Substrate processing method and plasma processing apparatus

Abstract

Provided are a substrate processing method and plasma processing apparatus that favorably remove organic films.　The substrate processing method has: a step for preparing a substrate in which a silicon-containing etching target film is laminated with an organic film formed on the etching target film and having a pattern of openings formed therein; a step for forming a pattern of openings in the etching target film using the organic film as a mask and generating a plasma of a first fluorine-containing gas; and a step for removing the organic film after the pattern of openings has been formed in the etching target film. The organic film removal step has: (a) a step for generating a plasma of an ashing gas to which a second fluorine-containing gas has been added and removing the organic film; and (b) a second step for generating a plasma of the ashing gas after step (a) and removing the organic film.

Description

Substrate processing method and plasma processing apparatus

[0001] The present disclosure relates to a substrate processing method and a plasma processing apparatus.

[0002] In Patent Document 1, a silicon oxide film is plasma-etched through an organic film mask, and then O ２ An etching method is disclosed in which a plasma of a gas is generated to ash the mask.

[0003] Japanese Patent Application Laid-Open No. 2019-9189

[0004] In one aspect, the present disclosure provides a substrate processing method and a plasma processing apparatus that suitably remove an organic film.

[0005] In order to solve the above-mentioned problems, according to one aspect, there is provided a substrate processing method comprising the steps of: preparing a substrate on which a silicon-containing film to be etched and an organic film formed on the film to be etched and having an opening pattern formed thereon; generating plasma of a first fluorine-containing gas and forming an opening pattern in the film to be etched using the organic film as a mask; and removing the organic film after forming the opening pattern in the film to be etched, wherein the step of removing the organic film comprises: (a) generating plasma of an ashing gas to which a second fluorine-containing gas has been added to remove the organic film; and (b) after step (a), generating plasma of the ashing gas to remove the organic film.

[0006] According to one aspect, it is possible to provide a substrate processing method and a plasma processing apparatus that suitably remove an organic film.

[0007] 1 is a diagram illustrating an example of the configuration of a capacitively coupled plasma processing apparatus. FIG. 2 is a flowchart illustrating an example of a substrate processing method. FIG. 3 is a schematic cross-sectional view of a substrate in each process. FIG. 4 is a schematic cross-sectional view of a substrate in each process. FIG. 5 is a flowchart illustrating an example of a process for removing an organic film in step S105. FIG. 6 is a schematic cross-sectional view of a substrate in the process for removing an organic film of the first reference example. FIG. 7 is a schematic cross-sectional view of a substrate in the process for removing an organic film of the first reference example. FIG. 8 is a schematic cross-sectional view of a substrate in the process for removing an organic film of the first reference example. FIG. 9 is a schematic cross-sectional view of a substrate in the process for removing an organic film of the second reference example. FIG. 10 is a schematic cross-sectional view of a substrate in the process for removing an organic film of the second reference example. FIG. 11 is a schematic cross-sectional view of a substrate in the process for removing an organic film of the second reference example. 1 is a schematic cross-sectional view of a substrate in a process for removing an organic film according to an embodiment of the present invention;

[0008] Various exemplary embodiments will be described in detail below with reference to the drawings, in which the same or equivalent parts are designated by the same reference numerals.

[0009] [Plasma Processing System] An example of the configuration of a plasma processing system will be described below. Fig. 1 is an example of a diagram for explaining an example of the configuration of a capacitively coupled plasma processing apparatus 1.

[0010] The plasma processing system includes a capacitively coupled plasma processing apparatus 1 and a controller 2. The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply 20, a power supply 30, and an exhaust system 40. The plasma processing apparatus 1 also includes a substrate support 11 and a gas inlet. The gas inlet is configured to introduce at least one process gas into the plasma processing chamber 10. The gas inlet includes a showerhead 13. The substrate support 11 is disposed within the plasma processing chamber 10. The showerhead 13 is disposed above the substrate support 11. In one embodiment, the showerhead 13 forms at least a portion of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the showerhead 13, a sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 has at least one gas inlet for supplying at least one processing gas into the plasma processing space 10s and at least one gas outlet for exhausting gas from the plasma processing space 10s. The plasma processing chamber 10 is grounded. The showerhead 13 and the substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0011] The substrate support 11 includes a main body 111 and a ring assembly 112. The main body 111 has a central region 111a for supporting 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 in a plan view. The substrate W is disposed on the central region 111a of the main body 111, and the ring assembly 112 is disposed on the annular region 111b of the main body 111 so as to surround the substrate W on the central region 111a of the main body 111. Therefore, the central region 111a is also called a substrate support surface for supporting the substrate W, and the annular region 111b is also called a ring support surface for supporting the ring assembly 112.

