Plasma processing method and plasma processing system

Abstract

To provide a technology for improving an etching rate.SOLUTION: There is provided a plasma processing method to be executed by a plasma processing apparatus including a chamber. This method includes the steps of: (a) providing a substrate on a substrate support unit in the chamber, the substrate having a lamination film including a silicone oxide film and a silicon nitride film; and (b) generating plasma from processing gas containing HF gas and at least either of CxFy gas (x and y are integers equal to or larger than 1) and phosphorus-containing gas to etching the lamination film. In the step (b), the substrate support unit is controlled to be at a temperature equal to or higher than 0°C and equal to or lower than 70°C and is supplied with a bias RF signal equal to or higher than 10 kW or a bias DC signal equal to or higher than 4kV.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 multilayer film having different dielectric constants. [Prior art documents] [Patent documents]

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

[0004] The present disclosure provides 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: (a) providing a substrate having a stacked film including a silicon oxide film and a silicon nitride film on a substrate support in the chamber; (b) mixing HF gas and C x F y and generating plasma from a processing gas containing at least one of a gas (x and y are integers of 1 or more) and a phosphorus-containing gas, and etching the laminated film, wherein in the step (b), the substrate support is controlled to a temperature of 0°C or more and 70°C or less, and a bias RF signal of 10 kW or more or a bias DC signal of 4 kV or more is supplied. 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 illustrating an example of a cross-sectional structure of a substrate W. FIG. [Figure 4] 1 is a graph showing the measurement results of Experiment 1. [Diagram 5] 13 is a graph showing the measurement results of Experiment 2. [Figure 6] 13 is a graph showing the measurement results of Experiment 3. [Figure 7] 13 is a graph showing the measurement results of Experiment 4. [Figure 8] 13 is a flowchart showing a modified example of the present processing method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0009] In one exemplary embodiment, 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 stacked film including a silicon oxide film and a silicon nitride film on a substrate support in the chamber; (b) mixing HF gas and C x F y and generating a plasma from a processing gas containing at least one of a gas (x and y are integers of 1 or more) and a phosphorus-containing gas, and etching the laminated film, wherein in step (b), the substrate support is controlled to a temperature of 0°C or more and 70°C or less, and a bias RF signal of 10 kW or more or a bias DC signal of 4 kV or more is supplied.

[0010] In one exemplary embodiment, the substrate has a carbon-containing film defining at least one opening on a film stack.

[0011] In one exemplary embodiment, the carbon-containing film is a photoresist film, a spin-on carbon film, or an amorphous carbon film.

[0012] In one exemplary embodiment, C x F y The gas includes at least one selected from the group consisting of C3F6 gas, C4F8 gas, C4F6 gas, and C3F8 gas.

[0013] In one exemplary embodiment, the phosphorus-containing gas is a phosphorus halide gas.

[0014] In one exemplary embodiment, the halogenated phosphorus gas is a fluorinated phosphorus gas.

[0015] In one exemplary embodiment, the phosphorus-containing gas is PF3 gas, PF5 gas, POF3 gas, HPF6 gas, PCl3 gas, PCl5 gas, POCl3 gas, PBr3 gas, PBr5 gas, POBr3 gas, PI3 gas, PO 10 gas, P4O8 gas, P4O6 gas, PH3 gas, Ca3P2 gas, H3PO4 gas, and Na3PO4 gas.

[0016] In one exemplary embodiment, the process gas further comprises an oxygen-containing gas.

[0017] In one exemplary embodiment, the oxygen-containing gas is at least one gas selected from the group consisting of O2, CO, CO2, H2O, and H2O2.

[0018] In one exemplary embodiment, the process gas is u H v F w It further includes a gas (where u and v are integers equal to or greater than 1, and w is an integer equal to or greater than 0).

[0019] In one exemplary embodiment, C u H v F w The gas is at least one gas selected from the group consisting of CH2F2 gas, CHF3 gas, CH3F gas, C4H2F6 gas, C3H2F4 gas, and CH4 gas.

[0020] In one exemplary embodiment, the bias DC signal is a voltage pulse that includes two alternating periods of different voltage levels.

[0021] In one exemplary embodiment, the step (b) comprises: (b1) mixing HF gas and C x F y (b2) generating plasma from a processing gas containing at least one of HF gas and a phosphorus-containing gas at a first flow rate ratio to etch the laminated film; x F y and generating plasma from a process gas containing at least one of a nitrogen gas and a phosphorus-containing gas at a second flow ratio different from the first flow ratio, to etch the laminated film.

