Etching method, method for manufacturing DRAM capacitor, and plasma processing apparatus

Abstract

The present invention provides a technique for improving the etching selection ratio of a silicon nitride film with respect to a mask. The etching method includes: (a) a step of providing a substrate including a laminated film including two or more different silicon-containing films, a single-layer film containing silicon and nitrogen on the laminated film, and a mask on the single-layer film on a substrate support portion in a chamber, the mask having a side wall defining at least one opening; (b) setting the temperature of the substrate support part or the substrate to 10 DEG C or more; and (c) etching the single-layer film using plasma generated from a first processing gas containing a hydrogen fluoride gas.

Description

TECHNICAL FIELD

[0001] An exemplary embodiment of the present application relates to an etching method, a manufacturing method of a DRAM capacitor, and a plasma processing apparatus. BACKGROUND

[0002] A technique of etching a silicon-containing film is disclosed in Patent Literature 1.

[0003] PRIOR ART DOCUMENT

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2016-21546 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] The present application provides a technique of improving an etching selectivity of a silicon nitride film with respect to a mask.

[0008] TECHNICAL SOLUTION FOR SOLVING THE PROBLEMS

[0009] An etching method in one exemplary embodiment of the present application includes:

[0010] (a) a step of providing a substrate including a laminated film, a single layer film containing silicon and nitrogen on the laminated film, and a mask on the single layer film, to a substrate support portion in a chamber, wherein the laminated film includes two or more different silicon-containing films, and the mask has a side wall defining at least one opening;

[0011] (b) a step of setting a temperature of the substrate support portion or the substrate to 10°C or higher; and

[0012] (c) a step of etching the single layer film using plasma generated from a first processing gas including hydrogen fluoride gas.

[0013] EFFECT OF THE INVENTION

[0014] According to one exemplary embodiment of the present application, a technique of improving an etching selectivity of a silicon nitride film with respect to a mask can be provided. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a view for explaining a structure example of a plasma processing system.

[0016] Figure 2 is a view for explaining a structure example of a plasma processing apparatus of an electric capacity coupling type.

[0017] Figure 3 is a flowchart showing an example of an etching method.

[0018] Figure 4 is a view for explaining an example of a cross-sectional structure of the substrate W.

[0019] Figure 5 is a flowchart showing an example of the step ST3.

[0020] Figure 6 is a view for explaining an example of a cross-sectional structure of the substrate W after the silicon nitride film is etched.

[0021] Figure 7 is a view for explaining an example of a cross-sectional structure of the substrate W after the laminated film is etched. DETAILED DESCRIPTION

[0022] Hereinafter, each embodiment of the present application will be described.

[0023] In one illustrative embodiment, there is provided an etching method, comprising: (a) a step of providing a substrate including a laminated film, a single layer film containing silicon and nitrogen on the laminated film, and a mask on the single layer film, to a substrate support portion in a chamber, wherein the laminated film includes two or more different silicon-containing films, and the mask has a side wall defining at least one opening; (b) a step of setting a temperature of the substrate support portion or the substrate to 10°C or higher; and (c) a step of etching the single layer film using plasma generated from a first process gas including a hydrogen fluoride gas.

[0024] In one illustrative embodiment, the laminated film has at least one laminated structure including a first silicon-containing film and a second silicon-containing film on the first silicon-containing film, the first silicon-containing film containing silicon and nitrogen, and the second silicon-containing film containing silicon and oxygen.

[0025] In one illustrative embodiment, the mask includes at least one selected from a silicon-containing film, a metal-containing film, and a carbon-containing film.

[0026] In one illustrative embodiment, the mask includes at least one selected from a metal, a carbide of the metal, and a silicide of the metal, the metal being selected from at least one of tungsten, molybdenum, ruthenium, and titanium.

[0027] In one illustrative embodiment, the mask includes at least one selected from BSi, WSi, and WSiN.

[0028] In one illustrative embodiment, the width of the opening is 50 nm or less.

[0029] In one illustrative embodiment, the single layer film is thicker than the first silicon-containing film.

[0030] In one illustrative embodiment, the first process gas further includes at least one carbon-containing gas selected from a fluorocarbon gas and a hydrofluorocarbon gas.

[0031] In one illustrative embodiment, the ratio of the flow rate of the hydrogen fluoride gas to the flow rate of the carbon-containing gas is 1 or more and 5 or less.

[0032] In one illustrative embodiment, the fluorocarbon gas includes at least one selected from the group consisting of C4F6 gas, C4F8 gas, and C3F8 gas.

[0033] In one illustrative embodiment, the hydrofluorocarbon gas includes at least one selected from the group consisting of CH2F2 gas, CHF3 gas, CH3F gas, C3H2F4 gas, and C4H2F6 gas.

[0034] In one illustrative embodiment, the first processing gas further includes an oxygen-containing gas.

[0035] In one illustrative embodiment, the oxygen-containing gas includes at least one selected from the group consisting of O2 gas, CO gas, and CO2 gas.

[0036] In one illustrative embodiment, the first processing gas further includes a fluorine-containing gas that does not contain carbon.

[0037] In one illustrative embodiment, the fluorine-containing gas includes NF3 gas.

[0038] In one illustrative embodiment, in the step (b), the temperature of the substrate support portion or the substrate is set to a range of 40°C or more and 90°C or less.

[0039] In one illustrative embodiment, further comprising: (d) after the step (c), a step of etching the laminated film using a plasma generated from a second processing gas.

[0040] In one illustrative embodiment, the second processing gas includes at least one carbon-containing gas selected from the group consisting of hydrogen fluoride gas, fluorocarbon gas, and hydrofluorocarbon gas.

[0041] In one illustrative embodiment, in the step (d), the temperature of the substrate support portion or the substrate at the time of etching the second silicon-containing film possessed by the laminated film is set to be higher than the temperature of the substrate support portion or the substrate at the time of etching the first silicon-containing film possessed by the laminated film.

