Substrate processing method and substrate processing device

Abstract

The present invention provides a substrate processing method and a substrate processing apparatus. The substrate processing method includes providing a substrate, forming a protective film, and etching. The providing substrate step provides a substrate having an etched film, a first mask formed on the etched film, and a second mask formed to cover at least a portion of the first mask. The forming protective film step utilizes plasma generated from a first gas to form a protective film on the sidewalls of the second mask. The etching step utilizes plasma generated from a second gas to etch the etched film. According to the present invention, loss of stacked masks can be suppressed.

Description

Technical Field

[0001] The present invention relates to a substrate processing method and a substrate processing device. Background Art

[0002] Conventionally, a process of selectively etching an interlayer insulating film using stacked masks has been performed. In addition, as a selective etching, there is a technique of selectively etching a silicon nitride region relative to a silicon oxide region, for example.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-98480. Summary of the Invention

[0006] Problems to be solved by the invention

[0007] The present invention provides a substrate processing method and a substrate processing apparatus capable of suppressing loss of stacked masks.

[0008] Technical means to solve the problem

[0009] A substrate processing method according to one embodiment of the present invention includes providing a substrate, forming a protective film, and etching. The providing substrate step comprises providing a substrate having a film to be etched, a first mask formed over the film to be etched, and a second mask formed to cover at least a portion of the first mask. The forming protective film step utilizes plasma generated from a first gas to form a protective film on the sidewalls of the second mask. The etching step utilizes plasma generated from a second gas to etch the film to be etched.

[0010] Effects of the Invention

[0011] According to the present invention, it is possible to suppress loss of stacked masks. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 FIG. 1 is a diagram showing an example of a plasma processing system according to an embodiment of the present invention.

[0013] Figure 2 This is a diagram showing an example of forming a multilayer wiring.

[0014] Figure 3 This is a diagram schematically illustrating an example of a processing flow in this embodiment.

[0015] Figure 4 This is a flowchart showing an example of etching processing in this embodiment.

[0016] Figure 5This is a diagram schematically illustrating an example of formation of side deposition in this embodiment.

[0017] Figure 6 This is a diagram schematically illustrating an example of repetition of side deposition and etching in this embodiment.

[0018] Figure 7 This is a diagram showing an example of the repetition of side deposition and etching in the present embodiment and the comparative example using a time axis.

[0019] Figure 8 This is a diagram showing an example of a cross section before and after side deposition in this embodiment.

[0020] Figure 9 This is a diagram showing an example of experimental results in this embodiment.

[0021] Figure 10 This is a diagram showing an example of experimental results in a comparative example.

[0022] Figure 11 This is a diagram showing an example of comparison of lateral bending (bowing) with and without side deposition.

[0023] Description of Reference Numerals

[0024] 1 Plasma treatment system

[0025] 1a Plasma treatment device

[0026] 1b Control Unit

[0027] 10 Plasma processing chamber

[0028] 11 Support

[0029] 20 Gas supply unit

[0030] 30 RF power supply unit

[0031] 40 Exhaust System

[0032] 222 1st etched film

[0033] 224 Mask 1

[0034] 225 Second Mask

[0035] 228 Side deposition (sediment)

[0036] W substrate DETAILED DESCRIPTION

[0037] Hereinafter, embodiments of the disclosed substrate processing method and substrate processing apparatus will be described in detail based on the accompanying drawings.

[0038] Until now, there has been a process of selectively etching interlayer insulating films using stacked masks. For example, there is a technology that, when generating a pattern for forming a multilayer wiring, forms a thin CF film on the mask surface using a gas containing CHF while allowing the processing of the etched film (interlayer insulating film) to proceed. However, it is difficult to form a CF film in the deeper part of the stacked mask, and the mask protection is not sufficient, resulting in mask loss, and sometimes it is not possible to obtain a sufficient selectivity. In addition, only when the mask protection is insufficient during the etching process, a process is performed to combine it with the film forming process of the protective film. However, by introducing the film forming process, clogging of the pattern or film formation on the surface of the etched film may occur. In this case, the etching stop phenomenon (etching stop) may occur before the etched film is processed into the desired shape. Therefore, it is desired to have a technology that suppresses the mask loss in the stacked mask without causing etching stop.

