Method for etching and plasma processing system

Abstract

To suppress abnormalities of the shape of etching.SOLUTION: The method for etching includes the steps of: providing a substrate having a silicon-containing film and a mask in a chamber; and etching the silicon-containing film. The etching step etches the silicon-containing film by using plasma generated from first processing gas including hydrogen fluoride gas, hydrogen fluoride, and reaction control gas for controlling reaction with the silicon-containing film. The first processing gas includes at least one of a reaction acceleration gas for promoting the reaction as a reaction control gas and a reaction suppression gas for suppressing the reaction. The step also etches the silicon-containing film by using plasma generated from second processing gas including HF gas. The second processing gas includes the reaction acceleration gas for promoting the reaction at a smaller partial pressure than the partial pressure of the reaction acceleration gas of the first processing gas, or includes the reaction suppression gas for suppressing the reaction at a higher partial pressure than the partial pressure of the reaction suppression gas of the first processing gas, or does not include the reaction control gas.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] Exemplary embodiments of the present disclosure relate to an etching method and a plasma processing system. [Background technology]

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

[0003] [Patent Document 1] JP 2016-39310 A Summary of the Invention [Problem to be solved by the invention]

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

[0005] In one exemplary embodiment of the present disclosure, an etching method is carried out in a plasma processing apparatus having a chamber, the method including: (a) providing a substrate having a silicon-containing film and a mask on the silicon-containing film on a substrate support in the chamber; and (b) etching the silicon-containing film, the step (b) including: (b-1) etching the silicon-containing film using plasma generated from a first process gas including a hydrogen fluoride gas and a reaction control gas for controlling a reaction between the hydrogen fluoride and the silicon-containing film, the first process gas including: The etching method includes the steps of: (a) containing, as a gas, at least one of a reaction promoting gas that promotes the reaction and a reaction inhibiting gas that inhibits the reaction; and (b-2) etching the silicon-containing film using plasma generated from a second process gas that contains hydrogen fluoride gas, wherein the second process gas contains a reaction promoting gas that promotes the reaction at a partial pressure lower than that of the reaction promoting gas in the first process gas and / or contains a reaction inhibiting gas that inhibits the reaction at a partial pressure higher than that of the reaction inhibiting gas in the first process gas, or does not contain the reaction control gas. Effect of the Invention

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

[0007] [Figure 1] 1 illustrates a schematic diagram of an exemplary plasma processing system. [Diagram 2] 4 is a flow chart illustrating an exemplary embodiment of the present processing method. [Diagram 3] 2 is a diagram showing an example of a cross-sectional structure of a substrate W. FIG. [Figure 4] 13 is an example of a timing chart of step ST2 when a reaction promoting gas is used. [Diagram 5] 13 is an example of a timing chart of step ST2 when a reaction inhibiting gas is used. [Figure 6A]13 is a diagram showing an example of a cross-sectional structure of the substrate W at the end of the H period. FIG. [Figure 6B] 13 is a diagram showing an example of a cross-sectional structure of the substrate W at the end of the L period. FIG. [Figure 7] 13 is another example of the timing chart of step ST2 when a reaction promoting gas is used. [Figure 8] 13 is another example of the timing chart of step ST2 when a reaction inhibiting gas is used. [Figure 9A] 13 is a diagram showing an example of a cross-sectional structure of the substrate W at the end of the H1 period. FIG. [Figure 9B] 13 is a diagram showing an example of a cross-sectional structure of the substrate W at the end of the L1 period. FIG. [Figure 10] 13 is a flowchart showing a modified example of the present processing method. [Figure 11] 13 is a flowchart showing a modified example of the present processing method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Each embodiment of the present disclosure will be described below.

[0009] In one exemplary embodiment, there is provided an etching method that is performed in a plasma processing apparatus having a chamber, the etching method including: (a) providing a substrate having a silicon-containing film and a mask on the silicon-containing film on a substrate support in the chamber; and (b) etching the silicon-containing film, the step (b) including: (b-1) etching the silicon-containing film using plasma generated from a first process gas including hydrogen fluoride gas and a reaction control gas that controls a reaction between the hydrogen fluoride and the silicon-containing film, the first process gas including, as a reaction control gas, at least one of a reaction promoting gas that promotes the reaction and a reaction inhibiting gas that inhibits the reaction; and (b-2) etching the silicon-containing film using plasma generated from a second process gas including hydrogen fluoride gas, the second process gas including a reaction promoting gas at a partial pressure lower than that of the reaction promoting gas in the first process gas and / or a reaction inhibiting gas that inhibits the reaction at a partial pressure higher than that of the reaction inhibiting gas in the first process gas, or no reaction control gas is included.

[0010] In one exemplary embodiment, there is provided an etching method in which in step (b), step (b-2) is performed after step (b-1).

[0011] In one exemplary embodiment, there is provided an etching method in which in step (b), step (b-1) is performed after step (b-2).

[0012] In one exemplary embodiment, in step b), steps (b-1) and (b-2) are repeated alternately.

[0013] In one exemplary embodiment, in the step (b), switching between the step (b-1) and the step (b-2) is performed based on at least one of a depth of a recess formed in the silicon-containing film by etching, an aspect ratio of the recess, and an etching time.

[0014] In one exemplary embodiment, in step (b-1), plasma is generated from a first process gas using a pulse wave of a source RF signal having a first duty ratio, and in step (b-2), plasma is generated from a second process gas using a pulse wave of a source RF signal having a second duty ratio smaller than the first duty ratio.

[0015] In one exemplary embodiment, the reaction promoting gas is at least one selected from the group consisting of a phosphorus-containing gas, a nitrogen-containing gas, and a hydrogen-containing gas.

[0016] In one exemplary embodiment, the phosphorus-containing gas is a phosphorus halide gas.

[0017] In one exemplary embodiment, the nitrogen-containing gas is NH 3 Gas, NF 3 Gas, NO gas and NO 2 The gas is at least one selected from the group consisting of gases.

[0018] In one exemplary embodiment, the hydrogen-containing gas is a gas having an OH group.

[0019] In one exemplary embodiment, the reaction inhibitor gas is a chlorine-containing gas.

[0020] In one exemplary embodiment, the chlorine-containing gas is Cl 2 Gas, SiCl 2 Gas, SiH 2 Cl 2 Gas, SiCl 4 Gas, Si 2 Cl 6 Gas, CHCl 3 Gas, CCl 4 Gas and BCl 3 The gas is at least one selected from the group consisting of gases.

[0021] In one exemplary embodiment, in both the first process gas and the second process gas, the partial pressure of hydrogen fluoride gas is the highest, excluding the inert gas.

[0022] In one exemplary embodiment, at least one of the first process gas and the second process gas further comprises at least one selected from the group consisting of a carbon-containing gas, an oxygen-containing gas, a carbon-free fluorine-containing gas, and a halogen-containing gas other than fluorine.

[0023] In one exemplary embodiment, the reaction inhibiting gas contained in the first process gas and the reaction inhibiting gas contained in the second process gas are the same type of gas.

[0024] In one exemplary embodiment, the reaction promoting gas contained in the first process gas and the reaction promoting gas contained in the second process gas are the same type of gas.

