Etching method and plasma processing apparatus

Abstract

The etching method includes: a step a of providing a substrate including a first film and a second film having an opening in the first film, the first film including a metal element and a non-metal element; a step b of forming a protective film on a side wall of a recess formed in the first film corresponding to the opening; and a step c in which the first film is etched through the opening using plasma generated from a processing gas containing a halogen-containing gas at the same time as or after the step b.

Description

Technical Field

[0001] Exemplary embodiments of the present invention relate to an etching method and a plasma processing apparatus. Background Art

[0002] In the manufacture of electronic devices, in order to form a recess on a film, the film is sometimes subjected to plasma etching. In order to form such a recess, a mask is formed on the film to be etched. As a mask, a resist mask is known. The resist mask is consumed during the plasma etching of the film to be etched. Therefore, a hard mask has been used. As a hard mask, as described in Patent Document 1, a hard mask formed of tungsten silicide (WSi) is known.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2007-294836. Summary of the invention

[0006] Technical problem to be solved by the invention

[0007] The present invention provides a technique capable of etching a film while suppressing shape abnormality.

[0008] Technical means for solving technical problems

[0009] In an exemplary embodiment, an etching method includes: step a, providing a substrate, the substrate including a first film and a second film having an opening on the first film, the first film including a metal element and a non-metal element; step b, forming a protective film on a side wall of a recessed portion formed in the first film corresponding to the opening; and step c, simultaneously with or after step b, etching the first film through the opening using plasma generated from a processing gas including a halogen-containing gas.

[0010] Effects of the Invention

[0011] According to an exemplary embodiment, there is provided a technique capable of etching a film while suppressing shape abnormality. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 FIG. 1 is a diagram schematically showing a plasma processing apparatus according to an exemplary embodiment.

[0013] Figure 2 FIG. 1 is a diagram schematically showing a plasma processing apparatus according to an exemplary embodiment.

[0014] Figure 3is a flow chart of an etching method according to an exemplary embodiment.

[0015] Figure 4 It can be applied Figure 3 A cross-sectional view of a substrate of an example of the method.

[0016] Figure 5 is a cross-sectional view showing one process of an etching method according to an exemplary embodiment.

[0017] Figure 6 is a cross-sectional view showing one process of an etching method according to an exemplary embodiment.

[0018] Figure 7 is a cross-sectional view showing one process of an etching method according to an exemplary embodiment.

[0019] Figure 8 is a cross-sectional view showing one process of an etching method according to an exemplary embodiment.

[0020] Fig. 9 is a cross-sectional view showing one process of an etching method according to an exemplary embodiment.

[0021] Fig.10 This is an example of a timing chart showing the temporal changes of the generation source electric power (also referred to as the generation source power) and the bias electric power (also referred to as the bias power).

[0022] Fig.11 This is an example of a timing chart showing the temporal changes in the generated source (Source) electric power and the bias (Bias) electric power.

[0023] Fig.12 This is an example of a timing chart showing the temporal changes in the generated source electric power and the bias electric power.

[0024] Fig.13 This is an example of a timing chart showing the temporal changes in the generated source electric power and the bias electric power.

[0025] Fig.14 is a flow chart of an etching method according to an exemplary embodiment.

[0026] Fig.15 is a cross-sectional view showing one process of an etching method according to an exemplary embodiment.

[0027] Fig.16 is a cross-sectional view showing one process of an etching method according to an exemplary embodiment.

[0028] Fig.17 is a cross-sectional view showing one process of an etching method according to an exemplary embodiment.

[0029] Fig.18 is a cross-sectional view showing one process of an etching method according to an exemplary embodiment.

[0030] Fig.19 is a diagram showing a substrate processing system according to an exemplary embodiment.

[0031] Fig. 20 FIG. 1 is a cross-sectional view of an example of a substrate including a second film having a sparse or dense pattern.

[0032] Fig.21 is a flow chart of an etching method according to an exemplary embodiment.

[0033] Fig. 22 This is an example of a timing chart showing the temporal changes in the generation source electric power and the gas amount.

[0034] Fig.23 This is an example of a timing chart showing the temporal changes in the generation source electric power and the gas amount. DETAILED DESCRIPTION

[0035] Hereinafter, various exemplary embodiments will be described in detail with reference to the accompanying drawings. In addition, in each of the drawings, the same reference numerals are given to the same or corresponding parts.

[0036] Figure 1 : is a diagram for illustrating a structural example of a plasma processing system. In one embodiment, the plasma processing system includes a plasma processing device 1 and a control unit 2. The plasma processing system is an example of a substrate processing system, and the plasma processing device 1 is an example of a substrate processing device. The plasma processing device 1 includes a plasma processing chamber 10, a substrate support portion 11, and a plasma generating portion 12. The plasma processing chamber 10 has a plasma processing space. In addition, the plasma processing chamber 10 has: at least one gas supply port for supplying at least one processing gas to the plasma processing space; and at least one gas exhaust port for exhausting gas from the plasma processing space. The gas supply port is connected to the gas supply portion 20 described later, and the gas exhaust port is connected to the exhaust system 40 described later. The substrate support portion 11 is arranged in the plasma processing space and has a substrate supporting surface for supporting a substrate.

[0037] The plasma generating unit 12 is configured to generate plasma from at least one processing gas supplied into the plasma processing space. The plasma formed in the plasma processing space may be a capacitively coupled plasma (CCP: Capacitively Coupled Plasma), an inductively coupled plasma (ICP: Inductively Coupled Plasma), an ECR plasma (Electron-Cyclotron-Resonance Plasma: Electron Cyclotron Resonance Plasma), a helicon wave excited plasma (HWP: Helicon Wave Plasma) or a surface wave plasma (SWP: Surface Wave Plasma), etc. In addition, various types of plasma generating units including an AC (Alternating Current: Alternating Current) plasma generating unit and a DC (Direct Current: Direct Current) plasma generating unit may also be used. In one embodiment, the AC signal (AC electric power) used by the AC plasma generating unit has a frequency in the range of 100kHz to 10GHz. Therefore, the AC signal includes an RF (Radio Frequency: Radio Frequency) signal and a microwave signal. In one embodiment, the RF signal has a frequency in the range of 100kHz to 150MHz.

[0038] The control unit 2 processes computer-executable commands that enable the plasma processing device 1 to perform various processes described in this specification. The control unit 2 can be configured to control the various elements of the plasma processing device 1 to perform the various processes described herein. In one embodiment, a part or all of the control unit 2 can be included in the plasma processing device 1. The control unit 2 can include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The control unit 2 is implemented, for example, by a computer 2a. The processing unit 2a1 can be configured to perform various control actions by reading a program from the storage unit 2a2 and executing the read program. The program can be stored in the storage unit 2a2 in advance, or it can be obtained through a medium when necessary. The obtained program is stored in the storage unit 2a2, and is read and executed from the storage unit 2a2 by the processing unit 2a1. The medium can be various storage media readable by the computer 2a, or it can be a communication line connected to the communication interface 2a3. The processing unit 2a1 can be a CPU (Central Processing Unit). The storage unit 2a2 may include a RAM (Random Access Memory), a ROM (Read Only Memory), a HDD (Hard Disk Drive), an SSD (Solid State Drive), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing device 1 via a communication line such as a LAN (Local Area Network).

[0039] Hereinafter, a configuration example of a capacitive coupling type plasma processing apparatus will be described as an example of the plasma processing apparatus 1 . Figure 2 It is a diagram for explaining a configuration example of a capacitive coupling type plasma processing apparatus.

[0040] A 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. In addition, the plasma processing apparatus 1 includes a substrate support unit 11 and a gas introduction unit. The gas introduction unit is configured to be able to introduce at least one processing gas into the plasma processing chamber 10. The gas introduction unit includes a shower head 13. The substrate support unit 11 is disposed in the plasma processing chamber 10. The shower head 13 is disposed above the substrate support unit 11. In one embodiment, the shower head 13 constitutes at least a portion of the top (ceiling) of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the shower head 13, the side wall 10a of the plasma processing chamber 10, and the substrate support unit 11. The plasma processing chamber 10 is grounded. The shower head 13 and the substrate support unit 11 are electrically insulated from the shell of the plasma processing chamber 10.

[0041] The substrate support portion 11 includes a main body 111 and a ring assembly 112. The main body 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 111 surrounds the central region 111a of the main body 111 when viewed from above. The substrate W is arranged on the central region 111a of the main body 111, and the ring assembly 112 is arranged on the annular region 111b of the main body 111 in a manner of surrounding the substrate W on the central region 111a of the main body 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 a ring support surface for supporting the ring assembly 112.

[0042] 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 can act (function) as a lower electrode. The electrostatic chuck 1111 is arranged on the base 1110. The electrostatic chuck 1111 includes a ceramic component 1111a and an electrostatic electrode 1111b arranged in the ceramic component 1111a. The ceramic component 1111a has a central area 111a. In one embodiment, the ceramic component 1111a also has an annular area 111b. In addition, other components surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating component, may have an annular area 111b. In this case, the ring assembly 112 may be arranged on the annular electrostatic chuck or the annular insulating component, or on both the electrostatic chuck 1111 and the annular insulating component. In addition, at least one RF / DC electrode coupled to the RF power supply 31 and / or DC power supply 32 described later may also be arranged in the ceramic component 1111a. In this case, at least one RF / DC electrode functions as a lower electrode. In the case where the bias RF signal and / or DC signal described later is supplied to at least one RF / DC electrode, the RF / DC electrode may also be referred to as a bias electrode. In addition, the conductive component of the base 1110 and at least one RF / DC electrode may also function as a plurality of lower electrodes. In addition, the electrostatic electrode 1111b may function as a lower electrode. Therefore, the substrate support portion 11 includes at least one lower electrode.

[0043] The ring assembly 112 includes one or more ring-shaped components. In one embodiment, the one or more ring-shaped components include one or more edge rings and at least one cover ring. The edge ring is formed of a conductive material or an insulating material, and the cover ring is formed of an insulating material.

[0044] In addition, the substrate support portion 11 may include a temperature adjustment module, which is 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 path 1110a or a combination thereof. A heat transfer fluid such as brine or gas flows in the flow path 1110a. In one embodiment, the flow path 1110a is formed in the base 1110, and one or more heaters are arranged in the ceramic part 1111a of the electrostatic chuck 1111. In addition, the substrate support portion 11 may include a heat transfer gas supply portion, which is configured to supply a heat transfer gas to the gap between the back side of the substrate W and the central area 111a.

[0045] The showerhead 13 is configured to be able to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The showerhead 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b and a plurality of gas introduction ports 13c. The processing gas supplied to the gas supply port 13a is introduced into the plasma processing space 10s from the plurality of gas introduction ports 13c through the gas diffusion chamber 13b. In addition, the showerhead 13 includes at least one upper electrode. In addition, in addition to the showerhead 13, the gas introduction unit may also include one or more side gas injection units (SGI: Side Gas Injector), which are installed in one or more openings formed in the side wall 10a.

