Substrate processing method

Abstract

This substrate processing method includes: applying atmospheric pressure plasma to an aqueous solution containing a noble metal and thereby forming, on a silicon substrate, a catalyst layer containing fine particles of the noble metal; and etching the silicon substrate, on which the catalyst layer has been formed, using an etching solution containing an oxidant and hydrogen fluoride.

Description

Substrate processing method

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

[0002] Patent Document 1 discloses that "the etching method includes: forming a first layer on a substrate containing a semiconductor material, one main surface of which has a first region and a second region adjacent to each other, covering the first region and the second region, the first layer having a plurality of openings or one or more openings defining a plurality of island-shaped portions in the portion covering the first region, and being a continuous film in the portion covering the second region; forming a catalyst layer containing a noble metal by plating on the portions of the main surface that are exposed in the plurality of openings or the one or more openings; forming a second layer that covers a portion of the catalyst layer adjacent to the boundary between the first region and the second region and exposes a portion of the catalyst layer spaced from the boundary; and etching the substrate with an etching agent containing an oxidant and hydrogen fluoride in the presence of the catalyst layer and the second layer."

[0003] Japanese Patent Application Laid-Open No. 2022-144046

[0004] The present disclosure provides a substrate processing method that can realize the formation of fine patterns.

[0005] A substrate processing method according to one aspect of the present disclosure includes applying atmospheric pressure plasma to an aqueous solution containing a precious metal to form a catalyst layer containing fine particles of the precious metal on a silicon substrate, and etching the silicon substrate on which the catalyst layer has been formed using an etching solution containing an oxidizing agent and hydrogen fluoride.

[0006] According to the present disclosure, it is possible to form fine patterns.

[0007] FIG. 1 is a schematic cross-sectional view showing an example of the configuration of a substrate processing apparatus according to a first embodiment. FIG. 2 is a flowchart showing an example of a process flow for substrate processing according to the first embodiment. FIG. 3 is a diagram showing an example of experimental results according to the first embodiment. FIG. 4 is a diagram showing an example of experimental results according to the first embodiment. FIG. 5 is a schematic cross-sectional view showing an example of the configuration of a substrate processing apparatus according to a second embodiment. FIG. 6 is a diagram showing an example of experimental results according to the second embodiment. FIG. 7 is a diagram showing an example of experimental results according to the second embodiment. FIG. 8 is a diagram showing an example of experimental results according to the second embodiment. FIG. 9 is a diagram showing an example of experimental results according to the second embodiment. FIG. 10 is a diagram showing an example of a process for forming drainage holes in a catalyst layer. FIG. 11 is a diagram showing an example of a process for forming a guide around a catalyst layer.

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the disclosed substrate processing method will be described in detail with reference to the accompanying drawings. However, the disclosed technology is not limited to the following embodiments.

[0009] Metal-Assisted Chemical Etching (MacEtch), which uses a precious metal as a catalyst, is a known method for forming high-aspect-ratio structures on semiconductor substrates. In the MacEtch method, electrons are transferred between the semiconductor substrate and an oxidizing agent at the catalyst, generating holes. The holes generated by the catalyst migrate to the surface of the semiconductor substrate, where the semiconductor substrate, e.g., silicon, near the catalyst is preferentially oxidized by the oxidizing agent. Silicon oxide is wet-etched with hydrogen fluoride in an etching solution. During this process, hydrogen bubbles are generated as a reaction product, preventing the hydrogen fluoride from reaching the silicon oxide region, resulting in etching proceeding only at the edge of the catalyst. For example, if the catalyst is formed by plating a precious metal, the catalyst size will be approximately 5 μm, and the MacEtch reaction may cease before the desired high-aspect-ratio structure is formed. To address this issue, for example, forming drainage holes in the catalyst allows the hydrogen fluoride to reach the silicon oxide region. However, when forming a fine pattern on a substrate, it may be difficult to form drain holes in the catalyst.

