Plasma processing method and plasma processing system

Abstract

To provide technology to improve etching rates.SOLUTION: A plasma processing method performed in a plasma processing apparatus having a chamber is provided. The method comprises the steps of (a) providing a substrate having an etch target film including a silicon oxide film and a silicon nitride film and a mask film defining an opening on the etch target film on a substrate support portion in the chamber, (b) etching a silicon nitride film by generating plasma from a first process gas containing HF gas, CxFy gas (x and y are one or more integers) or CsHtFu gas (s, t and u are one or more integers) and an oxygen-containing gas, and (c) etching the silicon oxide film by generating plasma from a second process gas containing HF gas, CvFw gas (v and w are integers of 1 or more), and an oxygen-containing gas, and in (b) and (c), the temperature of the substrate support portion is set to 0°C or lower.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Patent Document 1 discloses a method for etching a substrate on which a silicon oxide film, a silicon nitride film, and a polysilicon mask are formed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-21546 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides techniques for improving the etching rate. [Means for solving the problem]

[0005] In one exemplary embodiment of the present disclosure, a plasma processing method is carried out in a plasma processing apparatus having a chamber, the method comprising the steps of: (a) providing a substrate having an etching target film including a silicon oxide film and a silicon nitride film, and a mask film defining an opening on the etching target film, on a substrate support in the chamber; (b) providing a HF gas and a C x F y Gas (x and y are integers equal to or greater than 1) or C s H t F u (c) generating plasma from a first process gas containing a gas (where s, t, and u are integers of 1 or more) and an oxygen-containing gas to etch the silicon nitride film; v F wand generating plasma from a second process gas containing a gas (v and w are integers equal to or greater than 1) and an oxygen-containing gas to etch the silicon oxide film, wherein in steps (b) and (c), the temperature of the substrate support is set to 0° C. or lower. Effect of the Invention

[0006] According to an exemplary embodiment of the present disclosure, the etching rate can be improved. [Brief description of the drawings]

[0007] [Figure 1] 1 illustrates a schematic diagram of an exemplary plasma processing system. [Diagram 2] 4 is a flowchart illustrating an example 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 a diagram showing an example of a cross-sectional structure of the substrate W after completion of step ST32. FIG. [Diagram 5] 13 is a diagram showing an example of a cross-sectional structure of the substrate W after completion of step ST34. [Figure 6] FIG. 13 is a diagram showing the results of etching in Examples 5 to 7. [Figure 7] FIG. 13 is a diagram showing the results of etching in Example 8. [Figure 8] FIG. 13 is a diagram showing the results of etching in Example 9. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0009] In one exemplary embodiment, a plasma processing method is carried out in a plasma processing apparatus having a chamber, the method comprising the steps of: (a) providing a substrate having a film to be etched, the film including a silicon oxide film and a silicon nitride film, and a mask film defining an opening on the film to be etched, on a substrate support in the chamber; (b) providing a gas mixture containing HF gas and C x F y Gas (x and y are integers equal to or greater than 1) or C s H t F u (c) generating plasma from a first process gas containing a gas (where s, t, and u are integers of 1 or more) and an oxygen-containing gas to etch the silicon nitride film; v F w and generating plasma from a second process gas containing a gas (v and w are integers equal to or greater than 1) and an oxygen-containing gas to etch the silicon oxide film, wherein in (b) and (c), the temperature of the substrate support is set to 0° C. or lower.

[0010] In one exemplary embodiment, the first process gas comprises a different type of gas than the second process gas.

[0011] In one exemplary embodiment, the first process gas is s H t F u Contains gas.

[0012] In one exemplary embodiment, the first process gas is x F y Gas included, C x F y The gas is C contained in the second process gas. v F w It is a different gas than gas.

[0013] In one exemplary embodiment, in (b), the temperature of the substrate support is set to a first temperature, and in (c), the temperature of the substrate support is set to a second temperature that is lower than the first temperature.

[0014] In one exemplary embodiment, in (b), a bias signal of a first output is supplied to the substrate support, and in (c), a bias signal of a second output smaller than the first output is supplied to the substrate support, or no bias signal is supplied to the substrate support.

[0015] In one exemplary embodiment, (b) a pulse wave of a bias signal having a first duty ratio is supplied to the substrate support, and (c) a pulse wave of a bias signal having a second duty ratio smaller than the first duty ratio is supplied to the substrate support.

[0016] In one exemplary embodiment, the bias signal is a bias DC signal.

[0017] In one exemplary embodiment, (b) a bias RF signal at a first frequency is provided to the substrate support, and (c) a bias RF signal at a second frequency lower than the first frequency is provided to the substrate support.

[0018] In one exemplary embodiment, in (b), a heat transfer gas at a first pressure is supplied between the substrate and the substrate support, and in (c), a heat transfer gas at a second pressure lower than the first pressure is supplied between the substrate and the substrate support.

[0019] In one exemplary embodiment, in (b), the temperature of the heat transfer fluid supplied to the substrate support is set to a third temperature, and in (c), the temperature of the heat transfer fluid supplied to the substrate support is set to a fourth temperature lower than the third temperature.