[0046] The gas supply unit 20 may further include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply unit 20 is configured to supply at least one processing gas from the respectively corresponding gas source 21 to the shower head 13 via the respectively corresponding flow controller 22. Each flow controller 22 may also include, for example, a mass flow controller or a pressure-controlled flow controller. Moreover, the gas supply unit 20 may further include at least one flow modulation device for modulating or pulsing the flow of at least one processing gas.

[0047] 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. Thus, plasma can be formed 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 generating unit 12. In addition, by supplying a bias RF signal to at least one lower electrode, a bias potential can be generated on the substrate W, and ion components in the formed plasma can be introduced into the substrate W.

[0048] In one embodiment, the RF power supply 31 includes a first RF generator 31a and a second RF generator 31b. The first RF generator 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 electric power) for plasma generation. In one embodiment, the generation source RF signal has a frequency in the range of 10 MHz to 150 MHz. In one embodiment, the first RF generator 31a may also be configured to generate a plurality of generation source RF signals having 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.

[0049] The second RF generating 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 electric power). The frequency of the bias RF signal may be the same as or different from the frequency of the generating source RF signal. In one embodiment, the bias RF signal has a frequency lower than the frequency of the generating source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 100kHz to 60MHz. In one embodiment, the second RF generating unit 31b may also 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. In addition, in various embodiments, at least one of the generating source RF signal and the bias RF signal may also be pulsed.

[0050] In addition, 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 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.

[0051] In various embodiments, the first and second DC signals may also 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 pulse may have a pulse waveform of a rectangle, a trapezoid, a triangle, or a combination thereof. In one embodiment, a waveform generator for generating a sequence of voltage pulses from a DC signal is connected between the first DC generator 32a and at least one lower electrode. Therefore, the first DC generator 32a and the waveform generator constitute a voltage pulse generator. In the case where 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 pulse may have a positive polarity or a negative polarity. In addition, the sequence of voltage pulses may also include one or more positive polarity voltage pulses and one or more negative polarity voltage pulses in one cycle. In addition, the first and second DC generators 32a, 32b may be provided in addition to the RF power supply 31, or the first DC generator 32a may be provided instead of the second RF generator 31b.

[0052] The exhaust system 40 can be connected to the gas exhaust port 10e provided at the bottom of the plasma processing chamber 10, for example. The exhaust system 40 can also include a pressure regulating valve and a vacuum pump. The pressure in the plasma processing space 10s can be adjusted by the pressure regulating valve. The vacuum pump can include a turbomolecular pump, a dry pump, or a combination thereof.

[0053] Figure 3 is a flow chart of an etching method according to an exemplary embodiment. Figure 3 The etching method MT1 shown (hereinafter referred to as "method MT1") can be performed by the plasma processing apparatus 1 of the above-mentioned embodiment. The method MT1 can be applied to a substrate W.

[0054] Figure 4 It can be applied Figure 3 A cross-sectional view of a substrate of an example of the method. Figure 4 As shown, in one embodiment, the substrate W includes a first film F1 and a second film F2 on the first film F1. The substrate W may further include a third film F3 under the first film F1. The substrate W may further include a base region UR under the third film F3.

[0055] The first film F1 contains metal elements and non-metal elements. The first film F1 may contain at least one transition metal element selected from tungsten, titanium, molybdenum, hafnium, zirconium, and ruthenium as a metal element. The first film F1 may also contain at least one non-metal element selected from silicon, carbon, nitrogen, oxygen, hydrogen, boron, and phosphorus. The first film F1 may contain at least one transition metal element selected from tungsten silicide (W x Si y ), tungsten silicon nitride (W x Si yN z ), tungsten borosilicate (W x Si y B z ) and tungsten carbide (W x Si y C z ). The composition ratios x, y, and z may each be a real number greater than 0. The first film F1 may also be a film for forming a hard mask.

[0056] The second film F2 has an opening OP. The second film F2 may also have a plurality of openings OP. The opening OP may have a hole pattern or a line pattern. The size (CD) of the opening OP may be less than 30 nm. The second film F2 may also be a mask. The second film F2 may be a silicon-containing film or a silicon oxide film. The second film F2 may also be a resist mask. The second film F2 may also be a photoresist mask containing tin. The second film F2 may also be a resist mask for EUV exposure. The second film F2 may also have a sparse or dense pattern (see Fig. 20 ). The second film F2 may also have a plurality of first openings OP arranged at a first pitch PT1 and having a first size CD1, and a plurality of second openings OP arranged at a second pitch PT2 and having a second size CD2. The second pitch PT2 is different from the first pitch PT1. The second size CD2 is different from the first size CD1. The "size" mentioned here refers to the diameter of the circle (Diameter across) when the opening is circular, and refers to at least one of the major diameter and minor diameter of the ellipse when the opening is elliptical. When the opening is elliptical, the comparison between the first size CD1 and the second size CD2 is carried out by comparing the major diameters with each other or the minor diameters with each other.

[0057] The second film F2 can also be formed by pattern reversal. For example, a fourth film is formed on the first film F1, and the fourth film is patterned by photolithography and etching. Thereafter, a fifth film is formed on the patterned fourth film, and the opening of the fourth film is filled with the fifth film. Thereafter, the patterned fourth film is removed by peeling, whereby the remaining fifth film becomes the second film F2. The pattern reversal technology is described in, for example, a Japanese patent application filed on October 25, 2021 (Japanese Patent Application No. 2021-173638). The entirety of Japanese Patent Application No. 2021-173638 is incorporated into this specification by reference.

[0058] The third film F3 may be a silicon-containing film or a nitride film. The silicon-containing film may be a silicon nitride film (SiN film) or a silicon carbonitride film (SiCN film). The third film F3 may be an etching stopper layer.

[0059] The base region UR may include, for example, at least one film used for a memory device such as DRAM or 3D-NAND.

[0060] Hereinafter, the case where the method MT1 is applied to the substrate W using the plasma processing apparatus 1 according to the above embodiment is taken as an example. Figure 3 to Figure 13 Method MT1 will be described. Figures 5 to 9 1 and 2 are cross-sectional views showing a process of an etching method according to an exemplary embodiment. When the plasma processing apparatus 1 is used, the method MT1 can be performed in the plasma processing apparatus 1 by controlling each part of the plasma processing apparatus 1 by the control unit 2. In the method MT1, as shown in FIG. Figure 2 As shown, a substrate W disposed on a substrate support 11 in a plasma processing chamber 10 is processed.

[0061] like Figure 3 As shown, method MT1 may include steps ST1 to ST5. Steps ST1 to ST5 can be performed sequentially. Steps ST1 to ST5 can be performed in situ (also called "on-site"). Method MT1 may not include at least one of steps ST1, ST2, and ST5. Step ST1 may be performed after step ST4 or step ST5.

[0062] (Process ST1)

[0063] In step ST1, plasma processing chamber 10 is cleaned. A cleaning gas may be used in step ST1. The cleaning gas may contain fluorine, chlorine, or oxygen.

[0064] (Process ST2)

[0065] In step ST2, precoating is performed on the inner wall of the plasma processing chamber 10. A precoating gas may be used in step ST2. The precoating gas may include at least one of silicon tetrachloride (SiCl4) gas and aminosilane-based gas.

[0066] (Process ST3)

[0067] In step ST3, provide Figure 4 The substrate W is shown. The substrate W can be provided into the plasma processing chamber 10. The substrate W can be supported by the substrate support 11 in the plasma processing chamber 10. The base region UR can be arranged between the substrate support 11 and the third film F3.

[0068] (Process ST4)

[0069] In step ST4, if Figure 5 to Figure 7As shown, the first film F1 is etched through the opening OP. Step ST4 may include step ST41, step ST42, and step ST43. Step ST42 may be performed after step ST41 or before step ST41. Step ST43 may be performed after step ST41 and step ST42.

[0070] (Process ST41)

[0071] In step ST41, if Figure 5 As shown, the first film F1 is etched through the opening OP using the first plasma PL1 generated from the first processing gas containing the halogen-containing gas. As a result, a recess RS corresponding to the opening OP is formed in the first film F1. The first plasma PL1 can be generated by supplying high-frequency electric power (first high-frequency electric power). The high-frequency electric power may be a continuous wave or a pulse. The high-frequency electric power may also be a generation source electric power.

[0072] In step ST41, bias power (first bias power) may be supplied to the substrate support portion 11. The bias power may be a continuous wave or a pulse.

[0073] In step ST41, the first plasma PL1 may be generated at a first pressure. The first pressure may be 30 mTorr (4 Pa) or less.

[0074] In step ST41 , the temperature of the substrate support portion 11 may be 60° C. or higher, or 100° C. or higher.

[0075] The halogen-containing gas may include a chlorine-containing gas or a fluorine-containing gas. Examples of chlorine-containing gases include chlorine gas. Examples of fluorine-containing gases include CF4 gas and NF3 gas. The first processing gas may also include an inert gas. Examples of inert gases include rare gases and nitrogen.

[0076] Step ST41 may include a deposition step and an etching step. The deposition step and the etching step may be separated by changing the conditions over time. The deposition step and the etching step may also be separated by adjusting the generation source power and the bias power. The deposition step and the etching step may also be separated by staggering the phase of the pulse of the generation source power and the phase of the pulse of the bias power.

[0077] (Process ST42)

[0078] In step ST42, if Figure 6As shown, the side wall RSa of the recess RS formed by the step ST41 is modified by the second plasma PL2 generated from the second process gas. As a result, a modified region MR is formed on the side wall RSa of the recess RS. The second process gas is different from the first process gas. The second process gas may contain an oxygen-containing gas. Examples of oxygen-containing gases include oxygen. The second process gas may also contain an inert gas. Examples of inert gases include rare gases and nitrogen. The modified region MR may contain an oxide of a metal element contained in the first film F1, or may contain an oxide of a non-metallic element contained in the first film F1. The bottom RSb of the recess RS may also be modified by the second plasma PL2.

[0079] In step ST42 , the pressure in the plasma processing chamber 10 may be higher than 50 mTorr (6.7 Pa).

[0080] In step ST42 , the temperature of the substrate support portion 11 may be 60° C. or higher, or 100° C. or higher.

[0081] (Process ST43)

[0082] In step ST43, step ST41 and step ST42 are repeated. The modified region MR of the side wall RSa of the recess RS suppresses etching of the side wall RSa in the subsequent step ST41. The modified region MR formed at the bottom RSb of the recess RS is removed by etching in the subsequent step ST41. Figure 7 As shown, step ST43 may be performed until the bottom RSb of the recess RS reaches the third film F3.