[0010] An example of catalyst layer formation will now be described with reference to Figures 10 and 11. Figure 10 is a diagram showing an example of a process for forming drain holes in a catalyst layer. States 101 to 105 shown in Figure 10 show the process flow for forming a noble metal (gold) pad as a catalyst layer on a substrate W1 and performing the MacEtch method. In state 101, the substrate W1 has an anti-reflection film 111 and a photoresist 112 formed on a silicon substrate 110, and a pattern with a hole 113 formed in the photoresist 112. A pillar 114 is formed in the center of the hole 113.

[0011] In state 102, the anti-reflection film 111 is etched, and the bottom of the hole 113 reaches the silicon substrate 110. In state 103, a titanium film 115 and a gold film 116 are formed by film formation on the surface of the photoresist 112 and on the side and bottom of the hole 113. In state 104, the photoresist 112 is removed, and a pad 117 made of the titanium film 115 and the gold film 116 is formed. The pad 117 is an example of a catalyst layer. In state 105, the anti-reflection film 111 is etched, and a drain hole 118 is formed in the center of the pad 117. The substrate W1 is then etched by the MacEtch method.

[0012] In the substrate W1, the pillars 114 for forming the drain holes 118 are holes 113 with a formable CD (Critical Dimension), so application is limited to relatively large pattern applications (on the order of μm), such as TSVs (Through Silicon Vias), etc. In other words, if holes corresponding to pads are formed with the smallest CD that can be formed by the process in order to form fine patterns, pillars that require a CD smaller than the pads cannot be formed.

[0013] 11 is a diagram showing an example of a process for forming a guide around a catalytic layer. States 121 to 124 shown in FIG. 11 show a process flow for forming a noble metal (gold) pad as a catalytic layer on a substrate W2, forming a guide around the pad, and performing the MacEtch method. In state 121, the substrate W2 has a silicon substrate 130 on which a spin-on-carbon (SOC) film 131, anti-reflection films 132 and 133, and a photoresist 134 are formed, and a pattern with a hole 135 is formed in the photoresist 134.

[0014] In state 122, the anti-reflection films 132 and 133 are etched, and the bottom of the hole 135 reaches the SOC film 131. In state 123, the SOC film 131 is processed into a recessed shape by high-pressure (radical-rich) plasma. That is, the SOC film 131 is etched laterally (over-etched) beyond the anti-reflection films 132 and 133 and the photoresist 134, as shown in region 136. In state 124, a gold film 137 is formed by a film deposition process on the surface of the photoresist 134 and on the side and bottom surfaces of the hole 135. At the bottom of the hole 135, the gold film 137 formed on the surface of the silicon substrate 130 serves as a pad 138. The pad 138 is an example of a catalyst layer. Furthermore, a gap 139 is formed around the pad 138 (region 136) between the pad 138 and the SOC film 131 during etching by the MacEtch method, allowing hydrogen fluoride and hydrogen to enter and exit. That is, the gold film 137 is not formed on the bottom surface of the gap 139, and the surface of the silicon substrate 130 is exposed to the etching solution. Thereafter, the substrate W2 is subjected to an etching process by the MacEtch method.

[0015] In the substrate W2, the SOC film 131 acting as a guide is present around the pad 138 via a gap 139, which can suppress the movement of electrons and prevent the surface of the silicon substrate 130 from becoming rough. However, since the process includes a step of over-etching the SOC film 131, it is difficult to form pillars and drain holes in the pad 138 as shown in FIG.

[0016] Therefore, it is expected that the MacEtch method will be able to form fine patterns.

[0017] First Embodiment [Configuration of Substrate Processing Apparatus] Fig. 1 is a schematic cross-sectional view showing an example of the configuration of a substrate processing apparatus according to a first embodiment. The substrate processing apparatus 1 includes an apparatus main body 10 and a control device 11. The substrate processing apparatus 1 shown in Fig. 1 uses, for example, an inkjet nozzle as a droplet source and an atmospheric pressure non-equilibrium capacitively coupled plasma (CCP) discharge vessel as a reactor. The apparatus main body 10 includes a vessel 12, an inkjet head 13, a stage 14, an RF (Radio Frequency) power supply 16, electrodes 20 and 21, and a gas supply unit 30.