[0042] In one exemplary embodiment, a method for manufacturing a DRAM capacitor is provided, comprising: (a) providing a substrate comprising a multilayer film, a silicon- and nitrogen-containing monolayer film on the multilayer film, and a mask on the monolayer film onto a substrate support in a cavity, wherein the multilayer film comprises two or more different silicon-containing films, and the mask has a sidewall with at least one opening; (b) setting the temperature of the substrate support or the substrate to 10°C or higher; (c) etching the monolayer film using plasma generated from a first process gas containing hydrogen fluoride gas; and (d) etching the multilayer film using plasma generated from a second process gas.

[0043] In one exemplary embodiment, a plasma processing apparatus is provided, comprising a chamber, a substrate support disposed within the chamber, a plasma generation unit, and a control unit, the control unit performing: (a) controlling the provision of a substrate comprising a laminated film, a silicon- and nitrogen-containing monolayer film on the laminated film, and a mask on the monolayer film to the substrate support within the chamber, wherein the laminated film comprises two or more different silicon-containing films, and the mask has a sidewall with at least one defined opening; (b) controlling the setting of the temperature of the substrate support or the substrate to 10°C or higher; and (c) controlling the etching of the monolayer film using plasma generated from a first processing gas containing hydrogen fluoride gas.

[0044] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Furthermore, the same or similar elements will be labeled with the same reference numerals in the drawings, and repeated descriptions will be omitted. Unless otherwise specified, positional relationships such as up, down, left, and right are described based on the positional relationships shown in the drawings. The scale of the drawings does not represent an actual scale, and the actual scale is not limited to the scale shown.

[0045] <An example of a plasma processing system>

[0046] Figure 1This is a diagram illustrating a structural example of a plasma processing system. In one embodiment, the plasma processing system includes a plasma processing apparatus 1 and a control unit 2. The plasma processing system is an example of a substrate processing system, and the plasma processing apparatus 1 is an example of a substrate processing apparatus. The plasma processing apparatus 1 includes a plasma processing chamber 10, a substrate support 11, and a plasma generation unit 12. The plasma processing chamber 10 has a plasma processing space. Furthermore, the plasma processing chamber 10 has at least one gas supply port for supplying at least one processing gas into the plasma processing space, and at least one gas outlet for discharging gas from the plasma processing space. The gas supply port is connected to the gas supply unit 20 (described later), and the gas outlet is connected to the exhaust system 40 (described later). The substrate support 11 is disposed within the plasma processing space and has a substrate support surface for supporting a substrate.

[0047] The plasma generation unit 12 is configured to generate plasma from at least one process gas supplied to the plasma processing space. The plasma generated in the plasma processing space can be capacitively coupled plasma (CCP), inductively coupled plasma (ICP), electron-cyclotron-resonance plasma (ECR), helicon wave plasma (HWP), or surface wave plasma (SWP), etc. Furthermore, various types of plasma generation units, including AC (alternating current) plasma generation units and DC (direct current) plasma generation units, can also be used. In one embodiment, the AC signal (AC power) used in the AC plasma generation unit has a frequency in the range of 100 kHz to 10 GHz. Therefore, the AC signal includes RF (radio frequency) signals and microwave signals. In one embodiment, the RF signal has a frequency in the range of 100 kHz to 150 MHz.

[0048] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform the various steps described herein. The control unit 2 may be configured to control the various elements of the plasma processing apparatus 1 to perform the various steps described herein. In one embodiment, part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The control unit 2 may be implemented, for example, by a computer 2a. The processing unit 2a1 may be configured to read a program from the storage unit 2a2 and execute the read program to perform various control actions. The program may be pre-stored in the storage unit 2a2 or retrieved via a medium when needed. The retrieved program is stored in the storage unit 2a2 and read and executed by the processing unit 2a1. The medium may be various storage media readable by the computer 2a or a communication line connected to the communication interface 2a3. The processing unit 2a1 may be a CPU (Central Processing Unit). The storage unit 2a2 may include RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or a combination thereof. The communication interface 2a3 can communicate with the plasma processing device 1 via a communication line such as a LAN (Local Area Network).

[0049] Hereinafter, a structural example of a capacitively coupled plasma processing device, which is an example of plasma processing device 1, will be described. Figure 2 This is a diagram illustrating a structural example of a capacitively coupled plasma processing device.

[0050] The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply 30, and an exhaust system 40. Furthermore, the plasma processing apparatus 1 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 spray head 13. The substrate support 11 is disposed within the plasma processing chamber 10. The spray head 13 is disposed above the substrate support 11. In one embodiment, the spray head 13 constitutes at least a portion of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the spray head 13, the sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 is grounded. The spray head 13 and the substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0051] The substrate support portion 11 includes a main body portion 111 and a ring assembly 112. The main body portion 111 has a central region 111a for supporting a substrate W and an annular region 111b for supporting the ring assembly 112. A wafer is an example of a substrate W. The annular region 111b of the main body portion 111 surrounds the central region 111a of the main body portion 111 in a top view. The substrate W is disposed on the central region 111a of the main body portion 111, and the ring assembly 112 is disposed on the annular region 111b of the main body portion 111 in such a way that it surrounds the substrate W on the central region 111a of the main body portion 111. Therefore, the central region 111a is also referred to as a substrate support surface for supporting the substrate W, and the annular region 111b is also referred to as an annular support surface for supporting the ring assembly 112.