[0083] (Process ST5)

[0084] In step ST5, if Figure 8 and Fig. 9 As shown, the first film F1 is further etched. Step ST5 may be started when the bottom RSb of the recess RS reaches the third film F3. Step ST5 may be an over-etching step. Step ST5 may include steps ST51, ST52, and ST53. Step ST5 may not include at least one of steps ST52 and ST53. Step ST52 may be performed after step ST51 or before step ST51. Step ST53 may be performed after steps ST51 and ST52.

[0085] (Process ST51)

[0086] In step ST51, if Figure 8As shown, the first film F1 is etched through the opening OP using the third plasma PL3 generated from the third process gas containing the halogen-containing gas. The first film F1 can be etched in the lateral direction. In the step ST51, the third film F3 can be etched using the third plasma PL3. In the lower part of the first film F1 adjacent to the interface between the first film F1 and the third film F3, the size of the recess RS formed by the third plasma PL3 can also be smaller than the size of the recess formed when the first plasma PL1 is used instead of the third plasma PL3. The etching rate of the third film F3 by the third plasma PL3 can be smaller than the etching rate of the first film F1 by the third plasma PL3, and can also be greater than the etching rate of the third film F3 by the first plasma PL1. The size of the recess refers to the length in the direction perpendicular to the depth direction of the recess. Alternatively, the size of the recess refers to the diameter of the recess.

[0087] The third plasma PL3 can be generated by supplying high-frequency electric power (second high-frequency electric power). The high-frequency electric power can be a continuous wave or a pulse. The high-frequency electric power can also be a generating source electric power. When the electric power is a pulse, the energy per unit time of the electric power is the average value of the pulse. For example, when the electric power in the on state of the pulse is 100W, the electric power in the off state of the pulse is 0W, and the duty cycle is 50%, the average value of the pulse is 50W.

[0088] In step ST51, bias power (second bias power) may be supplied to the substrate support portion 11. The bias power may be a continuous wave or a pulse. The energy per unit time of the second bias power in step ST51 may be greater than the energy per unit time of the first bias power in step ST41. Thus, in step ST51, the etching rate of the third film F3 by the third plasma PL3 increases.

[0089] The first bias power in step ST41 may be a first pulse. The second bias power in step ST51 may be a second pulse. The product of the duty cycle and the amplitude of the second pulse (effective power) may be greater than the product of the duty cycle and the amplitude of the first pulse (effective power). Thus, the energy per unit time of the second bias power may also be greater than the energy per unit time of the first bias power. For example, when the duty cycle of the second pulse is greater than the duty cycle of the first pulse, the energy per unit time of the second bias power can be increased. For example, when the maximum value of the second pulse is greater than the maximum value of the first pulse, the energy per unit time of the second bias power can be increased.

[0090] Examples of the types of gases included in the third process gas may be the same as the examples of the types of gases included in the first process gas. The third process gas may include a reaction promoting gas that increases the etching rate of the third plasma PL3 on the third film F3. The reaction promoting gas may include a hydrogen-containing gas and a C x H y F z (x is an integer greater than 1, y and z are integers greater than 0) at least one of the gases. The hydrogen-containing gas may also be hydrogen gas. x H y F z The gas may be a fluorocarbon gas, a hydrofluorocarbon gas, or a hydrocarbon gas (hydrocarbon gas). The third process gas may include a reaction-promoting gas as a halogen-containing gas, or may include a reaction-promoting gas in addition to a halogen gas. The third process gas may also include an oxygen-containing gas. Examples of the oxygen-containing gas include oxygen.

[0091] In step ST51, the third plasma PL3 may be generated at a second pressure. The second pressure in step ST51 may be lower than the first pressure in step ST41. Thus, in step ST51, etching anisotropy is improved, and thus the etching rate of the third film F3 by the third plasma PL3 increases.

[0092] In the step ST51 , the etching rate of the third film F3 by the third plasma PL3 may be increased by changing the temperature of the substrate support portion 11 .

[0093] The total flow rate of the third processing gas in process ST51 can be greater than the total flow rate of the first processing gas in process ST41. Thus, the residence time of the gas in process ST51 can be shortened. Therefore, the reaction product near the bottom RSb of the recess RS can be quickly detached. That is, exhaust is promoted, and the reaction product is easily taken out of the recess RS. The reaction species that cause shape abnormalities (notching) will not be retained near the bottom RSb of the recess RS and will be easily discharged. When the total flow rate of the gas is increased, the pressure can be constant in process ST41 and process ST51, and the flow ratio of each gas can be constant in process ST41 and process ST51.

[0094] (Process ST52)

[0095] In step ST52, if Fig. 9As shown, the side wall RSa of the recess RS formed by the step ST51 is modified by the fourth plasma PL4 generated from the fourth process gas. As a result, a modified region MR is formed on the side wall RSa of the recess RS at the lower portion of the first film F1 adjacent to the interface between the first film F1 and the third film F3. Examples of the types of gases contained in the fourth process gas may be the same as the examples of the types of gases contained in the second process gas. The partial pressure of the oxygen-containing gas in the fourth process gas may be lower than the partial pressure of the oxygen-containing gas in the second process gas.

[0096] (Process ST53)

[0097] In step ST53, step ST51 and step ST52 are repeated. The modified region MR of the side wall RSa of the recess RS suppresses etching of the side wall RSa in the subsequent step ST51. Step ST53 may be performed until the size (CD) of the bottom RSb of the recess RS reaches a desired size.

[0098] After step ST4 or step ST5 , the aspect ratio of recess RS may be greater than 5 or greater than 10. If the depth of recess RS is D1 and the size of the recess RS at the upper end of recess RS is D2 , the aspect ratio of recess RS is represented by D1 / D2 .

[0099] After step ST5 , the modified region MR of the side wall RSa of the recess RS may be removed using, for example, diluted hydrofluoric acid (DHF).

[0100] Figure 10 to Figure 13 1 is an example of a timing diagram showing the time variation of the source power and the bias power. These timing diagrams are related to step ST41. The source power may be a high-frequency power HF applied to the relative electrode (upper electrode). The bias power may be a high-frequency power LF applied to the electrode in the main body 111 of the substrate support 11. In the case of supplying a pulse of power, the pulse may be generated by switching the power on and off, or the pulse may be generated according to the magnitude of the power value.

[0101] like Fig.10As shown, in step ST41, a pulse of the generated source electric power can be supplied, and a continuous wave of the bias electric power can be supplied. The generated source electric power can also be applied periodically with a period CY. The period CY can include a first period PA and a second period PB. The second period PB is a period after the first period PA. In the first period PA, the generated source electric power can be maintained at a high electric power H2, and the bias electric power can be maintained at a high electric power H1. In this specification, the value of the generated source electric power and the value of the bias electric power can also be the effective values ​​of the high-frequency electric power, respectively. In the second period PB, the generated source electric power can be maintained at a low electric power L2, and the bias electric power can be maintained at a high electric power H1. The low electric power L2 can also be 0W.

[0102] like Fig.11 As shown, in step ST41, a continuous wave of the generated source power may be supplied, and a pulse of the bias power may be supplied. The bias power may also be applied periodically with a period CY. In the first period PA, the bias power may be maintained at a high power H1, and the generated source power may be maintained at a high power H2. In the second period PB, the bias power may be maintained at a low power L1, and the generated source power may be maintained at a high power H2. The low power L1 may be 0W.

[0103] like Fig.12 As shown, in step ST41, a pulse of the generating source power may be supplied, and a pulse of the bias power may be supplied. The generating source power and the bias power may also be applied periodically with a period CY. The pulse of the generating source power may be synchronized with the pulse of the bias power. In the first period PA, the bias power may be maintained at a high power H1, and the generating source power may be maintained at a high power H2. In the second period PB, the bias power may be maintained at a low power L1, and the generating source power may be maintained at a low power L2.

[0104] like Fig.13 As shown, in step ST41, a pulse of source power may be supplied and a pulse of bias power may be supplied. The source power and the bias power may be applied periodically with a period CY. The period CY may include a first period PA, a second period PB and a third period PC. The third period PC is a period after the second period PB. The phase of the pulse of the source power may be offset from the phase of the pulse of the bias power. In the first period PA, the bias power may be maintained at a low power L1, and the source power may be maintained at a high power H2. In the first period PA, a first plasma PL1 (refer to Figure 5). During the second period PB, the bias power can be maintained at low power L1, and the source power can be maintained at high power H2. During the second period PB, ions with high energy collide with the bottom RSb of the recess RS. During the third period PC, the bias power can be maintained at low power L1, and the source power can be maintained at low power L2. During the third period PC, etching byproducts (byproducts) are discharged from the recess RS.

[0105] According to the above-mentioned plasma processing device 1 and method MT1, since the first plasma PL1 can be generated by a pulse of high-frequency electric power, the excessive dissociation of the halogen-containing gas can be suppressed. Therefore, the etching of the side wall RSa of the recess RS can be suppressed. Therefore, the first film F1 can be etched while suppressing the abnormal shape (bowing) of the side wall RSa of the recess RS. Therefore, the verticality of the side wall RSa of the recess RS and the local dimensional uniformity of the recess RS are improved. In addition, the in-plane uniformity of the etching rate of the first film F1 is also improved. Furthermore, by suppressing the excessive dissociation of the halogen-containing gas, the etching amount of the second film F2 can be reduced. Therefore, the etching selectivity of the first film F1 relative to the second film F2 can be improved.

[0106] According to the above-mentioned plasma processing apparatus 1 and method MT1, in step ST5, the difference between the etching rate of the third film F3 and the etching rate of the first film F1 can be reduced. Therefore, in step ST5, in the lower part of the first film F1 adjacent to the interface between the first film F1 and the third film F3, the side etching of the side wall RSa of the recess RS can be suppressed. Thus, the generation of notches caused by side etching can be suppressed. Therefore, the first film F1 can be etched while suppressing shape abnormalities (notches).

[0107] When the generation of notches is suppressed, the dimensional uniformity of the bottom RSb of the recess RS can be improved. As an indicator of dimensional uniformity, the value (3σ) of LCDU (Local CD Uniformity) can be used. A reduction in the value of LCDU means an improvement in dimensional uniformity. According to the above-mentioned plasma processing device 1 and method MT1, the value of LCDU of the recess RS can be reduced to, for example, less than 1.5 nm.

[0108] Various experiments performed to evaluate the method MT1 are described below. The experiments described below do not limit the present invention.

[0109] (First Experiment)

[0110] In the first experiment, a substrate having a WSi film and a mask on the WSi film was prepared. The mask was a silicon oxide film having an opening. For this substrate, steps ST41 to ST43 of method MT1 were performed to etch the WSi film. In step ST41, a processing gas containing chlorine was used. In step ST41, plasma was generated by pulses of source electric power (high frequency electric power HF). The duty cycle of the pulse was 75%. In step ST42, a processing gas containing oxygen was used.

[0111] (Second experiment)

[0112] The second experiment was conducted in the same manner as the first experiment except that the duty ratio of the pulse was set to 50%.

