherein the second processing gas does not contain phosphorus-containing gas, or contains phosphorus-containing gas at a flow rate less than that of the phosphorus-containing gas in the first processing gas.

[0197] (Note A20) The etching of the silicon-containing film in step (b) above is stopped while the silicon-containing film remains between the undercoat and the bottom of the recess. The etching of the silicon-containing film in step (c) above is started in the above state and carried out over a period including the time when the underlying film is exposed. The etching method described in Appendix A19.

[0198] (Note A21) The etching method described in any one of the appendices A16 to A20, wherein the second processing gas further comprises a noble gas.

[0199] (Note A22) The etching method according to Appendix A21, wherein the first processing gas does not contain the noble gas, or contains the noble gas at a flow rate less than the flow rate of the noble gas in the second processing gas.

[0200] (Note A23) The etching method according to Appendix A21 or A22, wherein the noble gas includes at least one selected from the group consisting of argon gas, krypton gas, xenon gas, and radon gas.

[0201] (Note A24) The etching method according to Appendix A22 or A23, wherein each of the first and second processing gases contains nitrogen trifluoride gas.

[0202] (Note A25) The first processing gas includes nitrogen trifluoride gas. The second processing gas either does not contain nitrogen trifluoride gas, or contains nitrogen trifluoride gas at a flow rate lower than that of the nitrogen trifluoride gas in the first processing gas. The second processing gas further contains an oxygen-containing gas and a noble gas. The first processing gas either does not contain a noble gas, or contains a noble gas at a flow rate lower than that of the noble gas in the second processing gas. The etching method described in Appendix A19 or A20.

[0203] (Note A26) The etching method according to any one of the appendices A16 to A25, wherein step (b) above involves etching the silicon-containing film while forming a first protrusion at a first position on the mask that reduces the width of the opening of the mask, and forming a second protrusion at a second position on the mask below the first position that reduces the width of the opening of the mask.

[0204] (Note A27) The first processing gas further contains a carbon-containing gas which is the source of the first protrusion. The metal-containing gas in the first processing gas is the source of the second protrusion. In (b) above, the amounts of hydrogen species and fluorine species in the first plasma are adjusted so that the second protrusion is formed below the first protrusion. The etching method described in Appendix A26.

[0205] (Note A28) Chamber and, The substrate support portion in the chamber, Plasma generation section, A control unit configured to control the plasma generation unit, Includes, The control unit, (a) A step of providing a substrate having a base film, a silicon-containing film on the base film, and a mask on the silicon-containing film into the chamber, (b) A step of etching the silicon-containing film to form recesses using a first plasma generated from a first processing gas containing hydrogen fluoride gas and tungsten-containing gas, (c) A step of further etching the silicon-containing film using a second plasma generated from a second processing gas containing hydrogen fluoride gas after the step of (b), wherein the second processing gas does not contain the tungsten-containing gas, or contains the tungsten-containing gas at a flow rate lower than that of the tungsten-containing gas in the first processing gas, An etching apparatus configured to perform a process that includes the following.

[0206] (Note A29) The etching apparatus described in Appendix A28 includes WF6 as the tungsten-containing gas.

[0207] (Note A30) The etching apparatus according to Appendix A28 or A29, wherein the first processing gas further comprises a phosphorus-containing gas.

[0208] (Note A31) The etching apparatus as described in Appendix A30, wherein the second processing gas does not contain phosphorus-containing gas, or contains phosphorus-containing gas at a flow rate lower than that of the phosphorus-containing gas in the first processing gas.

[0209] (Note A32) The control unit, The etching of the silicon-containing film in (b) above is stopped while the silicon-containing film remains between the base film and the bottom of the recess. The etching of the silicon-containing film in (c) above is performed starting in the above state and during a period including when the underlying film is exposed. It is configured in such a way. Note Etching apparatus as described in A31.

[0210] (Note A33) The etching apparatus described in any one of the appendices A28 to A32 further comprises xenon gas as the second processing gas.

[0211] (Note A34) The etching apparatus according to Supplementary Note A33, wherein the first processing gas either does not contain xenon gas or contains xenon gas at a flow rate less than that of the xenon gas in the second processing gas.

[0212] (Supplementary Note A35) The etching apparatus according to Supplementary Note A34, wherein each of the first processing gas and the second processing gas contains nitrogen trifluoride gas.