[0020] In one exemplary embodiment, the mask film is a polysilicon film, a boron doped silicon film, a tungsten-containing film, an amorphous carbon film, a tin oxide film, or a titanium-containing film.

[0021] In one exemplary embodiment, the opening width of the mask membrane is 50 nm or less.

[0022] In one exemplary embodiment, Cx F y Gas or C v F w 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 gas includes at least one selected from the group consisting of gases.

[0023] In one exemplary embodiment, C s H t F u Gas is 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 H2 F 6 Gas, C. 5 H 2 F 10 Gas and C 5 H 3 F 7 The gas includes at least one selected from the group consisting of gases.

[0024] In one exemplary embodiment, the first process gas and the second process gas have a highest flow rate of HF gas.

[0025] In one exemplary embodiment, at least one of the first process gas and the second process gas further comprises a phosphorus-containing gas.

[0026] In one exemplary embodiment, at least one of the first process gas and the second process gas is WF 6 It further comprises a gas.

[0027] In one exemplary embodiment, in (b) and (c), the temperature of the substrate support is set to -50°C or lower.

[0028] In one exemplary embodiment, a plasma processing method is carried out in a plasma processing apparatus having a chamber, the method comprising the steps of: (a) providing a substrate having a film to be etched, the film including a silicon oxide film and a silicon nitride film, and a mask film defining an opening on the film to be etched, on a substrate support in the chamber; (b) generating a first plasma from a first process gas, and absorbing a HF species and a C x F y species (x and y are integers equal to or greater than 1) or C s H t F u (c) generating a second plasma from a second process gas, and etching the silicon nitride film with an HF species (where s, t, and u are integers of 1 or more) and an oxygen active species; and v F wand etching the silicon oxide film with a species (v and w are integers of 1 or more) and an oxygen active species, wherein in (b) and (c), the temperature of the substrate support is set to 0° C. or less.

[0029] In one exemplary embodiment, the HF species is CH 2 F 2 Gas, C. 3 H 2 F 4 Gas and C 4 H 2 F 6 The gas is generated from at least one gas selected from the group consisting of gases.

[0030] In one exemplary embodiment, the apparatus includes a chamber, a substrate support provided in the chamber, a plasma generating unit, and a control unit, and the control unit (a) provides a substrate having an etching target film including a silicon oxide film and a silicon nitride film, and a mask film defining an opening on the etching target film, on the substrate support unit, and (b) generates a HF gas and a C x F y Gas (x and y are integers equal to or greater than 1) or C s H t F u (c) generating plasma from a first process gas containing a gas (where s, t, and u are integers of 1 or more) and an oxygen-containing gas to etch the silicon nitride film; and (b) generating plasma from a first process gas containing a HF gas and a C v F w and generating a plasma from a second process gas containing a gas (where v and w are integers equal to or greater than 1) and an oxygen-containing gas to etch a silicon oxide film, and in (b) and (c), a plasma processing system is provided that performs control such that the temperature of the substrate support is set to 0° C. or lower.

[0031] 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.

[0032] <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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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).

[0047] <An example of a plasma processing method> Fig. 2 is a flowchart showing a plasma processing method (hereinafter also referred to as "this processing method") according to one exemplary embodiment. As shown in Fig. 2, this processing method includes a step ST1 of providing a substrate, a step ST2 of setting the temperature of a substrate support, and a step ST3 of etching a film to be etched 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.

[0048] (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 disposed on the upper surface of the substrate support 11 so as to face the upper electrode, and is held on the substrate support 11 by an electrostatic chuck 1111.

[0049] 3 is a diagram showing an example of a cross-sectional structure of a substrate W provided in step ST1. The substrate W has an etching target film EF and a mask film MF formed in this order on an undercoat film UF. The substrate W may be, for example, a substrate for manufacturing a DRAM.

[0050] The undercoat film UF may be, for example, a silicon wafer, an organic film formed on a silicon wafer, a dielectric film, a metal film, a semiconductor film, etc. The undercoat film UF may be configured by laminating a plurality of films.

[0051] The film EF to be etched is, for example, a silicon oxide film (SiO x Membrane) EF 2 and the silicon oxide film EF 2 Silicon nitride film EF formed on 1 The etching target film EF is a laminated film including a film to be etched by the present processing method.

[0052] The undercoat film UF and / or the etching target film EF may be formed by a CVD method, a spin coating method, etc. The undercoat film UF and / or the etching target film EF may be a flat film, or may be a film having projections and recesses.

[0053] The mask film MF is formed on the etching target film EF. The mask film MF defines at least one opening OP on the etching target film EF. The opening OP is a space on the etching target film EF and is surrounded by the sidewall of the mask film MF. That is, in FIG. 3, the upper surface of the etching target film EF has a region covered by the mask film MF and a region exposed at the bottom of the opening OP.

[0054] The openings OP may have any shape in a plan view of the substrate W, i.e., when the substrate W is viewed from the top to the 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 film MF may have a plurality of side walls that define a plurality of openings OP. The plurality of openings OP may each have a linear shape and be arranged at regular intervals to form a line and space pattern. Also, the plurality of openings OP may each have a hole shape and form an array pattern.