[0018] The container 12 is made of, for example, ABS (Acrylonitrile Butadiene Styrene) resin and has a substantially rectangular cross-sectional shape, and supports the inkjet head 13 and the electrodes 20 and 21. The container 12 has an open portion at the bottom such that a slit 12a is formed between the electrodes 20 and 21. The container 12 also has a gas inlet 15 disposed therein for supplying a rare gas (noble gas) to a space 12b between the container 12 and the inkjet head 13.

[0019] The inkjet head 13 has a head body 13a fixed to the top of the container 12 and a nozzle portion 13b arranged so as to be able to eject droplets 50 toward the slit 12a. The inkjet head 13 ejects, as droplets 50, an aqueous solution containing a compound of a precious metal, for example, an aqueous solution containing one or more of gold chloride and chloroauric acid. The precious metal may be, in addition to gold, silver, platinum, rhodium, palladium, ruthenium, etc. A solution supply mechanism (not shown) is connected to the inkjet head 13.

[0020] The stage 14 is disposed opposite the slit 12a of the container 12. The substrate W is placed on the stage 14. The stage 14 is generally disk-shaped and made of ceramics such as aluminum nitride. Lifting pins (not shown) for raising and lowering the substrate W may be provided inside the stage 14 so as to be protruding and retracting from the upper surface of the stage 14. The stage 14 may have, as a holding mechanism for the substrate W, for example, an electrostatic chuck or a mechanical chuck (not shown), but the holding mechanism for the substrate W is not limited to these. Furthermore, the stage 14 may have a temperature control mechanism such as a heater and a coolant flow path inside.

[0021] The RF power supply 16 is coupled to the electrode 20 and is configured to generate a source RF signal (source RF power) for plasma generation via at least one impedance matching circuit. In one embodiment, the source RF signal has a frequency within the UHF (Ultra High Frequency) band (300 MHz to 3 GHz). In one embodiment, the RF power supply 16 may be configured to generate multiple source RF signals having different frequencies. The generated one or more source RF signals are supplied to the electrode 20.

[0022] The electrodes 20, 21 are made of a conductive material, such as copper. The electrodes 20, 21 are arranged at the bottom of the vessel 12 such that an end 20a of the electrode 20 faces an end 21a of the electrode 21, forming a slit 12a. The electrode 20 is connected to an RF power supply 16, and the electrode 21 is grounded. When a source RF signal is supplied from the RF power supply 16 to the electrode 20, atmospheric pressure plasma P is generated between the end 20a and the end 21a. In addition, a flow path (not shown) is provided inside the electrodes 20, 21, and cooling water is supplied to the flow path to cool the electrodes 20, 21.

[0023] The gas supply unit 30 may include at least one gas source 30a and at least one flow controller 30b. In one embodiment, the gas supply unit 30 is configured to supply at least one noble gas from a corresponding gas source 30a to the gas inlet unit 15 via a corresponding flow controller 30b. For example, the gas supply unit 30 is configured to supply argon gas to the gas inlet unit 15 via the flow controller 30b. Each flow controller 30b may include, for example, a mass flow controller or a pressure-controlled flow controller. Furthermore, the gas supply unit 30 may include one or more flow modulation devices that modulate or pulse the flow rate of the at least one noble gas.

[0024] The control device 11 has a processor, a memory, and an input / output interface. The memory stores programs, process recipes, etc. The processor reads and executes the programs from the memory, thereby controlling each part of the device main body 10 via the input / output interface based on the process recipes stored in the memory.