[0025] In one exemplary embodiment, there is provided an etching method performed in a plasma processing apparatus having a chamber, the etching method including: (a) providing a substrate having a silicon-containing film and a mask on the silicon-containing film on a substrate support in the chamber; and (b) etching the silicon-containing film, the etching method including: (b-1) etching the silicon-containing film using plasma containing active species of hydrogen fluoride generated from a first process gas, the first process gas including at least one of a reaction promoting gas that promotes the reaction and a reaction inhibiting gas that inhibits the reaction as a reaction control gas that controls a reaction between the hydrogen fluoride and the silicon-containing film; and (b-2) etching the silicon-containing film using plasma containing active species of hydrogen fluoride generated from a second process gas, the second process gas including a reaction promoting gas at a partial pressure lower than that of the reaction promoting gas in the first process gas and / or a reaction inhibiting gas that inhibits the reaction at a partial pressure higher than that of the reaction inhibiting gas in the first process gas, or including no reaction control gas.

[0026] In one exemplary embodiment, the activated hydrogen fluoride species is generated from at least one of hydrogen fluoride gas or a hydrofluorocarbon gas.

[0027] In one exemplary embodiment, activated species of hydrogen fluoride are generated from a fluorine-containing gas and a hydrogen-containing gas.

[0028] In one exemplary embodiment, the present invention includes a chamber, a substrate support provided in the chamber, a plasma generating unit, and a control unit, and the control unit executes (a) a control of providing a substrate having a silicon-containing film and a mask on the silicon-containing film on the substrate support in the chamber, and (b) a control of etching the silicon-containing film, the control of (b) being (b-1) a control of etching the silicon-containing film using plasma generated from a first process gas including a hydrogen fluoride gas and a reaction control gas that controls a reaction between the hydrogen fluoride gas and the silicon-containing film, the first process gas being a reaction control gas that controls a reaction between the hydrogen fluoride gas and the silicon-containing film, The plasma processing system includes: (a) a control in which at least one of a reaction promoting gas that promotes a reaction and a reaction inhibiting gas that inhibits a reaction is used as a reaction control gas; and (b-2) a control in which a silicon-containing film is etched using plasma generated from a second process gas that contains hydrogen fluoride gas, the second process gas containing a reaction promoting gas at a partial pressure lower than that of the reaction promoting gas in the first process gas and / or a reaction inhibiting gas that inhibits a reaction at a partial pressure higher than that of the reaction inhibiting gas in the first process gas, or no reaction control gas is used.

[0029] Hereinafter, each embodiment of the present disclosure will be described in detail with reference to the drawings. In each drawing, the same or similar elements are given the same reference numerals, and duplicated explanations will be omitted. Unless otherwise specified, the positional relationship such as up, down, left, right, etc. will be described based on the positional relationship shown in the drawing. The dimensional ratio of the drawings does not indicate the actual ratio, and the actual ratio is not limited to the illustrated ratio.

[0030] <Example of plasma processing system configuration> An example of the configuration of a plasma processing system will be described below. Fig. 1 is a diagram for explaining an example of the configuration of a capacitively coupled plasma processing apparatus.

[0031] The plasma processing system includes a capacitively coupled plasma processing device 1 and a controller 2. The capacitively coupled plasma processing device 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply 30, and an exhaust system 40. The plasma processing device 1 also includes a substrate support 11 and a gas inlet. The gas inlet is configured to introduce at least one processing gas into the plasma processing chamber 10. The gas inlet includes a shower head 13. The substrate support 11 is disposed in the plasma processing chamber 10. The shower head 13 is disposed above the substrate support 11. In one embodiment, the shower head 13 forms at least a part of a ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the shower head 13, a sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 has at least one gas inlet for supplying at least one processing gas to the plasma processing space 10s and at least one gas outlet for exhausting gas from the plasma processing space. The plasma processing chamber 10 is grounded. The showerhead 13 and the substrate support 11 are electrically isolated from the plasma processing chamber 10 housing.

[0032] The substrate support 11 includes a main body 111 and a ring assembly 112. The main body 111 has a central region 111a for supporting 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 111 surrounds the central region 111a of the main body 111 in a plan view. The substrate W is disposed on the central region 111a of the main body 111, and the ring assembly 112 is disposed on the annular region 111b of the main body 111 so as to surround the substrate W on the central region 111a of the main body 111. Therefore, the central region 111a is also called a substrate support surface for supporting the substrate W, and the annular region 111b is also called a ring support surface for supporting the edge ring assembly 112.

[0033] In one embodiment, the main body 111 includes a base 1110 and an electrostatic chuck 1111. The base 1110 includes a conductive member. The conductive member of the base 1110 may function as a lower electrode. The electrostatic chuck 1111 is disposed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic electrode 1111b disposed within the ceramic member 1111a. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Note that other members surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member, may have the annular region 111b. In this case, the ring assembly 112 may be disposed on the annular electrostatic chuck or the annular insulating member, or may be disposed on both the electrostatic chuck 1111 and the annular insulating member. Also, an RF or DC electrode may be disposed in the ceramic member 1111a, in which case the RF or DC electrode functions as the lower electrode. When a bias RF signal or DC signal, which will be described later, is connected to the RF or DC electrode, the RF or DC electrode is also called a bias electrode. Note that both the conductive member of the base 1110 and the RF or DC electrode may function as two lower electrodes.

[0034] The ring assembly 112 includes one or more annular members. In one embodiment, the one or more annular members include one or more edge rings and at least one cover ring. The edge rings are formed of a conductive or insulating material, and the cover rings are formed of an insulating material.

[0035] The substrate support 11 may also include a temperature adjustment module configured to adjust at least one of the electrostatic chuck 1111, the ring assembly 112, and the substrate to a target temperature. The temperature adjustment module may include a heater, a heat transfer medium, a flow passage 1110a, or a combination thereof. A heat transfer fluid such as a brine or a gas flows through the flow passage 1110a. In one embodiment, the flow passage 1110a is formed in the base 1110, and one or more heaters are disposed in the ceramic member 1111a of the electrostatic chuck 1111. The substrate support 11 may also include a heat transfer gas supply configured to supply a heat transfer gas between the back surface of the substrate W and the central region 111a.

[0036] The shower head 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The shower head 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and multiple gas inlets 13c. The processing gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s from the multiple gas inlets 13c. The shower head 13 also includes an upper electrode. Note that the gas introduction unit may include, in addition to the shower head 13, one or more side gas injectors (SGIs) attached to one or more openings formed in the sidewall 10a.

[0037] The gas supply 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply 20 is configured to supply at least one process gas from a respective gas source 21 through a respective flow controller 22 to the showerhead 13. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, the gas supply 20 may include one or more flow modulation devices to modulate or pulse a flow rate of the at least one process gas.

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

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

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

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

[0042] In various embodiments, at least one of the first and second DC signals may be pulsed. In this case, a sequence of DC-based 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 of these pulse waveforms. In one embodiment, a waveform generator for generating a sequence of voltage pulses from the DC signal is connected between the first DC generator 32a and at least one lower electrode. Thus, the first DC generator 32a and the waveform generator constitute a voltage pulse generator. When the second DC generator 32b and the waveform generator constitute a voltage pulse generator, the voltage pulse generator is connected to at least one upper electrode. The voltage pulses may have a positive polarity or a negative polarity. Also, the sequence of voltage pulses may include one or more positive polarity voltage pulses and one or more negative polarity voltage pulses within one period. The first and second DC generating units 32a, 32b may be provided in addition to the RF power supply 31, or the first DC generating unit 32a may be provided in place of the second RF generating unit 31b.