[0022] In one exemplary embodiment, in step (b), steps (b1) and (b2) are repeated alternately.

[0023] In one exemplary embodiment, the step (b) further comprises the steps of: (b3) mixing HF gas and C x F y The method further includes the step of generating plasma from a process gas containing at least one of a nitrogen gas and a phosphorus-containing gas at a third flow ratio different from the first flow ratio and the second flow ratio, to etch the laminated film.

[0024] In one exemplary embodiment, the step (b) further comprises the steps of: (b4) mixing HF gas and C x F y At least one of gas and phosphorus-containing gas and C u H v F w(b5) generating plasma from a processing gas containing HF gas and C gas at a fourth flow rate ratio to etch the laminated film; x F y At least one of gas and phosphorus-containing gas and C u H v F w and generating plasma from a process gas containing the gas and the gas at a fifth flow ratio different from the fourth flow ratio, to etch the laminated film.

[0025] In one exemplary embodiment, steps (b4) and (b5) are repeated alternately.

[0026] In one exemplary embodiment, the step (b) further comprises the steps of: (b6) mixing HF gas and C x F y At least one of gas and phosphorus-containing gas and C u H v F w The method further includes the step of generating plasma from a process gas containing a gas and a gas at a sixth flow rate ratio different from the fourth flow rate ratio and the fifth flow rate ratio, to etch the laminated film.

[0027] 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 stacked film including a silicon oxide film and a silicon nitride film on a substrate support in the chamber; (b) generating a plasma in the chamber; and (c) mixing an HF species and a C x F y and etching the laminated film with a species (x and y are integers of 1 or more) and a phosphorus active species, wherein in step (b), the temperature of the substrate support is controlled to be equal to or higher than 0°C and equal to or lower than 70°C, and a bias RF signal of 10 kW or more or a bias DC signal of 4 kV or more is supplied.

[0028] In one exemplary embodiment, the apparatus includes a chamber, a substrate support provided in the chamber, a power source, and a controller, and the controller controls: (a) providing a substrate having a stacked film including a silicon oxide film and a silicon nitride film on the substrate support; and (b) activating the power from the power source to oxidize HF gas and C x F y and generating a plasma from a processing gas containing at least one of a gas containing a nitrogen gas (x and y are integers of 1 or more) and a phosphorus-containing gas, and etching the laminated film. In the control of (b), the temperature of the substrate support is controlled to be equal to or higher than 0°C and equal to or lower than 70°C, and a bias RF signal of 10 kW or more or a bias DC signal of 4 kV or more is supplied from a power supply.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

[0045] <An example of 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, and a step ST2 of etching a laminated film on the substrate. The processing in each step may be performed in the plasma processing system shown in Fig. 1. In the following, an example will be described in which a control unit 2 controls each part of the plasma processing apparatus 1 to perform this processing method on a substrate W.

[0046] (Step ST1: Providing the substrate) In step ST1, the substrate W is provided in a plasma processing space 10s of the plasma processing apparatus 1. The substrate W is 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.

[0047] 3 is a diagram showing an example of a cross-sectional structure of a substrate W provided in step ST1. The substrate W has a laminated film LF and a mask film MF formed in this order on an undercoat film UF. The substrate W may be used for manufacturing semiconductor devices including semiconductor memory devices such as DRAMs and 3D-NAND flash memories.

[0048] 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.

[0049] The laminated film LF is a silicon oxide film (SiO x The laminated film LF includes a silicon oxide film LF1 and a silicon nitride film LF2. The laminated film LF may be a multi-layer film formed by alternately laminating a plurality of silicon oxide films LF1 and silicon nitride films LF2. The laminated film LF is a film to be etched by the present processing method.

[0050] The undercoat film UF and / or the laminated film LF may be formed by a CVD method, a spin coating method, etc. The undercoat film UF and / or the laminated film LF may be a flat film or may be a film having projections and recesses.

[0051] The mask film MF is formed on the laminate film LF. The mask film MF defines at least one opening OP on the laminate film LF. The opening OP is a space on the laminate film LF and is surrounded by the sidewall of the mask film MF. That is, in FIG. 3, the upper surface of the laminate film LF has an area covered by the mask film MF and an area exposed at the bottom of the opening OP.

[0052] The openings OP may have any shape in a plan view of the substrate W, i.e., when the substrate W is viewed from 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.