[0025] For example, the control device 11 controls each component of the substrate processing apparatus 1 to perform a substrate processing method described below. To cite a detailed example, the control device 11 executes a process of loading and preparing the substrate W to be placed on the stage 14. The control device 11 controls the gas supply unit 30 to supply a rare gas to the space 12b. The rare gas supplied to the space 12b passes through the slit 12a and flows toward the substrate W. The control device 11 controls the RF power supply 16 to generate atmospheric pressure plasma P between the ends 20a and 21a of the slit 12a. The control device 11 controls the inkjet head 13 to eject droplets 50 of an aqueous solution containing a precious metal from the nozzle unit 13b through the slit 12a toward the substrate W. The control device 11 controls the position of the inkjet head 13 in the in-plane direction (horizontal direction) of the substrate W to eject the droplets 50 at any position on the substrate W. The substrate W is, for example, a silicon substrate.

[0026] The droplets 50 are transformed into noble metal particles by the atmospheric pressure plasma P, and a catalyst layer 60 containing the noble metal particles is formed on the substrate W. The particle diameter of the noble metal particles contained in the catalyst layer 60 is, for example, submicron particles of 0.3 μm or more and 0.6 μm or less, with a particle size distribution of 3% to 9%. While FIG. 1 depicts the catalyst layer 60 as being composed of multiple noble metal particles, the catalyst layer 60 may also be composed of single noble metal particles. That is, in the catalyst layer 60, one or more of the noble metal particles serve as catalysts (corresponding to the noble metal pads described above). That is, in the catalyst layer 60, the noble metal particles are disposed in locations where high aspect ratio structures, such as trenches or holes, are desired to be formed. When the catalyst layer 60 is composed of multiple noble metal particles, it can also be described as a discontinuous layer formed of a noble metal with voids between the particles. Furthermore, when an aqueous solution containing one or more of gold chloride and chloroauric acid is used as the droplets 50, the catalyst layer 60 contains gold particles. Thereafter, the substrate W is subjected to an etching process (oxidation-reduction solution reaction process) by the MacEtch method using an etching apparatus (not shown). In this etching process, the etching solution contains an oxidizing agent and hydrogen fluoride (hydrofluoric acid). The oxidizing agent is, for example, hydrogen peroxide.

[0027] [Substrate Processing Method] Next, substrate processing according to a first embodiment will be described as a substrate processing method. Fig. 2 is a flowchart showing an example of the flow of substrate processing according to the first embodiment. In the substrate processing apparatus 1, the substrate processing shown in Fig. 2 is realized by controlling each part of the apparatus main body 10 by the control device 11.

[0028] First, the substrate W is carried into the lower part of the container 12 and placed on the stage 14 (step S101). Then, the control device 11 opens the valve of the gas source 30a and controls the flow rate controller 30b so that a predetermined flow rate of the rare gas is supplied to the space 12b of the container 12. The rare gas supplied to the space 12b passes through the slit 12a and flows toward the substrate W.

[0029] Next, the control device 11 controls the RF power supply 16 to generate atmospheric pressure plasma P between the end 20a and the end 21a of the slit 12a. The control device 11 controls the inkjet head 13 to eject droplets 50 of an aqueous solution containing a precious metal from the nozzle portion 13b through the slit 12a toward the substrate W. The droplets 50 are converted into fine particles of the precious metal by the atmospheric pressure plasma P, and a catalyst layer 60 containing the fine particles of the precious metal is formed on the substrate W (step S102). In other words, a plasma treatment process is performed on the substrate W by the atmospheric pressure plasma P.

[0030] When the plasma treatment process is completed, the processed substrate W is carried out from below the container 12 by a robot arm (not shown) (step S103).

[0031] The substrate W unloaded from the substrate processing apparatus 1 is transferred to an etching apparatus (not shown), where etching is performed by the MacEtch method (step S104). As a result, each of the noble metal particles acts as a catalyst, thereby realizing the formation of a fine pattern on the substrate W. That is, by using a noble metal (gold) particle pattern with a uniform particle size distribution as a catalyst for the oxidation-reduction solution reaction, a fine etching shape can be realized.

[0032] In other words, the substrate processing method includes applying atmospheric pressure plasma P to an aqueous solution containing a precious metal to form a catalyst layer 60 containing fine particles of the precious metal on a silicon substrate (substrate W), and etching the silicon substrate on which the catalyst layer 60 has been formed using an etching solution containing an oxidizing agent and hydrogen fluoride. The atmospheric pressure plasma P also applies the aqueous solution to droplets 50 generated by the inkjet method.