[0039] [Structure of Plasma Processing System 1]

[0040] Figure 1 FIG. 1 is a diagram showing an example of a plasma processing system according to an embodiment of the present invention. Figure 1 As shown, in one embodiment, a plasma processing system 1 includes a plasma processing apparatus 1a and a control unit 1b. The plasma processing apparatus 1a includes a plasma processing chamber 10, a gas supply unit 20, an RF (Radio Frequency) power supply unit 30, and an exhaust system 40. In addition, the plasma processing apparatus 1a includes a support unit 11 and an upper electrode shower head 12. The support unit 11 is disposed in the lower region of the plasma processing space 10s within the plasma processing chamber 10. The upper electrode shower head 12 is disposed above the support unit 11 and can function as a portion of the ceiling of the plasma processing chamber 10.

[0041] The support portion 11 is capable of supporting the substrate W in the plasma processing space 10s. In one embodiment, the support portion 11 includes a lower electrode 111, an electrostatic chuck 112, and an edge ring 113. The electrostatic chuck 112 is arranged on the lower electrode 111 and is capable of supporting the substrate W on the upper surface of the electrostatic chuck 112. The edge ring 113 is arranged on the upper surface of the peripheral portion of the lower electrode 111 in a manner surrounding the substrate W. In addition, although not shown in the figure, in one embodiment, the support portion 11 may also include a temperature adjustment module that can adjust at least one of the electrostatic chuck 112 and the substrate W to a target temperature. The temperature adjustment module may include a heater, a flow path, or a combination thereof. A temperature adjustment fluid such as a refrigerant or a heat transfer gas can flow in the flow path.

[0042] The upper electrode shower head 12 can supply one or more process gases from the gas supply unit 20 to the plasma processing space 10s. In one embodiment, the upper electrode shower head 12 has a gas inlet 12a, a gas diffusion chamber 12b, and a plurality of gas outlets 12c. The gas inlet 12a is in fluid communication with the gas supply unit 20 and the gas diffusion chamber 12b. The plurality of gas outlets 12c are in fluid communication with the gas diffusion chamber 12b and the plasma processing space 10s. In one embodiment, the upper electrode shower head 12 can supply one or more process gases from the gas inlet 12a through the gas diffusion chamber 12b and the plurality of gas outlets 12c to the plasma processing space 10s.

[0043] The gas supply unit 20 may include one or more gas sources 21 and one or more flow controllers 22. In one embodiment, the gas supply unit 20 can supply one or more process gases from corresponding gas sources 21 to the gas inlet 12a via corresponding flow controllers 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Furthermore, the gas supply unit 20 may include one or more flow modulators to modulate or pulse the flow of one or more process gases.

[0044] The RF power supply unit 30 can supply RF power, such as one or more RF signals, to one or more electrodes, such as the lower electrode 111, the upper electrode showerhead 12, or both the lower electrode 111 and the upper electrode showerhead 12. This generates plasma from the one or more process gases supplied to the plasma processing space 10s. Therefore, the RF power supply unit 30 can function as at least a portion of a plasma generation unit capable of generating plasma from one or more process gases in a plasma processing chamber. In one embodiment, the RF power supply unit 30 includes two RF generators 31a and 31b and matching circuits 32a and 32b. In one embodiment, the RF power supply unit 30 can supply a first RF signal from the first RF generator 31a to the lower electrode 111 via the first matching circuit 32a. For example, the first RF signal can have a frequency in the range of 27 MHz to 100 MHz.

[0045] In one embodiment, the RF power supply unit 30 can supply a second RF signal from the second RF generator 31b to the lower electrode 111 via the second matching circuit 32b. For example, the second RF signal can have a frequency in the range of 400 kHz to 13.56 MHz. Alternatively, a DC (direct current) pulse generator can be used in place of the second RF generator 31b.