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

[0044] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to execute various steps described in the present disclosure. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to execute various steps described herein. In one embodiment, a part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include, for example, a computer 2a. The computer 2a may include, for example, a processing unit (CPU: Central Processing Unit) 2a1, a storage unit 2a2, and a communication interface 2a3. The processing unit 2a1 may be configured to read a program from the storage unit 2a2 and execute the read program to perform various control operations. This program may be stored in the storage unit 2a2 in advance, or may be acquired via a medium when necessary. The acquired program is stored in the storage unit 2a2, and is read from the storage unit 2a2 by the processing unit 2a1 and executed. The medium may be various storage media readable by the computer 2a, or may be a communication line connected to the communication interface 2a3. The storage unit 2a2 may include a random access memory (RAM), a read only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a local area network (LAN).

[0045] <An example of an etching method> Fig. 2 is a flowchart showing an etching method (hereinafter also referred to as "this processing method") according to one example embodiment. As shown in Fig. 2, this processing method includes a step ST1 of providing a substrate, and a step ST2 of etching a silicon-containing film on the substrate. The processing in each step may be performed in the plasma processing system shown in Fig. 1. In the following, an example will be described in which a control unit 2 controls each part of the plasma processing apparatus 1 to perform this processing method on a substrate W.

[0046] (Step ST1: Providing the substrate) In step ST1, the substrate W is provided in a plasma processing space 10s of the plasma processing apparatus 1. The substrate W is provided in a central region 111a of the substrate support 11. The substrate W is then held on the substrate support 11 by an electrostatic chuck 1111.

[0047] 3 is a diagram showing an example of a cross-sectional structure of a substrate W provided in step ST1. The substrate W has a silicon-containing film SF and a mask MF laminated in this order on an undercoat film UF. The substrate W may be used for manufacturing a semiconductor device. The semiconductor device may include, for example, a semiconductor memory device such as a DRAM or a 3D-NAND flash memory.

[0048] The undercoat film UF is, for example, a silicon wafer or an organic film, a dielectric film, a metal film, a semiconductor film, etc., formed on a silicon wafer. The undercoat film UF may be configured by laminating a plurality of films.

[0049] The silicon-containing film SF is a film to be etched in this processing method. The silicon-containing film SF is, for example, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a polycrystalline silicon film. The silicon-containing film SF may be formed by stacking a plurality of films. For example, the silicon-containing film SF may be formed by alternately stacking a silicon oxide film and a silicon nitride film. Alternatively, for example, the silicon-containing film SF may be formed by alternately stacking a silicon oxide film and a polycrystalline silicon film.

[0050] The mask MF is a film that functions as a mask in etching the silicon-containing film SF. The mask MF may be, for example, a polysilicon film, a boron-doped silicon film, a tungsten-containing film (e.g., a WC film, a WSi film, etc.), an amorphous carbon film, a tin oxide film, or a titanium-containing film (e.g., a TiN film, etc.).

[0051] 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 and is surrounded by the sidewall 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.

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

[0053] Each of the films constituting the substrate W (the base film UF, the silicon-containing film SF, and the mask MF) may be formed by a CVD method, an ALD method, a spin coating method, or the like. 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 a flat film or may have irregularities. The substrate W may further have another film below the base film UF, and the laminated film of the silicon-containing film SF and the base film UF may function as a multilayer mask. In other words, the laminated film of the silicon-containing film SF and the base film UF may be used as a multilayer mask to etch the other film.

[0054] At least a part of the process of forming each film on the substrate W may be performed in the space of the plasma processing chamber 10. In one example, a step of etching the mask MF to form an opening OP may be performed in the plasma processing chamber 10. That is, the opening OP and the etching of the silicon-containing film SF described later may be performed consecutively in the same chamber. Also, after all or a part of each film on the substrate W is formed in an apparatus or chamber outside the plasma processing apparatus 1, the substrate W may be carried into the plasma processing space 10s of the plasma processing apparatus 1 and disposed in the central region 111a of the substrate support 11 to provide the substrate.

[0055] After the substrate W is provided to the central region 111a of the substrate support 11, the temperature of the substrate support 11 is adjusted to a set temperature by a temperature adjustment module. The set temperature may be, for example, 70°C or less, 0°C or less, -10°C or less, -20°C or less, -30°C or less, -40°C or less, -50°C or less, -60°C or less, or -70°C or less. In one example, adjusting or maintaining the temperature of the substrate support 11 includes adjusting or maintaining the temperature of the heat transfer fluid flowing through the flow path 1110a to a set temperature or a temperature different from the set temperature. In one example, adjusting or maintaining the temperature of the substrate support 11 includes controlling the pressure of a heat transfer gas (e.g., He) between the electrostatic chuck 1111 and the back surface of the substrate W. The timing at which the heat transfer fluid starts to flow through the flow path 1110a may be before or after the substrate W is placed on the substrate support 11, or may be the same as the substrate W. In the present processing method, the temperature of the substrate support 11 may be adjusted to a set temperature before step ST1. That is, the substrate W may be provided to the substrate support 11 after the temperature of the substrate support 11 has been adjusted to the set temperature.

[0056] (Step ST2: Etching) In step ST2, the silicon-containing film SF of the substrate W is etched. Step ST2 includes a first etching step ST21 and a second etching step ST22. Step ST2 may include a step ST23 for determining whether an etching stop condition is satisfied. That is, steps ST21 and ST22 may be alternately repeated until it is determined in step ST23 that the etching stop condition is satisfied. During the process in step ST2, the temperature of the substrate support 11 is maintained at the set temperature adjusted in step ST1.

[0057] (Step ST21: First Etching) In step ST21, the silicon-containing film SF is etched using plasma generated from a first process gas. First, the first process gas is supplied from the gas supply unit 20 into the plasma processing space 10s. The first process gas contains hydrogen fluoride (HF) gas and a reaction control gas that controls the reaction between the hydrogen fluoride and the silicon-containing film. The first process gas may contain a reaction promotion gas that promotes the reaction between the hydrogen fluoride and the silicon-containing film as the reaction control gas. The first process gas may contain a reaction inhibition gas that inhibits the reaction. The first process gas may contain both the reaction promotion gas and the reaction inhibition gas.

[0058] Next, a source RF signal is supplied to the lower electrode of the substrate support 11 and / or the upper electrode of the shower head 13. This generates a high-frequency electric field between the shower head 13 and the substrate support 11, and plasma is generated from the first processing gas in the plasma processing space 10s. In addition, a bias signal is supplied to the lower electrode of the substrate support 11, and a bias potential is generated 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 the silicon-containing film SF is etched by the active species.

[0059] (Step ST22: Second Etching) In a second etching step ST22, the silicon-containing film SF is further etched by using plasma generated from a second processing gas. First, a second processing gas is supplied into the plasma processing space 10s from the gas supply unit 20. The second processing gas contains hydrogen fluoride (HF) gas.