[0055] The opening width of the opening OP may be 50 nm or less. The opening width may be 30 nm or less. The opening width may be 15 nm or more and 25 nm or less.

[0056] The mask film MF may be, for example, a polysilicon film, a boron-doped silicon film, a tungsten-containing film (for example, a WC film, a WSi film, etc.), an amorphous carbon film, a tin oxide film, or a titanium-containing film (for example, a TiN film, etc.). The mask film MF may be a single-layer mask consisting of one layer, or a multi-layer mask consisting of two or more layers. The mask film MF may be formed by a CVD method, a spin coating method, or the like. The mask film MF may be formed by lithography. The opening OP may be formed by etching the mask film MF.

[0057] At least a part of the process for forming each component of the substrate W may be performed in the plasma processing chamber 10. In one example, a step of etching the mask film 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 etching target film EF described later may be performed consecutively in the same chamber. Also, after all or a part of each component of 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 placed on the upper surface of the substrate support 11.

[0058] (Substrate ST2: Set the temperature of the substrate support part) In step ST2, the temperature of the substrate support 11 is set to a target temperature of 0° C. or less. The target temperature may be −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.

[0059] Setting the temperature of the substrate support 11 to a target temperature includes, but is not limited to, measuring the temperature of the substrate support 11 and adjusting the temperature of the substrate support 11 by a temperature adjustment module so that the temperature of the substrate support 11 becomes the target temperature. In one example, setting the temperature of the substrate support 11 to a target temperature includes (a) setting the temperature of the substrate W or the temperature of the heat transfer fluid flowing through the flow path 1110a to the target temperature or a temperature different from the target temperature so that the temperature of the substrate support 11 becomes the target temperature, and (b) setting the temperature of the substrate support 11 or the heat transfer fluid flowing through the flow path 1110a to the target temperature or a temperature different from the target temperature so that the temperature of the substrate W becomes the target temperature. Furthermore, "setting" a temperature includes inputting, selecting, or storing the temperature in the control unit 2.

[0060] In this processing method, step ST2 may be performed before step ST1. That is, the substrate W may be provided to the substrate support 11 after the temperature of the substrate support 11 is set to the target temperature.

[0061] (Step ST3: Etching of the film EF to be etched) In step ST3, the film EF to be etched is etched. Step ST3 includes step ST31 of supplying a first process gas, step ST32 of generating plasma from the first process gas, step ST33 of supplying a second process gas, and step ST34 of generating plasma from the second process gas. During the process in step ST3, the temperature of the substrate support 11 is set to the target temperature of 0° C. or less set in step ST2. In one embodiment, the pressure in the plasma processing space 10s may be set to 30 mT (4.0 Pa) or less.

[0062] In step ST31, a first process gas is supplied into the plasma processing space 10s. The first process gas is a mixture of HF gas and C x F y Gas (x and y are integers equal to or greater than 1) or C s H t F u gas (where s, t, and u are integers of 1 or greater) and an oxygen-containing gas.

[0063] In the first process gas, the flow rate of HF gas may be the highest. In one example, the flow rate of HF gas may be 70 volume % or more, or 80 volume % or more, of the total flow rate of the first process gas. In addition, in the first process gas, a gas capable of generating HF species in the chamber may be used instead of or together with HF gas. The HF species includes at least one of hydrogen fluoride gas, radicals, and ions. The gas capable of generating HF species is, for example, 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 H2 F 6 Gas, C. 5 H 2 F 10 Gas and C 5 H 3 F 7 At least one selected from the group consisting of gases capable of generating HF species may be used. In one example, the gas may be CH 2 F 2 Gas, C. 3 H 2 F 4 Gas and C 4 H 2 F 6 At least one gas selected from the group consisting of gases is used.

[0064] C x F y 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 gas may include at least one selected from the group consisting of gases.

[0065] C s H t F u Gas is 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 H2 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 first process gas may include at least one selected from the group consisting of C x F y Gas and C s H t F u The gas may include both gas and gas.

[0066] The oxygen-containing gas is, for example, O 2 , CO, CO 2 , H 2 O and H 2 O 2 At least one gas selected from the group consisting of: 2 Oxygen-containing gases other than O, i.e., O 2 , CO, CO 2 and H 2 O 2 The flow rate of the oxygen-containing gas may include at least one gas selected from the group consisting of C x F y Gas and C s H t F u This may be adjusted according to the gas flow rate.

[0067] In step ST32, a source RF signal (RF power) is supplied from the first RF generating unit 31a to the lower electrode and / or the upper electrode. This generates plasma from the first process gas. In addition, a bias RF signal is supplied from the second RF generating unit 31b to the lower electrode as a bias signal (power), and a bias potential is generated on the substrate. This causes active species such as ions and radicals in the generated plasma to be attracted to the substrate W and pass through the opening OP of the mask film MF to the silicon nitride film EF. 1 As described above, during etching, the temperature of the substrate support 11 is set to a target temperature of 0° C. or lower.