[0033] [Experimental Results] Next, experimental results according to the first embodiment will be described with reference to Fig. 3 and Fig. 4. Fig. 3 and Fig. 4 are diagrams showing an example of experimental results according to the first embodiment. Fig. 3 shows gold particles 141 contained in a catalyst layer 60 formed on a surface 140 of a substrate W before etching processing by the MacEtch method. The gold particles 141 were obtained by using gold (III) chloride tetrahydrate as the aqueous solution containing the noble metal of the droplets 50, and then eluting the catalyst layer 60 with a concentration of 2 [mol / m ３The particle size of the gold particles 141 was 0.1 μm. The particle size of the gold particles 141 can be controlled by the concentration of the gold compound contained in the droplets 50.

[0034] 4 shows holes 143 formed by gold microparticles 141 in a cross section 142 of a substrate W after etching by the MacEtch method. The holes 143 are formed in a substantially linear shape from top to bottom. The aspect ratio of the width to the depth of the holes 143 was approximately 1:3. These experimental results demonstrate that the gold microparticles generated in the first embodiment enable etching by the MacEtch method, and that fine patterns can be formed.

[0035] Second Embodiment In the first embodiment described above, atmospheric pressure plasma P was applied to droplets 50 being dropped by the inkjet method, but atmospheric pressure plasma P may also be applied to an aqueous solution (liquid film) dropped onto a substrate W, and this embodiment will be described as a second embodiment. In the second embodiment, the same components as those in the substrate processing apparatus 1 of the first embodiment are designated by the same reference numerals, and descriptions of the overlapping components and operations will be omitted.

[0036] [Configuration of Substrate Processing Apparatus] Figure 5 is a schematic cross-sectional view showing an example of the configuration of a substrate processing apparatus according to the second embodiment. The substrate processing apparatus 200 includes an apparatus main body 210 and a control device 211. The substrate processing apparatus 200 shown in Figure 5 uses, for example, an inkjet nozzle as a droplet source and an atmospheric pressure non-equilibrium capacitively coupled plasma (CCP) discharge as a reactor. The apparatus main body 210 includes an inkjet head 213, a stage 214, an electrode group 215, a pulsed power supply 216, and a mechanism for moving the substrate W (not shown).

[0037] The inkjet head 213 has a head body 213a provided above the electrode group 215 and a nozzle portion 213b arranged so as to be able to eject droplets 250 toward spaces between the electrodes of the electrode group 215. The inkjet head 213 ejects, as droplets 250, an aqueous solution containing a compound of a precious metal, for example, an aqueous solution containing one or more of gold chloride and chloroauric acid. The precious metal may be, in addition to gold, silver, platinum, rhodium, palladium, ruthenium, or the like. A solution supply mechanism (not shown) is connected to the inkjet head 213.

[0038] The stage 214 is disposed opposite the electrode group 215. A substrate W is placed on the stage 214. The stage 214 is rectangular, with its longitudinal direction aligned with the direction indicated by the arrow in the figure, i.e., the movement direction of the substrate W, and is formed of a conductor such as copper. The stage 214 may be substantially disk-shaped like the stage 14. The stage 214 also serves as a grounded electrode 221 facing the electrode group 215. The stage 214 may be formed of ceramics such as aluminum nitride and may have the electrode 221 disposed therein. The stage 214 may also include a substrate W movement mechanism (not shown). The stage 214 may also include an electrostatic chuck or a mechanical chuck (not shown). The mechanism for holding the substrate W on the stage 214 is not limited to these. The stage 214 may also include a temperature control mechanism, such as a heater and a coolant flow path.