[0012] In one embodiment, the main body 111 includes a base 1110 and an electrostatic chuck 1111. The base 1110 includes a conductive member. The conductive member of the base 1110 can function as a lower electrode. The electrostatic chuck 1111 is disposed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic electrode 1111b disposed within the ceramic member 1111a. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Note that the annular region 111b may also be provided by another member surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member. In this case, the ring assembly 112 may be disposed on the annular electrostatic chuck or the annular insulating member, or may be disposed on both the electrostatic chuck 1111 and the annular insulating member. Furthermore, at least one RF / DC electrode coupled to an RF (Radio Frequency) power supply 31 and / or a DC (Direct Current) power supply 32 (described later) may be disposed within the ceramic member 1111a. In this case, the at least one RF / DC electrode functions as a lower electrode. When a bias RF signal and / or a DC signal (described later) is supplied to the at least one RF / DC electrode, the RF / DC electrode is also called a bias electrode. Note that the conductive member of the base 1110 and the at least one RF / DC electrode may function as multiple lower electrodes. Furthermore, the electrostatic electrode 1111b may function as a lower electrode. Therefore, the substrate support 11 includes at least one lower electrode.

[0013] The ring assembly 112 includes one or more annular members. In one embodiment, the one or more annular members include one or more edge rings and at least one cover ring. The edge rings are formed of a conductive or insulating material, and the cover rings are formed of an insulating material.

[0014] The substrate support 11 may also include a temperature adjustment module configured to adjust at least one of the electrostatic chuck 1111, the ring assembly 112, and the substrate W to a target temperature. The temperature adjustment module may include a heater, a heat transfer medium, a flow passage 1110a, or a combination thereof. A heat transfer fluid such as brine or a gas flows through the flow passage 1110a. In one embodiment, the flow passage 1110a is formed in the base 1110, and one or more heaters are disposed in the ceramic member 1111a of the electrostatic chuck 1111. The substrate support 11 may also include a heat transfer gas supply configured to supply a heat transfer gas to a gap between the back surface of the substrate W and the central region 111a.

[0015] The showerhead 13 is configured to introduce at least one process 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 multiple gas inlets 13c. The process gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s from the multiple gas inlets 13c. The showerhead 13 also includes at least one upper electrode. In addition to the showerhead 13, the gas inlet may also include one or more side gas injectors (SGIs) attached to one or more openings formed in the sidewall 10a.

[0016] The gas supply unit 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply unit 20 is configured to supply at least one process gas from a corresponding gas source 21 to the showerhead 13 via a corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, the gas supply unit 20 may include one or more flow modulation devices to modulate or pulse the flow rate of the at least one process gas.

[0017] The power supply 30 includes an RF power supply 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power supply 31 is configured to supply at least one RF signal (RF power) to at least one lower electrode and / or at least one upper electrode. This generates a plasma from at least one process gas supplied to the plasma processing space 10s. Therefore, the RF power supply 31 can function as at least a part of a plasma generating unit configured to generate a plasma from one or more process gases in the plasma processing chamber 10. Furthermore, by supplying a bias RF signal to the at least one lower electrode, a bias potential is generated on the substrate W, thereby attracting ion components in the formed plasma to the substrate W.

[0018] In one embodiment, the RF power supply 31 includes a first RF generating unit 31a and a second RF generating unit 31b. The first RF generating unit 31a is coupled to at least one lower electrode and / or at least one upper electrode via at least one impedance matching circuit and is configured to generate a source RF signal (source RF power) for plasma generation. In one embodiment, the source RF signal has a frequency in the range of 10 MHz to 150 MHz. In one embodiment, the first RF generating unit 31a may be configured to generate multiple source RF signals having different frequencies. The generated one or more source RF signals are supplied to at least one lower electrode and / or at least one upper electrode.