[0068] The timing to start supplying the bias signal may be the same as or different from the timing to start supplying the source RF signal. A bias DC signal may be used as the bias signal (power). That is, a negative bias DC signal may be supplied from the DC generating unit 32a to the lower electrode to generate a bias potential on the substrate W. Both the source RF signal and the bias signal may be continuous waves, or one may be a continuous wave and the other may be a pulse wave.

[0069] 4 is a diagram showing an example of a cross-sectional structure of the substrate W after the step ST32 is completed. As shown in FIG. 4, the silicon nitride film EF 1 The bottom BT of the recess formed in the silicon oxide film EF 2 Silicon oxide film EF 2 When the surface of the silicon oxide film EF is exposed, step ST32 is completed. 2 In other words, in step ST32, the silicon oxide film EF may be partially etched away from the silicon oxide film EF. 2 A part of the insulating film may be over-etched in the depth direction.

[0070] In step ST33, a second process gas is supplied into the plasma processing space 10s. The second process gas is a mixture of HF gas and C v F w gas (where v and w are integers of 1 or greater) and an oxygen-containing gas.

[0071] In the second process gas, the flow rate of the HF gas may be the largest. In one example, the flow rate of the HF gas is The concentration of HF in the second process gas may be 70% by volume or more, or may be 80% by volume or more. As in the first process gas, a gas capable of generating HF species in the chamber may be used in place of or together with the HF gas in the second process gas.

[0072] C v F w 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 gas may include at least one selected from the group consisting of gases.

[0073] The oxygen-containing gas is, for example, O 2 , CO, CO 2 , H 2 O and H 2 O 2 At least one gas selected from the group consisting of: 2 Oxygen-containing gases other than O, i.e., O 2 , CO, CO 2 and H 2 O 2 The flow rate of the oxygen-containing gas may include at least one gas selected from the group consisting of C v F w This may be adjusted according to the gas flow rate.

[0074] The type of gas contained in the second process gas may be different from that of the first process gas. In one example, the first process gas is C x F y In the case where the second process gas contains C vF w Gas is C x F y The first process gas may be a gas different from the first process gas. s H t F u If the second process gas contains C s H t F u It does not have to contain gas.

[0075] The type of gas contained in the second process gas may be the same as the type of gas contained in the first process gas. In one example, the first process gas is C x F y In the case where the second process gas contains C v F w Gas is C x F y The gas may be the same type as the gas.

[0076] The flow rates of the same type of gas contained in the first process gas and the second process gas may be the same or different, for example, the flow rates of HF gas contained in the first process gas and the second process gas may be the same or different.

[0077] In step ST34, a source RF signal (RF power) is supplied from the first RF generator 31a to the lower electrode and / or the upper electrode. This generates plasma from the second process gas. In addition, a bias RF signal is supplied from the second RF generator 31b to the lower electrode as a bias signal (power), and a bias potential is generated on the substrate. This causes active species such as ions and radicals in the generated plasma to be attracted to the substrate W and pass through the opening OP of the mask film MF to the silicon oxide film EF. 2 As described above, the temperature of the substrate support 11 is set to a target temperature of 0° C. or lower during the etching.

[0078] The timing to start supplying the bias signal may be the same as or different from the timing to start supplying the source RF signal. A bias DC signal may be used as the bias signal (power). That is, a negative bias DC signal may be supplied from the DC generating unit 32a to the lower electrode to generate a bias potential on the substrate W. Both the source RF signal and the bias signal may be continuous waves, or one may be a continuous wave and the other may be a pulse wave.

[0079] 5 is a diagram showing an example of a cross-sectional structure of the substrate W after the step ST34 is completed. As shown in FIG. 5, the silicon oxide film EF 2 When the bottom BT of the recess formed in the base film UF reaches the base film UF and the surface of the base film UF is exposed, step ST34 is terminated. Note that step ST34 may be terminated after a part of the base film UF is etched. That is, in step ST34, a part of the base film UF may be over-etched in the depth direction. With the above, this processing method is terminated.

[0080] In this processing method, while the temperature of the substrate support 11 is set to 0° C. or less, plasma generated from a first processing gas containing HF gas is used to form a silicon nitride film EF 1 In addition, while the temperature of the substrate support 11 is set to 0° C. or lower, the silicon oxide film EF is etched using plasma generated from a second process gas containing HF gas (step ST32). 2 The silicon nitride film EF is etched (step ST34). 1 and silicon oxide film EF 2 The adsorption coefficients of HF species in plasma to the silicon nitride film EF are higher at low temperatures below 0° C. 1 and silicon oxide film EF 2 The adsorption of HF species in the plasma to the SiO 2 film can be promoted, and thus the etching rate can be improved by the present processing method.

[0081] In one embodiment, at least one of the first process gas and the second process gas may further include a phosphorus-containing gas. The phosphorus-containing gas is a gas that is capable of oxidizing the silicon nitride film EF of the HF species in the plasma. 1 Or silicon oxide film EF 2 This can promote adsorption to the surface of the substrate, thereby contributing to an improvement in the etching rate.