[0053] The mask film MF is, for example, a carbon-containing film. For example, the carbon-containing film may be an amorphous carbon film, a spin-on carbon film, or a photoresist film. 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 opening OP may be formed by etching the mask film MF. The mask film MF may be formed by lithography.

[0054] 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 laminated film LF 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.

[0055] (Step ST2: Etching of laminated film LF) In step ST2, the laminated film LF is etched. Step ST2 includes step ST21 of setting the temperature of the substrate support 11, step ST22 of supplying a processing gas, and step ST23 of generating plasma.

[0056] In step ST21, the temperature of the substrate support 11 is adjusted to a set temperature of 0° C. or more and 70° C. or less by the temperature adjustment module. The set temperature may be 1° C. or more and 60° C. or less, or may be 30° C. or more and 60° C. or less. The temperature of the substrate support 11 is maintained at the set temperature in the subsequent processing in step ST2. In one example, adjusting or maintaining the temperature of the substrate support 11 includes adjusting or maintaining the temperature of the heat transfer fluid flowing through the flow path 1110a at the set temperature. Adjusting or maintaining the temperature of the substrate support 11 includes adjusting or maintaining the temperature of the heat transfer fluid flowing through the flow path 1110a at a temperature different from the set temperature so that the temperature of the substrate support 11 becomes the set temperature. The timing at which the heat transfer fluid starts to flow through the flow path 1110a may be before or after the substrate W is placed on the substrate support 11, or may be the same as the substrate W. In another example, adjusting or maintaining the temperature of the substrate support 11 includes adjusting or maintaining the temperature of the substrate W at the set temperature. Furthermore, adjusting or maintaining the temperature of the substrate support 11 includes adjusting or maintaining the temperature of the substrate W at a temperature different from the set temperature so that the temperature of the substrate support 11 becomes the set temperature. Furthermore, "adjusting" or "maintaining" the temperature includes inputting, selecting or storing the temperature in the control unit 2.

[0057] In step ST22, a processing gas is supplied into the plasma processing space 10s. The processing gas includes HF gas. The HF gas may be contained in the processing gas at, for example, 50% by volume or more, 60% by volume or more, or 70% by volume or more. The HF gas to be used may be high purity, for example, 99.999% or more purity. The processing gas may include, in addition to HF gas, C x F y The process gas includes a C gas (where x and y are integers equal to or greater than 1) or a phosphorus-containing gas. x F y The gas may include both a nitrogen gas and a phosphorus-containing gas. x F y The gas can contribute to an improvement in the etching rate of the silicon oxide film LF1. The phosphorus-containing gas promotes the adsorption of the HF gas to a silicon nitride film or a silicon oxide film, and can contribute to an improvement in the etching rate of these films.

[0058] C for HF gas x F y The flow rate ratio of the gas or the phosphorus-containing gas may be appropriately set based on the configuration of the laminated film LF and the pattern of the mask film MF. For example, the flow rate ratio may be set based on the composition ratio of the silicon oxide film LF1 in the laminated film LF. In one example, the larger the composition ratio of the silicon oxide film LF1 in the laminated film LF, the higher the concentration of C gas relative to the HF gas. x F y The flow rate ratio of the gas or the phosphorus-containing gas may be increased. The process gas may include a gas capable of generating HF species in the chamber instead of or in addition to the HF gas. The HF species includes at least one of hydrogen fluoride gas, radicals, and ions. Examples of the gas capable of generating HF species include CH2F2 gas, C3H2F4 gas, C3H2F6 gas, C3H3F5 gas, C4H2F6 gas, C4H5F5 gas, C4H2F8 gas, C5H2F6 gas, C5H2F 10 At least one selected from the group consisting of CH2F2 gas, C3H2F4 gas, and C4H2F6 gas may be used as the gas capable of generating HF species. In one example, at least one selected from the group consisting of CH2F2 gas, C3H2F4 gas, and C4H2F6 gas is used as the gas capable of generating HF species.

[0059] C x F y The gas may be at least one selected from the group consisting of C3F6 gas, C4F6 gas, C4F8 gas, and C3F8 gas.

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

[0061] The process gas may further include an oxygen-containing gas. The oxygen-containing gas may suppress clogging of the mask film MF during etching. For example, at least one gas selected from the group consisting of O2, CO, CO2, H2O, and H2O2 may be used as the oxygen-containing gas. In one example, the process gas may include an oxygen-containing gas other than H2O, i.e., at least one gas selected from the group consisting of O2, CO, CO2, and H2O2. The flow rate of the oxygen-containing gas is C x Fy This may be adjusted according to the gas flow rate.