[0113] (Third Experiment)

[0114] The third experiment was conducted in the same manner as the first experiment except that a continuous wave of the generation source electric power was used instead of a pulse of the generation source electric power.

[0115] (Experimental results)

[0116] In the cross section of the substrate, the etching selectivity of the WSi film relative to the mask was calculated by measuring the depth of the recessed portion formed in the WSi film and the remaining thickness of the mask. The etching selectivity in the first experiment was 2.44. The etching selectivity in the second experiment was 2.90. The etching selectivity in the third experiment was 2.16. It can be seen that the etching selectivity is improved by using a pulse to generate source power. In addition, it can be seen that the etching selectivity is improved by reducing the duty cycle of the pulse.

[0117] (Fourth Experiment)

[0118] In the fourth experiment, a substrate having a WSi film and a mask on the WSi film was prepared. The mask was a silicon oxide film having a plurality of hole patterns. For this substrate, steps ST41 to ST43 and ST51 of method MT1 were performed to etch the WSi film. Steps ST52 and ST53 were not performed. In steps ST41 and ST51, a processing gas containing chlorine was used. In step ST42, a processing gas containing oxygen was used.

[0119] (Fifth Experiment)

[0120] The fifth experiment was conducted in the same manner as the fourth experiment except that the steps ST52 and ST53 were conducted after the step ST51. In the step ST52, a processing gas containing oxygen was used.

[0121] (Experimental results)

[0122] The LCDU value was calculated based on the size of the bottom of the plurality of recesses (holes) formed in the WSi film. The LCDU value of the fourth experiment was smaller than the LCDU value of the fifth experiment. It can be seen that in the overetching process, by not modifying the side wall RSa of the recess RS, the size uniformity of the bottom RSb of the recess RS is improved.

[0123] (Sixth Experiment)

[0124] In the sixth experiment, a substrate having a WSi film and a mask on the WSi film was prepared. The mask was a silicon oxide film having a plurality of hole patterns. For this substrate, steps ST41 to ST43 and ST51 of method MT1 were performed to etch the WSi film. Steps ST52 and ST53 were not performed. In steps ST41 and ST51, a processing gas containing chlorine was used. In step ST42, a processing gas containing oxygen was used. In step ST51, plasma was generated by biasing a pulse of high-frequency electric power.

[0125] (Seventh Experiment)

[0126] The seventh experiment was conducted in the same manner as the sixth experiment except that the duty ratio of the pulse was increased by 5% in step ST51.

[0127] (Eighth Experiment)

[0128] The eighth experiment was conducted in the same manner as the sixth experiment except that the duty ratio of the pulse was increased by 15% in step ST51.

[0129] (Ninth Experiment)

[0130] The ninth experiment was conducted in the same manner as the sixth experiment except that a processing gas containing oxygen gas and hydrofluorocarbon gas was used in step ST51.

[0131] (Experimental results)

[0132] The LCDU value was calculated based on the size of the bottom of the plurality of recesses (holes) formed in the WSi film. The LCDU values ​​of the seventh and eighth experiments were smaller than the LCDU value of the sixth experiment. It can be seen that the uniformity of the size of the bottom RSb of the recess RS is improved by increasing the duty cycle of the pulse of the bias high-frequency electric power in the etching process of the over-etching process.

[0133] The LCDU value of Experiment 9 is smaller than the LCDU value of Experiment 6. This shows that the dimensional uniformity of the bottom RSb of the recess RS is improved by using a processing gas containing a hydrofluorocarbon gas in the etching process of the over-etching process.

[0134] Fig.14 is a flow chart of an etching method according to an exemplary embodiment. Fig.14 The etching method MT2 shown (hereinafter referred to as "method MT2") can be performed by the plasma processing apparatus 1 of the above embodiment. The method MT2 can be applied to Figure 4 The substrate W.

[0135] Hereinafter, the case where the method MT2 is applied to the substrate W using the plasma processing apparatus 1 according to the above embodiment is taken as an example. Figure 14 to Figure 18 Method MT2 will be described. Figure 15 to Figure 18 , respectively, are cross-sectional views showing a process of an etching method according to an exemplary embodiment. When the plasma processing apparatus 1 is used, the method MT2 can be executed in the plasma processing apparatus 1 by controlling each part of the plasma processing apparatus 1 by the control unit 2. In the method MT2, as Figure 2 As shown, a substrate W disposed on a substrate support 11 in a plasma processing chamber 10 is processed.

[0136] like Fig.14 As shown, method MT2 may include steps ST1 to ST3 and steps ST6 to ST7. Steps ST1 to ST3 and steps ST6 to ST7 may be performed sequentially. Steps ST1 to ST3 and steps ST6 to ST7 may also be performed in-situ. Method MT2 may not include at least one of steps ST1 and ST2. Step ST1 may be performed after step ST7. Steps ST1 to ST3 may be performed in the same manner as steps ST1 to ST3 of method MT1.

[0137] (Process ST6)

[0138] In step ST6, if Fig.15 As shown, a protective film DP1 is formed on the side wall RSa of the recess RS formed in the first film F1 corresponding to the opening OP. The protective film DP1 may not be formed on the bottom RSb of the recess RS, but may be formed on the bottom RSb of the recess RS. The protective film DP1 may also be formed on the second film F2. The protective film DP1 may be formed using the plasma PL5 generated from the processing gas. The protective film DP1 may be formed by CVD. In step ST6, by increasing the pressure or adjusting the temperature, the thickness of the protective film DP1 on the side wall RSa of the recess RS can be made greater than the thickness of the protective film DP on the bottom RSb of the recess RS.

[0139] The processing gas in step ST6 may include at least one of a silicon-containing gas, a carbon-containing gas, a boron-containing gas, a phosphorus-containing gas, a metal-containing gas, a sulfur-containing gas, a bromine-containing gas, and an iodine-containing gas. Examples of silicon-containing gases include SiCl4 gas and SiF4 gas. Examples of carbon-containing gases include fluorocarbon gas, hydrofluorocarbon gas, and hydrocarbon gas. Examples of boron-containing gases include BCl3 gas. Examples of phosphorus-containing gases include PF x gas. Examples of metal-containing gases include WF6 gas and TiCl4 gas. Examples of sulfur-containing gases include SO2 gas and COS gas. Examples of bromine-containing gases include HBr gas. Examples of iodine-containing gases include HI.

[0140] The processing gas in the first example in step ST6 includes HBr gas. The processing gas in the first example may also include oxygen. In this case, the protective film DP1 includes SiBr x O y .

[0141] The second example of the processing gas in step ST6 includes SiCl4 gas and oxygen. In this case, the protective film DP1 includes SiO x .

[0142] The processing gas in the third example of step ST6 contains BCl3 gas and oxygen. In this case, the protective film DP1 contains BO x .

[0143] The processing gas in the fourth example of step ST6 includes C4F8 gas or C4F6 gas. In this case, the protective film DP1 includes C x F y .

[0144] The fifth example of the processing gas in step ST6 includes CH3F gas or CH4 gas. In this case, the protective film DP1 includes C x H y .

[0145] The processing gas in the sixth example in step ST6 includes COS gas or CH x F y gas.

[0146] The recessed portion RS can be formed by etching performed simultaneously with the step ST6 or before the step ST6. In this case, the etching can be performed in the same manner as the etching in the step ST7.

[0147] (Process ST7)

[0148] In step ST7, if Fig.16As shown, the first film F1 is etched through the opening OP using plasma PL6 generated from the processing gas containing the halogen-containing gas. Step ST7 may be performed simultaneously with step ST6. The plasma processing chamber for performing step ST7 may be the same as or different from the plasma processing chamber for performing step ST6.

[0149] Step ST7 may include step ST71, step ST72, and step ST73. Step ST7 may not include at least one of step ST72 and step ST73. Step ST72 may be performed after step ST71 or before step ST71. Step ST73 may be performed after step ST71 and step ST72. Step ST6 may be performed between step ST71 and step ST72 or between step ST72 and step ST73. Step ST6 may be performed simultaneously with step ST71 or simultaneously with step ST72.

[0150] (Process ST71)

[0151] In step ST71, if Fig.16 As shown, the first film F1 is etched through the opening OP by the plasma PL6. As a result, the bottom RSb of the recess RS is etched, so that the recess RS becomes deeper. Step ST71 can be performed in the same manner as step ST41 of method MT1.

[0152] (Process ST72)

[0153] Step ST72 can be performed in the same manner as step ST42 of method MT1.

[0154] (Process ST73)

[0155] In step ST73, step ST71 and step ST72 are repeated.

[0156] After step ST7 , the thickness of the protective film DP1 may be 25% or less of the size of the recess RS. For example, when the size of the recess RS is 20 nm, the thickness of the protective film DP1 may be 5 nm or less. The size of the recess RS is the size of the upper end of the recess RS.

[0157] After step ST7 , the protective film DP1 can be removed using, for example, diluted hydrofluoric acid (DHF).

[0158] According to the above-mentioned plasma processing device 1 and method MT2, in step ST7, the etching of the side wall RSa of the recess RS of the first film F1 can be suppressed by the protective film DP1. Therefore, the first film F1 can be etched while suppressing the shape abnormality (bow shape). In addition, the LCDU value of the bottom RSb of the recess RS can be reduced. In addition, the etching of the second film F2 can be suppressed by the protective film DP1 on the second film F2. Therefore, the etching selectivity of the first film F1 to the second film F2 can be improved.

[0159] like Fig.14 As shown, in method MT2, step ST6 may include step ST61, step ST62, and step ST63. Step ST61, step ST62, and step ST63 may be performed sequentially. Step ST6 may not include step ST63.

[0160] In step ST61, if Fig.17 As shown, a precursor layer AB is formed on the side wall RSa of the recess RS. The precursor layer AB may be an adsorption layer. In step ST61, plasma PL7 may be generated from a precursor gas for forming the precursor layer AB. It is also possible to form the precursor layer AB by exposing the substrate W to the precursor gas without generating the plasma PL7. Examples of precursor gases include aminosilane-based gases. The chemical species (i.e., chemical species) in the plasma PL7 may also form the precursor layer AB. The precursor layer AB may not be formed on the bottom RSb of the recess RS, but may be formed on the bottom RSb of the recess RS. The precursor layer AB may also be formed on the second film F2.

[0161] In step ST62, if Fig.18 As shown, the precursor layer AB can be modified. By modifying the precursor layer AB, a protective film DP2 is formed. In step ST62, a plasma PL8 can be generated from a processing gas containing a modifying gas for modifying the precursor layer AB. The modifying gas can contain an oxygen-containing gas. The processing gas can also contain an inert gas. The precursor layer AB can also be modified by a chemical species in the plasma PL8. The chemical species used in step ST62 can be the same as or different from the etchant in the plasma PL6 in step ST7. Step ST62 can be performed simultaneously with step ST7 or before step ST7.