[0082] 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 PFh ) where the sum of g and h is 3 or 5. Fluorophosphines include HPF 2 , H 2 PF 3 The 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 the phosphorus-containing molecules contained in the processing gas are in a liquid or solid form, the phosphorus-containing molecules may be vaporized by heating or the like and supplied into the plasma processing space 10s.

[0083] In one embodiment, at least one of the first process gas and the second process gas is tungsten hexafluoride (WF 6 ) gas. 6 The gas can contribute to suppression of bowing in the etching processes of steps ST32 and ST34.

[0084] In one embodiment, at least one of the first process gas and the second process gas may further include a noble gas, such as Ar or Kr.

[0085] In one embodiment, the silicon nitride film EF 1 The temperature of the substrate support 11 during the etching (step ST32) may be set to the first temperature. 2 The temperature of the substrate support 11 in the etching of the silicon nitride film EF (step ST34) may be set to a second temperature lower than the first temperature. The adsorption coefficient of HF species to a silicon nitride film is maximized at a higher temperature than the adsorption coefficient of HF species to a silicon oxide film. Therefore, by setting the temperature of the substrate support 11 to the first temperature higher than the second temperature in step ST32, the silicon nitride film EF 1The adsorption of HF species to the silicon oxide film can be promoted. Conversely, the adsorption coefficient of HF species to the silicon nitride film is maximized at a lower temperature than the adsorption coefficient of HF species to the silicon oxide film. Therefore, in step ST34, the temperature of the substrate support is set to a second temperature lower than the first temperature, so that the adsorption of HF species to the silicon oxide film EF can be promoted. 2 As a result, the etching rate of the film EF to be etched can be improved.

[0086] In one embodiment, setting the temperature of the substrate support part 11 to the first temperature and the second temperature includes adjusting the temperature of the substrate support part 11 by changing the amount of heat input to the substrate W and the substrate support part 11 through the following Control 1 to Control 5. In one embodiment, one of Controls 1 to 5 is performed. In one embodiment, a plurality of Controls 1 to 5 is performed.

[0087] (Control 1) In step ST32, a bias signal of a first output may be supplied to the substrate support part 11. Then, in step ST34, a bias signal of a second output smaller than the first output may be supplied to the substrate support part 11. The bias signal may be a bias RF signal or a bias DC signal. The output of the bias signal may be adjusted by the second RF generating part 31b or the bias DC generating part 32a. The bias signal may be a pulse wave or a continuous wave. Note that, when the bias signal is a bias RF signal, the "output" of the bias signal is the effective value of the power of the bias RF signal. When the bias signal is a bias DC signal, the "output" of the bias signal is the absolute value of the voltage of the bias DC signal (when the bias DC signal is a pulse wave, the effective value of the absolute value of the voltage).

[0088] (Control 2) In step ST32, a pulse wave of a bias signal having a first duty ratio may be supplied to the substrate support part 11. Then, in step ST34, a pulse wave of a bias signal having a second duty ratio smaller than the first duty ratio may be supplied to the substrate support part 11. The bias signal may be a bias RF signal or a bias DC signal. The duty ratio of the bias signal may be adjusted by the second RF generating part 31b or the bias DC generating part 32a. The duty ratio of the bias signal is the proportion of a period during which the power or voltage level is high in the period of the pulse wave.

[0089] (Control 3) In step ST32, a bias signal of a first frequency may be supplied to the substrate support part 11. Then, in step ST34, a bias signal of a second frequency lower than the first frequency may be supplied to the substrate support part 11. The bias signal may be a bias RF signal or a bias DC signal. The frequency of the bias signal may be adjusted by the second RF generating part 31b or the bias DC generating part 32a.

[0090] (Control 4) In step ST32, a heat transfer gas at a first pressure may be supplied from the heat transfer gas supply unit to between the substrate W and the substrate support unit 11 (central region 111a). Then, in step ST34, a heat transfer gas at a second pressure lower than the first pressure may be supplied from the heat transfer gas supply unit to between the substrate W and the substrate support unit 11 (central region 111a). The supply pressure of the heat transfer gas may be adjusted by the heat transfer gas supply unit.

[0091] (Control 5) In step ST32, the temperature of the heat transfer fluid flowing through flow path 1110a may be set to a third temperature. Then, in step ST34, the temperature of the heat transfer fluid may be set to a fourth temperature lower than the third temperature. The third temperature may be the same as or different from the first temperature. The fourth temperature may be the same as or different from the second temperature.

[0092] <Example> Next, examples of the present processing method will be described. The present disclosure is not limited to the following examples.