[0213] (Supplementary Note A36) The first processing gas contains nitrogen trifluoride gas, the second processing gas either does not contain nitrogen trifluoride gas or contains nitrogen trifluoride gas at a flow rate less than that of the nitrogen trifluoride gas in the first processing gas, the second processing gas further contains an oxygen-containing gas and a noble gas, the first processing gas either does not contain a noble gas or contains a noble gas at a flow rate less than that of the noble gas in the second processing gas, The etching apparatus according to Supplementary Note A31 or A32.

[0214] (Supplementary Note A37) The first processing gas further contains a carbon-containing gas that is a source for forming a first convex portion that reduces the width of the opening of the mask at a first position of the mask, the tungsten-containing gas in the first processing gas is a source for forming a second convex portion that reduces the width of the opening of the mask at a second position of the mask below the first position, In (b), the control unit is configured to adjust the amount of hydrogen chemical species and the amount of fluorine chemical species in the first plasma in order to form the second convex portion below the first convex portion. The etching apparatus according to any one of Supplementary Notes A28 to A36.

[0215] (Supplementary Note A38) Further comprising a gas supply unit configured to supply the first processing gas and the second processing gas into the chamber, The control unit is configured to further control the gas supply unit, An etching apparatus according to any one of appended claims A28 to A37.

[0216] (Appended claim A39) A chamber, A substrate support part in the chamber, A plasma generation part, A control unit configured to control the plasma generation part, Including, The control unit, (a) A step of providing a substrate having an etching target film and a mask on the etching target film in the chamber, (b) A step of etching the etching target film using plasma generated from a processing gas containing hydrogen fluoride gas to form a concave portion, Executing a process including the above, and executing the above (b) in a state where a metal supply source exists in the chamber to form a first convex portion that reduces the width of the opening of the mask at a first position of the mask, and a second convex portion that reduces the width of the opening of the mask at a second position of the mask below the first position, while etching the etching target film, and is configured to be, An etching apparatus.

[0217] (Appended claim A40) The processing gas further includes a metal-containing gas, The metal supply source is the metal-containing gas, An etching apparatus according to appended claim A39.

[0218] (Appended claim A41) The metal supply source is formed of a metal-containing material, and is an upper electrode disposed above the substrate support part so as to face the substrate support part and / or an edge ring made of a metal-containing material disposed around the substrate supported by the substrate support part. An etching apparatus according to appended claim A39.

[0219] The following describes several experimental examples.

[0220] (Examples 1 and 2 of the experiment)

[0221] In the first and second experimental examples, a silicon-containing film on a sample substrate was etched using a plasma processing apparatus 1. The sample substrate had a multilayer film as a silicon-containing film on a base film, and a mask formed from amorphous carbon on the multilayer film. The multilayer film contained multiple silicon oxide films and multiple silicon nitride films stacked alternately. The etching in the first and second experimental examples included a first etching step and a second etching step following the first etching step. In the first experimental example, a mixed gas containing HF gas, PF3 gas, and a halogen-containing gas was used as the first processing gas in the first etching step. The halogen-containing gas contained NF3 gas, Cl2 gas, and HBr gas. In the first experimental example, the same mixed gas as the first processing gas was used as the second processing gas in the second etching step, except that it did not contain PF3 gas. In the second experimental example, the same mixed gas as the first processing gas in the first experimental example was used as the first processing gas in the first etching step and as the second processing gas in the second etching step. In the first and second experimental examples, the first etching process was stopped while a silicon-containing film remained between the base film and the bottom of the recess, and the second etching process was started in this state.

[0222] In the first and second experimental examples, the maximum width of the recess formed in the silicon-containing film (i.e., Boeing CD) and the width at the bottom of the recess (i.e., bottom CD) were determined. The difference between Boeing CD and bottom CD, i.e., the CD bias, was then calculated. The Boeing CD in the first experimental example was approximately the same as that in the second experimental example, and the bottom CD in the first experimental example was approximately 11 nm larger than that of the bottom CD in the second experimental example. Furthermore, the CD bias in the second experimental example was 47.6 nm, while the CD bias in the first experimental example was 35.2 nm. From these results, it was confirmed that by reducing the flow rate of phosphorus-containing gas in the second processing gas from that of the first processing gas, or by setting it to zero, it is possible to enlarge the bottom CD and reduce the CD bias, that is, it is possible to make the shape of the longitudinal cross-section of the recess rectangular.