[0046] Although not shown in the figure, other embodiments are also contemplated within the present invention. For example, in an alternative embodiment, the RF power supply unit 30 can supply a first RF signal from an RF generator to the lower electrode 111, a second RF signal from another RF generator to the lower electrode 111, and a third RF signal from yet another RF generator to the lower electrode 111. Furthermore, in other alternative embodiments, a DC voltage can be applied to the upper electrode showerhead 12.

[0047] In various embodiments, the amplitude of one or more RF signals (i.e., the first RF signal, the second RF signal, etc.) may be pulsed or modulated. Amplitude modulation includes pulsing the amplitude of the RF signal between an on state and an off state, or between two or more different on states.

[0048] The exhaust system 40 can be connected to, for example, an exhaust port 10e provided at the bottom of the plasma processing chamber 10. The exhaust system 40 includes a pressure valve and a vacuum pump. The vacuum pump includes a turbomolecular pump, a roughing pump, or a combination thereof.

[0049] In one embodiment, the control unit 1b processes computer-executable commands that cause the plasma processing apparatus 1a to implement the various steps described herein. The control unit 1b is capable of controlling various components of the plasma processing apparatus 1a to implement the various steps described herein. In one embodiment, a portion or all of the control unit 1b may be included in the plasma processing apparatus 1a. The control unit 1b may also include, for example, a computer 51. The computer 51 may include, for example, a processing unit (CPU: Central Processing Unit) 511, a storage unit 512, and a communication interface 513. The processing unit 511 is capable of performing various control operations based on programs stored in the storage unit 512. The storage unit 512 may include RAM (Random Access Memory), ROM (Read Only Memory), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface 513 can communicate with the plasma processing apparatus 1a via a communication line such as a LAN (Local Area Network).

[0050] [Formation of Multilayer Wiring]

[0051] Figure 2 FIG is a diagram showing an example of forming a multilayer wiring. Figure 2 As shown in the state 200a, a base pattern 201, an interlayer insulating film 202, a trench mask 203, a through hole mask 204 and a resist film 205 are stacked on a substrate W where multilayer wiring is formed. Figure 2 The substrate W is omitted in the following description. In addition, in the following description, the stacking order of the interlayer insulating film 202 (etched film) is sometimes expressed as the first mask and the second mask. Figure 2 In this case, the interlayer insulating film 202 becomes the film to be etched, the trench mask 203 becomes the first mask, and the through-hole mask 204 becomes the second mask.

[0052] In the multilayer wiring step, from state 200a, through-hole mask 204 is first etched to state 200b. Next, from state 200b, interlayer insulating film 202 is etched to state 200c. Here, during the etching of interlayer insulating film 202, the etching selectivity ratio of two masks disposed at different levels, namely trench mask 203 and through-hole mask 204, is determined. In this embodiment, to achieve this etching selectivity ratio, deposits (hereinafter also referred to as side deposits) are formed on the sidewalls of through-hole mask 204 (second mask).

[0053] Figure 3FIG is a diagram schematically illustrating an example of a processing flow in this embodiment. Figure 3 As shown, in the state 210, a base pattern 221, a first etched film 222, a second etched film 223, a first mask 224, a second mask 225, a SiARC film 226, and a resist film 227 are stacked on the substrate W. Figure 3 The substrate W is omitted. As an example, the first etched film 222 to the second mask 225 are shown. Examples of the first etched film 222 and the second etched film 223 include low-k films such as SiOC films or SiOCH films, or SiO2 films. Examples of the first mask 224 include metal-containing films such as TiN films or WC films. Examples of the second mask 225 include an SOC (Spin On Carbon) film, which is an example of a carbon-containing film.