[0039] The electrode group 215 includes a plurality of linear electrodes 220. Each electrode 220 is formed of a conductor such as tungsten and is surrounded by a dielectric 220a such as a mullite tube. Each electrode 220 is arranged, for example, such that its longitudinal direction is perpendicular to the direction of movement of the substrate W. The electrodes 220 are spaced apart such that droplets 250 can pass through them. Each electrode 220 is coupled to a pulsed power supply 216. When a source pulse signal is supplied from the pulsed power supply 216 to each electrode 220, atmospheric pressure plasma P is generated between each electrode 220 and the substrate W.

[0040] The pulsed power supply 216 is coupled to each electrode 220 of the electrode group 215 and is configured to generate a source pulse signal (source pulse power) for plasma generation via at least one impedance matching circuit. In one embodiment, the source pulse signal is a repetitive pulse in nanosecond units, and has, for example, a peak voltage of 7.0 kV to 9.5 kV, a pulse width of 10 ns, a repetition frequency of 20 kHz, and a power of 5.0 W to 17.6 W. In one embodiment, the pulsed power supply 216 may be configured to generate multiple source pulse signals having different pulses. The generated one or more source pulse signals are supplied to each electrode 220 of the electrode group 215.

[0041] The control device 211 has a processor, a memory, and an input / output interface. The memory stores programs, process recipes, etc. The processor reads and executes the programs from the memory, thereby controlling each part of the device main body 210 via the input / output interface based on the process recipes stored in the memory.

[0042] For example, the control device 211 controls each component of the substrate processing apparatus 200 to perform the substrate processing method. To cite a detailed example, the control device 211 executes a process of loading and preparing the substrate W to be placed on the stage 214. The control device 211 controls the pulse power supply 216 to generate atmospheric pressure plasma P between each electrode 220 and the substrate W. The control device 211 controls the inkjet head 213 to eject droplets 250 of an aqueous solution containing a precious metal from the nozzle portion 213b toward the substrate W through the electrodes 220. At this time, a guide pattern for guiding the position of the aqueous solution may be formed on the substrate W. In this case, a catalyst layer 260, which will be described later, is formed along the guide pattern. The control device 211 controls a substrate W movement mechanism (not shown) to move the substrate W in the direction of the arrow in FIG. 5, thereby enabling the formation of a large-area pattern on the substrate W. The substrate W is, for example, a silicon substrate.

[0043] The droplets 250 are dropped onto the substrate W, forming a liquid film of the aqueous solution on the substrate W. The liquid film of the aqueous solution is transformed into fine particles of precious metal by the atmospheric pressure plasma P, and a catalyst layer 260 containing the fine particles of precious metal is formed on the substrate W. The particle diameter of the fine particles of precious metal contained in the catalyst layer 260 is, for example, submicron particles of 0.3 μm or more and 0.6 μm or less, with a particle size distribution of 3% to 9%. While FIG. 5 depicts the catalyst layer 260 as being composed of multiple fine particles of precious metal (layered), the catalyst layer 260 may also be composed of fine particles of a single precious metal. That is, in the catalyst layer 260, one or more of the fine particles of precious metal serve as catalysts (corresponding to the above-mentioned noble metal pads). That is, in the catalyst layer 260, the fine particles of precious metal are arranged in the locations where high aspect ratio structures, such as trenches or holes, are desired to be formed (locations where guide patterns are formed). When the catalytic layer 260 is composed of multiple noble metal particles, it can also be described as a discontinuous layer formed of noble metal with voids between the multiple particles. The substrate processing apparatus 200 can form more noble metal particles than the substrate processing apparatus 1 of the first embodiment. Furthermore, when an aqueous solution containing one or more of gold chloride and chloroauric acid is used as the droplets 250, the catalytic layer 260 contains gold particles. The substrate W is then subjected to an etching process (oxidation-reduction solution reaction process) using the MacEtch method in an etching apparatus (not shown). In this etching process, the etching solution contains an oxidant and hydrogen fluoride (hydrofluoric acid). The oxidant is, for example, hydrogen peroxide.

[0044] [Substrate Processing Method] Next, a substrate processing method according to a second embodiment will be described. In the following description of the substrate processing according to the second embodiment, differences from the substrate processing according to the first embodiment shown in FIG.