[0019] The second RF generator 31b is coupled to at least one lower electrode via at least one impedance matching circuit and is configured to generate a bias RF signal (bias RF power). The frequency of the bias RF signal may be the same as or different from the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency lower than the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 100 kHz to 60 MHz. In one embodiment, the second RF generator 31b may be configured to generate multiple bias RF signals having different frequencies. The generated one or more bias RF signals are supplied to at least one lower electrode. In various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0020] The power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generator 32a and a second DC generator 32b. In one embodiment, the first DC generator 32a is connected to the at least one lower electrode and configured to generate a first DC signal. The generated first bias DC signal is applied to the at least one lower electrode. In one embodiment, the second DC generator 32b is connected to the at least one upper electrode and configured to generate a second DC signal. The generated second DC signal is applied to the at least one upper electrode.

[0021] In various embodiments, at least one of the first and second DC signals may be pulsed. In this case, a sequence of voltage pulses is applied to at least one lower electrode and / or at least one upper electrode. The voltage pulses may have a rectangular, trapezoidal, triangular, or combination thereof pulse waveform. In one embodiment, a waveform generator for generating the sequence of voltage pulses from the DC signal is connected between the first DC generator 32a and at least one lower electrode. Thus, the first DC generator 32a and the waveform generator constitute a voltage pulse generator. When the second DC generator 32b and the waveform generator constitute a voltage pulse generator, the voltage pulse generator is connected to at least one upper electrode. The voltage pulses may have either positive or negative polarity. Furthermore, the sequence of voltage pulses may include one or more positive voltage pulses and one or more negative voltage pulses within one period. The first and second DC generating units 32a and 32b may be provided in addition to the RF power supply 31, or the first DC generating unit 32a may be provided instead of the second RF generating unit 31b.

[0022] The exhaust system 40 may be connected to, for example, a gas exhaust port 10e provided at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure in the plasma processing space 10s is regulated by the pressure regulating valve. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0023] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform various processes described in this disclosure. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to perform various processes described herein. In one embodiment, part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The control unit 2 may be implemented by, for example, a computer 2a. The processing unit 2a1 may be configured to read a program from the storage unit 2a2 and execute the read program to perform various control operations. This program may be stored in the storage unit 2a2 in advance or may be acquired via a medium when needed. The acquired program is stored in the storage unit 2a2 and read from the storage unit 2a2 by the processing unit 2a1 for execution. The medium may be various storage media readable by the computer 2a or a communication line connected to the communication interface 2a3. The processing unit 2a1 may be a CPU (Central Processing Unit). The storage unit 2a2 may include a random access memory (RAM), a read-only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a local area network (LAN).

[0024] Next, an example of a substrate processing method will be described with reference to Fig. 2 and Figs. 3A to 3E. Fig. 2 is a flowchart showing an example of the substrate processing method. Figs. 3A to 3E are exemplary cross-sectional views of the substrate W in each step. Here, an example will be described in which a pattern of multiple vias (holes, openings 305) is formed in a film 300 to be etched.

[0025] In step S101, a substrate W is prepared. Here, the control unit 2 controls a transfer device (not shown) to transfer the substrate W into the plasma processing chamber 10 and place the substrate W in the central region 111a of the substrate support 11. Fig. 3A is a schematic cross-sectional view showing an example of the substrate W to be prepared. The substrate W has a film to be etched 300, an organic film 310, a silicon-containing film 320, and a photoresist film 330.

[0026] The film to be etched 300 has a first film 301 and a second film 302 formed on the first film 301 .

[0027] The first film 301 is, for example, an insulating film. The first film 301 may also be a film used as an interlayer insulating film (low-k film). The first film 301 is also a film containing silicon (Si). The first film 301 may also be, for example, a SiOC film, a SiCOH film, or the like.

[0028] The second film 302 is, for example, an insulating film, and is formed on the first film 301. The second film 302 functions as an etching stop layer when etching the organic film 310. The second film 302 is a film containing silicon (Si) and oxygen (O). The second film 302 is, for example, a film containing tetraethoxysilane (TEOS), SiO ２ The second film 302 may be any of a silicon-containing film, ...