[0052] In one embodiment, the main body 111 includes a base 1110 and an electrostatic chuck 1111. The base 1110 includes a conductive component. The conductive component of the base 1110 functions as a lower electrode. The electrostatic chuck 1111 is disposed on the base 1110. The electrostatic chuck 1111 includes a ceramic component 1111a and an electrostatic electrode 1111b disposed within the ceramic component 1111a. The ceramic component 1111a has a central region 111a. In one embodiment, the ceramic component 1111a also has an annular region 111b. Furthermore, other components surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating component, may also have an annular region 111b. In this case, the ring assembly 112 may be disposed on the annular electrostatic chuck or the annular insulating component, or on both the electrostatic chuck 1111 and the annular insulating component. Furthermore, at least one RF / DC electrode coupled to the RF power supply 31 and / or DC power supply 32 (described later) may also be disposed within the ceramic component 1111a. In this case, the at least one RF / DC electrode functions as a lower electrode. When a bias RF signal and / or DC signal (described later) are supplied to the at least one RF / DC electrode, the RF / DC electrode is also referred to as a bias electrode. Furthermore, the conductive components of the base 1110 and the at least one RF / DC electrode may also function as multiple lower electrodes. Additionally, the electrostatic electrode 1111b may also function as a lower electrode. Therefore, the substrate support portion 11 includes at least one lower electrode.

[0053] The ring assembly 112 includes one or more annular components. In one embodiment, the one or more annular components 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.

[0054] Furthermore, the substrate support 11 may also include a temperature control module configured to adjust at least one of the electrostatic chuck 1111, the ring assembly 112, and the substrate to a target temperature. The temperature control module may include a heater, a heat transfer medium, a flow path 1110a, or a combination thereof. A heat transfer fluid such as brine or gas can flow in the flow path 1110a. In one embodiment, the flow path 1110a is formed within the base 1110, and one or more heaters are disposed within the ceramic component 1111a of the electrostatic chuck 1111. Additionally, the substrate support 11 may also include a heat transfer gas supply section configured to supply heat transfer gas to the gap between the back surface of the substrate W and the central region 111a.

[0055] The spray head 13 is configured to introduce at least one process gas from the gas supply unit 20 into the plasma processing space 10s. The spray head 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and a plurality of gas inlets 13c. The process gas supplied to the gas supply port 13a is introduced into the plasma processing space 10s through the gas diffusion chamber 13b and the plurality of gas inlets 13c. Furthermore, the spray head 13 includes at least one upper electrode. In addition to the spray head 13, the gas inlet may also include one or more side gas injectors (SGIs) mounted on one or more openings formed in the sidewall 10a.

[0056] The gas supply unit 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply unit 20 is configured to supply at least one process gas from its respective gas source 21 to the spray head 13 via its respective flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Furthermore, the gas supply unit 20 may include at least one flow modulation device for modulating or pulsed the flow rate of the at least one process gas.

[0057] The power supply 30 includes an RF power supply 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power supply 31 is configured to supply at least one RF signal (RF power) to at least one lower electrode and / or at least one upper electrode. This generates plasma from at least one processing gas supplied to the plasma processing space 10s. Therefore, the RF power supply 31 can function as at least a part of the plasma generation unit 12. Furthermore, by supplying a bias RF signal to at least one lower electrode, a bias potential is generated on the substrate W, which can attract ionic components in the generated plasma to the substrate W.

[0058] In one embodiment, the RF power supply 31 includes a first RF generation unit 31a and a second RF generation unit 31b. The first RF generation unit 31a is coupled to at least one lower electrode and / or at least one upper electrode via at least one impedance matching circuit, and is configured to generate a generation source RF signal (generation source RF power) for plasma generation. In one embodiment, the generation source RF signal has a frequency in the range of 10MHz to 150MHz. In one embodiment, the first RF generation unit 31a may also be configured to generate multiple generation source RF signals with different frequencies. The generated one or more generation source RF signals are supplied to at least one lower electrode and / or at least one upper electrode.

[0059] The second RF generation unit 31b is coupled to at least one lower electrode via at least one impedance matching circuit, and is configured to generate a bias RF signal (bias RF power). The frequency of the bias RF signal may be the same as or different from the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency lower than that of the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 100 kHz to 60 MHz. In one embodiment, the second RF generation unit 31b may also be configured to generate multiple bias RF signals with different frequencies. The generated one or more bias RF signals are supplied to at least one lower electrode. Furthermore, in various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0060] Furthermore, the power supply 30 may include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generating unit 32a and a second DC generating unit 32b. In one embodiment, the first DC generating unit 32a is connected to at least one lower electrode and is configured to generate a first DC signal. The generated first DC signal is applied to at least one lower electrode. In one embodiment, the second DC generating unit 32b is connected to at least one upper electrode and is configured to generate a second DC signal. The generated second DC signal is applied to at least one upper electrode.

[0061] In various embodiments, the first and second DC signals can be pulsed. In this case, a sequence of voltage pulses is applied to at least one lower electrode and / or at least one upper electrode. The voltage pulses can have rectangular, trapezoidal, triangular, or combinations thereof pulse waveforms. In one embodiment, a waveform generation unit for generating a sequence of voltage pulses from the DC signals is connected between the first DC generation unit 32a and at least one lower electrode. Therefore, the first DC generation unit 32a and the waveform generation unit constitute a voltage pulse generation unit. When the second DC generation unit 32b and the waveform generation unit constitute a voltage pulse generation unit, the voltage pulse generation unit is connected to at least one upper electrode. The voltage pulses can have positive or negative polarity. Furthermore, the sequence of voltage pulses can include one or more positive voltage pulses and one or more negative voltage pulses within one cycle. Additionally, the first and second DC generation units 32a and 32b can be provided outside the RF power supply 31, or the first DC generation unit 32a can be provided instead of the second RF generation unit 31b.