[0162] In step ST63 , the step of forming the precursor layer AB and the step of modifying the precursor layer AB are repeated.

[0163] The gas inlet 13c (see FIG. 14 ) to which the reforming gas for reforming the precursor layer AB is supplied in step ST62 Figure 2), which may be different from the gas inlet 13c to which the precursor gas for forming the precursor layer AB is supplied in step ST61. Thus, clogging of the gas inlet 13c due to deposition of the protective film DP2 near the gas inlet 13c can be suppressed.

[0164] At least one of the period for supplying the precursor gas in step ST61, the period for supplying the modified gas in step ST62, and the period for supplying the processing gas in step ST7 may be changed according to the depth or specification of the recess RS. At least one of the period for supplying the precursor gas in step ST61, the period for supplying the modified gas in step ST62, and the period for supplying the processing gas in step ST7 may be lengthened as the recess RS becomes deeper. For example, if the recess RS becomes deeper, it is difficult for the precursor gas to reach the bottom RSb of the recess RS. As the recess RS becomes deeper, the period for supplying the precursor gas is extended in step ST61, thereby making it easier for the precursor gas to reach the bottom RSb of the recess RS.

[0165] As described above, the protective film DP2 can be formed by ALD. In step ST62, chemical species (e.g., oxygen radicals) in the plasma PL8 are easily adsorbed on the surface of the precursor layer AB. Therefore, the adsorption probability of the chemical species in the plasma PL8 increases on the side wall RSa of the recess RS, and on the other hand, the adsorption probability of the chemical species in the plasma PL8 decreases on the bottom RSb of the recess RS. Therefore, the protective film DP2 is easily formed on the side wall RSa, but difficult to form on the bottom RSb. Therefore, in step ST7, the side wall RSa is difficult to be etched, and the bottom RSb is easy to be etched.

[0166] Furthermore, since the protection film DP2 is relatively thin, clogging by the protection film DP2 is less likely to occur at the upper end of the side wall RSa of the recess RS.

[0167] When the step ST62 and the step ST7 are performed simultaneously, even if the protection film DP2 is formed on the bottom RSb of the recess RS, it can be removed by etching. On the other hand, the protection film DP2 is formed on the side wall RSa of the recess RS.

[0168] Various experiments performed to evaluate the method MT2 are described below. The experiments described below do not limit the present invention.

[0169] (Experiment 10)

[0170] In the tenth experiment, a substrate having a WSi film and a mask on the WSi film was prepared. The mask was a silicon oxide film having an opening. For this substrate, steps ST6 to ST7 of method MT2 were performed to etch the WSi film. Step ST71 was performed simultaneously with step ST6. In steps ST6 and ST71, a processing gas containing chlorine gas and SiCl4 gas was used. In step ST72, a processing gas containing oxygen gas was used.

[0171] (Experiment 11)

[0172] The eleventh experiment was conducted in the same manner as the tenth experiment except that the processing gas did not contain SiCl 4 gas in step ST6 and step ST71 .

[0173] (Experiment 12)

[0174] The twelfth experiment was conducted in the same manner as the tenth experiment except that the processing gas further contained oxygen in step ST6 and step ST71.

[0175] (Experiment 13)

[0176] The thirteenth experiment was conducted in the same manner as the twelfth experiment except that the processing gas did not contain SiCl 4 gas in step ST6 and step ST71 .

[0177] (Experimental results)

[0178] In the cross section of the substrate, the etching selectivity of the WSi film relative to the mask was calculated by measuring the depth of the concave portion formed in the WSi film and the remaining thickness of the mask. The etching selectivity in the tenth experiment was 4.43. The etching selectivity in the eleventh experiment was 2.37. The etching selectivity in the twelfth experiment was 5.22. The etching selectivity in the thirteenth experiment was 3.76. It can be seen that in step ST6, the etching selectivity is improved by forming a silicon oxide film on the mask using SiCl4 gas.

[0179] (Experiment 14)

[0180] In the fourteenth experiment, a substrate having a WSi film and a mask on the WSi film was prepared. The mask was a silicon oxide film having a plurality of hole patterns. For this substrate, steps ST6 to ST7 of method MT2 were performed to etch the WSi film. Step ST71 was performed simultaneously with step ST6. In steps ST6 and ST71, a processing gas containing chlorine gas, NF3 gas, oxygen gas, and SiCl4 gas was used. In step ST72, a processing gas containing oxygen gas was used.

[0181] (Experiment 15)

[0182] The fifteenth experiment was conducted in the same manner as the fourteenth experiment except that a processing gas containing chlorine gas, helium gas, and CF 4 gas was used in step ST6 and step ST71 . The processing gas did not contain SiCl 4 gas.

[0183] (Experimental results)

[0184] The LCDU value was calculated based on the size of the bottom of multiple recesses (holes) formed in the WSi film. The LCDU value of the 14th experiment was 1.5nm. The LCDU value of the 15th experiment was 2.1nm. It can be seen that by forming a silicon oxide film on the side wall of the recess based on SiCl4 gas, the uniformity of the size of the recess is improved.

[0185] (Experiment 16)

[0186] In the sixteenth experiment, a substrate having a Si film and a mask on the Si film was prepared. The mask was a silicon oxide film having an opening. For this substrate, steps ST6 to ST7 of method MT2 were performed to etch the Si film. Steps ST63, ST72, and ST73 were not performed. Step ST71 was performed simultaneously with step ST62. In step ST61, an aminosilane-based gas was used to form a precursor layer in a recessed portion formed in the Si film corresponding to the opening. No plasma was generated in step ST61. In steps ST62 and ST71, a processing gas containing HBr gas and oxygen was used to simultaneously perform modification of the precursor layer and etching of the Si film. HBr gas contributes to etching of the Si film. Oxygen contributes to modification of the precursor layer. Thus, a silicon oxide film was formed on the surface of the mask and the sidewalls of the recessed portion.

[0187] (Experiment 17)

[0188] The seventeenth experiment was conducted in the same manner as the sixteenth experiment except that step ST6 was not conducted.

[0189] (Experimental results)

[0190] In the cross section of the substrate, the size of the concave portion at the position where the bow was observed (bow size) was measured. In the 16th experiment, the bow size was 14.9 nm. In the 17th experiment, the bow size was 16.3 nm. It can be seen from this that the bow can be suppressed when the precursor layer is formed.

[0191] In the 16th experiment, the etching selectivity of the mask to the Si film was 6.9. In the 17th experiment, the etching selectivity of the mask to the Si film was 4.9 nm. It can be seen from this that the etching selectivity can be improved when the precursor layer is formed.

[0192] Further, using diluted hydrofluoric acid, the silicon oxide film formed on the side wall of the recess was removed. By measuring the size of the recess before and after removal, the thickness of the silicon oxide film was calculated. In the 16th experiment, the thickness of the silicon oxide film was 4.6. In the 17th experiment, the thickness of the silicon oxide film was 6.8nm. It can be seen from this that when a precursor layer is formed, the thickness of the silicon oxide film can be reduced. If the thickness of the silicon oxide film can be reduced, the clogging of the upper end of the recess can be suppressed.

[0193] (Experiment 18)

[0194] The eighteenth experiment was conducted in the same manner as the sixteenth experiment except that the ratio of the flow rate of the oxygen gas to the total flow rate of the processing gas was increased in step ST62 and step ST71.

[0195] (Experiment 19)

[0196] The nineteenth experiment was conducted in the same manner as the seventeenth experiment except that the ratio of the flow rate of the oxygen gas to the total flow rate of the processing gas was increased in step ST62 and step ST71.

[0197] (Experimental results)

[0198] The etching rate of the Si film in the 18th experiment is the same as the etching rate of the Si film in the 16th experiment. The etching rate of the Si film in the 19th experiment is smaller than the etching rate of the Si film in the 17th experiment. It can be seen that when the precursor layer is not formed, if the flow rate ratio of oxygen is increased, the etching rate of the Si film decreases. On the other hand, it can be seen that when the precursor layer is formed, the etching rate of the Si film does not decrease even if the flow rate ratio of oxygen is increased.

[0199] The results of the sixteenth to nineteenth experiments can also be applied to etching of WSi films.

[0200] Fig.19 is a diagram showing a substrate processing system according to an exemplary embodiment. Fig.19 The substrate processing system PS shown can be used in the method MT1 or the method MT2. The substrate processing system PS includes load ports 102a-102d, containers 4a-4d, loading modules LM, aligners AN, load lock modules LL1, LL2, process modules PM1-PM6, transport modules TM and a control unit 2. In addition, the number of load ports, the number of containers, and the number of load lock modules in the substrate processing system PS can be any number greater than one. In addition, the number of process modules in the substrate processing system PS can be any number greater than one.

[0201] The loading ports 102a to 102d are arranged along one edge of the loading module LM. The containers 4a to 4d are respectively mounted on the loading ports 102a to 102d. The containers 4a to 4d are, for example, containers called FOUPs (Front Opening Unified Pods). The containers 4a to 4d are respectively configured to accommodate substrates W therein.

[0202] The loading module LM has a chamber. The pressure in the chamber of the loading module LM is set to atmospheric pressure. The loading module LM has a conveying device TU1. The conveying device TU1 is, for example, a conveying robot, and is controlled by the control unit 2. The conveying device TU1 is configured to be able to convey the substrate W through the chamber of the loading module LM. The conveying device TU1 is capable of conveying the substrate W between each of the containers 4a~4d and the aligner AN, between the aligner AN and each of the loading lock modules LL1~LL2, and between each of the loading lock modules LL1~LL2 and each of the containers 4a~4d. The aligner AN is connected to the loading module LM. The aligner AN is configured to be able to perform position adjustment (position calibration) of the substrate W.

[0203] The load lock module LL1 and the load lock module LL2 are respectively disposed between the loading module LM and the conveying module TM. The load lock module LL1 and the load lock module LL2 respectively provide a preliminary decompression chamber.

[0204] The transport module TM is connected to each module of the loading lock module LL1 and the loading lock module LL2 via a gate valve. The transport module TM has a transport chamber TC whose internal space is configured to be depressurized. The transport module TM has a transport device TU2. The transport device TU2 is, for example, a transport robot and is controlled by the control unit 2. The transport device TU2 is configured to be able to transport the substrate W via the transport chamber TC. The transport device TU2 can be in the loading lock module LL1~

[0205] LL2 and each of the processing modules PM1 to PM6, and between the processing modules PM1 to PM6

[0206] The substrate W is transported between any two processing modules in PM6.

[0207] The process modules PM1 to PM6 are each a device configured to perform a dedicated substrate process. One of the process modules PM1 to PM6 may be the plasma processing device 1 used in the method MT1 or the method MT2.