[0223] (Experimental examples 3 to 5)

[0224] In the third to fifth experimental examples, the silicon-containing film on the same sample substrate as in the first experimental example was etched using the plasma processing apparatus 1. The etching in the third to fifth experimental examples included a first etching step and a second etching step following the first etching step. In the third and fourth experimental examples, a mixed gas containing HF gas, WF6 gas, PF3 gas, halogen-containing gas, and carbon-containing gas was used as the first processing gas in the first etching step. The halogen-containing gas contained NF3 gas, Cl2 gas, and HBr gas. The carbon-containing gas contained hydrofluorocarbon gas. In the third experimental example, the same mixed gas as the first processing gas in the third experimental example was used as the second processing gas in the second etching step, except that it did not contain WF6 gas and PF3 gas. In the fourth experimental example, the same mixed gas as the first processing gas in the fourth experimental example was used as the second processing gas in the second etching step, except that it did not contain WF6 gas and PF3 gas and further contained xenon gas. In the fifth experimental example, the same mixed gas as the first processing gas in the third experimental example was used as the first processing gas in the first etching step, except that it did not contain WF6 gas. In the fifth experimental example, the same mixed gas as the second processing gas in the third experimental example was used as the second processing gas in the second etching step. In the third to fifth experimental examples, the first etching step was stopped with a silicon-containing film remaining between the undercoat and the bottom of the recess, and the second etching step was started in this state.

[0225] In the third to fifth experimental examples, the maximum width of the recess formed in the silicon-containing film (i.e., Boeing CD) and the width at the bottom of the recess (i.e., Bottom CD) were determined. Then, the difference between Boeing CD and Bottom CD, i.e., the CD bias, was calculated. The Boeing CD in the third and fourth experimental examples was approximately 7 nm smaller than the Boeing CD in the fifth experimental example. From this result, it was confirmed that Boeing can be suppressed by using a first processing gas containing a metal-containing gas such as WF6 gas. Furthermore, the Bottom CD in the third experimental example was approximately the same as the Bottom CD in the fifth experimental example, but the Bottom CD in the fourth experimental example was approximately 5 nm larger than the Bottom CD in the fifth experimental example. From this, it was confirmed that a relatively large Bottom CD can be obtained by using a second processing gas containing a first noble gas such as xenon gas. Furthermore, while the CD bias in the fifth experimental example was 37.6 nm, the bottom CD in the third experimental example was 33.7 nm, and the bottom CD in the fourth experimental example was 25.9 nm. From these results, it was confirmed that by using a first processing gas containing a metal-containing gas such as WF6 gas, it is possible to suppress the bowing CD and make the shape of the longitudinal cross-section of the recess rectangular. It was also confirmed that by using a second processing gas containing a first noble gas such as xenon gas, it is possible to enlarge the bottom CD and further make the shape of the longitudinal cross-section of the recess rectangular.

[0226] (Experimental examples 6 and 7)

[0227] In the sixth and seventh experimental examples, the silicon-containing film on the same sample substrate as in the first experimental example was etched using the plasma processing apparatus 1. The etching in the sixth and seventh experimental examples included a first etching step and a second etching step following the first etching step. In the sixth and seventh experimental examples, a mixed gas containing HF gas, PF3 gas, halogen-containing gas, and carbon-containing gas was used as the first processing gas in the first etching step. The halogen-containing gases included NF3 gas, Cl2 gas, and HBr gas. The carbon-containing gas contained fluorocarbon gas. In the sixth and seventh experimental examples, a mixed gas containing a noble gas in addition to all the gases in the first processing gas of each experimental example was used as the second processing gas in the second etching step. In the sixth experimental example, the noble gas was xenon gas, and in the seventh experimental example, the noble gas was argon gas. In the sixth and seventh experimental examples, the first etching process was stopped while a silicon-containing film remained between the base film and the bottom of the recess, and the second etching process was started in this state.

[0228] In the sixth and seventh experimental examples, the maximum width of the recess formed in the silicon-containing film (i.e., Boeing CD) and the width at the bottom of the recess (i.e., bottom CD) were determined. The difference between Boeing CD and bottom CD, i.e., the CD bias, was then calculated. The Boeing CDs in the sixth and seventh experimental examples were approximately the same. Furthermore, the bottom CD in the sixth experimental example was 29 nm larger than the bottom CD in the seventh experimental example. Also, the CD bias in the seventh experimental example was 67 nm, while the CD bias in the sixth experimental example was 30 nm. From these results, it was confirmed that by using a first noble gas such as xenon gas in the second etching process, it is possible to enlarge the bottom CD and further rectangularize the shape of the longitudinal cross-section of the recess.