[0062] The exhaust system 40 can be connected to a gas outlet 10e, for example, located at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure regulating valve allows for the regulation of the pressure within the plasma processing space 10s. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0063] <An example of an etching method>

[0064] Figure 3 This is a flowchart illustrating an example of an etching method (hereinafter also referred to as "this method") according to an exemplary implementation. Figure 3 As shown, in one embodiment, the method includes a step ST1 of providing a substrate, a step ST2 of setting the temperature of the substrate support or the substrate, and a step ST3 of etching. In one embodiment, the processing in each step can be performed in a plasma processing apparatus 1 (see reference 1). Figure 2 The method is executed within the plasma processing apparatus 1. In the following example, the control unit 2 controls each part of the plasma processing apparatus 1 to execute this method.

[0065] (Step ST1: Provide the substrate)

[0066] In step ST1, the substrate W can be provided to the plasma processing space 10s of the plasma processing apparatus 1. In one embodiment, the substrate W is provided to the central region 111a of the substrate support 11 and held on the substrate support 11 by an electrostatic chuck 1111.

[0067] Figure 4This is a diagram illustrating an example of the cross-sectional structure of the substrate W provided in step ST1. The substrate W has a laminated film SF, a silicon nitride film F1, and a mask MF. In one embodiment, the laminated film SF, the silicon nitride film F1, and the mask MF are formed on a base film UF. In one embodiment, the substrate W can be formed by sequentially laminating the base film UF, the laminated film SF, the silicon nitride film F1, and the mask MF from bottom to top. In one embodiment, the substrate W is used for the manufacture of a semiconductor device. The semiconductor device is, for example, a DRAM capacitor.

[0068] In one embodiment, the substrate UF is a silicon wafer or an organic film, dielectric film, metal film, semiconductor film, etc., formed on a silicon wafer. The substrate UF can be composed of multiple film layers stacked together.

[0069] In one embodiment, the laminated film SF is the film to be etched in this method. In one embodiment, the laminated film SF has two or more different silicon-containing films. The laminated film SF comprises at least one laminated structure containing a first silicon-containing film and a second silicon-containing film. The first silicon-containing film may be a silicon nitride film SF2 containing silicon and nitrogen. The second silicon-containing film may be a silicon oxide film SF1 containing silicon and oxygen. The silicon oxide film SF1 and the silicon nitride film SF2 may contain impurities such as phosphorus, boron, and nitrogen.

[0070] In one embodiment, the laminated SF film can be as follows: Figure 4 As shown, the film is constructed by alternately stacking multiple layers of silicon oxide film SF1 and silicon nitride film SF2. In one embodiment, the stacked film SF can be constructed by stacking silicon oxide film SF1 and silicon nitride film SF2 in a given order. The stacked film SF may have silicon oxide film SF1 on top of silicon nitride film SF2, and silicon nitride film F1 on top of silicon oxide film SF1. The silicon nitride film SF2 of the stacked film SF may be a thinner film than the silicon nitride film F1 on the stacked film SF.

[0071] In one embodiment, the silicon nitride film F1 is the film to be etched in this method. The silicon nitride film F1 can be disposed on the laminated film SF and directly below the mask MF. The silicon nitride film F1 is an example of a monolayer film containing silicon and nitrogen. The silicon nitride film F1 may contain impurities such as phosphorus, boron, and nitrogen. The silicon nitride film F1 may be thicker than the silicon nitride film SF1.

[0072] In one embodiment, the mask MF is a film that acts as a mask during the etching of the silicon nitride film F1. The mask MF can be a different film from the film to be etched. The mask MF can be formed of a material whose etching rate for the plasma generated in step ST3 described later is lower than that for the silicon nitride film F1 and the stacked film SF. The mask MF can contain at least one selected from silicon-containing films, metal-containing films, and carbon-containing films. The mask MF can be a polycrystalline silicon film or a film containing boron and silicon. The mask MF can be, for example, a BSi (boron silicide) film. The mask MF can contain a film of a material selected from at least one selected from tungsten, molybdenum, ruthenium, and titanium. The mask MF can, for example, contain a carbide or silicide of tungsten, molybdenum, or titanium. The mask MF can contain tungsten and at least one selected from silicon, carbon, and nitrogen. In one example, the mask MF can contain at least one selected from WC (tungsten carbide), WSi (tungsten silicide), WSiN, and WSiC, and can contain at least one selected from WSi and WSiN. The mask MF can also be an amorphous carbon film. A mask (MF) can be a single-layer mask consisting of a single film or a multilayer mask consisting of two or more stacked films.

[0073] like Figure 4 As shown, the mask MF may have sidewalls with at least one opening OP on the silicon nitride film F1. The mask MF may have an opening OP. The opening OP is a space on the silicon nitride film F1 that can be surrounded by the sidewalls of the mask MF. That is, the upper surface of the silicon nitride film F1 may have an area covered by the mask MF and an area exposed at the bottom of the opening OP.

[0074] The opening OP is in the top view of the substrate W, that is, from... Figure 4 When viewing the substrate W from above, it can have any shape. This shape can be, for example, a circle, an ellipse, a rectangle, a line, or a combination of more than one of these. The mask MF can have multiple sidewalls, which can define multiple openings (OPs). The multiple openings (OPs) can each have a line shape and be arranged at certain intervals to form a line and space pattern. Furthermore, the multiple openings (OPs) can each have a aperture shape, forming an array pattern. The width of the openings (OPs) can be less than 50 nm.

[0075] The various films constituting the substrate W (base film UF, laminated film SF, silicon nitride film F1, and mask MF) can be formed using methods such as CVD, ALD, and spin coating. The opening OP can be formed by etching the mask MF. Alternatively, the mask MF can also be formed using photolithography. Furthermore, each film can be planar or have an uneven surface. Additionally, the substrate W may have other films beneath the base film UF; the laminated film composed of silicon nitride film F1, laminated film SF, and base film UF can function as a multilayer mask. That is, the laminated film of silicon nitride film F1, laminated film SF, and base film UF can be used as a multilayer mask to etch the other films.