[0060] The second process gas may include at least one of a reaction promoting gas that promotes the reaction between hydrogen fluoride and the silicon-containing film and a reaction inhibiting gas that inhibits the reaction. When the second process gas includes a reaction promoting gas, the partial pressure of the reaction promoting gas may be smaller than the partial pressure of the reaction promoting gas in the first process gas. When the second process gas includes a reaction inhibiting gas, the partial pressure of the reaction inhibiting gas may be larger than the partial pressure of the reaction inhibiting gas in the first process gas. When the second process gas includes both a reaction promoting gas and a reaction inhibiting gas, the partial pressure of the reaction promoting gas may be smaller than the partial pressure of the reaction promoting gas in the first process gas, the partial pressure of the reaction inhibiting gas may be larger than the partial pressure of the reaction inhibiting gas in the first process gas, or both.

[0061] The second process gas does not need to include a gas that controls (inhibits or promotes) the reaction between hydrogen fluoride and the silicon-containing film.

[0062] Next, similarly to step ST21, a source RF signal is supplied to the lower electrode of the substrate support 11 and / or the upper electrode of the shower head 13. This generates a high-frequency electric field between the shower head 13 and the substrate support 11, and plasma is generated from the second process gas in the plasma processing space 10s. In addition, a bias signal is supplied to the lower electrode of the substrate support 11, and a bias potential is generated 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 the silicon-containing film SF is further etched by the active species.

[0063] The switching from step ST21 to step ST22 may be performed based on, for example, at least one of the depth of the recess formed in the silicon-containing film SF by etching, the aspect ratio of the recess, and the etching time.

[0064] In steps ST21 and ST22, the bias signal may be a bias RF signal supplied from the second RF generating unit 31b. Also, the bias signal may be a bias DC signal supplied from the DC generating unit 32a. Note that the bias signal does not have to be supplied in steps ST21 and ST22.

[0065] In steps ST21 and ST22, the source RF signal and the bias signal may both be continuous waves or pulse waves, or one may be a continuous wave and the other a pulse wave. When both the source RF signal and the bias signal are pulse waves, the periods of both pulse waves may be synchronized. When a bias DC signal is used, the pulse wave may have a rectangular, trapezoidal, triangular or combination thereof. The polarity of the bias DC signal may be negative or positive, as long as the potential of the substrate W is set to provide a potential difference between the plasma and the substrate to attract ions.

[0066] When a pulse wave is used as the source RF signal or the bias signal, the duty ratio of the pulse wave may be appropriately set, for example, 1 to 80%, or 5 to 50%. Here, the duty ratio is the ratio of a period in which the power or voltage level is high in the cycle of the pulse wave. The duty ratio of the pulse wave may be the same or different between step ST21 and step ST22. In one example, the duty ratio of the pulse wave of the source RF signal in step ST22 may be smaller than the duty ratio of the pulse wave of the source RF signal in step ST21. By reducing the duty ratio, the heat input to the substrate W by the plasma is suppressed, and the temperature of the substrate W is lower than that in step ST22. Hydrogen fluoride tends to be more easily adsorbed to the silicon-containing film SF as the temperature of the substrate W decreases, so that by reducing the duty ratio, the adsorption of hydrogen fluoride to the silicon-containing film SF can be promoted.

[0067] (Step ST23: End determination) In step ST23, it is determined whether the stop condition is satisfied. The stop condition may be, for example, whether the number of repetitions of step ST21 and step ST22 as one cycle has reached a given number. The stop condition may be, for example, whether the etching time has reached a given time. The stop condition may be, for example, whether the depth of the recess formed by etching has reached a given depth. If it is determined that the stop condition is not satisfied in step ST23, the cycle including step ST21 and step ST22 is repeated. If it is determined that the stop condition is satisfied in step ST23, the present processing method is terminated. Note that the determination of whether the stop condition is satisfied may be performed between step ST21 and step ST22 in addition to step ST23.

[0068] (Composition of process gas) In the first process gas, the partial pressure of HF gas may be the highest among all gases except the inert gas. In the second process gas, the partial pressure of HF gas may be the highest among all gases except the inert gas. In one example, in the first process gas and / or the second process gas, the HF gas may be contained at 50 volume % or more, 60 volume % or more, 70 volume % or more, or 80 volume % or more with respect to the total flow rate excluding the inert gas. In addition, the HF gas used may be high purity, for example, 99.999% or more purity.

[0069] The reaction promoting gas contained in the first process gas and / or the second process gas may be, for example, a gas (adsorption promoting gas) that promotes the adsorption of active species of hydrogen fluoride in plasma to the silicon-containing film SF. Here, the active species of hydrogen fluoride includes at least one of hydrogen fluoride gas, radicals, and ions. As the reaction promoting gas, at least one selected from the group consisting of a phosphorus-containing gas, a nitrogen-containing gas, and a hydrogen-containing gas may be used. When both the first process gas and the second process gas contain a reaction promoting gas, the type of reaction promoting gas contained in the first process gas and the type of reaction promoting gas contained in the second process gas may be the same or different.

[0070] A phosphorus-containing gas is a gas that contains phosphorus-containing molecules. 4 O 10 ), tetraphosphorus octoxide (P 4 O 8 ), tetraphosphorus hexaoxide (P 4 O 6 ) and other oxides. 2 O 5 Phosphorus-containing molecules are sometimes called phosphorus trifluoride (PF 3 ), phosphorus pentafluoride (PF 5 ), phosphorus trichloride (PCl 3 ), phosphorus pentachloride (PCl 5 ), phosphorus tribromide (PBr 3 ), phosphorus pentabromide (PBr 5 ), phosphorus iodide (PI 3 The phosphorus-containing molecule may be a halide (phosphorus halide) such as phosphorus fluoride (POF). That is, the phosphorus-containing molecule may contain fluorine as a halogen element, such as phosphorus fluoride. Alternatively, the phosphorus-containing molecule may contain a halogen element other than fluorine as a halogen element. The phosphorus-containing molecule may be phosphoryl fluoride (POF 3 ), phosphoryl chloride (POCl 3 ), phosphoryl bromide (POBr 3 The phosphorus-containing molecule may be a phosphoryl halide such as a phosphine (PH 3 ), calcium phosphide (Ca 3 P 2 etc.), phosphoric acid (H 3 PO 4 ), Sodium phosphate (Na 3 PO 4 ), hexafluorophosphate (HPF 6 ) and the like. Phosphorus-containing molecules include fluorophosphines (H g PF h ) where the sum of g and h is 3 or 5. Fluorophosphines include HPF 2 , H 2 PF 3The treatment gas may include one or more of the above phosphorus-containing molecules as the at least one phosphorus-containing molecule. For example, the treatment gas may include PF 3 , PCl 3 , P.F. 5 , PCl 5 , POCl 3 , PH 3 , PBr 3 , or PBr 5 When each phosphorus-containing molecule is a liquid or solid, the phosphorus-containing molecule can be vaporized by heating or the like and supplied into the plasma processing space 10s.

[0071] An example of a nitrogen-containing gas is NH 3 Gas, NF 3 Gas, NO Gas, NO 2 At least one selected from the group consisting of gases may be used.