[0054] As a process flow, first, in state 210, the SiARC film 226 is etched using plasma generated by CF4 gas, etc., leading to state 211. Next, in state 211, the second mask 225 and the resist film 227 are etched using plasma generated by N2 / H2 gas, etc., leading to state 212. At this point, the second etched film 223 and a portion of the first mask 224 are exposed. Next, in state 212, the exposed second etched film 223 and the SiARC film 226 are etched using plasma generated by CF4 / CHF3 gas, etc., leading to state 213. Next, in state 213, a deposition 228 is formed on the sidewalls of the second mask 225 using plasma generated by the first gas, leading to state 214. The first gas is, for example, a gas containing hydrocarbons and nitrogen, and C3H6 / N2 gas or CH4 / N2 gas can be used. The first gas can also be used in conjunction with hydrocarbon gas and nitrogen-containing gas, or in place of nitrogen-containing gas, in the form of an oxygen-containing gas such as O2 or CO. Alternatively, a silicon- and fluorine-containing gas such as SiH4 / CF4 or SiF4 can be used as the first gas. Next, in state 214, the first etched film 222 is etched using plasma generated by the second gas, resulting in state 215. The second gas is a gas containing fluorine and hydrogen, and for example, CF4 / H2 gas or HF / CH4 can be used. This can suppress mask loss on the first mask 224 and the second mask 225.

[0055] [Substrate processing method]

[0056] Next, the substrate processing method according to this embodiment will be described. Figure 4 : is a flowchart showing an example of etching processing in this embodiment. Figure 4 The flowchart is described in detail Figure 3 FIG. 2 is a diagram of the processing from state 213 to state 215 in the processing flow of FIG.

[0057] In the substrate processing method of this embodiment, the control unit 1b opens the opening portion (not shown) to make the film to be etched (interlayer insulating film) in an etchable state ( Figure 3 The substrate W in the state 213) is brought into the plasma processing chamber 10 and placed on the electrostatic chuck 112 of the support portion 11 (the mounting table). The substrate W is held on the electrostatic chuck 112 by applying a DC voltage to the electrostatic chuck 112. The control unit 1b then closes the opening and controls the exhaust system 40 to exhaust gas from the plasma processing space 10s, so that the atmosphere of the plasma processing space 10s reaches a predetermined vacuum level. In addition, the control unit 1b controls the temperature of the substrate W by controlling a temperature control module (not shown) to adjust the temperature so that the temperature of the substrate W is within a predetermined temperature range (step S1).

[0058] Next, the control unit 1b supplies C3H6 / N2 gas as the first gas to the gas inlet 12a. After being supplied to the gas inlet 12a, the first gas is supplied to the gas diffusion space 12b and diffuses. After diffusing in the gas diffusion space 12b, the first gas is supplied in a shower pattern through the plurality of gas outlets 12c into the plasma processing space 10s of the plasma processing chamber 10, filling the plasma processing space 10s.

[0059] The control unit 1b controls the RF power supply unit 30 to supply an RF signal for plasma excitation to the lower electrode 111. Specifically, the RF signal, which is high-frequency power, is applied to the lower portion. In the plasma processing space 10s, the RF signal is supplied to the lower electrode 111, generating plasma. At this time, the plasma is self-biased, resulting in inverse anisotropic CVD (Chemical Vapor Deposition), forming deposits (side deposits 228) on the sidewalls of the second mask 225 on the substrate W (step S2).

[0060] Here, use Figure 5 The formation of side deposits will be described. Figure 5 Schematically illustrates an example of the formation of side deposition in this embodiment. Figure 5 In the example, the first mask (equivalent to Figure 3 The first mask 224 is formed. Figure 5 In the state 230a, the plasma of C3H6 gas generated by supplying RF signal to the lower electrode 111 (lower application) is formed on the etched film 231 (equivalent to Figure 3 ) is formed on the first etched film 222. In addition, in the state 230a, the mask 232 (equivalent to Figure 3Deposits 233 are formed on the second mask 225. Deposits 233 and 234 are formed by the overlapping of the anisotropic supply of ions and the unidirectional flow of plasma CVD. In particular, deposit 233 is formed by the application of the lower portion to the sidewalls of mask 232, forming a protruding tip.

[0061] In addition, Figure 5 In state 230b, the deposits 233 and 234 are etched by the plasma of N2 gas generated by the application from below. The anisotropic removal by N ions can remove the deposits 233a on the upper surface of the mask 232, but cannot remove the side deposits 233b on the sidewalls of the mask 232. The deposits 234 can be removed by the anisotropic removal by N ions.