[0029] The organic film 310 is a film containing carbon (C) and is formed on the second film 302 of the film 300 to be etched. The organic film 310 is also referred to as the bottom layer (BL) of a three-layer mask (organic film 310, silicon-containing film 320, and photoresist film 330). The organic film 310 may be, for example, an amorphous carbon (a-C) film, a spin-on carbon (SOC) film, or the like.

[0030] The silicon-containing film 320 is a film containing silicon (Si) and is formed on the organic film 310. The silicon-containing film 320 is a film disposed in the middle layer of a three-layer mask (organic film 310, silicon-containing film 320, and photoresist film 330), and is also referred to as an ML (middle layer). The silicon-containing film 320 is a film containing silicon (Si) and carbon (C). The silicon-containing film 320 may be, for example, a SiOC film, a SiON film, or the like. The silicon-containing film 320 has a higher carbon (C) content than the second film 302.

[0031] The photoresist film 330 is an organic film in which a pattern of openings 335 is formed, and is formed on the silicon-containing film 320. The photoresist film 330 is the film disposed on the uppermost layer of a three-layer mask (organic film 310, silicon-containing film 320, and photoresist film 330). The photoresist film 330 is an organic film in which a pattern of openings 335 is formed by, for example, EUV (extreme ultraviolet) exposure. The pattern of openings 335 has a pattern of multiple circles arranged in a plan view of the substrate W from above.

[0032] In step S102, a pattern of openings 325 is formed in the silicon-containing film 320. FIG. 3B is a schematic cross-sectional view illustrating an example of the substrate W after processing in step S102. Here, the controller 2 controls the gas supply unit 20 to supply a third fluorine (F)-containing gas into the plasma processing chamber 10, controls the first RF generator 31a to supply a source RF signal to the upper electrode or the lower electrode, and controls the second RF generator 31b to supply a bias RF signal to the lower electrode. Thus, plasma of the third fluorine (F)-containing gas is generated, and the silicon-containing film 320 is etched using the photoresist film 330 on which the pattern of openings 335 has been formed as a mask, thereby forming the pattern of openings 325 in the silicon-containing film 320. In this manner, through the processes from step S101 to step S102, a substrate W is prepared which is stacked with a film 300 to be etched, an organic film 310 formed on the film 300 to be etched, and a silicon-containing film 320 formed on the organic film 310 and having a pattern of openings 325 formed thereon.

[0033] In step S103, a pattern of openings 315 is formed in the organic film 310. FIG. 3C is a schematic cross-sectional view showing an example of the substrate W after the process in step S103. Here, the control unit 2 controls the gas supply unit 20 to supply a process gas (e.g., N ２ / H ２ Gas: N ２ Gas and H ２ The first RF generator 31a is controlled to supply a source RF signal to the upper electrode or the lower electrode, and the second RF generator 31b is controlled to supply a bias RF signal to the lower electrode. ２ / H ２ A plasma of the silicon-containing film (gas) is generated, and the organic film 310 is etched using the silicon-containing film 320 on which the pattern of the openings 325 is formed as a mask, thereby forming a pattern of the openings 315 in the organic film 310 .

[0034] In step S104, a via etching process is performed on the target film 300. FIG. 3D is a cross-sectional view showing an example of the substrate W after the process in step S104. Here, the control unit 2 controls the gas supply unit 20 to supply a first fluorine (F)-containing gas into the plasma processing chamber 10, controls the first RF generator 31a to supply a source RF signal to the upper electrode or the lower electrode, and controls the second RF generator 31b to supply a bias RF signal to the lower electrode. This generates plasma of the first fluorine (F)-containing gas, and etches the target film 300 (first film 301 and second film 302) using the organic film 310 on which the pattern of openings 315 is formed as a mask, thereby forming a pattern of openings 305 (vias, holes) in the target film 300. The first fluorine (F)-containing gas may be a gas containing fluorine (F) and carbon (C) (fluorocarbon-based gas), for example, C. ４ F ８ , C.F. ４ The gas may be any of the above.

[0035] In step S105, the organic film 310 is removed. Fig. 3E is a schematic cross-sectional view showing an example of the substrate W after the processing in step S105.