[0076] In one embodiment, at least a portion of the steps for forming the films of the substrate W can be performed within the plasma processing space for 10 seconds as part of step ST1. For example, in the case of forming the opening OP of the mask MF by etching, the etching of the mask MF in step ST1 and the etching of the silicon nitride film F1 and the stacked film SF in step ST3 (described later) can be performed continuously within the plasma processing space for 10 seconds. In one embodiment, the substrate W can be provided to the plasma processing space for 10 seconds after all or part of the films of the substrate W have been formed in a device or chamber outside the plasma processing apparatus 1.

[0077] (Step ST2: Temperature setting)

[0078] In step ST2, the temperature of the substrate support 11 or the substrate W can be set to a predetermined temperature. In one embodiment, after the substrate W is provided to the central region 111a of the substrate support 11, the temperature of the substrate support 11 or the substrate W is adjusted to the set temperature by a temperature control module. In one embodiment, the temperature of the substrate support 11 or the substrate W is set to 10°C or higher. In another embodiment, the temperature of the substrate support 11 or the substrate W is set within the range of 40°C to 90°C, or 40°C to 80°C. In one embodiment, the process of adjusting or maintaining the temperature of the substrate support 11 or the substrate W includes adjusting or maintaining the temperature of the heat transfer fluid flowing in the flow path 1110a at or below the set temperature. In one example, the process of adjusting or maintaining the temperature of the substrate support 11 or the substrate W includes controlling the pressure of the heat transfer gas (e.g., He) between the electrostatic chuck 1111 and the back surface of the substrate W. Furthermore, the timing of the heat transfer fluid starting to flow into flow path 1110a can be before, after, or simultaneously with the substrate W being placed on substrate support 11. Additionally, the temperature of substrate support 11 or substrate W can be adjusted before step ST1. That is, substrate W can be provided to substrate support 11 after the temperature of substrate support 11 or substrate W has been adjusted to a set temperature.

[0079] (Step ST3: Etching)

[0080] In step ST3, the silicon nitride film F1 and the stacked film SF can be etched. Figure 5 This is a flowchart illustrating an example of step ST3. In one embodiment, step ST3 includes step ST3-1 of etching the silicon nitride film F1 using a first processing gas, and step ST3-2 of etching the multilayer film SF using a second processing gas.

[0081] In step ST3-1, firstly, it can be obtained from Figure 2 The gas supply unit 20 shown supplies a first processing gas into the plasma processing space for 10 seconds. The first processing gas may contain hydrogen fluoride gas and at least one carbon-containing gas selected from CF gas (fluorocarbon gas) and CHF gas (hydrofluorocarbon gas). The ratio of the flow rate of hydrogen fluoride gas to the flow rate of the carbon-containing gas (hydrogen fluoride gas flow rate / carbon-containing gas flow rate) may be 1 to 5 or more, or 2 to 4 or less. In one embodiment, the first processing gas may contain hydrogen fluoride gas, CF gas, CHF gas, oxygen-containing gas, and a carbon-free fluorinated gas. In one embodiment, the first processing gas may not contain CHF gas, but may contain hydrogen fluoride gas, CF gas, oxygen-containing gas, and a carbon-free fluorinated gas.

[0082] The CF gas may contain at least one selected from C4F6, C4F8, and C3F8 gases. In one example, the CF gas may be at least one selected from C4F6, C4F8, C3F8, CF4, C2F2, C2F4, C3F6, and C5F8 gases.

[0083] CHF gas may contain at least one gas selected from CH2F2, CHF3, CH3F, C3H2F4, and C4H2F6. In one example, CHF gas may be selected from CH2F2, CHF3, CH3F, C3H2F4, C4H2F6, C2HF5, C2H2F4, C2H3F3, C2H4F2, C3HF7, C3H2F2, C3H2F6, C3H3F5, C4H5F5, C4H2F8, C5H2F6, and C5H2F6. 10 At least one of the following: gas and C5H3F7 gas.

[0084] The oxygen-containing gas may include at least one selected from O2 gas, CO gas, and CO2 gas. In one example, the oxygen-containing gas may be, for example, at least one selected from O2 gas, CO gas, CO2 gas, H2O gas, and H2O2 gas.

[0085] Fluorine-containing gases that do not contain carbon can include NF3 gas.

[0086] In step ST3-1, plasma can be generated from the first process gas and used to etch the silicon nitride film F1.

[0087] In one implementation, the generator RF signal is then supplied to... Figure 2 The lower electrode of the substrate support 11 and / or the upper electrode of the spray head 13 are shown. This generates a high-frequency electric field between the spray head 13 and the substrate support 11, generating plasma from the processing gas within the plasma processing space for 10 seconds. At this time, a bias signal can be supplied to the lower electrode of the substrate support 11. In this case, a bias potential is generated between the plasma and the substrate W. Ions, free radicals, and other active species in the plasma are attracted to the substrate W, and these active species are used to etch the silicon nitride film F1. The bias signal can be a bias RF signal supplied from the RF power supply 31 or a bias DC signal supplied from the DC power supply 32.

[0088] Figure 6 This is a diagram illustrating an example of the cross-sectional structure of the substrate W after the silicon nitride film F1 has been etched in step ST3-1. In one embodiment, the portion of the silicon nitride film F1 not covered by the mask MF (the portion exposed in the opening OP) is etched to form a recess.

[0089] Next, in Figure 5 In step ST3-2 shown, plasma can be generated from the second process gas and used to etch the stacked SF film.