[0062] Thus, in step S2, when plasma is generated by supplying a gas containing a film-forming component such as C3H6 and a gas containing a removing component such as N2, the formation of the deposit and the removal of the deposit are performed simultaneously. That is, the state 230a and the state 230b are performed simultaneously. As a result, as shown in the state 230c, a side deposit 233b (equivalent to Figure 3 ). That is, the side deposition 233b can be achieved by the inherently isotropic film formation of plasma CVD, the anisotropic supply of ions due to the downward application of an RF signal, and the anisotropic removal of carbon due to N. Furthermore, step S2 can be performed using any other method as long as it can form the side deposition 233b shown in state 230c. For example, the side deposition 233b can be formed on the sidewall of the mask 232 by sequentially performing the steps of forming a plasma using a gas having a film-forming component and removing the plasma using a gas having a removal component. Alternatively, the side deposition 233b can be formed on the sidewall of the mask 232 by repeatedly performing the steps of forming the deposition and removing the deposition.

[0063] return Figure 4 . When exhausting the first gas, the control unit 1b supplies CF4 / H2 gas as the second gas to the gas inlet 12a. After being supplied to the gas inlet 12a, the second gas is supplied to the gas diffusion space 12b and diffused. After diffusing in the gas diffusion space 12b, the second gas is supplied in a shower pattern through the plurality of gas outlets 12c into the plasma processing space 10s of the plasma processing chamber 10, filling the plasma processing space 10s.

[0064] The control unit 1b controls the RF power supply unit 30 to supply an RF signal for plasma excitation to the lower electrode 111. In other words, the RF signal is applied to the lower portion. In the plasma processing space 10s, the supply of the RF signal to the lower electrode 111 generates plasma. In the plasma processing space 10s, the first etched film 222 of the substrate W is etched by the plasma of the second gas (step S3).

[0065] Here, use Figure 6 , illustrating the repeated execution of side deposition and etching. Figure 6 Schematically illustrates an example of the repetition of side deposition and etching in this embodiment. Figure 6 In the figure, the substrate W, the base pattern 221 and the second etched film 223 are omitted. Figure 6 Status 241 with Figure 3 Corresponding to the state 213, a deposition 228 is formed on the side wall of the second mask 225. Figure 6 In state 242, the first etched film 222 is etched using plasma generated from CF4 / H2 gas. At this time, ions 244 etch the first etched film 222 to form grooves 245. On the other hand, due to the presence of side deposits 228, the ions 244 do not collide with the first mask 224, and the first mask 224 is not etched. In state 242, when the side deposits 228 are consumed by etching, the process shifts again to state 241 where the side deposits 228 are formed. That is, the formation of the side deposits 228 in state 241 and the etching of the first etched film 222 in state 242 are repeated until the grooves 245 reach a desired depth in state 243. The predetermined number of repetitions can be determined, for example, by preliminary experiments.

[0066] return Figure 4 Description. The control unit 1b determines whether the deposit formation step and the etching step have been repeatedly performed a specified number of times (step S4). The specified number of times can be, for example, three times. When the control unit 1b determines that the specified number of times has not been repeated (step S4: No), the processing returns to step S2. On the other hand, when the control unit 1b determines that the specified number of times has been repeated (step S4: Yes), the processing ends. In addition, the control unit 1b may also determine in step S4 whether the etched film has obtained a specified shape.

[0067] When the process is complete, the control unit 1b controls the RF power supply unit 30 to stop supplying the RF signal to the lower electrode 111. Furthermore, the control unit 1b applies DC voltages of opposite polarity to the electrostatic chuck 112 to remove static electricity, thereby peeling the substrate W from the electrostatic chuck 112. The control unit 1b opens an opening (not shown). The substrate W is then removed from the plasma processing space 10s of the plasma processing chamber 10 through the opening.

[0068] [Experimental Results]

[0069] Next, use Figures 7 to 11 , explain the experimental results. Figure 7 This is a diagram showing an example of repeated execution of side deposition and etching in this embodiment and the comparative example using a time axis. Figure 7 As shown in graph 251, in this embodiment, side deposition formation 253 ("D") and etching 254 ("E") were repeated three times under the following processing conditions. On the other hand, as shown in graph 252, in the comparative example, etching 255 ("E") was performed once under the following processing conditions.