[0036] As described above, in the processes shown in steps S101 to S103, the organic film 310 having the pattern of the openings 315 is formed on the film to be etched 300. That is, the processes shown in steps S101 to S103 result in preparing a substrate W on which the silicon-containing film to be etched 300 and the organic film 310 formed on the film to be etched 300 and having the pattern of the openings 315 formed thereon are stacked. Then, the organic film 310 having the pattern of the openings 315 can be used to form a pattern of the openings 305 (vias, holes) in the film to be etched 300.

[0037] Although the steps shown in steps S101 to S105 have been described as being performed in one plasma processing chamber 10, this is not limited to this, and for example, a configuration using multiple plasma processing chambers 10 may also be used.

[0038] Next, the process of removing the organic film 310 in step S105 will be described with reference to Fig. 4. Fig. 4 is a flowchart showing an example of the process of removing the organic film 310 in step S105.

[0039] In step S201, a plasma of an ashing gas to which a fluorine (F)-containing gas is added is generated, and a first ashing process is performed to ash the organic film 310.

[0040] Here, the control unit 2 controls the gas supply unit 20 to supply an ashing gas containing a second fluorine (F)-containing gas into the plasma processing chamber 10, and controls the first RF generator 31a to supply a source RF signal to the upper electrode. Note that the control unit 2 may or may not control the second RF generator 31b to supply a bias RF signal to the lower electrode.

[0041] In step S202, a second ashing process is performed in which a plasma of an ashing gas is generated and the organic film 310 is ashed.

[0042] Here, the control unit 2 controls the gas supply unit 20 to supply an ashing gas into the plasma processing chamber 10, and also controls the first RF generator 31a to supply a source RF signal to the upper electrode. Note that the control unit 2 may control the second RF generator 31b to supply a bias RF signal to the lower electrode, or may not supply a bias RF signal.

[0043] Here, the ashing gas may be an oxygen (O)-containing gas. Specifically, the ashing gas may be a CO ２ Gas, O ２ Any of the gases can be used.

[0044] The fluorine (F)-containing gas is C ４ F ８ , C.F. ４ , N.F. ３ Any of the following can be used.

[0045] Furthermore, the power of the source RF signal supplied to the upper electrode in the first ashing process and the second ashing process is a power that selectively etches the organic film (carbon-containing film) 310 relative to the second film (silicon-containing film) 302. The power of the source RF signal is lower than the power that sputters the second film (silicon-containing film) 302. In a plasma processing apparatus 1 that supplies a source RF signal to the upper electrode and a bias RF signal to the lower electrode, the bias RF signal supplied to the lower electrode primarily affects the ion energy in the ashing gas plasma. In this case, the power of the source RF signal supplied to the upper electrode is not particularly limited. Furthermore, the power of the bias RF signal supplied to the lower electrode is preferably close to 0 W. Specifically, the ion energy of the ashing gas plasma generated by the bias RF signal supplied to the lower electrode is preferably in the range of 0 to 100 eV. This generates a plasma of ashing gas with low ion energy that selectively etches the organic film (carbon-containing film) 310 while suppressing etching of the second film (silicon-containing film) 302 .

[0046] Furthermore, the frequency of the source RF signal supplied to the upper electrode in the first ashing process and the second ashing process is 60 MHz or higher (e.g., 100 MHz), thereby generating a plasma of the ashing gas with a high ion flux.

[0047] In this way, by using plasma of an ashing gas with low ion energy, it is possible to selectively ash the organic film (carbon-containing film) 310 while suppressing etching (sputtering) of the second film 302. Furthermore, by using plasma of an ashing gas with low ion energy and high ion flux, it is possible to suppress a decrease in the ashing rate of the organic film (carbon-containing film) 310.

[0048] Furthermore, the power of the bias RF signal supplied to the lower electrode in the first ashing process and the second ashing process is smaller than the power of the source RF signal, thereby suppressing sputtering of the second film 302 by ions.

[0049] Next, the process for removing the organic film in this embodiment (S105 in FIG. 2, S201 to S202 in FIG. 4) will be further described in comparison with the process for removing the organic film in the reference example.

[0050] 5A to 5D are examples of schematic cross-sectional views of the substrate W during the process of removing the organic film 310 according to the first reference example.