[0229] (Experimental examples 8-10)

[0230] In experimental examples 8 to 10, the silicon-containing film on the same sample substrate as in experimental example 1 was etched using the plasma processing apparatus 1. The etching in experimental examples 8 to 10 included a first etching step and a second etching step following the first etching step. In experimental examples 8 to 10, a mixed gas containing HF gas, WF6 gas, PF3 gas, halogen-containing gas, and carbon-containing gas was used as the first processing gas in the first etching step. The halogen-containing gas contained NF3 gas, Cl2 gas, and HBr gas. The carbon-containing gas contained hydrofluorocarbon gas. In experimental example 8, the second processing gas in the second etching step was the same mixed gas as the first processing gas in experimental example 8, except that it did not contain WF6 gas and PF3 gas, and further contained xenon gas. In experimental example 9, the second processing gas in the second etching step was the same mixed gas as the second processing gas in experimental example 8, except that it contained O2 gas instead of NF3 gas. In the 10th experimental example, the same mixed gas as in the 9th experimental example was used as the second processing gas in the second etching step, except that argon gas was included instead of xenon gas.

[0231] In the 8th to 10th experimental examples, the maximum width of the recess formed in the silicon-containing film (i.e., the bowing CD) and the width at the bottom of the recess (i.e., the bottom CD) were obtained. Then, the difference between the bowing CD and the bottom CD, i.e., the CD bias, was obtained. In the 9th experimental example, the bottom CD was 0.7 nm smaller than the bottom CD of the 8th experimental example, but the bowing CD was 2.3 nm smaller than the bowing CD of the 8th experimental example. Therefore, in the 9th experimental example, the CD bias was 1.6 nm smaller than the CD bias of the 8th experimental example. From this result, it was confirmed that by using an oxygen-containing gas such as O2 gas instead of NF3 gas in the second etching process, bowing can be suppressed and the shape in the longitudinal section of the recess can be further rectangularized. Also, in the 10th experimental example, as a result of the bottom CD being enlarged compared to the bottom CD of the 9th experimental example, the CD bias was 2.3 nm smaller than the CD bias of the 9th experimental example. From this result, it was confirmed that by using a second noble gas such as argon gas as the noble gas used together with O2 gas instead of NF3 gas in the second etching process, the bottom CD can be enlarged and the shape in the longitudinal section of the recess can be further rectangularized.

[0232] From the above description, it will be understood that the various embodiments of the present disclosure are described herein for the purpose of explanation and that various changes can be made without departing from the scope and gist of the present disclosure. Therefore, the various embodiments disclosed herein are not intended to be limiting, and the true scope and gist are indicated by the appended claims.

Explanation of Reference Numerals

[0233] 1... Plasma processing apparatus, 2... Control unit, 10... Plasma processing chamber, 10s... Plasma processing space, 11... Substrate support part, 13... Shower head, 20... Gas supply part, 31a... First RF generation part, 31b... Second RF generation part, 32a... First DC generation part, SF... Silicon-containing film, MF... Mask, OP... Opening, RC... Recess, UF... Underlying film, W... Substrate.

Claims

1. (a) A step of providing a substrate having a base film, a silicon-containing film on the base film, and a mask on the silicon-containing film into a chamber, (b) A step of etching the silicon-containing film to form recesses using a first plasma generated from a first processing gas containing hydrogen fluoride gas and tungsten-containing gas, (c) After (b) above, a step of further etching the silicon-containing film using a second plasma generated from a second processing gas containing hydrogen fluoride gas, Includes, The second processing gas either does not contain tungsten-containing gas, or contains tungsten-containing gas at a flow rate lower than that of the tungsten-containing gas in the first processing gas. Etching method.

2. The tungsten-containing gas is WF ６ The etching method according to claim 1, including the following:

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

4. The etching method according to claim 3, wherein the second processing gas does not contain phosphorus-containing gas, or contains phosphorus-containing gas at a flow rate less than that of the phosphorus-containing gas in the first processing gas.

5. The etching of the silicon-containing film in (b) above is stopped while the silicon-containing film remains between the underlayer film and the bottom of the recess. The etching of the silicon-containing film in (c) above is initiated in the state described above and carried out over a period including the time when the underlying film is exposed. The etching method according to claim 4.