[0070] <Processing Conditions of This Embodiment>

[0071] (Formation of side deposits)

[0072] Temperature: -70°C

[0073] Pressure in plasma processing chamber 10: 30 mTorr

[0074] RF signal power: 300W

[0075] Processing gas: C3H6 / N2=10 / 290sccm

[0076] Processing time: 7 seconds

[0077] (Etching)

[0078] Temperature: -70°C

[0079] Pressure in plasma processing chamber 10: 25 mTorr

[0080] RF signal power: 1400W

[0081] Processing gas: CF4 / H2=35 / 130sccm

[0082] Processing time: 10 seconds

[0083] <Processing Conditions of Comparative Example>

[0084] (Etching)

[0085] Temperature: -70°C

[0086] Pressure in plasma processing chamber 10: 25 mTorr

[0087] RF signal power: 1400W

[0088] Processing gas: CF4 / H2=35 / 130sccm

[0089] Processing time: 10 seconds, 20 seconds, 30 seconds

[0090] Figure 8 This is a diagram showing an example of a cross section before and after side deposition in this embodiment. Figure 8 Cross-section 261 shows a state before the formation of side deposits in this embodiment. In cross-section 261, the second etched film 223, the first mask 224, and the second mask 225 are etched, and the first etched film 222 is etched. Cross-section 262 shows a state after the formation of side deposits in this embodiment. In cross-section 262, side deposits 264 are formed in regions 263 of the sidewalls of the second mask 225.

[0091] Figure 9 This is a diagram showing an example of experimental results in this embodiment. Figure 9 Experimental results 271 to 273 are shown when steps S2 and S3 are repeated one to three times, respectively. The center portions of experimental results 271 to 273 show the CD (critical dimension) values, which are 33 nm, 39 nm, and 37 nm, respectively. Furthermore, the lower portions of experimental results 271 to 273 are magnified views of the area around the second mask 225.

[0092] Figure 10 This is a diagram showing an example of experimental results in a comparative example. Figure 10 Experimental results 281-283 are shown for comparative example processing conditions with processing times of 10 seconds, 20 seconds, and 30 seconds, respectively. The center portion of experimental results 281-283 shows the CD values, which are 39 nm, 45 nm, and 53 nm, respectively. Furthermore, the lower portion of experimental results 281-283 is an enlarged view of the area surrounding the second mask 225.

[0093] Compare Figure 9 The experimental results 271~273 and Figure 10 Experimental results 281 to 283 show that the first mask 224 (TiN) was not depleted in experimental results 271 to 273. Furthermore, a comparison of the CD values ​​shows that bowing was suppressed in experimental results 271 to 273. Furthermore, a comparison of experimental results 271 and 281 shows that a difference in CD occurs even in the initial stages of the etching reaction.

[0094] Figure 11 This is a diagram showing an example of comparison of lateral deflection with and without side deposition. Figure 11 The experimental results 271a shown are Figure 9 The experimental results of 271 are enlarged. In addition, Figure 11 The experimental results 281a shown are Figure 10 This is an enlarged view of experimental result 281. In experimental result 271a, side deposits 275 are confirmed, with a CD of 33 nm. On the other hand, in experimental result 281a, there is no side deposit in region 285, which serves as the sidewall of the second mask 225, and the CD is 39 nm. This indicates that the widening of the CD, or Bow, is caused not only by the loss of the first mask 224 (TiN) but also by the oblique incidence of ions. In other words, the formation of side deposits has two effects: protecting the first mask 224 and suppressing the widening of the CD; and narrowing the pattern opening to receive only the vertically incident component, suppressing bowing.

[0095] Furthermore, in the above-described embodiment, the plasma processing system 1 is configured to include the plasma processing apparatus 1 a and the control unit 1 b . However, a substrate processing apparatus may also include the plasma processing apparatus 1 a and the control unit 1 b .