[0072] The hydrogen-containing gas may be a gas having an OH group. 2 O gas, H 2 O 2 At least one selected from the group consisting of gases and alcohols may be used.

[0073] The reaction suppressing gas contained in the first process gas and / or the second process gas may be, for example, a gas that suppresses the reaction between the active species of hydrogen fluoride in the plasma and the silicon-containing film SF by removing (scavenging) the active species of hydrogen in the plasma. For example, a chlorine-containing gas may be used as the reaction suppressing gas. In one example, the chlorine-containing gas is Cl 2 Gas, SiCl 2 Gas, SiH 2 Cl 2 Gas, SiCl 4 Gas, Si 2 Cl 6 Gas, CHCl 3 Gas, CCl 4 Gas and BCl 3In the case where both the first process gas and the second process gas contain a reaction inhibitor gas, the type of the reaction inhibitor gas contained in the first process gas and the type of the reaction inhibitor gas contained in the second process gas may be the same or different.

[0074] The first process gas and / or the second process gas may further include a carbon-containing gas. The carbon-containing gas may be, for example, one or both of a fluorocarbon gas and a hydrofluorocarbon gas. In one example, the fluorocarbon gas is CF 4 Gas, C. 2 F 2 Gas, C. 2 F 4 Gas, C. 3 F 6 Gas, C. 3 F 8 Gas, C. 4 F 6 Gas, C. 4 F 8 Gas and C 5 F 8 In one example, the hydrofluorocarbon gas is at least one selected from the group consisting of CHF 3 Gas, CH 2 F 2 Gas, CH 3 F gas, C 2 HF 5 Gas, C. 2 H 2 F 4 Gas, C. 2 H 3 F 3 Gas, C. 2 H 4 F 2 Gas, C. 3 HF 7 Gas, C. 3 H 2 F 2 Gas, C. 3 H 2 F 4 Gas, C. 3 H 2 F 6 Gas, C. 3 H 3 F 5 Gas, C.4 H 2 F 6 Gas, C. 4 H 5 F 5 Gas, C. 4 H 2 F 8 Gas, C. 5 H 2 F 6 Gas, C. 5 H 2 F 10 Gas and C 5 H 3 F 7 The carbon-containing gas may be at least one selected from the group consisting of carbon-containing gases. The carbon-containing gas may be a straight-chain gas having an unsaturated bond. The straight-chain carbon-containing gas having an unsaturated bond may be, for example, C 3 F 6 (Hexafluoropropene) gas, C 4 F 8 (Octafluoro-1-butene, Octafluoro-2-butene) gas, C 3 H 2 F 4 (1,3,3,3-tetrafluoropropene) gas, C 4 H 2 F 6 (trans-1,1,1,4,4,4-hexafluoro-2-butene) gas, C 4 F 8 O (pentafluoroethyl trifluorovinyl ether) gas, CF 3 COF gas (1,2,2,2-tetrafluoroethane-1-one), CHF 2 COF (difluoroacetic acid fluoride) gas and COF 2 (carbonyl fluoride) gas may be at least one selected from the group consisting of gases.

[0075] The first process gas and / or the second process gas may further include an oxygen-containing gas. The oxygen-containing gas may be, for example, O 2 , CO and CO 2 The gas may be at least one gas selected from the group consisting of:

[0076] The first process gas and / or the second process gas may further include a carbon-free fluorine-containing gas. In one example, the carbon-free fluorine-containing gas is SF 6 , N.F. 3 , XeF 2 , SiF 4 , IF 5 , IF 7 ,BrF 5 , AsF 5 , N.F. 5 , B.F. 3 and W.F. 6 It may be at least one selected from the group consisting of:

[0077] The first process gas and / or the second process gas may further include a halogen-containing gas other than fluorine. The halogen-containing gas other than fluorine may be, for example, HBr gas, HI gas, or I 2 The gas may be at least one selected from the group consisting of gases.

[0078] The first process gas and / or the second process gas may further include an inert gas, such as a noble gas, such as Ar gas, He gas, or Kr gas, or N 2 Gas is fine.

[0079] The first process gas and / or the second process gas may include a gas capable of generating HF species in the plasma instead of or in addition to HF gas.

[0080] The gas capable of generating HF species is, for example, a hydrofluorocarbon gas. The hydrofluorocarbon gas may have a carbon number of 2 or more, 3 or more, or 4 or more. In one example, the hydrofluorocarbon gas is CH 2 F 2 Gas, C. 3 H 2 F 4 Gas, C. 3 H 2 F 6 Gas, C. 3 H 3 F 5 Gas, C. 4 H 2 F 6 Gas, C.4 H 5 F 5 Gas, C. 4 H 2 F 8 Gas, C. 5 H 2 F 6 Gas, C. 5 H 2 F 10 Gas and C 5 H 3 F 7 The hydrofluorocarbon gas is at least one selected from the group consisting of CH 2 F 2 Gas, C. 3 H 2 F 4 Gas, C. 3 H 2 F 6 Gas and C 4 H 2 F 6 The gas is at least one selected from the group consisting of gases.

[0081] Examples of gases capable of generating HF species include fluorine-containing gases and hydrogen-containing gases. Examples of fluorine-containing gases include fluorocarbon gases. In one example, the fluorocarbon gas is C 2 F 2 Gas, C. 2 F 4 Gas, C. 3 F 6 Gas, C. 3 F 8 Gas, C. 4 F 6 Gas, C. 4 F 8 Gas and C 5 F 8 The fluorine-containing gas is at least one selected from the group consisting of NF 3 Gas or SF 6 The hydrogen-containing gas may be, for example, H 2 Gas, CH 4 Gas and NH 3 The gas is at least one selected from the group consisting of gases.

[0082] (An example of process ST2) FIG. 4 is an example of a timing chart for step ST2 when a reaction promoting gas is used. FIG. 4 shows an example in which a reaction promoting gas is used as a reaction control gas, and the silicon-containing film SF is etched in one cycle of a first etching step ST21 and a second etching step ST2. In FIG. 4, the vertical axis indicates the partial pressure of the reaction promoting gas contained in the first process gas or the second process gas, and the adsorption level of hydrogen fluoride to the silicon-containing film SF. The horizontal axis indicates the etching time. "P B " is when the partial pressure of the reaction promoter gas is zero or "P A " is smaller than "L B " is the adsorption level (adsorption amount) of hydrogen fluoride to the silicon-containing film SF. A In FIG. 4, time 0 to t11 corresponds to step ST21 (hereinafter, this period is referred to as "H period"), and time t11 to t12 corresponds to step ST22 (hereinafter, this period is referred to as "L period").

[0083] 4, the partial pressure of the reaction promoting gas is constant within each period (H period and L period), but may be changed (decreased, increased, or increased or decreased) stepwise or continuously within each period. In this case, the adsorption level of hydrogen fluoride gas may change in accordance with the change.

[0084] 4 is a timing chart in the case where a reaction promoting gas is used as the reaction controlling gas in step ST2, but instead of or in addition to this, a reaction inhibiting gas may be used as the reaction controlling gas. FIG. 5 is an example of a timing chart of step ST2 in the case where a reaction inhibiting gas is used. As shown in FIG. 5, the partial pressure of the reaction inhibiting gas is made low or zero (P D ), and in the L period, the partial pressure of the reaction inhibitor gas is increased (P C ) may be used. This allows the adsorption level of hydrogen fluoride (L C ) is the adsorption level during the L period (L D ) will be higher.