[0090] In step ST3-2, firstly, it can be obtained from Figure 2 The gas supply unit 20 shown supplies a second processing gas into the plasma processing space for 10 seconds. The second processing gas may contain at least one carbon-containing gas selected from hydrogen fluoride, CF, and CHF. The second processing gas may not contain hydrogen fluoride. In one embodiment, the second processing gas may contain CF, an oxygen-containing gas, and a carbon-free fluorine-containing gas. In one embodiment, the second processing gas may also contain CHF. Alternatively, the second processing gas may be the same as the first processing gas.

[0091] The CF gas may contain at least one selected from C4F6, C4F8, and C3F8 gases. In one example, the CF gas may be at least one selected from C4F6, C4F8, C3F8, CF4, C2F2, C2F4, C3F6, and C5F8 gases.

[0092] CHF gas may contain at least one gas selected from CH2F2, CHF3, CH3F, C3H2F4, and C4H2F6. In one example, CHF gas may be selected from CH2F2, CHF3, CH3F, C3H2F4, C4H2F6, C2HF5, C2H2F4, C2H3F3, C2H4F2, C3HF7, C3H2F2, C3H2F6, C3H3F5, C4H5F5, C4H2F8, C5H2F6, and C5H2F6. 10 At least one of the following: gas and C5H3F7 gas.

[0093] The oxygen-containing gas may include at least one selected from O2, CO, and H2O. In one example, the oxygen-containing gas may be a gas selected from at least one of O2, CO, CO2, H2O, and H2O2.

[0094] Fluorine-containing gases that do not contain carbon can include NF3 gas.

[0095] In step ST3-2, plasma can be generated from the second processing gas and used to etch the stacked SF film.

[0096] At this point, similar to step ST3-1, the generated source RF signal is supplied to... Figure 2 The lower electrode of the substrate support 11 and / or the upper electrode of the spray head 13, as shown, generate plasma from the second processing gas within the plasma processing space for 10 seconds. At this time, a bias signal can be supplied to the lower electrode of the substrate support 11. The bias signal can be a bias RF signal supplied from the RF power supply 31 or a bias DC signal supplied from the DC power supply 32. Using the generated plasma, the silicon oxide film SF1 and the silicon nitride film SF2 of the stacked film SF are alternately etched.

[0097] When etching the silicon oxide film SF1 and the silicon nitride film SF2, the types of gases constituting the second processing gas can be the same or different. When the types of gases in the second processing gas are different, during the etching of the silicon oxide film SF1, the second processing gas can include CF gas, oxygen-containing gas, and a carbon-free fluorine-containing gas. During the etching of the silicon nitride film SF1, it can include CF gas, CHF gas, oxygen-containing gas, and a carbon-free fluorine-containing gas.

[0098] In step ST3-2, the temperature of the substrate support 11 or substrate W when etching the silicon oxide film SF1 can be set higher than the temperature of the substrate support 11 or substrate W when etching the silicon nitride film SF2.

[0099] Figure 7 This is a diagram illustrating an example of the cross-sectional structure of the substrate W after the laminated film SF has been etched in step ST3-2. In one embodiment, the portion of the laminated film SF not covered by the mask MF (the portion exposed in the opening OP) is etched to form a recess.

[0100] According to this exemplary embodiment, the etching method includes: (a) providing a substrate W comprising a silicon nitride film F1 and a mask MF on the silicon nitride film F1 onto a substrate support 11 disposed within a chamber 10; (b) setting the temperature of the substrate support 11 or the substrate W to 10°C or higher; and (c) etching the silicon nitride film F1 using plasma generated from a first processing gas, wherein the first processing gas comprises hydrogen fluoride gas and at least one carbon-containing gas selected from CF gas and CHF gas. By including hydrogen fluoride gas in the first processing gas, the etch selectivity of the silicon nitride film F1 relative to the mask MF can be improved. Furthermore, by including a carbon-containing gas in the first processing gas, the walls of the holes in the silicon nitride film F1 can be protected, and the bowing effect, in which a portion of the hole diameter increases, can be suppressed.

[0101] <Example>

[0102] An experiment was conducted to etch a substrate with a mask on a silicon nitride film using a specified processing gas. The temperature of the substrate support was set to 10°C or higher. The processing gases described in (1) to (3) below were used in the experiment.

[0103] (1) Processing gas containing CH2F2 gas (flow rate ratio CH2F2 gas:C4F6 gas:HF=4.5:1:0)

[0104] (2) Processing gas containing CH2F2 gas, C4F6 gas, and hydrogen fluoride gas (flow rate ratio CH2F2 gas:C4F6 gas:HF=1:1:4)

[0105] (3) Processing gas containing C4F6 gas and hydrogen fluoride gas (flow ratio CH2F2 gas:C4F6 gas:HF=0:1:2.5)

[0106] When using processing gases (2) and (3), the etch rate of the mask decreased compared to the case where processing gas (1) was used. The bow-shaped effect of the pores in the silicon nitride film was reduced. When using processing gas (3), the etch rate of the mask decreased compared to the case where processing gas (2) was used, while the etch rate of the silicon nitride film increased. The bow-shaped effect of the pores in the silicon nitride film was reduced. Based on this experiment, it was confirmed that by including hydrogen fluoride gas and at least one carbon-containing gas selected from CF gas and CHF gas in the processing gas, the etch selectivity of the silicon nitride film relative to the mask was improved, and the bow-shaped effect of the pores in the silicon nitride film was reduced.

[0107] In the above embodiments, this method is not limited to inductively coupled plasma processing devices, but can also be carried out in other types of plasma processing devices, such as plasma processing devices that generate capacitively coupled plasma, plasma processing devices that generate ECR plasma, plasma processing devices that generate helical wave excited plasma, or plasma processing devices that generate surface wave plasma.

[0108] The embodiments of the present invention also include the following aspects.