[0051] 5A is an example of a schematic cross-sectional view of the substrate W after the via etching process (S104) and before the ashing process of the organic film 310. Deposits 316 derived from the first fluorine (F)-containing gas used in etching the target film 300 in step S104 are deposited on the sidewalls and upper portion of the organic film 310.

[0052] 5B is an example of a schematic cross-sectional view of the substrate W during the ashing process of the organic film 310. Here, a plasma of ashing gas with high ion energy is generated. As a result, ions 400 of the ashing gas are attracted to the substrate W and ash the organic film 310 and deposits 316 derived from the first fluorine (F)-containing gas. Note that the ions 400 of the ashing gas with high ion energy also ash silicon (Si)-containing deposits (see reference numeral 317 in FIG. 6A , which will be described later). Some of the ions 400 of the ashing gas are reflected by the sidewall of the organic film 310 and collide with the second film 302. This may result in the corners of the second film 302 being chipped off.

[0053] 5C is an example of a schematic cross-sectional view of the substrate W during the ashing process of the organic film 310. Here, in order to sufficiently remove the organic film 310, over-etching is performed in the ashing process of the organic film 310. That is, the ashing process is continued even after the organic film 310 is removed and the second film 302 is exposed. The corners 302a of the second film 302 are sputtered by ions 400 of the ashing gas, which may result in the corners 302a of the second film 302 being scraped off. That is, there is a risk that the via diameter CD of the opening 305 will widen.

[0054] 5D is an example of a schematic cross-sectional view of the substrate W during the ashing process of the organic film 310. In this example, the ashing process continues even after the organic film 310 is removed and the second film 302 is exposed. The upper surface of the second film 302 is sputtered by ions 400 of the ashing gas, causing oxides 302c scattered from the second film 302 to be non-uniformly redeposited on the second film 302. As a result, corners 302b of the second film 302 grow in a direction that closes the opening 305, forming a necking shape.

[0055] As shown in Fig. 5C, the corners 302a of the second film 302 are removed, causing the via diameter CD to expand non-uniformly. Furthermore, as shown in Fig. 5D, a necking shape is formed at the corners 302b of the second film 302, causing the via diameter CD to narrow non-uniformly. Therefore, the uniformity of the via diameter CD in the multiple openings 305 decreases.

[0056] 6A to 6C are examples of schematic cross-sectional views of the substrate W during the process of removing the organic film 310 according to the second reference example.

[0057] 6A is an example of a schematic cross-sectional view of the substrate W during the via etching process (S104). Deposits 316 derived from the first fluorine (F)-containing gas used in etching the target film 300 in step S104 are deposited on the sidewalls and upper portion of the organic film 310. In addition, when the target film 300 (first film 301, second film 302) is etched, silicon (Si)-containing deposits 317 are deposited on the sidewalls of the organic film 310.

[0058] 6B is an example of a schematic cross-sectional view of the substrate W during the ashing process of the organic film 310. Here, plasma of an ashing gas with low ion energy is generated. As a result, ions 410 of the ashing gas ash the organic film 310 and the deposits 316 derived from the first fluorine (F)-containing gas. On the other hand, silicon (Si)-containing deposits 317 are not ashed and remain on the sidewall of the organic film 310.

[0059] 6C is an example of a schematic cross-sectional view of the substrate W after ashing of the organic film 310. Using plasma of ashing gas with low ion energy prevents the corners of the second film 302 from being scraped off and prevents redeposition caused by sputtering of the second film 302. That is, the formation of necking at the openings 305 in the second film 302 is prevented. This improves the uniformity of the via diameter CD in the multiple openings 305. Meanwhile, residues of silicon (Si)-containing deposits 317 remain on the upper surface of the second film 302.

[0060] 7A to 7C are examples of schematic cross-sectional views of a substrate in a process for removing an organic film according to this embodiment.

[0061] Before the first ashing process (S201), as shown in FIG. 6A described above, deposits 316 derived from the first fluorine (F)-containing gas and silicon (Si)-containing deposits 317 are deposited on the sidewalls and upper portion of the organic film 310.