[0085] Fig. 6A is a diagram showing an example of a cross-sectional structure of the substrate W at the end (time t11) of the H period (step ST21) in Fig. 4 or Fig. 5. Fig. 6B is a diagram showing an example of a cross-sectional structure of the substrate W at the end (time t12) of the L period (step ST22) in Fig. 4 or Fig. 5.

[0086] 6A, the portion of the silicon-containing film SF exposed at the opening OP is etched in the depth direction (the direction from top to bottom in FIG. 6A) by the treatment in the H period (step ST21), forming a recess RC. In the H period, the silicon-containing film SF may be etched until the bottom of the recess RC reaches the undercoat film UF or just before it reaches the bottom.

[0087] During the H period (step ST21), the adsorption level of hydrogen fluoride to the silicon-containing film (L A Or L C ) is larger than the L period (step ST21) (see FIGS. 4 and 5). As a result, in the H period, adsorption of hydrogen fluoride to the silicon-containing film SF is promoted, and the silicon-containing film SF is etched at a higher etching rate than in the L period. On the other hand, in the H period, reaction products (by-products) generated by etching increase compared to the L period. The reaction by-products are adsorbed to the side walls of the recess RC and may hinder etching in the horizontal direction (left and right direction in FIG. 6A). As a result, the recess RC may have a shape that tapers along the depth direction (see FIG. 6A).

[0088] In the subsequent L period (step ST22), the adsorption level of hydrogen fluoride to the silicon-containing film (L B Or L D ) is smaller than that in the H period (step ST21) (see FIGS. 4 and 5). As a result, in the L period, adsorption of hydrogen fluoride to the silicon-containing film SF is suppressed, and the silicon-containing film SF is etched at a lower etching rate than in the H period. On the other hand, in the L period, reaction by-products generated by etching are reduced compared to the H period, and adsorption to the side walls of the recess RC is suppressed. As a result, etching progresses in the horizontal direction, and the recess RC approaches a rectangular shape from a tapered shape (see FIG. 6B). In other words, the verticality of the recess RC is increased.

[0089] 4 or 5, the silicon-containing film SF is etched at a high etching rate in period H (step ST21), and then the bottom of the recess RC of the silicon-containing film SF is widened in period L (step ST22). This makes it possible to improve the verticality of the recess formed by etching and suppress shape abnormalities while suppressing a decrease in the etching rate throughout step ST2.

[0090] (Another example of process ST2) FIG. 7 is another example of a timing chart of the step ST2 when a reaction promoting gas is used. FIG. 7 shows an example in which a reaction promoting gas is used as a reaction controlling gas, and one cycle of a first etching step ST21 and a second etching step ST2 is repeated multiple times to etch the silicon-containing film SF. The vertical and horizontal axes of FIG. 7 are the same as those of FIG. 4, and "P B " is when the partial pressure of the reaction promoter gas is zero or "P A " is smaller than "L B " is the adsorption level (adsorption amount) of hydrogen fluoride to the silicon-containing film SF. A In FIG. 7, times 0 to t21 and times t22 to t23 correspond to step ST21 (hereinafter these periods will be referred to as "H1 period", "H2 period", etc.). Also, times t21 to t22 and times t23 to t24 correspond to step ST22 (hereinafter these periods will be referred to as "L1 period", "L2 period", etc.).

[0091] 7, the partial pressure of the reaction promoting gas is constant in each period (H1 period, H2 period, L1 period, L2 period, etc.), but may be changed (decreased, increased, or increased or decreased) stepwise or continuously within each period. In this case, the adsorption level of hydrogen fluoride may change in accordance with the change.

[0092] 7 is a timing chart in the case where a reaction promoting gas is used as the reaction controlling gas in step ST2, but instead of or in addition to this, a reaction inhibiting gas may be used as the reaction controlling gas. FIG. 8 is another example of a timing chart for step ST2 in the case where a reaction inhibiting gas is used. As shown in FIG. 5, in step ST1 (H1 period, H2 period), the partial pressure of the reaction inhibiting gas is made low or zero (P D ), and in step ST2 (period L1, period L2), the partial pressure of the reaction inhibitor gas is increased (P C ) may be used. This allows the adsorption level (L C ) is the adsorption level (L D ) will be higher.

[0093] Fig. 9A is a diagram showing an example of the cross-sectional structure of the substrate W at the end (time t21) of the H1 period (step ST21 of the first cycle) in Fig. 7 or Fig. 8. Fig. 9B is a diagram showing an example of the cross-sectional structure of the substrate W at the end (time t22) of the L1 period (step ST22 of the first cycle) in Fig. 7 or Fig. 8.

[0094] As shown in Fig. 9A, the processing in the H1 period (step ST21 of the first cycle) etches the portion of the silicon-containing film SF exposed at the opening OP in the depth direction (from top to bottom in Fig. 9A) to form a recess RC. In the H1 period, the silicon-containing film SF is etched until the recess RC reaches a given depth (for example, a depth of 1 / n of the thickness of the silicon-containing film SF when steps ST21 and ST22 are repeated for n cycles). In the H1 period, like the above-mentioned H period, the silicon-containing film SF is etched at a higher etching rate than in the L1 period, while the recess RC may have a tapered shape in the depth direction (see Fig. 9A).

[0095] In the subsequent L1 period (step ST22 of the first cycle), like in the above-described L period, the silicon-containing film SF is etched at a lower etching rate than in the H1 period, while etching proceeds in the horizontal direction, and the recess RC approaches a rectangle from a tapered shape (see FIG. 9B). That is, the verticality of the recess RC increases.

[0096] 6 or 7, step ST1 (period H1, period H2, etc.) of etching the silicon-containing film SF at a high etching rate and step ST2 (period L1, period L2) of widening the bottom of the recess RC of the silicon-containing film SF are alternately repeated. This makes it possible to increase the verticality of the recess formed by etching and suppress shape abnormalities while suppressing a decrease in the etching rate in step ST2.

[0097] <Modification> The embodiments of the present disclosure may be modified in various ways without departing from the scope and spirit of the present disclosure. For example, the following modifications are possible.

[0098] Fig. 10 is a flow chart showing a modified example of the present processing method. As shown in Fig. 10, in the etching process, the order of the first etching and the second etching may be reversed. That is, the silicon-containing film SF may be etched using the second processing gas first (step ST21A), and then the silicon-containing film SF may be etched using the first processing gas (step ST23A). In addition to step ST23, the determination of whether the stop condition is satisfied in step ST2A may be performed between step ST21A and step ST22A.

[0099] Fig. 11 is a flow chart showing a modified example of the present processing method. As shown in Fig. 11, in the etching step, only the first etching may be performed. That is, in the etching step ST2B, the silicon-containing film SF may be etched using the first processing gas (step ST2B).