[0109] (Note 1)

[0110] An etching method comprising:

[0111] (a) The step of providing a substrate comprising a multilayer film, a silicon and nitrogen-containing monolayer film on the multilayer film, and a mask on the monolayer film to a substrate support in a cavity, wherein the multilayer film comprises two or more different silicon-containing films, and the mask has a sidewall with at least one opening.

[0112] (b) The step of setting the temperature of the substrate support or the substrate to 10°C or higher; and

[0113] (c) The step of etching the monolayer film using plasma generated from a first processing gas containing hydrogen fluoride gas.

[0114] (Note 2)

[0115] According to the etching method described in Appendix 1, in which,

[0116] The aforementioned laminated film has at least one laminated structure comprising a first silicon-containing film and a second silicon-containing film on the first silicon-containing film.

[0117] The first silicon-containing film mentioned above contains silicon and nitrogen.

[0118] The aforementioned second silicon-containing film contains silicon and oxygen.

[0119] (Note 3)

[0120] According to the etching method described in Appendix 1, in which,

[0121] The aforementioned mask comprises at least one selected from silicon-containing films, metal-containing films, and carbon-containing films.

[0122] (Note 4)

[0123] According to the etching method described in Appendix 1, in which,

[0124] The mask comprises at least one selected from metals, carbides of the metals, and silicides of the metals, wherein the metals are selected from at least one selected from tungsten, molybdenum, ruthenium, and titanium.

[0125] (Note 5)

[0126] According to the etching method described in Appendix 1, in which,

[0127] The aforementioned mask comprises at least one selected from BSi, WSi, and WSiN.

[0128] (Note 6)

[0129] According to any one of the etching methods described in Appendix 1 to 5, wherein,

[0130] The width of the aforementioned opening is less than 50 nm.

[0131] (Note 7)

[0132] According to the etching method described in Appendix 2, in which,

[0133] The aforementioned single-layer film is thicker than the aforementioned first silicon-containing film.

[0134] (Postscript 8)

[0135] According to any of the etching methods described in Appendix 1 to 7, wherein,

[0136] The first processing gas mentioned above also includes at least one carbon-containing gas selected from fluorocarbon gases and hydrofluorocarbon gases.

[0137] (Note 9)

[0138] According to the etching method described in Appendix 8, in which,

[0139] The ratio of the flow rate of the aforementioned hydrogen fluoride gas to the flow rate of the aforementioned carbon-containing gas is more than 1 and less than 5.

[0140] (Postscript 10)

[0141] According to the etching method described in Appendix 8 or 9, in which,

[0142] The aforementioned fluorocarbon gas contains at least one selected from C4F6, C4F8, and C3F8 gases.

[0143] (Postscript 11)

[0144] According to any of the etching methods described in Appendix 8 to 10, wherein,

[0145] The aforementioned hydrofluorocarbon gas contains at least one selected from CH2F2 gas, CHF3 gas, CH3F gas, C3H2F4 gas, and C4H2F6 gas.

[0146] (Postscript 12)

[0147] According to any of the etching methods described in Appendix 8 to 11, wherein,

[0148] The first processed gas also includes oxygen-containing gas.

[0149] (Postscript 13)

[0150] According to the etching method described in Appendix 12, in which,

[0151] The oxygen-containing gas mentioned above includes at least one selected from O2 gas, CO gas and CO2 gas.

[0152] (Postscript 14)

[0153] According to any of the etching methods described in Appendix 8 to 13, wherein,

[0154] The first processed gas also includes fluorine-containing gases that do not contain carbon.

[0155] (Postscript 15)

[0156] According to the etching method described in Appendix 14, in which,

[0157] The aforementioned fluorine-containing gases include NF3 gas.

[0158] (Postscript 16)

[0159] According to any of the etching methods described in Appendix 1 to 15, wherein,

[0160] In step (b) above, the temperature of the substrate support or the substrate is set to a range of 40°C to 90°C.

[0161] (Postscript 17)

[0162] The etching method described above according to any one of Appendices 1 to 16 further includes:

[0163] (d) After step (c) above, the above-mentioned laminated film is etched using plasma generated from the second processing gas.

[0164] (Postscript 18)

[0165] According to the etching method described in Appendix 17, in which,

[0166] The second processing gas mentioned above contains at least one carbon-containing gas selected from hydrogen fluoride gas, fluorocarbon gas, and hydrofluorocarbon gas.

[0167] (Postscript 19)

[0168] According to the etching method described in Appendix 17 or 18, wherein,

[0169] The aforementioned laminated film has at least one laminated structure comprising a first silicon-containing film and a second silicon-containing film on the first silicon-containing film.

[0170] The first silicon-containing film mentioned above contains silicon and nitrogen.

[0171] The second silicon-containing film mentioned above contains silicon and oxygen.

[0172] In step (d) above, the temperature of the substrate support or the substrate when etching the second silicon-containing film of the laminated film is set to be higher than the temperature of the substrate support or the substrate when etching the first silicon-containing film of the laminated film.

[0173] (Postscript 20)

[0174] A method for manufacturing a DRAM capacitor, comprising:

[0175] (a) The step of providing a substrate comprising a multilayer film, a silicon and nitrogen-containing monolayer film on the multilayer film, and a mask on the monolayer film to a substrate support in a cavity, wherein the multilayer film comprises two or more different silicon-containing films, and the mask has a sidewall with at least one opening.

[0176] (b) The step of setting the temperature of the substrate support or the substrate to 10°C or higher; and

[0177] (c) The step of etching the monolayer film using plasma generated from a first processing gas containing hydrogen fluoride gas, and

[0178] (d) The step of etching the above-mentioned laminated film using plasma generated from the second processing gas.

[0179] (Postscript 21)

[0180] A plasma processing apparatus includes a chamber, a substrate support disposed within the chamber, a plasma generation unit, and a control unit.