[0093] Example 1 In Example 1, the present processing method was applied using a plasma processing apparatus 1, and a substrate having a structure similar to that of the substrate W shown in FIG. 3 was etched. A polysilicon film was used as the mask film MF. The silicon nitride film EF in Example 1 1 and silicon oxide film EF 2 The etching conditions were as follows: The first process gas contained 80% by volume or more of HF gas, and the second process gas contained 85% by volume or more of HF gas. Silicon nitride film EF 1 Etching conditions (step ST32): Temperature of the substrate support: -70℃ Chamber pressure: 23mT First process gas: HF gas, C 4 H 2 F 6 Gas, O 2 gas Silicon oxide film EF 2 Etching conditions (step ST34): Temperature of the substrate support: -70℃ Chamber pressure: 15mT Second process gas: HF gas, C 4 F 8 Gas, C. 4 F 6 Gas, O 2 gas

[0094] (Reference example 1) In Reference Example 1, a substrate similar to that in Example 1 was etched using the plasma processing apparatus 1. Silicon nitride film EF in Reference Example 1 1 and silicon oxide film EF 2 The etching conditions are as follows: Silicon nitride film EF 1 Etching conditions: Temperature of the substrate support: 50℃ Chamber pressure: 10mT First process gas: C 4 F 8 Gas, C. 4 F 6 Gas, NF 3 Gas, CH 2 F 2 Gas, O 2 gas Silicon oxide film EF 2 Etching conditions: Temperature of the substrate support: 70℃ Chamber pressure: 10mT Second process gas: C 4 F 8 Gas, C. 4 F 6 Gas, NF 3 Gas, O 2 gas

[0095] The etching rate of the film EF to be etched in Example 1 was 546 [nm / min], and the selectivity ratio to the mask film MF was 6.1. In contrast, the etching rate of the film EF to be etched in Reference Example 1 was 130 [nm / min], and the selectivity ratio to the mask film MF was 4.7. That is, in Example 1, the etching rate was about 4 times as high as in Reference Example 1, and was significantly improved. Furthermore, in Example 1, the selectivity ratio was also improved by about 1.3 times as high as in Reference Example 1.

[0096] (Examples 2 to 4) In Examples 2 to 4, the present processing method was applied using the plasma processing apparatus 1 to etch the same substrate as in Example 1. Silicon nitride film EF in Example 2 1 and silicon oxide film EF 2 The etching conditions are as follows: The first and second process gases were the same, and both contained 80% or more by volume of HF gas. Silicon nitride film EF 1 Etching conditions (step ST32): Temperature of the substrate support: -70℃ Chamber pressure: 23mT First process gas: HF gas, C 4 F 8 Gas, C. 4 F 6 Gas, O 2 gas Silicon oxide film EF 2 Etching conditions (step ST34): Temperature of the substrate support: -70℃ Chamber pressure: 23mT Second process gas: HF gas, C 4 F 8 Gas, C. 4 F 6 Gas, O 2 gas

[0097] In Example 3, etching was performed under the same conditions as Example 2, except that the first and second processing gases contained 1.6 volume % of phosphorus-containing gas. In Example 4, etching was performed under the same conditions as Example 2, except that the first and second processing gases contained 3.2 volume % of phosphorus-containing gas. In Examples 3 and 4, PF 3 Gas was used.

[0098] In Example 2, the etching rate of the film EF to be etched was 372 [nm / min], and the selectivity ratio to the mask film MF was 3.0. In Example 3, the etching rate of the film EF to be etched was 471 [nm / min], and the selectivity ratio to the mask film MF was 3.4. In Example 4, the etching rate of the film EF to be etched was 530 [nm / min], and the selectivity ratio to the mask film MF was 3.2. That is, in Examples 3 and 4, which contain a phosphorus-containing gas as the first processing gas and the second processing gas, the etching rate and the selectivity were further improved compared to Example 2, which does not contain a phosphorus-containing gas.

[0099] (Examples 5 to 7) In Examples 5 to 7, the present processing method was applied using the plasma processing apparatus 1 to etch the same substrate as in Example 1. Silicon nitride film EF in Example 5 1and silicon oxide film EF 2 The etching conditions were as follows: The first processing gas and the second processing gas each contained 85% by volume or more of HF gas. Silicon nitride film EF 1 Etching conditions (step ST32): Temperature of the substrate support: -70℃ Chamber pressure: 15mT First process gas: HF gas, C 4 F 8 Gas, O 2 gas Silicon oxide film EF 2 Etching conditions (step ST34): Temperature of the substrate support: -70℃ Chamber pressure: 15mT Second process gas: HF gas, C 4 F 8 Gas, O 2 gas

[0100] In Example 6, the second process gas was 1 sccm of WF 6 The etching was carried out under the same conditions as in Example 5, except that the etching gas further contained WF 6 Etching was carried out under the same conditions as in Example 6, except that the gas flow rate was tripled (3 sccm).