[0096] As described above, according to this embodiment, the substrate processing apparatus (plasma processing system 1) includes a stage (support unit 11) and a control unit 1b. The stage can mount a substrate W having: a first etched film 222; a first mask 224 formed on the first etched film 222; and a second mask 225 formed to cover at least a portion of the first mask 224. The control unit 1b executes the steps of forming a protective film (side deposition 228) on the sidewalls of the second mask 225 using plasma generated from a first gas; and etching the first etched film 222 using plasma generated from a second gas. As a result, mask loss in the stacked masks can be suppressed. In addition, lateral bowing can be suppressed.

[0097] Furthermore, according to this embodiment, the step of forming a protective film includes the steps of forming a deposit on the upper surface and sidewalls of the second mask 225 and the surface of the first etched film 222; and removing the deposit formed on the surface of the first etched film 222 and forming a protective film on the sidewalls of the second mask 225. As a result, the first mask 224 can be protected.

[0098] Furthermore, according to this embodiment, the protective film is formed using plasma generated from the first gas by supplying RF power from the mounting table side on which the substrate W is mounted. As a result, the protective film can be formed on the sidewalls of the second mask 225 .

[0099] Furthermore, according to this embodiment, the protective film is formed up to the sidewall of the first mask 224 on the upper portion of the first mask 224 that is not covered by the second mask 225. As a result, the first mask 224 can be protected.

[0100] Furthermore, according to this embodiment, the first etching target film 222 is a Low-k film or a SiO 2 film. As a result, etching can be performed while suppressing side bowing.

[0101] Furthermore, according to this embodiment, the first mask 224 is a metal-containing film, and the second mask 225 is a carbon-containing film. As a result, mask loss in the stacked masks can be suppressed.

[0102] In addition, according to this embodiment, the first gas is a gas containing hydrocarbons and nitrogen, a gas containing hydrocarbons and oxygen, or a gas containing silicon and fluorine. As a result, a protective film containing carbon and silicon can be formed on the sidewalls of the second mask 225.

[0103] According to this embodiment, the second gas is a gas containing fluorine and hydrogen. As a result, the first film to be etched 222 can be etched.

[0104] Furthermore, according to this embodiment, the step of forming the protective film and the step of etching are alternately repeated at least once, which can further suppress mask loss in the stacked masks.

[0105] Furthermore, according to this embodiment, the step of forming the protective film and the step of etching are performed in the same processing container. As a result, the step of forming the protective film and the step of etching can be efficiently repeated.

[0106] Furthermore, according to this embodiment, the step of forming the protective film and the step of etching are performed in different processing containers. As a result, when processing a plurality of substrates W, each step can be performed efficiently.

[0107] Although various exemplary embodiments have been described above, the present invention is not limited to the exemplary embodiments described above, and various additions, omissions, substitutions, and changes may be made. Furthermore, elements in different exemplary embodiments may be combined to form other exemplary embodiments.

[0108] For example, in the above-described embodiment, a substrate W having a two-layer mask is processed as the object of processing. The two-layer mask includes a first mask formed on a film to be etched and a second mask formed so as to cover at least a portion of the first mask. However, the present invention is not limited to such a substrate having a two-layer mask, and a substrate having a multi-layer mask can also be processed as the object of processing. Here, a substrate having a multi-layer mask refers to a substrate having an etched film and a multi-layer mask formed on the etched film, the multi-layer mask including an n-th mask (n is an integer greater than or equal to 1) in the n-th layer from the etched film and an n+1-th mask formed in the n+1-th layer from the etched film so as to cover at least a portion of the n-th mask.

[0109] A substrate with multiple layers of masks can also be processed in the same manner as in the above-described embodiment. Specifically, the substrate with multiple layers of masks is brought into the plasma processing chamber 10 and held on the electrostatic chuck 112 provided on the stage (support portion 11). Next, a protective film is formed on the sidewalls of one or more masks other than the first mask formed on the film to be etched using plasma generated by the first gas. The film to be etched is then etched using plasma generated by the second gas.

[0110] Furthermore, when a substrate having multiple layers of masks is used as the target, a protective film can be formed by removing the deposits formed on the surface of the etched film after deposits have formed on the sidewalls of one or more masks other than the first mask and on the surface of the etched film, similar to the above-described embodiment. Alternatively, the protective film can be formed using plasma generated from a first gas by supplying RF power from the stage on which the substrate is mounted. Furthermore, the protective film can be formed from the upper portion of the first mask to the position of the sidewalls of the first mask.