[0062] The process gas is C u H v F w The gas may further include a gas (where u and v are integers equal to or greater than 1, and w is an integer equal to or greater than 0). u H v F w The gas may be at least one gas selected from the group consisting of CH2F2 gas, CHF3 gas, CH3F gas, C4H2F6 gas, C3H2F4 gas, and CH4 gas.

[0063] The process gas may further include a noble gas such as Ar or Kr, and may further include NF3 gas.

[0064] In step ST23, 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 processing gas supplied into the plasma processing space 10s. Also, a bias RF signal is supplied from the second RF generating unit 31b to the lower electrode as a bias signal (power). This generates a bias potential on the substrate W. Active species such as ions and radicals in the generated plasma are attracted to the substrate W, and the laminated film LF is etched. That is, a portion corresponding to the opening OP of the mask film MF is etched in the depth direction (the direction from top to bottom in FIG. 3), and a recess is formed in the laminated film LF. Note that the timing at which the supply of the source RF signal starts and the timing at which the supply of the bias signal starts may be simultaneous or different.

[0065] As the bias signal (power), a bias DC signal may be used instead of the bias RF signal. 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. The source RF signal and the bias signal may both be continuous waves, or one may be a continuous wave and the other may be a pulse wave.

[0066] When a bias RF signal is used as the bias signal, the effective value of the power of the bias RF signal is 10 kW or more. The effective value of the power of the bias RF signal may be 30 kW or less. When a negative polarity bias DC signal is used as the bias signal, the absolute value of the voltage of the bias DC signal (effective value of the absolute value of the voltage in the case of a pulse wave) is 4 kV or more. The absolute value of the voltage of the bias DC signal (effective value of the absolute value of the voltage in the case of a pulse wave) may be 15 kV or less.

[0067] The following describes experiments carried out to evaluate the present treatment method, but the present disclosure is not limited to the following experiments.

[0068] (Experiment 1) In experiment 1, plasma was generated in the plasma processing apparatus 1 under the following conditions to etch a silicon nitride film, a silicon oxide film, and a carbon-containing film, and the etching rates were measured. An amorphous carbon film was used as the carbon-containing film. Processing gas: HF gas, Ar gas Temperature setting for substrate support: 10℃ Chamber pressure: 25mT Source RF signal: 40MHz / 5.5kW Bias RF signal: 400kHz / 15kW

[0069] FIG. 4 is a graph showing the measurement results of Experiment 1. The vertical axis of FIG. 4 shows the etching rates (ER) [nm / min] of the silicon nitride film, silicon oxide film, and carbon-containing film. As shown in FIG. 4, the etching rate of the silicon nitride film was sufficiently higher than that of the carbon-containing film. This indicates that, at the set temperature of this processing method, HF species in the plasma, which is the etchant, are adsorbed to the silicon nitride film, and reactive ion etching can proceed. In contrast, the etching rate of the silicon oxide film was about the same as that of the carbon-containing film and was low. This is considered to be because the HF species in the plasma, which is the etchant, are not adsorbed to the silicon oxide film, and etching mainly occurs by sputtering. In other words, it indicates that, at the set temperature of this processing method, the HF species in the plasma, which is the etchant, are not easily adsorbed to the silicon oxide film. From Experiment 1, it can be seen that the above processing gas is not sufficient to improve the etching rate of a laminated film including a silicon nitride film and a silicon oxide film at the set temperature of this processing method.

[0070] (Experiment 2) In experiment 2, plasma was generated in the plasma processing apparatus 1 using the following three patterns of processing gas, and a silicon nitride film, a silicon oxide film, and a carbon-containing film were etched, and the etching rates were measured. An amorphous carbon film was used as the carbon-containing film. The other conditions were the same as those in experiment 1. Patterns 2 and 3 are examples of processing gases used in this processing method. The flow rate of HF gas in pattern 3 was twice that of HF gas in pattern 2. Pattern 1: C4F8 gas and O2 gas Pattern 2: C4F8 gas, HF gas and O2 gas Pattern 3: C4F8 gas, HF gas and O2 gas