[0208] Alternatively, step ST6 of method MT2 may be performed in one of the processing modules PM1 to PM6 , and step ST7 of method MT2 may be performed in another of the processing modules PM1 to PM6 .

[0209] Fig.21 is a flow chart of an etching method according to an exemplary embodiment. Fig.21 The etching method MT3 shown (hereinafter referred to as "method MT3") can be performed by the plasma processing apparatus 1 of the above embodiment. The method MT3 can also be performed by Fig.19 Method MT3 can be applied to Figure 4 The substrate W.

[0210] Hereinafter, the case where the method MT3 is applied to the substrate W using the plasma processing apparatus 1 according to the above embodiment is taken as an example. Figure 5 to Figure 7 and Figure 21 to Figure 23 The MT3 method is explained. Fig. 22 and Fig.23 are examples of timing diagrams showing time variations of the generated source electric power and the gas amount, respectively. When the plasma processing device 1 is used, the method MT3 can be executed in the plasma processing device 1 by controlling the various parts of the plasma processing device 1 by the control unit 2. In the method MT3, as Figure 2 As shown, a substrate W disposed on a substrate support 11 in a plasma processing chamber 10 is processed.

[0211] like Fig.21 As shown, method MT3 may include step ST3 and step ST4a. Step ST3 and step S4a may be performed sequentially. Before step ST3, at least one of step ST1 and step ST2 of method MT1 may be performed. Step ST5 of method MT1 may also be performed after step ST4a. Step ST3 may be performed in the same manner as step ST3 of method MT1.

[0212] (Step ST4a)

[0213] In step ST4a, Figure 5 to Figure 7 As shown, the first film F1 is etched through the opening OP. Step ST4a may include step ST41, step ST41a, step ST42, and step ST43. Step ST41, step ST41a, step ST42, and step ST43 may be performed sequentially. Step ST4a may not include at least one of step ST41a and step ST43. Step ST41 and step ST42 may be performed in the same manner as step ST41 and step ST42 of method MT1.

[0214] (Step ST41a)

[0215] In step ST41a, the internal space of the plasma processing chamber 10 is purged. In step ST41a, a purge gas may be supplied into the plasma processing chamber 10, or the internal space of the plasma processing chamber 10 may be depressurized. By purging the internal space of the plasma processing chamber 10, the first processing gas remaining in the plasma processing chamber 10 is exhausted. Therefore, from the start of step ST41a, the amount of the first processing gas in the plasma processing chamber 10 gradually decreases as time passes.

[0216] (Process ST43)

[0217] In step ST43, step ST41, step ST41a, and step ST42 are repeated. When method MT3 does not include step ST41a, step ST41 and step ST42 are repeated.

[0218] In the case where method MT3 includes step ST41a, in step ST41a, the first processing gas remaining in the plasma processing chamber 10 is exhausted. In step ST41a, the halogen active species in the first plasma PL1 generated in step ST41 can also be exhausted. As a result, in step ST42, the halogen active species are difficult to mix into the second plasma PL2. Therefore, in step ST42, the etching of the side wall RSa of the recess RS due to the halogen active species can be suppressed. Examples of halogen active species include chlorine radicals, fluorine radicals, chloride ions, and fluorine ions. The halogen active species reacts with the oxygen radicals in the second plasma PL2 and the metal element (e.g., tungsten) contained in the first film F1 to generate a metal halogen oxide (e.g., WOF). x or WOCl x ). The metal halide oxide has high volatility and can therefore promote etching of the side wall RSa of the recess RS.

[0219] Alternatively, the effective value of the electric power of the generating source used to generate the second plasma PL2 may be increased continuously or in stages at the beginning (initial stage) of step ST42 of method MT3. Thus, at the beginning of step ST42, the plasma density can be increased continuously or in stages. In this case, the initial plasma density of step ST42 is low, so even if halogen active species are mixed into the second plasma PL2 at the beginning of step ST42, the generation reaction of the metal halogen oxide is difficult to proceed. Thus, because the time (purge time) of step ST41a can be shortened, the productivity is improved. The time of step ST41a may also be zero. That is, method MT3 may not include step ST41a.

[0220] Fig. 22 and Fig.231 and 2 are examples of timing charts showing time changes of the generated source power and the gas amount. These timing charts are related to step ST4a. The vertical axis of the timing chart represents the effective value of the generated source power or the gas amount in the plasma processing chamber 10.

[0221] like Fig. 22 As shown, the cycle including the step ST41, the step ST41a and the step ST42 can be repeated periodically with a cycle CY1. The cycle CY1 can include a first period PA1, a second period PB1 and a third period PC1. The first period PA1, the second period PB1 and the third period PC1 correspond to the step ST41, the step ST41a and the step ST42, respectively. The second period PB1 is a period after the first period PA1. The third period PC1 is a period after the second period PB1.

[0222] During the first period PA1, the effective value of the generating source electric power for generating the first plasma PL1 can be maintained at a high electric power H2. Examples of the frequency of the generating source electric power include 40 MHz, 60 MHz, and 100 MHz. During the first period PA1, bias electric power may also be supplied to the substrate support portion 11. The bias electric power may also be a high-frequency electric power. Examples of the frequency of the bias electric power include 400 kHz and 3.2 MHz. The electric bias supplied to the substrate support portion 11 may also be a DC voltage pulse. The first processing gas is supplied at the beginning of the first period PA1, and the first processing gas is stopped at the end of the first period PA1. As a result, the amount of the first processing gas in the plasma processing chamber 10 increases from the first period PA1 to reach the gas amount GV1. Thereafter, the amount of the first processing gas is maintained at the gas amount GV1. During the first period PA1, the second processing gas is not supplied.

[0223] In the second period PB1, the effective value of the generated source power can be maintained at the low power L2. In the second period PB1, the bias power may not be supplied to the substrate support portion 11. In the second period PB1, the first process gas is not supplied. Therefore, from the beginning of the second period PB1, as time passes, the amount of the first process gas remaining in the plasma processing chamber 10 continuously decreases. At the end of the second period PB1, the amount of the first process gas in the plasma processing chamber 10 may be 0. In the second period PB1, the second process gas is not supplied.

[0224] In the third period PC1, the effective value of the generating source electric power for generating the second plasma PL2 can be maintained at the high electric power H2. The high electric power H2 in the third period PC1 may be different from the high electric power H2 in the first period PA1. In the third period PC1, the bias electric power may not be supplied to the substrate support portion 11. In the third period PC1, the first processing gas is not supplied. At the beginning of the third period PC1, the second processing gas is supplied, and at the end of the third period PC1, the second processing gas is stopped. As a result, the amount of the second processing gas in the plasma processing chamber 10 increases from the beginning of the third period PC1 to reach the gas amount GV2. Thereafter, the amount of the second processing gas is maintained at the gas amount GV2. In the first period PA1 after the third period PC1, the second processing gas is not supplied, so from the beginning of the first period PA1, as time passes, the amount of the second processing gas remaining in the plasma processing chamber 10 continuously decreases. At the end of the first period PA1 after the third period PC1, the amount of the second processing gas in the plasma processing chamber 10 may be 0.

[0225] like Fig.23 As shown, the cycle including the step ST41, the step ST41a and the step ST42 can be repeated periodically with a cycle CY2. The cycle CY2 may include a first period PA2, a second period PB2 and a third period PC2. The first period PA2, the second period PB2 and the third period PC2 correspond to the step ST41, the step ST41a and the step ST42, respectively. The second period PB2 is a period after the first period PA2. The third period PC2 is a period after the second period PB2. The cycle CY2 may not include the second period PB2.

[0226] In the first period PA2, the same process as the first period PA1 of the cycle CY1 can be performed. In the second period PB2, the same process as the second period PB1 of the cycle CY1 can be performed. However, at the end of the second period PB2, the amount of the first processing gas in the plasma processing chamber 10 can also be greater than 0.

[0227] At the beginning of the third period PC2, the effective value of the generation source electric power for generating the second plasma PL2 increases in stages. After the effective value of the generation source electric power reaches the high electric power H2 from the low electric power L2, it can be maintained at the high electric power H2. At the beginning of the third period PC2, the effective value of the generation source electric power can also be continuously increased. The high electric power H2 in the third period PC2 can also be different from the high electric power H2 in the first period PA2. In the third period PC2, the bias electric power can also not be supplied to the substrate support part 11. In the third period PC2, the first processing gas is not supplied. Therefore, from the beginning of the third period PC2, as time passes, the amount of the first processing gas remaining in the plasma processing chamber 10 continuously decreases. At the end of the third period PC2, the amount of the first processing gas in the plasma processing chamber 10 can be 0. At the beginning of the third period PC2, the second processing gas is started to be supplied, and at the end of the third period PC2, the second processing gas is stopped. As a result, the amount of the second process gas in the plasma processing chamber 10 increases from the third period PC2 to the gas amount GV2. Thereafter, the amount of the second process gas is maintained at the gas amount GV2. Since the second process gas is not supplied in the first period PA2 after the third period PC2, the amount of the second process gas remaining in the plasma processing chamber 10 continuously decreases as time passes from the beginning of the first period PA2. At the end of the first period PA1 after the third period PC2, the amount of the second process gas in the plasma processing chamber 10 may be 0.

[0228] Various exemplary embodiments have been described above, but the present invention is not limited to the exemplary embodiments described above, and various additions, omissions, substitutions, and changes may be made. In addition, elements in different embodiments may be combined to form other embodiments.

[0229] For example, the steps of method MT1, the steps of method MT2, and the steps of method MT3 may be combined arbitrarily. Step ST6 of method MT2 may be performed between steps ST3 and ST4 of method MT1.

[0230] Here, various exemplary embodiments included in the present invention are described in the following [E1] to [E53].

[0231] [E1]

[0232] An etching method, comprising:

[0233] Step a, providing a substrate, the substrate comprising a first film and a second film having an opening on the first film, the first film comprising a metal element and a non-metal element; and

[0234] Step b, etching the first film through the opening,

[0235] The process b comprises:

[0236] Step i, etching the first film through the opening using a first plasma generated from a first process gas including a halogen-containing gas by supplying a pulse of high-frequency electric power;

[0237] Step ii, modifying the side wall of the recess formed in the step i by using a second plasma generated from a second process gas; and

[0238] Step iii: repeatedly performing the steps i and ii.

[0239] According to the etching method [E1], since the first plasma is generated by the pulse of high-frequency electric power, excessive dissociation of the halogen-containing gas can be suppressed. Therefore, etching of the side wall of the recess can be suppressed. Therefore, according to the etching method [E1], the first film can be etched while suppressing shape abnormality.

[0240] [E2]

[0241] The etching method according to [E1], wherein:

[0242] In the step i, a continuous wave of bias electric power is supplied to a substrate supporting portion for supporting the substrate.

[0243] [E3]

[0244] The etching method according to [E1], wherein:

[0245] In the step i, a pulse of bias electric power is supplied to a substrate support portion for supporting the substrate.