[0045] In the second embodiment, in step S101 , the substrate W is carried below the electrode group 215 and placed on the stage 214 .

[0046] Next, in step S102, the control device 211 controls the pulse power supply 216 to generate atmospheric pressure plasma P between each electrode 220 and the substrate W. The control device 211 controls the inkjet head 213 to eject droplets 250 of an aqueous solution containing a precious metal from the nozzle portion 213b toward the substrate W through the electrodes 220. The droplets 250 are dropped onto the substrate W, and a liquid film of the aqueous solution is formed on the substrate W. The liquid film of the aqueous solution is converted into fine particles of the precious metal by the atmospheric pressure plasma P, and a catalyst layer 260 containing the fine particles of the precious metal is formed on the substrate W. The substrate W is moved by a substrate W moving mechanism (not shown), and the catalyst layer 260 is formed continuously, for example. In other words, a plasma treatment process is performed on the substrate W by the atmospheric pressure plasma P.

[0047] Thereafter, steps S103 and S104 are executed in the same manner as in the first embodiment. As a result, each of the noble metal particles acts as a catalyst, and a large number of noble metal particles can be formed, so that a large-area pattern can be formed on the substrate W.

[0048] In other words, the substrate processing method includes applying atmospheric pressure plasma P to an aqueous solution containing a precious metal to form a catalytic layer 260 containing fine particles of the precious metal on a silicon substrate (substrate W), and etching the silicon substrate on which the catalytic layer 260 has been formed using an etching solution containing an oxidizing agent and hydrogen fluoride. The atmospheric pressure plasma P is also applied to the aqueous solution dropped onto the silicon substrate (a liquid film of the aqueous solution formed by dropping the droplets 250).

[0049] [Experimental Results] Next, experimental results according to the second embodiment will be described with reference to Figs. 6 to 9. Figs. 6 to 9 are diagrams showing an example of experimental results according to the second embodiment. Fig. 6 shows gold particles 151 contained in a catalyst layer 260 formed on the front surface 150 of a substrate W before etching processing by the MacEtch method. The gold particles 151 were obtained by using gold (III) chloride tetrahydrate as the aqueous solution containing the noble metal in the droplets 250, and then eluting the catalyst layer 260 with a concentration of 100 [mol / m ３ The gold particles 151 had a particle size of 0.3 μm.

[0050] 7 shows a hole 153 formed by a gold particle 151a in a cross section 152 of a substrate W after etching processing by the MacEtch method. The gold particle 151a is one of a plurality of gold particles 151 generated. The hole 153 is formed in a substantially linear shape from the top to the bottom. The aspect ratio of the width to the depth of the hole 153 was approximately 1:12.

[0051] Cross section 154 shown in FIG. 8 is a cross section of substrate W at a different location from cross section 152 after etching, and shows holes 155 and 156 formed by gold particles 151b and 151c, respectively. Note that gold particles 151b and 151c are each one of the multiple gold particles 151 generated. Hole 155 is slightly inclined approximately one-third of the way from the top and approximately one-third of the way from the bottom, but is formed to a certain extent linearly. Hole 155 had an aspect ratio of width to depth of approximately 1:13. Hole 156 was formed in a substantially linear fashion from top to bottom. Hole 156 had an aspect ratio of width to depth of approximately 1:5. It is believed that gold particle 151c contains two adjacent gold particles 151 that are close to each other, forming one hole 156.

[0052] 9 is an enlarged view of the bottom of the hole 155 in the cross section 154. Gold particles 151b remain at the bottom of the hole 155, and it can be seen that the gold particles 151b acted as a catalyst to promote the etching process by the MacEtch method. These experimental results show that the second embodiment can form a large number of noble metal particles, thereby enabling the formation of a large-area pattern on the substrate W.

[0053] According to each embodiment described above, the substrate processing method includes applying atmospheric pressure plasma P to an aqueous solution (droplets 50, 250) containing a precious metal to form a catalyst layer (catalyst layer 60, 260) containing fine particles of the precious metal on a silicon substrate (substrate W), and etching the silicon substrate with the catalyst layer formed thereon using an etching solution containing an oxidizing agent and hydrogen fluoride. As a result, fine patterns can be formed in the etching process using the MacEtch method.