[0071] FIG. 5 is a graph showing the measurement results of Experiment 2. The vertical axis of FIG. 5 shows the etching rates (ER) [nm / min] of the silicon nitride film, silicon oxide film, and carbon-containing film in Patterns 1 to 3. As shown in FIG. 5, the etching rate of the silicon oxide film was sufficiently high relative to the carbon-containing film in all of Patterns 1 to 3. The etching rate of the silicon nitride film was lower than that of the carbon-containing film when the processing gas did not contain HF gas (Pattern 1), and increased rapidly and became sufficiently higher than that of the carbon-containing film when HF gas was contained. The etching rate of the carbon-containing film did not change much even when the flow rate of HF gas was doubled (Patterns 2 and 3), and was low in all of Patterns 1 to 3. From Experiment 2, it can be seen that when C4F8 gas is used as the processing gas in addition to HF gas at the set temperature of this processing method, the selectivity to the carbon-containing film can be increased while increasing the etching rates of both the silicon oxide film and the silicon nitride film.

[0072] (Experiment 3) In experiment 3, plasma was generated in the plasma processing apparatus 1 using the following three patterns of processing gas, and a silicon nitride film, a silicon oxide film, and a carbon-containing film were etched, and the etching rates were measured. An amorphous carbon film was used as the carbon-containing film. The other conditions were the same as in experiment 1. Pattern 6 is an example of a processing gas for this processing method. Pattern 4: C4F8 gas, CH2F2 gas, HF gas and O2 gas Pattern 5: C4F8 gas, C3H2F4 gas and O2 gas Pattern 6: C4F8 gas, HF gas and O2 gas

[0073] FIG. 6 is a graph showing the measurement results of Experiment 3. The vertical axis of FIG. 6 shows the etching rates (ER) [nm / min] of the silicon nitride film, silicon oxide film, and carbon-containing film in Patterns 4 to 6. As shown in FIG. 6, in the case of Pattern 6 containing HF gas as the processing gas, the etching rates of the silicon oxide film and silicon nitride film were improved by about 10 to 20% compared to Patterns 4 and 5 containing CH2F2 gas or C3H2F4 gas as the processing gas. The etching rate of the carbon-containing film was also about the same in Pattern 6 as in Patterns 4 and 5. From Experiment 3, it can be seen that when the processing gas contains HF gas at the set temperature of this processing method, the etching rate can be increased while maintaining a high selectivity to the carbon-containing film compared to when the processing gas contains CH2F2 gas or C3H2F4 gas.

[0074] (Experiment 4) In experiment 4, plasma was generated using HF gas and a phosphorus-containing gas in the plasma processing device 1, and a silicon nitride film, a silicon oxide film, and a carbon-containing film were etched, and the etching rates were measured. An amorphous carbon film was used as the carbon-containing film. PF3 gas was used as the phosphorus-containing gas, and the flow rate ratio (volume %) to the entire processing gas was changed to 0%, 2%, 7%, 11%, 20%, and 26%, and the etching rates were measured for each. The other conditions were the same as in Experiment 1.

[0075] FIG. 7 is a graph showing the measurement results of Experiment 4. In FIG. 7, the horizontal axis indicates the flow rate ratio [volume %] of the phosphorus-containing gas in the processing gas. The vertical axis indicates the etching rate (ER) [nm / min]. As shown in FIG. 7, as the flow rate ratio of the phosphorus-containing gas contained in the processing gas increases, the etching rates of the silicon oxide film and the silicon nitride film increase significantly. When the processing gas contains 26% phosphorus-containing gas, the etching rate is 5.6 times that of the silicon oxide film and 2.5 times that of the silicon nitride film, compared to when the processing gas does not contain phosphorus-containing gas (0 volume %). This is considered to be because the phosphorus-containing gas promotes the adsorption of the HF gas, which is the etchant, to the silicon nitride film and the silicon oxide film. Also, as shown in FIG. 7, the etching rate of the carbon-containing film does not increase even when the flow rate of the phosphorus-containing gas contained in the processing gas increases. From Experiment 4, it can be seen that when a phosphorus-containing gas is used as a processing gas in addition to HF gas at the set temperature of this processing method, the selectivity to the carbon-containing film can be increased while increasing the etching rates of both the silicon oxide film and the silicon nitride film.

[0076] <Example> Next, examples of the present processing method will be described. The present disclosure is not limited to the following examples.