[0100] As etching progresses, the temperature of the substrate W may increase due to heat input from the plasma. Here, hydrogen fluoride tends to be more easily adsorbed by the silicon-containing film SF as the temperature of the substrate W decreases. Therefore, as etching progresses, the amount of adsorbed hydrogen fluoride decreases, and the etching rate may decrease. Therefore, for example, a reaction promotion gas may be supplied from the middle to the end of the etching process when the etching rate may decrease. This makes it possible to suppress the decrease in the etching rate. The supply amount of the reaction promotion gas may be set based on the etching time, the temperatures of the substrate W and the substrate support 11, etc.

[0101] As the aspect ratio of the recess formed by etching increases, the amount of etchant (active species of hydrogen fluoride) supplied to the bottom of the recess decreases. Therefore, the partial pressure of the reaction control gas may be changed according to the aspect ratio of the recess. For example, the partial pressure of the reaction promotion gas may be made higher in etching the high aspect region than in etching the low aspect region. This can promote the reaction between the etchant and the silicon-containing film SF in the high aspect region.

[0102] The etching rate may decrease due to deposition of reaction by-products generated by etching the silicon-containing film SF. For this reason, a reaction inhibitor gas may be temporarily supplied during etching to promote volatilization of the reaction by-products. The reaction promoter gas may be supplied at a preset timing, or may be supplied according to the etching status estimated from the plasma light emission state, etc. The supply amount and supply time of the reaction inhibitor gas are not limited as long as they can promote volatilization of the reaction by-products.

[0103] Furthermore, the processing method may be performed using a plasma processing apparatus using any plasma source, such as an inductively coupled plasma or microwave plasma, other than the capacitively coupled plasma processing apparatus 1.

[0104] <Example> Next, examples of the present processing method will be described. The present disclosure is not limited to the following examples. (Examples 1 and 2) This processing method was applied using a plasma processing apparatus 1 to etch a substrate having the same structure as the substrate W shown in FIG. 3. An amorphous carbon film having a hole-shaped opening OP was used as the mask MF. A silicon oxide film was used as the silicon-containing film SF. The first processing gas contained HF gas and Cl as a reaction suppressing gas. 2 The second process gas contained HF gas and Cl as a reaction inhibitor gas. 2 The reaction inhibitor gas (Cl) in the second process gas was 2 The partial pressure of the reaction inhibitor gas (Cl 2 The partial pressure of the gas) was smaller than that of the gas. The temperature of the substrate support 11 was set to 15° C. In Example 1, one cycle of step ST21 (620 seconds) and step ST22 (310 seconds) in FIG. 2 was performed. In Example 2, four cycles of step ST21 (150 seconds) and step ST22 (50 seconds) in FIG. 2 were performed in this order.

[0105] (Reference example 1) In Reference Example 1, a substrate W having the same configuration as in Examples 1 and 2 was etched using a plasma processing apparatus 1. In Reference Example 1, etching was performed continuously for 840 seconds using the same processing gas as the first processing gas used in Examples 1 and 2. The temperature of the substrate support 11 was set to 15°C.

[0106] Table 1 shows the etching rates ER [nm / min] and BB bias [nm] of the silicon-containing films SF according to Example 1, Example 2, and Reference Example 1. The BB bias is the difference between the maximum opening width and the bottom opening width of the recess formed by etching, and the smaller this value is, the closer the recess is to a rectangle (the more vertical it is).

[0107] [Table 1]

[0108] In Example 1, the etching rate was slightly lower than in Reference Example 1, but the BB bias was small and the perpendicularity of the recesses was improved. In Example 2, the etching rate was higher than in Reference Example 1, and the BB bias was small and the perpendicularity of the recesses was improved. That is, in both Example 1 and Example 2, the perpendicularity of the recesses was improved (shape abnormalities were suppressed) while suppressing the decrease in the etching rate.

[0109] (Examples 3 and 4) This processing method was applied using a plasma processing apparatus 1 to etch a substrate having the same structure as the substrate W shown in FIG. 3. An amorphous carbon film having a hole-shaped opening OP was used as the mask MF. A silicon oxide film was used as the silicon-containing film SF. The first processing gas contained HF gas and PF as a reaction promoting gas. 3 The second process gas contained HF gas and PF 3 No gas was included. The temperature of the substrate support 11 was set to -20°C, and four cycles of step ST21A (40 seconds) and step ST22A (120 seconds) in Fig. 10 were performed. In Example 3, plasma was generated using a pulse wave of a source RF signal having the same duty ratio (37%) in both step ST21A and step ST22A. In Example 4, plasma was generated using a pulse wave of a source RF signal with a duty ratio of 29% in step ST21A, and a pulse wave of a source RF signal with a duty ratio of 37% in step ST22A.

[0110] Table 2 shows the etching rates ER [nm / min] and BB bias [nm] of the silicon-containing films SF according to Examples 3 and 4.

[0111] [Table 2]

[0112] In Example 4, the etching rate was slightly higher and the BB bias was slightly larger than those in Example 3. In Example 4, it is considered that the duty ratio in step ST21A was lower than that in step ST22B, thereby suppressing the heat input to the substrate W and suppressing the decrease in the etching rate.

[0113] The embodiments of the present disclosure further include the following aspects.

[0114] (Appendix 1) 1. A device manufacturing method carried out in a plasma processing apparatus having a chamber, comprising: (a) providing a substrate having a silicon-containing film and a mask on the silicon-containing film on a substrate support in a chamber; (b) etching the silicon-containing film; The step (b) comprises: (b-1) etching the silicon-containing film using plasma generated from a first process gas containing hydrogen fluoride gas and a reaction control gas that controls a reaction between the hydrogen fluoride and the silicon-containing film, the first process gas containing, as the reaction control gas, at least one of a reaction promoting gas that promotes the reaction and a reaction inhibiting gas that inhibits the reaction; (b-2) etching the silicon-containing film using plasma generated from a second process gas containing hydrogen fluoride gas, wherein the second process gas contains a reaction-promoting gas that promotes the reaction at a partial pressure lower than that of the reaction-promoting gas in the first process gas and / or contains a reaction-inhibiting gas that inhibits the reaction at a partial pressure higher than that of the reaction-inhibiting gas in the first process gas, or does not contain the reaction control gas.

[0115] (Appendix 2) A computer of a plasma processing system including a chamber, a substrate support provided in the chamber, and a plasma generating unit, (a) controlling a substrate having a silicon-containing film and a mask on the silicon-containing film to be provided on a substrate support in a chamber; (b) controlling the etching of the silicon-containing film; The control of (b) is (b-1) Control of etching the silicon-containing film using plasma generated from a first process gas containing hydrogen fluoride gas and a reaction control gas that controls a reaction between hydrogen fluoride and the silicon-containing film, wherein the first process gas contains, as the reaction control gas, at least one of a reaction promoting gas that promotes the reaction and a reaction inhibiting gas that inhibits the reaction; (b-2) a program for controlling etching of the silicon-containing film using plasma generated from a second process gas containing hydrogen fluoride gas, wherein the second process gas contains a reaction promoting gas that promotes the reaction at a partial pressure lower than that of the reaction promoting gas in the first process gas and / or contains a reaction inhibiting gas that inhibits the reaction at a partial pressure higher than that of the reaction inhibiting gas in the first process gas, or does not contain the reaction controlling gas.