[0111] In addition, as another method, it is considered to use unsaturated ALD (Atomic Layer Deposition) to form a film to the middle of the groove. However, unsaturated ALD is targeted at patterns with a high aspect ratio (for example, 5 or more). When applied to a pattern for forming multilayer wiring with a low aspect ratio, the film will be formed to the bottom of the groove. Moreover, when the film at the bottom of the groove is removed, there is a possibility of peeling off to the film formed on the mask. In contrast, in the above-mentioned embodiment, even for a pattern for forming multilayer wiring with a low aspect ratio, it is possible to form a side deposition instead of forming a film at the bottom of the groove, so that a sufficient selectivity can be obtained and the etched film can be selectively etched.

[0112] In the above embodiment, a gas containing hydrocarbon and nitrogen is used as the first gas, but the present invention is not limited thereto. For example, a gas containing silicon and fluorine or a gas containing a metal element (Ti, W) and chlorine may be used depending on the material of the film to be etched and the mask.

[0113] In the above embodiment, the RF signal is applied from below, but if the bias component is introduced, a substrate processing apparatus that applies the signal from above can also be used. Furthermore, by adjusting the bias voltage, the formation position of the side deposition can be adjusted.

Claims

1. A substrate processing method, characterized in that: include: providing a substrate having a film to be etched, a first mask formed on the film to be etched and having an opening portion with a first opening width, and a second mask covering a portion of the first mask and having an opening portion with a second opening width larger than the first opening width; forming a protective film on the sidewalls of the second mask using plasma generated from the first gas; and A step of etching the film to be etched using plasma generated from the second gas.

2. The substrate processing method according to claim 1, wherein: The step of forming a protective film comprises: forming a deposit on the upper surface and sidewalls of the second mask and the surface of the film to be etched; and The step of removing the deposit formed on the surface of the film to be etched and forming the protective film on the side wall of the second mask.

3. The substrate processing method according to claim 1 or 2, wherein: The step of forming the protective film forms the protective film by using plasma generated from the first gas by supplying RF power from the side of the mounting table on which the substrate is mounted.

4. The substrate processing method according to claim 1 or 2, wherein: The step of forming the protective film includes forming the protective film on the upper portion of the first mask that is not covered by the second mask, up to the position of the side wall of the first mask.

5. The substrate processing method according to claim 1 or 2, wherein: The etched film is a Low-k film or a SiO2 film.

6. The substrate processing method according to claim 1 or 2, wherein: The first mask is a metal-containing film, and the second mask is a carbon-containing film.

7. The substrate processing method according to claim 1 or 2, wherein: The first gas is a gas containing hydrocarbons and nitrogen, a gas containing hydrocarbons and oxygen, or a gas containing silicon and fluorine.

8. The substrate processing method according to claim 1 or 2, wherein: The second gas is a gas containing fluorine and hydrogen.

9. The substrate processing method according to claim 1 or 2, wherein: The step of forming the protective film and the step of etching are alternately and repeatedly performed at least once.

10. The substrate processing method according to claim 1 or 2, wherein: The step of forming the protective film and the step of etching are performed in the same processing container.

11. The substrate processing method according to claim 1 or 2, wherein: The step of forming the protective film and the step of etching are performed in different processing containers.

12. A substrate processing method, characterized in that: include: providing a substrate, wherein the substrate has an etched film and a multilayer mask formed on the etched film, the multilayer mask including an nth mask at the nth layer from the etched film and an n+1th mask at the n+1th layer from the etched film covering a portion of the nth mask, the nth mask having an opening portion having an nth opening width, and the n+1th mask having an opening portion having an n+1th opening width larger than the nth opening width, where n is an integer greater than 1; forming a protective film on the sidewalls of at least one mask other than the first mask in the multi-layer mask by using plasma generated from a first gas; and A step of etching the film to be etched using plasma generated from the second gas.

Images