[0077] (Examples 1 and 2) This processing method was applied using a plasma processing apparatus 1 to etch the laminated film LF of the substrate W shown in Fig. 3. In Examples 1 and 2, HF gas, PF3 gas, and Ar gas were used as processing gases. The flow rate ratio (volume %) of the phosphorus-containing gas to the processing gas was 13% in Example 1 and 20% in Example 2. Other conditions for both Example 1 and Example 2 are as follows. Temperature setting for substrate support: 10℃ Chamber pressure: 25mT Source RF signal: 40MHz / 5.5kW Bias RF signal: 400kHz / 15kW

[0078] (Reference example 1) In the reference example, the laminated film LF of the substrate W was etched under the same conditions as those in the example, except that the processing gas was changed as follows. Reference Example 1: HF gas, Ar gas

[0079] The etching rates of the laminated film LF in Examples 1 and 2 were 512 [nm / min] and 518 [nm / min], respectively. In contrast, the etching rate in Reference Example 1 was 231 [nm / min]. That is, the etching rates of the laminated film LF in both Examples 1 and 2 were significantly improved compared to Reference Example 1.

[0080] In this treatment method, in addition to HF gas, C x F y In this case, a gas containing phosphorus or a gas containing phosphorus is used, which can improve the etching rates of both the silicon oxide film LF1 and the silicon nitride film LF2 constituting the laminated film LF, and can improve the selectivity with respect to the mask film MF.

[0081] In addition, in this processing method, a bias RF signal of 10 kW or more or a bias DC signal of 4 kV or more is supplied as a bias signal during etching. By using a high-power bias RF signal, volatilization of reaction by-products generated by etching the laminated film LF can be promoted. For example, volatilization of reaction by-products mainly composed of ammonium silicofluoride (AFS) generated during etching of the silicon nitride film LF2 can be promoted. This can improve the etching rate of the laminated film LF.

[0082] <Modifications of this processing method> 8 is a flow chart showing a modified example of the present processing method. As shown in FIG. 8, the present modification is the same as the present processing method up to step ST21, but is different from the present processing method in the processing after step ST21. In the present modification, step ST2A of etching the laminated film LF includes step ST22a of supplying a first processing gas, step ST23a of generating plasma from the first processing gas, step ST22b of supplying a second processing gas, step ST23b of generating plasma from the second processing gas, and step ST24 of determining the end of etching, after step ST21 of adjusting the temperature of the substrate support part. In step ST2A, steps ST22a to ST23b are repeated until it is determined in step ST24 that the etching has ended.

[0083] The first process gas and the second process gas are HF gas and C x F y The first processing gas and the second processing gas contain at least one of a C gas and a phosphorus-containing gas, as in the present processing method. u H v F w It may further include other gases, such as a gas or an oxygen-containing gas.

[0084] The first and second process gases may have different process gas compositions and flow rates. In one example, the first process gas is a mixture of HF gas and C x F y The second process gas may include at least one of a HF gas and a phosphorus-containing gas at a first flow rate ratio. x F y The gas and / or the phosphorus-containing gas may be included at a second flow ratio different than the first flow ratio.

[0085] In one example, the first process gas is a mixture of HF gas and C x F y At least one of gas and phosphorus-containing gas and C u H v F w and a fourth flow ratio of HF gas and C x F yAt least one of gas and phosphorus-containing gas and C u H v F w and a gas at a fifth flow ratio different from the fourth flow ratio.

[0086] In this modification, the method may further include a step of supplying a third process gas and a step of generating plasma from the third process gas between step ST23b and step ST24. The third process gas may be a mixture of HF gas and C x F y The third process gas may include at least one of a HF gas and a phosphorus-containing gas at a third flow ratio different from the first flow ratio and the second flow ratio. x F y At least one of gas and phosphorus-containing gas and C u H v F w and a sixth flow ratio different from the fourth flow ratio and the fifth flow ratio.

[0087] In this modification, the step ST24 may be omitted, and the above steps using the first process gas, the second process gas, and the third process gas may be performed once each.

[0088] In this modification, the composition of the process gas can be optimized according to the composition ratio of the silicon oxide film LF1 and the silicon nitride film LF2 constituting the laminated film LF, the aspect ratio of the laminated film LF, etc. This can improve the etching rate of the entire laminated film LF.