[0062] 7A is an example of a schematic cross-sectional view of a substrate W during a first ashing process (S201). Here, plasma of ashing gas with low ion energy is generated. As a result, ions 410 of the ashing gas ash the organic film 310 and deposits 316 derived from the first fluorine (F)-containing gas. In addition, in the first ashing process (S201), a second fluorine (F)-containing gas is added, and fluorine (F) radicals 420 remove silicon (Si)-containing deposits 317.

[0063] 7B is an example of a schematic cross-sectional view of the substrate W during the second ashing process (S202). Here, plasma of an ashing gas with low ion energy is generated. As a result, ions 410 of the ashing gas ashes the organic film 310 and the deposits 316 derived from the first fluorine (F)-containing gas.

[0064] 7C is an example of a schematic cross-sectional view of the substrate W after the ashing process of the organic film 310. By using plasma of ashing gas with low ion energy, scraping of the corners of the second film 302 and redeposition due to sputtering of the second film 302 are suppressed. That is, formation of a necking shape at the opening 305 of the second film 302 is suppressed. In addition, the silicon (Si)-containing deposit 317 can be removed, and residue of the silicon (Si)-containing deposit 317 is suppressed from remaining on the upper surface of the second film 302.

[0065] It is preferable that the first ashing process (S201) in which the second fluorine (F)-containing gas is added be performed before the second ashing process (S202). By adding the second fluorine (F)-containing gas when the silicon (Si)-containing deposits 317 are widely dispersed on the sidewall, the silicon (Si)-containing deposits 317 can be removed more efficiently than when the second fluorine (F)-containing gas is added after the silicon (Si)-containing deposits 317 have aggregated (see FIG. 6C ).

[0066] Furthermore, by adding the second fluorine (F)-containing gas when a sufficient thickness of the organic film 310 remains on the target film 300, it is possible to prevent the second fluorine (F)-containing gas from etching the top surface of the target film 300. Furthermore, by adding the second fluorine (F)-containing gas when a sufficient thickness of the organic film 310 remains on the target film 300, it is possible to prevent a bowing shape from being formed in the opening 305 of the first film 301.

[0067] As described above, the method for removing the organic film 310 maintains the shape of the via (opening 305) formed in the target film 300 to be etched, improves the uniformity of the via diameter, and removes the organic film 310. Furthermore, the residue of the silicon (Si)-containing deposit 317 can be removed.

[0068] The embodiments disclosed above include, for example, the following: (Supplementary Note 1) A substrate processing method comprising the steps of: preparing a substrate having a silicon-containing film to be etched and an organic film formed on the film to be etched and having an opening pattern formed thereon; generating plasma of a first fluorine-containing gas and forming an opening pattern in the film to be etched using the organic film as a mask; and removing the organic film after forming the opening pattern in the film to be etched, wherein the step of removing the organic film comprises: (a) generating plasma of an ashing gas to which a second fluorine-containing gas has been added to remove the organic film; and (b) after step (a), generating plasma of the ashing gas to remove the organic film. (Supplementary Note 2) The substrate processing method according to Supplementary Note 1, wherein the step of removing the organic film comprises supplying a source RF signal to an upper electrode facing a lower electrode provided on a substrate support portion that supports the substrate. (Supplementary Note 3) The substrate processing method according to Supplementary Note 2, wherein, in the step of removing the organic film, the power of the source RF signal is a power that selectively etches the organic film with respect to the film to be etched. (Supplementary Note 4) The substrate processing method according to any one of Supplementary Notes 2 to 3, wherein, in the step of removing the organic film, the frequency of the source RF signal is 60 MHz or more. (Supplementary Note 5) The substrate processing method according to any one of Supplementary Notes 2 to 4, wherein, in the step of removing the organic film, a bias RF signal is supplied to the lower electrode. (Supplementary Note 6) The substrate processing method according to Supplementary Note 5, wherein, in the step of removing the organic film, the power of the bias RF signal is smaller than the power of the source RF signal. (Supplementary Note 7) The second fluorine-containing gas is C ４ F ８ , C.F. ４ , N.F. ３The substrate processing method according to any one of Supplementary Note 1 to Supplementary Note 6, wherein the ashing gas is an oxygen-containing gas. (Supplementary Note 8) The substrate processing method according to any one of Supplementary Note 1 to Supplementary Note 7, wherein the ashing gas is a CO ２ , O ２ (Supplementary Note 10) A plasma processing apparatus comprising: a substrate support part for supporting a substrate having a silicon-containing target film to be etched and an organic film formed on the target film to be etched and having an opening pattern formed thereon; a plasma processing chamber accommodating the substrate support part; a gas inlet part for introducing gas into the plasma processing chamber; a plasma generation part for generating plasma in the plasma processing chamber; and a control part, the plasma processing apparatus carrying out the steps of generating plasma of a first fluorine-containing gas and forming an opening pattern in the target film to be etched using the organic film as a mask; and removing the organic film after forming the opening pattern in the target film to be etched, the step of removing the organic film comprising: (a) generating plasma of an ashing gas to which a second fluorine-containing gas has been added, and removing the organic film; and (b) after the step (a), generating plasma of the ashing gas and removing the organic film.