[0181] The above-mentioned control department shall perform the following:

[0182] (a) Controlling the provision of a substrate comprising a multilayer film, a silicon and nitrogen-containing monolayer film on the multilayer film, and a mask on the monolayer film to a substrate support in a cavity, wherein the multilayer film comprises two or more different silicon-containing films, and the mask has a sidewall with at least one opening.

[0183] (b) Controlling the temperature of the substrate support or the substrate to 10°C or higher; and

[0184] (c) The etching of the monolayer film is controlled using plasma generated from a first processing gas containing hydrogen fluoride gas.

[0185] The above embodiments are described for illustrative purposes only and are not intended to limit the scope of the present invention. Various modifications can be made to the above embodiments without departing from the scope and spirit of the present invention. For example, some components of one embodiment can be added to other embodiments. Furthermore, some components of one embodiment can be replaced with corresponding components of other embodiments.

[0186] Explanation of reference numerals in the attached figures

[0187] 1……Plasma processing device, 2……Control unit, 10……Plasma processing chamber, 11……Substrate support unit, 12……Plasma generation unit, MF……Mask, OP……Opening, F1……Silicon nitride film, SF……Laminated film, SF1……Silicon oxide film, SF2……Silicon nitride film, UF……Base film, W……Substrate.

Claims

1. An etching method, characterized in that, include: (a) The step of providing a substrate comprising a multilayer film, a silicon and nitrogen-containing monolayer film on the multilayer film, and a mask on the monolayer film onto a substrate support in a cavity, wherein the multilayer film comprises two or more different silicon-containing films, and the mask has a sidewall with at least one defined opening. (b) The step of setting the temperature of the substrate support or the substrate to 10°C or higher; as well as (c) The step of etching the monolayer film using plasma generated from a first processing gas containing hydrogen fluoride gas.

2. The etching method according to claim 1, characterized in that: The laminated film has at least one laminated structure comprising a first silicon-containing film and a second silicon-containing film on the first silicon-containing film. The first silicon-containing film contains silicon and nitrogen. The second silicon-containing film contains silicon and oxygen.

3. The etching method according to claim 1, characterized in that: The mask comprises at least one selected from silicon-containing films, metal-containing films, and carbon-containing films.

4. The etching method according to claim 1, characterized in that: The mask comprises at least one selected from metals, carbides of said metals, and silicides of said metals, wherein said metal is selected from at least one selected from tungsten, molybdenum, ruthenium, and titanium.

5. The etching method according to claim 1, characterized in that: The mask comprises at least one selected from BSi, WSi, and WSiN.

6. The etching method according to claim 1, characterized in that: The width of the opening is less than 50 nm.

7. The etching method according to claim 2, characterized in that: The single-layer film is thicker than the first silicon-containing film.

8. The etching method according to claim 1, characterized in that: The first processing gas further includes at least one carbon-containing gas selected from fluorocarbon gases and hydrofluorocarbon gases.

9. The etching method according to claim 8, characterized in that: The ratio of the flow rate of the hydrogen fluoride gas to the flow rate of the carbon-containing gas is more than 1 and less than 5.

10. The etching method according to claim 8, characterized in that: The fluorocarbon gas contains at least one selected from C4F6, C4F8 and C3F8.

11. The etching method according to claim 8, characterized in that: The hydrofluorocarbon gas contains at least one selected from CH2F2 gas, CHF3 gas, CH3F gas, C3H2F4 gas, and C4H2F6 gas.

12. The etching method according to claim 8, characterized in that: The first processed gas also includes an oxygen-containing gas.

13. The etching method according to claim 12, characterized in that: The oxygen-containing gas includes at least one selected from O2 gas, CO gas, and CO2 gas.

14. The etching method according to claim 8, characterized in that: The first processed gas also includes a fluorine-containing gas that does not contain carbon.

15. The etching method according to claim 14, characterized in that: The fluorine-containing gas includes NF3 gas.

16. The etching method according to claim 1, characterized in that: In step (b), the temperature of the substrate support or the substrate is set to a range of 40°C to 90°C.

17. The etching method according to claim 2, characterized in that, Also includes: (d) After step (c), the laminated film is etched using plasma generated from the second processing gas.

18. The etching method according to claim 17, characterized in that: The second processing gas contains at least one carbon-containing gas selected from hydrogen fluoride gas, fluorocarbon gas, and hydrofluorocarbon gas.

19. The etching method according to claim 17, characterized in that: In step (d), the temperature of the substrate support or the substrate when etching the second silicon-containing film of the laminated film is set to be higher than the temperature of the substrate support or the substrate when etching the first silicon-containing film of the laminated film.

20. A method for manufacturing a DRAM capacitor, characterized in that, include: (a) The step of providing a substrate comprising a multilayer film, a silicon and nitrogen-containing monolayer film on the multilayer film, and a mask on the monolayer film onto a substrate support in a cavity, wherein the multilayer film comprises two or more different silicon-containing films, and the mask has a sidewall with at least one defined opening. (b) The step of setting the temperature of the substrate support or the substrate to 10°C or higher; (c) The step of etching the monolayer film using plasma generated from a first processing gas containing hydrogen fluoride gas, and (d) The step of etching the laminated film using plasma generated from the second processing gas.

21. A plasma processing apparatus, characterized in that: It includes a chamber, a substrate support disposed within the chamber, a plasma generation unit, and a control unit. The control unit performs: (a) Controlling the provision of a substrate comprising a multilayer film, a silicon and nitrogen-containing monolayer film on the multilayer film, and a mask on the monolayer film to a substrate support in a cavity, wherein the multilayer film comprises two or more different silicon-containing films, and the mask has a sidewall with at least one defined opening. (b) Controlling the temperature of the substrate support or the substrate to 10°C or higher; and (c) Controlled etching of the monolayer film using plasma generated from a first processing gas containing hydrogen fluoride gas.

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