[0089] 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]

[0090] REFERENCE SIGNS LIST 1: plasma processing apparatus, 2: control section, 10: plasma processing chamber, 10s: plasma processing space, 11: substrate support section, 13: shower head, 20: gas supply section, 31a: first RF generating section, 31b: second RF generating section, 32a: first DC generating section, MF: mask film, OP: opening, LF: laminated film, LF1: silicon oxide film, LF2: silicon nitride 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 stack including a silicon oxide film and a silicon nitride film on a substrate support in a chamber; (b) HF gas and C x F y generating plasma from a process gas containing at least one of a HF gas (x and y are integers of 1 or more) and a phosphorus-containing gas, and etching the laminated film, wherein the HF gas is contained in an amount of 50 volume % or more in the process gas; The plasma processing method, wherein in the step (b), the temperature of the substrate support is controlled to be equal to or higher than 0° C. and equal to or lower than 70° C., and a bias RF signal of 10 kW or higher or a bias DC signal of 4 kV or higher is supplied to the substrate support.

2. A plasma processing method carried out in a plasma processing apparatus having a chamber, comprising: (a) providing a substrate having a film stack including a silicon oxide film and a silicon nitride film on a substrate support in a chamber; (b) generating plasma from a process gas containing HF gas, and at least one of C x F y gas (x and y are integers of 1 or more) and a phosphorus-containing gas, and etching the laminated film; In the step (b), the temperature of the substrate support is controlled to be equal to or higher than 0° C. and equal to or lower than 70° C., and a bias RF signal of 10 kW or higher or a bias DC signal of 4 kV or higher is supplied to the substrate support; The process gas further includes a CuHvFw gas (wherein u and v are integers of 1 or more, and w is an integer of 0 or more); The step (b) comprises: (b4) generating plasma from a process gas containing HF gas, at least one of C x F y gas and a phosphorus-containing gas, and Cu H v F w gas at a fourth flow rate ratio, and etching the laminated film; (b5) generating plasma from a processing gas containing HF gas, at least one of C x F y gas and a phosphorus-containing gas, and CuH v F w gas at a fifth flow rate ratio different from the fourth flow rate ratio, and etching the laminated film, wherein in the step (b), the step (b4) and the step (b5) are alternately repeated.

3. A plasma processing method carried out in a plasma processing apparatus having a chamber, comprising: (a) providing a substrate having a film stack including a silicon oxide film and a silicon nitride film on a substrate support in a chamber; (b) generating plasma from a process gas containing HF gas, and at least one of C x F y gas (x and y are integers of 1 or more) and a phosphorus-containing gas, and etching the laminated film; In the step (b), the temperature of the substrate support is controlled to be equal to or higher than 0° C. and equal to or lower than 70° C., and a bias RF signal of 10 kW or higher or a bias DC signal of 4 kV or higher is supplied to the substrate support; The step (b) comprises: (b1) generating plasma from a process gas containing HF gas and at least one of C x F y gas and a phosphorus-containing gas at a first flow rate ratio to etch the laminated film; (b2) generating plasma from a processing gas containing HF gas and at least one of C x F y gas and a phosphorus-containing gas at a second flow rate ratio different from the first flow rate ratio, and etching the laminated film, wherein in the step (b), the step (b1) and the step (b2) are alternately repeated.

4. The plasma processing method according to claim 1 , wherein the substrate has a carbon-containing film on the laminated film, the carbon-containing film defining at least one opening.

5. The plasma processing method according to claim 4 , wherein the carbon-containing film is a photoresist film, a spin-on carbon film, or an amorphous carbon film.

6. Said C x F y Gas is C 3 F 6 Gas, C. 4 F 8 Gas, C. 4 F 6 Gas and C 3 F 8 6. The plasma processing method according to claim 1, further comprising at least one gas selected from the group consisting of:

7. 7. The plasma processing method according to claim 1, wherein the phosphorus-containing gas is a halogenated phosphorus gas.

8. 8. The plasma processing method according to claim 7, wherein the halogenated phosphorus gas is a fluorinated phosphorus gas.

9. The phosphorus-containing gas is PF 3 Gas, PF 5 Gas, POF 3 Gas, HPF 6 Gas, PCl 3 Gas, PCl 5 Gas, POCl 3 Gas, PBr 3 Gas, PBr 5 Gas, POBr 3 Gas, P.I. 3 Gas, P. 4 O 10 Gas, P. 4 O 8 Gas, P. 4 O 6 Gas, pH 3 Gas, Ca 3 P 2 Gas, H 3 P.O. 4 Gas and Na 3 P.O. 4 7. The plasma processing method according to claim 1, wherein the gas is at least one selected from the group consisting of gases.

10. 10. The plasma processing method according to claim 1, wherein the processing gas further contains an oxygen-containing gas.