[0116] (Appendix 3) A storage medium storing the program described in appendix 2. [Explanation of symbols]

[0117] REFERENCE SIGNS LIST 1: plasma processing apparatus, 2: control section, 10: plasma processing chamber, 10s: plasma processing space, 11: substrate support section, 13: shower head, 20: gas supply section, 31a: first RF generating section, 31b: second RF generating section, 32a: first DC generating section, SF: silicon-containing film, MF: mask, OP: opening, RC: recess, UF: base film, W: substrate

Claims

1. A chamber, a substrate support disposed within the chamber; a gas supply unit for supplying a process gas into the chamber; a plasma generating unit for generating plasma from the processing gas; A control unit; Equipped with The control unit is (a) providing a substrate having a silicon-containing film and a mask on the silicon-containing film on a substrate support in a chamber; (b) controlling the gas supply unit and the plasma generation unit to etch the silicon-containing film; The control of (b) is (b-1) supplying a first process gas containing hydrogen fluoride as the process gas and generating plasma from the first process gas; (b-2) supplying a second process gas containing hydrogen fluoride and a reaction inhibiting gas as the process gas, and generating plasma from the second process gas, the reaction inhibiting gas being a gas that inhibits a reaction between hydrogen fluoride and the silicon-containing film; Including, The first process gas does not contain the reaction inhibiting gas or contains the reaction inhibiting gas at a partial pressure lower than that of the reaction inhibiting gas in the second process gas. Plasma processing systems.

2. The plasma processing system of claim 1, wherein the reaction inhibitor gas is a chlorine-containing gas.

3. The plasma processing system of claim 2, wherein the chlorine-containing gas is at least one selected from the group consisting of Cl2 gas, SiCl2 gas, SiH2Cl2 gas, SiCl4 gas, Si2Cl6 gas, CHCl3 gas, CCl4 gas and BCl3 gas.

4. A plasma processing system as described in any one of claims 1 to 3, wherein the reaction inhibitor gas contained in the first processing gas and the reaction inhibitor gas contained in the second processing gas are the same type of gas.

5. A chamber, a substrate support disposed within the chamber; a gas supply unit for supplying a process gas into the chamber; a plasma generating unit for generating plasma from the processing gas; A control unit; Equipped with The control unit is (a) providing a substrate having a silicon-containing film and a mask on the silicon-containing film on a substrate support in a chamber; (b) controlling the gas supply unit and the plasma generation unit to etch the silicon-containing film; The control of (b) is (b-1) supplying a first process gas containing hydrogen fluoride and a reaction promoting gas as the process gas, and generating plasma from the first process gas, the reaction promoting gas being a gas that promotes a reaction between hydrogen fluoride and the silicon-containing film; (b-2) supplying a second process gas containing hydrogen fluoride as the process gas and generating plasma from the second process gas; Including, The second process gas does not contain the reaction accelerating gas or contains the reaction accelerating gas at a partial pressure lower than that of the reaction accelerating gas in the first process gas. Plasma processing systems.

6. The plasma processing system of claim 5, wherein the reaction promoting gas is at least one selected from the group consisting of a phosphorus-containing gas, a nitrogen-containing gas, and a hydrogen-containing gas.

7. The plasma processing system of claim 6, wherein the phosphorus-containing gas is a halogenated phosphorus gas.

8. The plasma processing system of claim 5, wherein the reaction promoting gas is at least one selected from the group consisting of a nitrogen-containing gas and a hydrogen-containing gas.

9. The plasma processing system of claim 8, wherein the nitrogen-containing gas is at least one gas selected from the group consisting of NH 3 gas, NF 3 gas, NO gas, and NO 2 gas.

10. The plasma processing system of claim 8, wherein the hydrogen-containing gas is a gas having an OH group.

11. A plasma processing system as described in any one of claims 5 to 10, wherein the reaction promoter gas contained in the first processing gas and the reaction promoter gas contained in the second processing gas are the same type of gas.

12. A plasma processing system as described in any one of claims 1 to 11, wherein in both the first processing gas and the second processing gas, the partial pressure of hydrogen fluoride gas is the highest, excluding inert gases.

13. A plasma processing system as described in any one of claims 1 to 12, wherein at least one of the first processing gas and the second processing gas further contains at least one gas selected from the group consisting of a carbon-containing gas, an oxygen-containing gas, a carbon-free fluorine-containing gas, and a halogen-containing gas other than fluorine.

14. The plasma processing system of claim 1, wherein in the step (b), the step (b-1) and the step (b-2) are repeated alternately.

15. A plasma processing system as described in any one of claims 1 to 14, wherein in the step (b), switching between the step (b-1) and the step (b-2) is performed based on at least one of the depth of a recess formed in the silicon-containing film by etching, the aspect ratio of the recess, and the etching time.

16. The method of claim 1, wherein in the step (b-1), a plasma is generated from the first process gas using a pulse wave of a source RF signal having a first duty ratio; 16. The plasma processing system according to claim 1, wherein in the step (b-2), plasma is generated from the second process gas by using a pulse wave of a source RF signal having a second duty ratio smaller than the first duty ratio.

17. A chamber, a substrate support disposed within the chamber; a gas supply unit for supplying a process gas into the chamber; a plasma generating unit for generating plasma from the processing gas; A control unit; Equipped with The control unit is (a) providing a substrate having a silicon-containing film and a mask on the silicon-containing film on a substrate support in a chamber; (b) controlling the gas supply unit and the plasma generation to etch the silicon-containing film with active species of hydrogen fluoride contained in the plasma; The control of (b) is (b-1) supplying a first processing gas as the processing gas and generating plasma from the first processing gas; (b-2) supplying a second process gas as the process gas and generating plasma from the second process gas, the second process gas including a reaction suppression gas that suppresses a reaction between hydrogen fluoride and the silicon-containing film; Including, The first process gas does not contain the reaction inhibiting gas or contains the reaction inhibiting gas at a partial pressure lower than that of the reaction inhibiting gas in the second process gas. Plasma processing systems.

18. A chamber, a substrate support disposed within the chamber; a gas supply unit for supplying a process gas into the chamber; a plasma generating unit for generating plasma from the processing gas; A control unit; Equipped with The control unit is (a) providing a substrate having a silicon-containing film and a mask on the silicon-containing film on a substrate support in a chamber; (b) controlling the gas supply unit and the plasma generation unit to etch the silicon-containing film with active species of hydrogen fluoride contained in the plasma; The control of (b) is (b-1) supplying a first process gas as the process gas and generating plasma from the first process gas, the first process gas including a reaction promoting gas that promotes a reaction between hydrogen fluoride and the silicon-containing film; (b-2) supplying a second processing gas as the processing gas and generating plasma from the second processing gas; Including, The second process gas does not contain the reaction accelerating gas or contains the reaction accelerating gas at a partial pressure lower than that of the reaction accelerating gas in the first process gas. Plasma processing systems.

19. The plasma processing system of claim 17 or 18, wherein the activated hydrogen fluoride species is generated from at least one gas selected from the group consisting of hydrogen fluoride gas and hydrofluorocarbon gas.

20. The plasma processing system of claim 17 or 18, wherein the activated species of hydrogen fluoride are generated from a fluorine-containing gas and a hydrogen-containing gas.

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