6. The etching method according to claim 1 or 2, wherein the second processing gas further comprises xenon gas.

7. The etching method according to claim 6, wherein the first processing gas does not contain xenon gas, or contains xenon gas at a flow rate less than the flow rate of the xenon gas in the second processing gas.

8. The etching method according to claim 7, wherein each of the first processing gas and the second processing gas contains nitrogen trifluoride gas.

9. The first processing gas includes nitrogen trifluoride gas. The second processing gas either does not contain nitrogen trifluoride gas, or contains nitrogen trifluoride gas at a flow rate lower than that of the nitrogen trifluoride gas in the first processing gas. The second processing gas further contains an oxygen-containing gas and a noble gas. The first processing gas does not contain noble gas, or contains noble gas at a flow rate less than that of the noble gas in the second processing gas. The etching method according to claim 4.

10. The etching method according to claim 1, wherein (b) is performed until the underlying film is exposed in the recess or until at least a portion of the underlying film is exposed in the recess.

11. The etching method according to claim 1, wherein (b) is carried out until a portion of the undercoat is etched.

12. The etching method according to claim 1, comprising performing a cycle including (b) and (c) multiple times.

13. The etching method according to claim 1, wherein (b) is an etching method according to claim 1, wherein the silicon-containing film is etched while forming a first protrusion at a first position of the mask that reduces the width of the opening of the mask, and forming a second protrusion at a second position of the mask below the first position that reduces the width of the opening of the mask.

14. The first processing gas further contains a carbon-containing gas which is the source of the first protrusion. The tungsten-containing gas in the first processing gas is the source of the second protrusion. In (b) above, the amounts of hydrogen species and fluorine species in the first plasma are adjusted so that the second protrusion is formed below the first protrusion. The etching method according to claim 13.

15. In (b) above, a reverse tapered recess is formed in the silicon-containing film, In (c) above, the shape of the recess is made rectangular. The etching method according to claim 1.

16. (a) A step of providing a substrate having a base film, a silicon-containing film on the base film, and a mask on the silicon-containing film into a chamber, (b) A step of etching the silicon-containing film using a first plasma generated from a first processing gas to form a recess, (c) After (b) above, a step of further etching the silicon-containing film using a second plasma generated from a second processing gas, Includes, The first processing gas comprises a single gas or mixed gas containing fluorine and hydrogen, and a metal-containing gas. The second processing gas includes a single gas or mixed gas containing fluorine and hydrogen, The second processing gas either does not contain the metal-containing gas, or contains the metal-containing gas at a flow rate lower than that of the metal-containing gas in the first processing gas. Etching method.

17. The etching method according to claim 16, wherein the metal-containing gas comprises at least one metal selected from the group consisting of tungsten, molybdenum, titanium, and ruthenium.

18. The etching method according to claim 16 or 17, wherein the first processing gas further comprises a phosphorus-containing gas.

19. The etching method according to claim 18, wherein the second processing gas does not contain phosphorus-containing gas, or contains phosphorus-containing gas at a flow rate less than that of the phosphorus-containing gas in the first processing gas.

20. The etching of the silicon-containing film in (b) above is stopped while the silicon-containing film remains between the underlayer film and the bottom of the recess. The etching of the silicon-containing film in (c) above is initiated in the state described above and carried out over a period including the time when the underlying film is exposed. The etching method according to claim 19.

21. The etching method according to claim 16, wherein the second processing gas further comprises a noble gas.

22. The etching method according to claim 21, wherein the first processing gas does not contain the noble gas, or contains the noble gas at a flow rate less than the flow rate of the noble gas in the second processing gas.

23. The etching method according to claim 21 or 22, wherein the noble gas includes at least one selected from the group consisting of argon gas, krypton gas, xenon gas, and radon gas.

24. The etching method according to claim 22, wherein each of the first processing gas and the second processing gas contains nitrogen trifluoride gas.

25. The first processing gas includes nitrogen trifluoride gas. The second processing gas either does not contain nitrogen trifluoride gas, or contains nitrogen trifluoride gas at a flow rate lower than that of the nitrogen trifluoride gas in the first processing gas. The second processing gas further contains an oxygen-containing gas and a noble gas. The first processing gas does not contain noble gas, or contains noble gas at a flow rate less than that of the noble gas in the second processing gas. The etching method according to claim 19.

26. The etching method according to claim 16, wherein (b) is an etching method in which the silicon-containing film is etched while forming a first protrusion at a first position of the mask that reduces the width of the opening of the mask, and forming a second protrusion at a second position of the mask below the first position that reduces the width of the opening of the mask.