[0246] The pulse of the high-frequency electric power is synchronized with the pulse of the bias electric power.

[0247] [E4]

[0248] The etching method according to [E1], wherein:

[0249] In the step i, a pulse of bias electric power is supplied to a substrate support portion for supporting the substrate.

[0250] The phase of the pulse of the high-frequency electric power is shifted from the phase of the pulse of the bias electric power.

[0251] [E5]

[0252] An etching method, comprising:

[0253] Step a, providing a substrate, the substrate comprising a first film, a second film having an opening on the first film, and a third film below the first film, wherein the first film comprises a metal element and a non-metal element;

[0254] Step b, etching the first film through the opening; and

[0255] Step c, after step b, further etching the first film,

[0256] The process b comprises:

[0257] Step i, etching the first film through the opening using a first plasma generated from a first process gas including a halogen-containing gas;

[0258] Step ii, modifying the side wall of the recess formed in the step i by using a second plasma generated from a second process gas; and

[0259] Step iii, repeatedly performing the steps i and ii,

[0260] The process c comprises:

[0261] step iv, etching the first film and the third film through the opening using a third plasma generated from a third process gas including a halogen-containing gas,

[0262] In a lower portion of the first film adjacent to an interface between the first film and the third film, a size of the recess formed by the third plasma is smaller than a size of the recess formed when the first plasma is used instead of the third plasma.

[0263] According to the etching method [E5], in step c, since etching of the side wall of the recess (side etching) can be suppressed, generation of notches due to side etching can be suppressed. Therefore, according to the etching method [E5], the first film can be etched while suppressing shape abnormality.

[0264] [E6]

[0265] The etching method according to [E5], wherein:

[0266] In the step i, a first bias electric power is supplied to a substrate supporting portion for supporting the substrate.

[0267] In the step iv, second bias power is supplied to a substrate supporting portion for supporting the substrate, and energy per unit time of the second bias power is greater than energy per unit time of the first bias power.

[0268] In this case, in step iv, chemical species in the third plasma are introduced into the substrate by the second bias electric power. Therefore, the etching rate of the third film in step iv increases.

[0269] [E7]

[0270] The etching method as described in [E6], wherein

[0271] The first bias electric power is a first pulse,

[0272] The second bias electric power is a second pulse,

[0273] The product of the duty cycle and the amplitude of the second pulse is greater than the product of the duty cycle and the amplitude of the first pulse.

[0274] [E8]

[0275] The etching method according to any one of [E5] to [E7], wherein

[0276] The third process gas includes a reaction-promoting gas that increases an etching rate of the third film by the third plasma.

[0277] In this case, the etching rate of the third film in step iv increases.

[0278] [E9]

[0279] The etching method according to [E8], wherein

[0280] The reaction promoting gas comprises a hydrogen-containing gas and C x H y F z (x is an integer greater than or equal to 1, and y and z are integers greater than or equal to 0) at least one of the gases.

[0281] [E10]

[0282] The etching method according to any one of [E5] to [E9], wherein

[0283] The step c does not include a step of modifying the side wall of the recessed portion using a fourth plasma generated from a fourth process gas.

[0284] In this case, in step iv, the side wall of the recessed portion is not excessively modified.

[0285] [E11]

[0286] The etching method according to any one of [E5] to [E9], wherein

[0287] The step c further includes a step v of modifying the side wall of the recessed portion using a fourth plasma generated from a fourth process gas.

[0288] In the step ii, the second processing gas comprises an oxygen-containing gas,

[0289] In step v, the fourth process gas includes an oxygen-containing gas.

[0290] A partial pressure of the oxygen-containing gas in the fourth process gas is lower than a partial pressure of the oxygen-containing gas in the second process gas.

[0291] In this case, in step iv, excessive oxidation of the side wall of the recessed portion can be suppressed.

[0292] [E12]

[0293] The etching method according to any one of [E5] to [E11], wherein

[0294] In the step i, a first high frequency electric power is supplied for generating the first plasma.

[0295] In the step iv, a second high frequency electric power is supplied for generating the third plasma.

[0296] The energy per unit time of the second high-frequency electric power is smaller than the energy per unit time of the first high-frequency electric power.

[0297] In this case, in step iv, excessive dissociation of the halogen-containing gas is suppressed, so that etching of the side wall of the recessed portion can be suppressed.

[0298] [E13]

[0299] The etching method according to any one of [E5] to [E12], wherein

[0300] In the step i, the first plasma is generated at a first pressure,

[0301] In the step iv, the third plasma is generated at a second pressure,

[0302] The second pressure is lower than the first pressure.

[0303] In this case, in step iv, the anisotropy of the chemical species in the third plasma when they migrate toward the substrate increases, thereby suppressing etching of the side wall of the recess.

[0304] [E14]

[0305] The etching method according to any one of [E5] to [E13], wherein

[0306] The third film is an etching stopper layer.

[0307] [E15]

[0308] The etching method according to any one of [E1] to [E14], wherein

[0309] The first film contains at least one transition metal element selected from tungsten, titanium, molybdenum, hafnium, zirconium, and ruthenium as the metal element.

[0310] [E16]

[0311] The etching method according to any one of [E1] to [E15], wherein

[0312] The first film includes at least one of silicon, carbon, nitrogen, oxygen, hydrogen, boron, and phosphorus as the non-metal element.

[0313] [E17]

[0314] The etching method according to [E16], wherein

[0315] The first film includes at least one tungsten compound selected from the group consisting of tungsten silicide, tungsten silicon nitride, tungsten silicon boride, and tungsten silicon carbide.

[0316] [E18]

[0317] The etching method according to any one of [E1] to [E17], wherein

[0318] The second film is a mask.

[0319] [E19]

[0320] The etching method according to any one of [E1] to [E18], wherein

[0321] In the step i, the temperature of the substrate support portion for supporting the substrate is 60° C. or higher.

[0322] [E20]

[0323] The etching method according to any one of [E1] to [E19], wherein

[0324] The second film has a plurality of first openings arranged at a first pitch and having a first size and a plurality of second openings arranged at a second pitch and having a second size, the second pitch being different from the first pitch and the second size being different from the first size.

[0325] [E21]

[0326] The etching method according to any one of [E1] to [E20], wherein

[0327] After the step iii, the aspect ratio of the recess is 5 or more.

[0328] [E22]

[0329] The etching method according to any one of [E1] to [E21], further comprising:

[0330] Step d: before step a or after step b, cleaning the chamber in which the first plasma is generated.

[0331] [E23]

[0332] The etching method according to any one of [E1] to [E22], further comprising:

[0333] Step e: before step a, pre-coating the inner wall of the chamber for generating the first plasma.

[0334] [E24]

[0335] The etching method according to any one of [E1] to [E23], wherein

[0336] The steps a to b are performed in-situ.

[0337] [E25]

[0338] A plasma processing device, comprising:

[0339] Chamber;

[0340] a substrate supporting portion for supporting a substrate in the chamber, wherein the substrate comprises a first film and a second film having an opening on the first film, wherein the first film comprises a metal element and a non-metal element;

[0341] a gas supply unit configured to supply a first processing gas and a second processing gas into the chamber, wherein the first processing gas includes a halogen-containing gas;

[0342] a plasma generating unit configured to generate a first plasma from the first processing gas in the chamber and to generate a second plasma from the second processing gas in the chamber; and

[0343] Control Department,

[0344] The control unit is configured to control the gas supply unit and the plasma generation unit to perform the following steps:

[0345] Step i, etching the first film through the opening using the first plasma by supplying a pulse of high frequency electric power,

[0346] Step ii, modifying the side wall of the recess formed in the step i by using the second plasma, and

[0347] Step iii: repeatedly performing the steps i and ii.

[0348] [E26]

[0349] A plasma processing device, comprising:

[0350] Chamber;

[0351] a substrate supporting portion for supporting a substrate in the chamber, the substrate comprising a first film, a second film having an opening on the first film, and a third film under the first film, the first film comprising a metal element and a non-metal element;

[0352] a gas supply unit configured to supply a first process gas, a second process gas, and a third process gas into the chamber, wherein the first process gas includes a halogen-containing gas and the third process gas includes a halogen-containing gas;

[0353] a plasma generating unit configured to generate a first plasma from the first process gas in the chamber, a second plasma from the second process gas in the chamber, and a third plasma from the third process gas in the chamber; and

[0354] Control Department,

[0355] The control unit is configured to control the gas supply unit and the plasma generation unit to perform the following steps:

[0356] Step i, etching the first film through the opening using the first plasma;

[0357] Step ii, using the second plasma to modify the side wall of the recess formed in the step i;

[0358] Step iii, repeatedly performing the step i and the step ii; and

[0359] step iv, after step iii, etching the first film and the third film through the opening using the third plasma,

[0360] The control unit is also configured to control the gas supply unit and the plasma generating unit so that the size of the recess formed by the third plasma in the lower portion of the first film adjacent to the interface between the first film and the third film is smaller than the size of the recess formed when the first plasma is used instead of the third plasma.

[0361] [E27]

[0362] The etching method according to any one of [E1] to [E24], wherein

[0363] The substrate further includes a third film below the first film,

[0364] The etching method further includes step c, which further etches the first film after step b.

[0365] The step c includes a step iv of etching the first film and the third film through the opening using a third plasma generated from a third process gas including a halogen-containing gas,

[0366] In a lower portion of the first film adjacent to an interface between the first film and the third film, a size of the recess formed by the third plasma is smaller than a size of the recess formed when the first plasma is used instead of the third plasma.

[0367] [E28]

[0368] The etching method according to any one of [E1] to [E24], wherein

[0369] The etching method further includes a step f of forming a protective film on a side wall of a recessed portion formed in the first film corresponding to the opening.

[0370] The step b is performed simultaneously with the step f or after the step f.

[0371] [E29]

[0372] An etching method, comprising:

[0373] Step a, providing a substrate, the substrate comprising a first film and a second film having an opening on the first film, the first film comprising a metal element and a non-metal element;

[0374] Step b, forming a protective film on the side wall of the concave portion formed in the first film corresponding to the opening; and

[0375] In step c, simultaneously with or after step b, the first film is etched through the opening using plasma generated from a process gas containing a halogen-containing gas.

[0376] According to the etching method [E29], in step c, the etching of the side wall of the concave portion of the first film can be suppressed by the protective film. Therefore, according to the etching method [E29], the first film can be etched while suppressing shape abnormality.

[0377] [E30]

[0378] The etching method according to [E29], wherein the step b comprises:

[0379] Step i, forming a precursor layer on the sidewall of the recess; and

[0380] Step ii: modifying the precursor layer.

[0381] [E31]

[0382] The etching method according to [E30], wherein

[0383] In the step i, plasma is generated.

[0384] [E32]

[0385] The etching method as described in [E30] or [E31], wherein

[0386] The step c and the step ii are performed simultaneously.