[0101] 6 is a diagram showing the results of etching in Examples 5 to 7. In FIG. 6, the vertical axis indicates the depth D [μm] of the recess formed in the opening OP of the mask film MF and the film to be etched EF. The area around 0 μm on the vertical axis indicates the depth D [μm] of the recess formed in the mask film MF and the silicon nitride film EF. 1 The area around -0.2 μm on the vertical axis is the boundary between the silicon nitride film EF 1 and silicon oxide film EF 2 In FIG. 6, the horizontal axis indicates the opening width CD [nm] of the opening OP of the mask film MF and the recess formed in the etching target film EF. As shown in FIG. 6, WF 6 In Examples 6 and 7, which further contain gas, WF6 Compared with Example 5, which does not contain gas, the mask film MF and the silicon oxide film EF 2 The bowing CD (maximum opening width) of the silicon oxide film EF was small, and bowing was suppressed. 2 The Boeing CD is Example 6 (WF 6 Gas: 1 sccm) and Example 7 (WF 6 Gas: 3 sccm) was the same as that of the silicon oxide film EF 2 The bowing suppression effect of the WF 6 This was also achieved by adding gas.

[0102] (Examples 8 and 9) In Examples 8 to 9, the plasma processing apparatus 1 was used to apply this processing method, and the same substrate as in Example 1 was etched. In Examples 8 and 9, 50% overetching was performed in step ST34. That is, in step ST34, the silicon oxide film EF was etched until the undercoat film UF was exposed. 2 Then, the silicon oxide film EF 2 The undercoat film UF was etched in the depth direction for half the time required for etching the undercoat film UF.

[0103] Silicon nitride film EF in Example 8 1 and silicon oxide film EF 2 The etching conditions were as follows: The first processing gas and the second processing gas each contained 85% by volume or more of HF gas. Silicon nitride film EF 1 Etching conditions (step ST32): Temperature of the substrate support: -70℃ Chamber pressure: 15mT First process gas: HF gas, C 4 F 8 Gas, O 2 gas Silicon oxide film EF 2 Etching conditions (step ST34): Temperature of the substrate support: -70℃ Chamber pressure: 15mT Second process gas: HF gas, C 4 F 8 Gas, C. 4 F 6 Gas, O 2 gas

[0104] In Example 9, the second process gas was 2 sccm of WF 6 Etching was carried out under the same conditions as in Example 8, except that a gas was further included.

[0105] FIG. 7 is a diagram showing the results of etching according to Example 8. In FIG. 7, "Example 8 (OE0%)" is the result before overetching in step ST34. "Example 8 (OE50%)" is the result after overetching in step ST34. FIG. 8 is a diagram showing the results of etching according to Example 9. In FIG. 8, "Example 9 (OE0%)" is the result before overetching in step ST34. "Example 9 (OE50%)" is the result after overetching in step ST34. In FIGS. 7 and 8, the vertical axis shows the depth D [μm] of the opening OP of the mask film MF and the recess formed in the film to be etched EF. The area around 0 μm on the vertical axis shows the depth D [μm] of the opening OP of the mask film MF and the recess formed in the film to be etched EF. 1 The area around -0.2 μm on the vertical axis is the boundary between the silicon nitride film EF 1 and silicon oxide film EF 2 7 and 8, the horizontal axis represents the opening width CD [nm] of the opening OP in the mask film MF and the recess formed in the etching target film EF.

[0106] As shown in FIG. 8, in Example 8, the mask film MF and the silicon oxide film EF were removed by overetching in step ST34. 2 The Boeing CD of 1000m2 was expanded. In response to this, WF 6 In Example 9 including the gas, the mask film MF and the silicon oxide film EF before and after the overetching in step ST34 2 There was little change in the Boeing CD of WF 6Example 9, which includes gas, was able to suppress the expansion of bowing due to over-etching.

[0107] This processing method may be modified in various ways without departing from the scope and spirit of the present disclosure. For example, this processing method may be performed using a plasma processing apparatus using any plasma source, such as an inductively coupled plasma or a microwave plasma, other than the capacitively coupled plasma processing apparatus 1. [Explanation of symbols]

[0108] REFERENCE SIGNS LIST 1: plasma processing apparatus, 2: control unit, 10: plasma processing chamber, 10s: plasma processing space, 11: substrate support unit, 13: shower head, 20: gas supply unit, 31a: first RF generation unit, 31b: second RF generation unit, 32a: first DC generation unit, MF: mask film, OP: opening, EF: film to be etched, EF 1 ……Silicon nitride film, EF 2 ……Silicon oxide film, UF…Base film, W…Substrate

Claims

1. 1. A plasma processing method performed in a plasma processing apparatus having a chamber, comprising: (a) providing a substrate having a film to be etched, the film including a silicon oxide film and a silicon nitride film, and a mask film defining an opening on the film to be etched, on a substrate support in a chamber; (b) HF gas and C x F y Gas (x and y are integers equal to or greater than 1) or C s H t F u generating plasma from a first process gas including a gas (where s, t, and u are integers of 1 or more) and an oxygen-containing gas to etch the silicon nitride film; (c) HF gas and C v F w generating plasma from a second process gas containing a gas (where v and w are integers of 1 or more) and an oxygen-containing gas to etch the silicon oxide film; A plasma processing method, wherein in (b) and (c), the temperature of the substrate support part is set to 0° C. or lower, in (b), the temperature of the substrate support part is set to a first temperature, and in (c), the temperature of the substrate support part is set to a second temperature lower than the first temperature.

2. The plasma processing method of claim 1 , wherein the first process gas includes a different type of gas than the second process gas.