27. The first processing gas further contains a carbon-containing gas which is the source of the first protrusion. The metal-containing gas in the first processing gas is the source of the second protrusion. In (b) above, the amounts of hydrogen species and fluorine species in the first plasma are adjusted so that the second protrusion is formed below the first protrusion. The etching method according to claim 26.

28. Chamber and, The substrate support portion in the chamber, Plasma generation section, A control unit configured to control the plasma generation unit, Includes, The control unit, (a) A step of providing a substrate having a base film, a silicon-containing film on the base film, and a mask on the silicon-containing film into the chamber, (b) A step of etching the silicon-containing film to form recesses using a first plasma generated from a first processing gas containing hydrogen fluoride gas and tungsten-containing gas, (c) A step after (b) above, further etching the silicon-containing film using a second plasma generated from a second processing gas containing hydrogen fluoride gas, wherein the second processing gas does not contain the tungsten-containing gas, or contains the tungsten-containing gas at a flow rate lower than that of the tungsten-containing gas in the first processing gas, An etching apparatus configured to perform a process that includes the following.

29. The tungsten-containing gas is WF ６ The etching apparatus according to claim 28, including the following:

30. The etching apparatus according to claim 28 or 29, wherein the first processing gas further comprises a phosphorus-containing gas.

31. The etching apparatus according to claim 30, wherein the second processing gas does not contain phosphorus-containing gas, or contains phosphorus-containing gas at a flow rate less than that of the phosphorus-containing gas in the first processing gas.

32. The control unit, The etching of the silicon-containing film in (b) above is stopped while the silicon-containing film remains between the base film and the bottom of the recess. The etching of the silicon-containing film in (c) above is performed starting in the above state and during a period including when the underlying film is exposed. The etching apparatus according to claim 31, configured as described above.

33. The etching apparatus according to claim 28 or 29, wherein the second processing gas further comprises xenon gas.

34. The etching apparatus according to claim 33, wherein the first processing gas does not contain xenon gas, or contains xenon gas at a flow rate less than the flow rate of the xenon gas in the second processing gas.

35. The etching apparatus according to claim 34, wherein each of the first processing gas and the second processing gas contains nitrogen trifluoride gas.

36. The first processing gas includes nitrogen trifluoride gas. The second processing gas either does not contain nitrogen trifluoride gas, or contains nitrogen trifluoride gas at a flow rate lower than that of the nitrogen trifluoride gas in the first processing gas. The second processing gas further contains an oxygen-containing gas and a noble gas. The first processing gas does not contain noble gas, or contains noble gas at a flow rate less than that of the noble gas in the second processing gas. The etching apparatus according to claim 31.

37. The first processing gas further comprises a carbon-containing gas which is a source for forming a first protrusion at a first position of the mask that reduces the width of the opening of the mask. The tungsten-containing gas in the first processing gas is a source for forming a second protrusion at a second position of the mask below the first position, which reduces the width of the opening of the mask. The control unit is configured in (b) to adjust the amount of hydrogen species and fluorine species in the first plasma in order to form the second protrusion below the first protrusion. The etching apparatus according to claim 28.

38. The system further comprises a gas supply unit configured to supply the first processing gas and the second processing gas into the chamber, The control unit is configured to further control the gas supply unit. The etching apparatus according to claim 28.

39. Chamber and, The substrate support portion in the chamber, Plasma generation section, A control unit configured to control the plasma generation unit, Includes, The control unit, (a) A step of providing a substrate having a film to be etched and a mask on the film to be etched into the chamber, (b) A step of etching the film to be etched using plasma generated from a processing gas containing hydrogen fluoride gas to form recesses, The process including (b) is performed, and (b) is performed in the chamber with a metal supply source present, thereby forming a first protrusion at a first position on the mask that reduces the width of the opening of the mask, and forming a second protrusion at a second position on the mask below the first position that reduces the width of the opening of the mask, while etching the film to be etched. Etching equipment.

40. The aforementioned processing gas further contains a metal-containing gas, The metal supply source is the metal-containing gas. The etching apparatus according to claim 39.

41. The etching apparatus according to claim 39, wherein the metal supply source is formed from a metal-containing material and is an upper electrode positioned above the substrate support so as to face the substrate support and / or an edge ring made of the metal-containing material positioned around the substrate supported by the substrate support.

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