[0069] The present invention is not limited to the configurations described in the above embodiments, but may be combined with other elements, etc. These aspects can be changed without departing from the spirit of the present invention, and can be appropriately determined depending on the application form.

[0070] This application claims priority based on Japanese Patent Application No. 2024-047099, filed on March 22, 2024, the entire contents of which are incorporated herein by reference.

[0071] REFERENCE SIGNS LIST W substrate 1 plasma processing apparatus 2 control unit 10 plasma processing chamber 11 substrate support unit 13 shower head (gas inlet unit) 30 power supply 31a first RF generating unit (plasma generating unit) 300 film to be etched 301 first film 302 second film 310 organic film 320 silicon-containing film 330 photoresist film 305, 315, 325, 335 openings

Claims

1. A substrate processing method comprising the steps of: preparing a substrate having a silicon-containing film to be etched and an organic film formed on the film to be etched and having an opening pattern formed thereon; generating plasma of a first fluorine-containing gas and forming an opening pattern in the film to be etched using the organic film as a mask; and removing the organic film after forming the opening pattern in the film to be etched, wherein the step of removing the organic film comprises: (a) generating plasma of an ashing gas to which a second fluorine-containing gas has been added to remove the organic film; and (b) after step (a), generating plasma of the ashing gas to remove the organic film.

2. The substrate processing method according to claim 1, wherein the step of removing the organic film comprises supplying a source RF signal to an upper electrode opposed to a lower electrode provided on a substrate support part that supports the substrate.

3. The substrate processing method according to claim 2, wherein in the step of removing the organic film, the power of the source RF signal is a power that selectively etches the organic film relative to the target film to be etched.

4. The substrate processing method according to claim 2, wherein in the step of removing the organic film, the frequency of the source RF signal is 60 MHz or higher.

5. The substrate processing method according to claim 2, wherein the step of removing the organic film comprises supplying a bias RF signal to the lower electrode.

6. The substrate processing method according to claim 5, wherein in the step of removing the organic film, the power of the bias RF signal is smaller than the power of the source RF signal.

7. The second fluorine-containing gas is C ４ F ８ , C.F. ４ , N.F. ３ The substrate processing method according to claim 1 , wherein the substrate processing method is any one of the following:

8. The substrate processing method according to claim 1, wherein the ashing gas is an oxygen-containing gas.

9. The ashing gas is CO ２ , O ２ The substrate processing method according to claim 8 , wherein the substrate processing method is any one of the following:

10. A plasma processing apparatus comprising: a substrate support part for supporting a substrate having a silicon-containing film to be etched and an organic film formed on the film to be etched and having an opening pattern formed thereon; a plasma processing chamber accommodating the substrate support part; a gas inlet part for introducing gas into the plasma processing chamber; a plasma generation part for generating plasma in the plasma processing chamber; and a control part, the plasma processing apparatus carrying out the steps of generating plasma of a first fluorine-containing gas and forming an opening pattern in the film to be etched using the organic film as a mask; and removing the organic film after forming the opening pattern in the film to be etched, the step of removing the organic film comprising: (a) a step of generating plasma of an ashing gas to which a second fluorine-containing gas has been added and removing the organic film; and (b) a second step of generating plasma of the ashing gas and removing the organic film after the step (a).

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