11. The oxygen-containing gas is O 2 , CO, CO 2 , H 2 O and H 2 O 2 11. The plasma processing method according to claim 10, wherein the gas is at least one gas selected from the group consisting of:

12. Said C u H v F w The gas is CH 2 F 2 Gas, CHF 3 Gas, CH 3 F gas, C 4 H 2 F 6 Gas, C. 3 H 2 F 4 Gas and CH 4 3. The plasma processing method according to claim 2, wherein the gas is at least one gas selected from the group consisting of gases.

13. 13. The plasma processing method according to claim 1, wherein the bias DC signal is a voltage pulse including two alternating periods of different voltage levels.

14. The step (b) comprises: (b3) HF gas and C x F y 4. The plasma processing method according to claim 3, further comprising the step of generating plasma from a processing gas containing at least one of a nitrogen gas and a phosphorus-containing gas at a third flow rate ratio different from the first flow rate ratio and the second flow rate ratio, to etch the laminated film.

15. The step (b) comprises: (b6) HF gas and C x F y At least one of a gas and a phosphorus-containing gas and C u H v F w 3. The plasma processing method according to claim 2, further comprising the step of generating plasma from a process gas containing a gas and a gas at a sixth flow rate ratio different from the fourth flow rate ratio and the fifth flow rate ratio, to etch the laminated film.

16. The method includes the steps of: providing a chamber; a substrate support unit provided in the chamber; a power source; and a control unit; The control unit is (a) controlling a substrate having a stack including a silicon oxide film and a silicon nitride film on the substrate support; (b) The power from the power source is used to generate HF gas and C x F y a control for etching the laminated film by generating plasma from a process gas containing at least one of a HF gas (x and y are integers of 1 or more) and a phosphorus-containing gas, the HF gas being contained in the process gas at 50 volume % or more; A plasma processing system, wherein in the control of (b), the substrate support is controlled to a temperature of 0° C. or more and 70° C. or less, and a bias RF signal of 10 kW or more or a bias DC signal of 4 kV or more is supplied from the power supply.

17. A method for manufacturing a substrate processing apparatus comprising: a chamber; a substrate support provided in the chamber; a power source; and a control unit; The control unit is (a) controlling a substrate having a stack including a silicon oxide film and a silicon nitride film on the substrate support; (b) generating plasma from a process gas including HF gas, and at least one gas selected from the group consisting of C x F y gas (x and y are integers of 1 or more) and a phosphorus-containing gas, by using electric power from the power source, and performing control to etch the laminated film; In the control of (b), the temperature of the substrate support is controlled to be equal to or higher than 0° C. and equal to or lower than 70° C., and a bias RF signal of 10 kW or higher or a bias DC signal of 4 kV or higher is supplied from the power source; The process gas further includes a CuHvFw gas (wherein u and v are integers of 1 or more, and w is an integer of 0 or more); The control of (b) is (b4) generating plasma from a process gas containing HF gas, at least one of C x F y gas and a phosphorus-containing gas, and Cu H v F w gas at a fourth flow rate ratio, and etching the laminated film; (b5) generating plasma from a processing gas containing HF gas, at least one of C x F y gas and a phosphorus-containing gas, and CuH v F w gas at a fifth flow rate ratio different from the fourth flow rate ratio, and etching the stacked film, wherein in the control of (b), the control of (b4) and the control of (b5) are alternately repeated.

18. A method for manufacturing a substrate processing apparatus comprising: a chamber; a substrate support provided in the chamber; a power source; and a control unit; The control unit is (a) controlling a substrate having a stack including a silicon oxide film and a silicon nitride film on the substrate support; (b) generating plasma from a process gas including HF gas, and at least one gas selected from the group consisting of C x F y gas (x and y are integers of 1 or more) and a phosphorus-containing gas, by using electric power from the power source, and performing control to etch the laminated film; In the control of (b), the temperature of the substrate support is controlled to be equal to or higher than 0° C. and equal to or lower than 70° C., and a bias RF signal of 10 kW or higher or a bias DC signal of 4 kV or higher is supplied from the power source; The control of (b) is (b1) generating plasma from a process gas containing HF gas and at least one of C x F y gas and a phosphorus-containing gas at a first flow rate ratio to etch the laminated film; (b2) generating plasma from a processing gas containing HF gas and at least one of C x F y gas and a phosphorus-containing gas at a second flow rate ratio different from the first flow rate ratio, and etching the laminated film, wherein in the control of (b), the control of (b1) and the control of (b2) are alternately repeated.

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