3. The first process gas is s H t F u The plasma processing method of claim 1 , comprising a gas.

4. The first process gas is x F y Including gas, the C x F y The gas is the C contained in the second process gas. v F w 3. The plasma processing method of claim 2, wherein the gas is a different gas.

5. 5. The plasma processing method according to claim 1, wherein in (b), a bias signal of a first output is supplied to the substrate support, and in (c), a bias signal of a second output smaller than the first output is supplied to the substrate support, or no bias signal is supplied to the substrate support.

6. 6. The plasma processing method according to claim 1, wherein in (b), a pulse wave of a bias signal having a first duty ratio is supplied to the substrate support portion, and in (c), a pulse wave of a bias signal having a second duty ratio smaller than the first duty ratio is supplied to the substrate support portion.

7. 7. The plasma processing method according to claim 5, wherein the bias signal is a bias DC signal.

8. 7. The plasma processing method according to claim 1, wherein in (b), a bias RF signal of a first frequency is supplied to the substrate support, and in (c), a bias RF signal of a second frequency lower than the first frequency is supplied to the substrate support.

9. 9. The plasma processing method according to claim 1, wherein in (b), a heat transfer gas at a first pressure is supplied between the substrate and the substrate support, and in (c), a heat transfer gas at a second pressure lower than the first pressure is supplied between the substrate and the substrate support.

10. 10. The plasma processing method according to claim 1 , wherein in (b), a temperature of the heat transfer fluid supplied to the substrate support is set to a third temperature, and in (c), a temperature of the heat transfer fluid supplied to the substrate support is set to a fourth temperature lower than the third temperature.

11. 11. The plasma processing method according to claim 1, wherein the mask film is a polysilicon film, a boron-doped silicon film, a tungsten-containing film, an amorphous carbon film, a tin oxide film, or a titanium-containing film.

12. 12. The plasma processing method according to claim 1, wherein the opening width of the mask film is 50 nm or less.

13. Said C x F y Gas or the above C v F w 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 13. The plasma processing method according to claim 1, further comprising at least one gas selected from the group consisting of:

14. Said C s H t F u The gas is CHF 3 Gas, CH 2 F 2 Gas, CH 3 F gas, C 2 H.F. 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 H.F. 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 14. The plasma processing method according to claim 1, further comprising at least one gas selected from the group consisting of:

15. 15. The plasma processing method according to claim 1, wherein a flow rate of an HF gas is the largest among the first processing gas and the second processing gas.

16. 16. The plasma processing method of claim 1, wherein at least one of the first process gas and the second process gas further contains a phosphorus-containing gas.

17. At least one of the first process gas and the second process gas is WF 6 The plasma processing method of claim 1 , further comprising a gas.

18. 18. The plasma processing method according to claim 1, wherein in the steps (b) and (c), the temperature of the substrate supporting part is set to −50° C. or lower.

19. The plasma processing method according to claim 1, wherein the substrate is a substrate for manufacturing DRAM.

20. 1. A plasma processing method performed in a plasma processing apparatus having a chamber, comprising: (a) providing a substrate having a film to be etched, the film including a silicon oxide film and a silicon nitride film, and a mask film defining an opening on the film to be etched, on a substrate support in a chamber; (b) generating a first plasma from a first process gas, and x F y (x and y are integers of 1 or more) or C s H t F u Etching the silicon nitride film with a species (s, t, and u are integers of 1 or more) and an oxygen active species; (c) generating a second plasma from a second process gas, and v F w a step of etching the silicon oxide film with a species (v and w are integers of 1 or more) and an oxygen active species; A plasma processing method, wherein in (b) and (c), the temperature of the substrate support part is set to 0° C. or lower, in (b), the temperature of the substrate support part is set to a first temperature, and in (c), the temperature of the substrate support part is set to a second temperature lower than the first temperature.

21. The HF species is CH 2 F 2 Gas, C. 3 H 2 F 4 Gas and C 4 H 2 F 6 21. The plasma processing method of claim 20, wherein the plasma is generated from at least one gas selected from the group consisting of gases.

22. The apparatus includes a chamber, a substrate support unit provided in the chamber, a plasma generating unit, and a control unit, The control unit is (a) providing a substrate on the substrate support, the substrate having an etching target film including a silicon oxide film and a silicon nitride film and a mask film defining an opening on the etching target film; (b) The electric power supplied from the plasma generating unit is used to generate HF gas and C x F y Gas (x and y are integers equal to or greater than 1) or C s H t F u generating a plasma from a first process gas including a gas (where s, t, and u are integers of 1 or more) and an oxygen-containing gas to etch the silicon nitride film; (c) By the power supplied from the plasma generating unit, HF gas and C v F w generating a plasma from a second process gas including a gas (where v and w are integers of 1 or more) and an oxygen-containing gas to etch the silicon oxide film; In (b) and (c), the temperature of the substrate support is set to 0° C. or lower, in (b), the temperature of the substrate support is set to a first temperature, and in (c), the temperature of the substrate support is set to a second temperature lower than the first temperature. A plasma processing system that performs the control.

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