[0387] [E33]

[0388] The etching method as described in [E30] or [E31], wherein

[0389] The step c is performed after the step ii.

[0390] [E34]

[0391] The etching method according to any one of [E30] to [E33], wherein

[0392] The chemical species used in the step ii is the same as the etchant in the plasma in the step c.

[0393] [E35]

[0394] The etching method according to any one of [E30] to [E33], wherein

[0395] The chemical species used in the step ii is different from the etchant in the plasma in the step c.

[0396] [E36]

[0397] The etching method according to any one of [E30] to [E35], wherein

[0398] In the step b, a gas inlet to which a reforming gas for reforming the precursor layer is supplied is different from a gas inlet to which a precursor gas for forming the precursor layer is supplied.

[0399] [E37]

[0400] The etching method according to any one of [E29] to [E36], wherein

[0401] The chamber in which the step c is performed is different from the chamber in which the step b is performed.

[0402] [E38]

[0403] The etching method according to any one of [E29] to [E37], wherein

[0404] After the step c, the thickness of the protective film is 25% or less of the size of the recessed portion.

[0405] [E39]

[0406] The etching method according to any one of [E29] to [E38], wherein

[0407] The first film contains at least one of tungsten, titanium, and molybdenum as the metal element.

[0408] [E40]

[0409] The etching method according to any one of [E29] to [E39], wherein

[0410] The first film contains at least one of silicon, carbon, nitrogen, oxygen, and hydrogen as the non-metal element.

[0411] [E41]

[0412] The etching method according to [E40], wherein

[0413] The first film includes tungsten silicide.

[0414] [E42]

[0415] The etching method according to any one of [E29] to [E41], wherein

[0416] In the step c, the temperature of the substrate support portion for supporting the substrate is 60° C. or higher.

[0417] [E43]

[0418] The etching method according to any one of [E29] to [E42], wherein

[0419] The second film has a plurality of first openings arranged at a first pitch and having a first size and a plurality of second openings arranged at a second pitch and having a second size, the second pitch being different from the first pitch and the second size being different from the first size.

[0420] [E44]

[0421] The etching method according to any one of [E29] to [E43], wherein

[0422] After the step c, the aspect ratio of the recess is 5 or more.

[0423] [E45]

[0424] The etching method according to any one of [E29] to [E44], further comprising:

[0425] Step d: before step a or after step c, cleaning the chamber in which the plasma is generated.

[0426] [E46]

[0427] The etching method according to any one of [E29] to [E45], further comprising:

[0428] Step e: before step a, pre-coating the inner wall of the chamber where the plasma is generated.

[0429] [E47]

[0430] The etching method according to any one of [E29] to [E46], wherein

[0431] The steps a to c are performed in-situ.

[0432] [E48]

[0433] A plasma processing device, comprising:

[0434] Chamber;

[0435] a substrate supporting portion for supporting a substrate in the chamber, wherein the substrate comprises a first film and a second film having an opening on the first film, wherein the first film comprises a metal element and a non-metal element;

[0436] a gas supply unit configured to supply a processing gas into the chamber, wherein the processing gas includes a halogen-containing gas;

[0437] a plasma generating unit configured to generate plasma from the processing gas in the chamber; and

[0438] Control Department,

[0439] The control unit is configured to control the gas supply unit and the plasma generating unit to form a protective film on the side wall of the recessed portion formed in the first film corresponding to the opening, and to etch the first film through the opening using the plasma while or after forming the protective film.

[0440] [E49]

[0441] The etching method according to any one of [E39] to [E47], wherein

[0442] The second film is a mask.

[0443] [E50]

[0444] The etching method according to any one of [E30] to [E36] and [E37] to [E47] citing [E30], wherein

[0445] At least one of a period during which the precursor gas is supplied in the step i, a period during which the reforming gas is supplied in the step ii, and a period during which the processing gas is supplied in the step c is changed according to the depth of the recess.

[0446] [E50]

[0447] The etching method according to any one of [E5] to [E13], wherein

[0448] The total flow rate of the third process gas is greater than the total flow rate of the first process gas.

[0449] [E51]

[0450] An etching method, comprising:

[0451] Step a, providing a substrate in a chamber, the substrate comprising a first film and a second film having an opening on the first film, the first film comprising a metal element and a non-metal element; and

[0452] step b, etching the first film through the opening,

[0453] The process b comprises:

[0454] Step b1, forming a concave portion in the first film using a first plasma generated from a first processing gas including a halogen-containing gas;

[0455] Step b2, purging the inner space of the chamber; and

[0456] In step b3, the side wall of the recess is modified by using a second plasma generated from a second processing gas.

[0457] [E52]

[0458] An etching method, comprising:

[0459] Step a, providing a substrate in a chamber, the substrate comprising a first film and a second film having an opening on the first film, the first film comprising a metal element and a non-metal element; and

[0460] step b, etching the first film through the opening,

[0461] The process b comprises:

[0462] Step b1, forming a concave portion in the first film using a first plasma generated from a first process gas including a halogen-containing gas; and

[0463] Step b2, modifying the side wall of the recessed portion using a second plasma generated from a second processing gas,

[0464] At the beginning of the step b2, the effective value of the high-frequency electric power for generating the second plasma is increased continuously or in stages.

[0465] [E53]

[0466] The etching method according to [E52], wherein

[0467] The step b further includes a step b3 of purging the inner space of the chamber between the step b1 and the step b2.

[0468] It can be understood from the above description that various embodiments of the present invention are described in this specification for the purpose of illustration, and various changes can be made without departing from the scope and spirit of the present invention. Therefore, the various embodiments recorded in this specification are not intended to limit the present invention, and the true scope and spirit are represented by the claims.

[0469] Description of Reference Numerals

[0470] 1…plasma processing device, 2…control unit, 10…plasma processing chamber, 11…substrate supporting unit, 12…plasma generating unit, 20…gas supply unit, DP1, DP2…protective film, F1…first film, F2…second film, OP…opening, PL6…plasma, RS…recess, RSa…side wall, W…substrate.

Claims

1. An etching method, characterized in that: include: Step a, providing a substrate, the substrate comprising a first film and a second film having an opening on the first film, the first film comprising a metal element and a non-metal element; Step b, forming a protective film on the side wall of the concave portion formed in the first film corresponding to the opening; and In step c, simultaneously with or after step b, the first film is etched through the opening using plasma generated from a processing gas containing a halogen-containing gas.

2. The etching method according to claim 1, characterized in that: The process b comprises: Step i, forming a precursor layer on the sidewall of the recess; and Step ii: modifying the precursor layer.

3. The etching method according to claim 2, characterized in that: In the step i, plasma is generated.

4. The etching method according to claim 2 or 3, characterized in that: The step c and the step ii are performed simultaneously.

5. The etching method according to claim 2 or 3, characterized in that: The step c is performed after the step ii.

6. The etching method according to claim 2 or 3, characterized in that: The chemical species used in the step ii is the same as the etchant in the plasma in the step c.

7. The etching method according to claim 2 or 3, characterized in that: The chemical species used in the step ii is different from the etchant in the plasma in the step c.

8. The etching method according to claim 2 or 3, characterized in that: In the step b, a gas inlet to which a reforming gas for reforming the precursor layer is supplied is different from a gas inlet to which a precursor gas for forming the precursor layer is supplied.

9. The etching method according to any one of claims 1 to 3, characterized in that: The chamber in which the step c is performed is different from the chamber in which the step b is performed.

10. The etching method according to any one of claims 1 to 3, characterized in that: After the step c, the thickness of the protective film is 25% or less of the size of the recessed portion.

11. The etching method according to any one of claims 1 to 3, characterized in that: The first film contains at least one transition metal element selected from tungsten, titanium, molybdenum, hafnium, zirconium, and ruthenium as the metal element.

12. The etching method according to any one of claims 1 to 3, characterized in that: The first film includes at least one of silicon, carbon, nitrogen, oxygen, hydrogen, boron, and phosphorus as the non-metal element.

13. The etching method according to claim 12, characterized in that: The first film includes at least one tungsten compound selected from the group consisting of tungsten silicide, tungsten silicon nitride, tungsten silicon boride, and tungsten silicon carbide.

14. The etching method according to any one of claims 1 to 3, characterized in that: In the step c, the temperature of the substrate support portion for supporting the substrate is 60° C. or higher.

15. The etching method according to any one of claims 1 to 3, characterized in that: The second film has a plurality of first openings arranged at a first pitch and having a first size and a plurality of second openings arranged at a second pitch and having a second size, the second pitch being different from the first pitch and the second size being different from the first size.

16. The etching method according to any one of claims 1 to 3, characterized in that: After the step c, the aspect ratio of the recess is 5 or more.

17. The etching method according to any one of claims 1 to 3, characterized in that: Also includes: Step d: before step a or after step c, cleaning the chamber in which the plasma is generated.

18. The etching method according to any one of claims 1 to 3, characterized in that: Also includes: Step e: before step a, pre-coating the inner wall of the chamber where the plasma is generated.

19. The etching method according to any one of claims 1 to 3, characterized in that: The steps a to c are performed in situ.

20. A plasma processing device, characterized in that: include: Chamber; a substrate supporting portion for supporting a substrate in the chamber, wherein the substrate comprises a first film and a second film having an opening on the first film, wherein the first film comprises a metal element and a non-metal element; a gas supply unit configured to supply a processing gas into the chamber, wherein the processing gas includes a halogen-containing gas; a plasma generating unit configured to generate plasma from the processing gas in the chamber; and Control Department, The control unit is configured to control the gas supply unit and the plasma generating unit to form a protective film on the side wall of the recessed portion formed in the first film corresponding to the opening, and to etch the first film through the opening using the plasma while or after forming the protective film.

21. An etching method, characterized in that: include: Step a, providing a substrate in a chamber, the substrate comprising a first film and a second film having an opening on the first film, the first film comprising a metal element and a non-metal element; and step b, etching the first film through the opening, The process b comprises: Step b1, forming a concave portion in the first film using a first plasma generated from a first processing gas including a halogen-containing gas; Step b2, purging the inner space of the chamber; and In step b3, the side wall of the recess is modified by using a second plasma generated from a second processing gas.

22. An etching method, characterized in that: include: Step a, providing a substrate in a chamber, the substrate comprising a first film and a second film having an opening on the first film, the first film comprising a metal element and a non-metal element; and step b, etching the first film through the opening, The process b comprises: Step b1, forming a concave portion in the first film using a first plasma generated from a first processing gas including a halogen-containing gas; and Step b2, modifying the side wall of the recessed portion using a second plasma generated from a second processing gas, At the beginning of the step b2, the effective value of the high-frequency electric power for generating the second plasma is increased continuously or in stages.

23. The etching method according to claim 22, characterized in that: The step b further includes a step b3, in which the inner space of the chamber is purged between the step b1 and the step b2.

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