[0054] According to each embodiment, the aqueous solution contains a gold compound as a noble metal, and the catalyst layer contains gold fine particles, so that the silicon substrate can be etched using the gold fine particles as a catalyst.

[0055] According to each embodiment, the compound is gold chloride, and as a result, gold microparticles can be formed by the atmospheric pressure plasma P.

[0056] According to each embodiment, the compound is chloroauric acid, and as a result, gold microparticles can be formed by the atmospheric pressure plasma P.

[0057] Furthermore, according to each embodiment, the particle diameter of the fine particles is 0.6 μm or less, which makes it possible to form a fine pattern in the etching process by the MacEtch method.

[0058] Furthermore, according to each embodiment, the particle size of the fine particles is 0.3 μm or more, which allows the particle size distribution to be within a predetermined range.

[0059] Furthermore, according to the first embodiment, the atmospheric pressure plasma P acts on the droplets 50 of the aqueous solution generated by the inkjet method. As a result, by controlling the position of the inkjet head 13 in the in-plane direction (horizontal direction) of the substrate W, it is possible to form a fine pattern at any position on the substrate W.

[0060] Furthermore, according to the second embodiment, the atmospheric pressure plasma P acts on the aqueous solution (droplets 250) dropped onto the silicon substrate, thereby enabling the formation of a large-area pattern on the substrate W.

[0061] According to each embodiment, the oxidizing agent is hydrogen peroxide, and as a result, the substrate W can be etched using the noble metal particles as a catalyst in the MacEtch method.

[0062] According to each embodiment, the catalyst layer is a discontinuous layer made of a noble metal, and as a result, the substrate W can be etched using the noble metal fine particles contained in the discontinuous layer as a catalyst in the MacEtch method.

[0063] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and various omissions, substitutions, and modifications may be made to the above-described embodiments without departing from the spirit and scope of the appended claims.

[0064] In the above-described embodiments, hydrogen peroxide is used as an oxidizing agent in the MacEtch method, but the present invention is not limited to this. For example, nitric acid, AgNO ３ , KAuCl ４ , HAuCl ４ , K. ２ PtCl ６ , H ２ PtCl ６ , Fe(NO ３ ) ３ , Ni(NO ３ ) ２ , Mg(NO ３ ) ２ , Na ２ S ２ O ８ , K. ２ S ２ O ８ , KMnO ４ and K. ２ Cr ２ O ７ etc. may also be used.

[0065] The present disclosure may also be configured as follows. (1) A substrate processing method comprising: applying atmospheric pressure plasma to an aqueous solution containing a noble metal to form a catalytic layer containing fine particles of the noble metal on a silicon substrate; and etching the silicon substrate with the catalytic layer formed thereon using an etching solution containing an oxidizing agent and hydrogen fluoride. (2) The substrate processing method according to (1), wherein the aqueous solution contains a gold compound as the noble metal, and the catalytic layer contains the gold fine particles. (3) The substrate processing method according to (2), wherein the compound is gold chloride. (4) The substrate processing method according to (2), wherein the compound is chloroauric acid. (5) The substrate processing method according to any one of (1) to (4), wherein the particle diameter of the fine particles is 0.6 μm or less. (6) The substrate processing method according to (5), wherein the particle diameter of the fine particles is 0.3 μm or more. (7) The substrate processing method according to any one of (1) to (6), wherein the atmospheric pressure plasma acts on droplets of the aqueous solution generated by an inkjet method. (8) The substrate processing method according to any one of (1) to (6), wherein the atmospheric pressure plasma acts on the aqueous solution dropped onto the silicon substrate. (9) The substrate processing method according to any one of (1) to (8), wherein the oxidizing agent is hydrogen peroxide. (10) The substrate processing method according to any one of (1) to (9), wherein the catalyst layer is a discontinuous layer formed of the noble metal.

[0066] 1,200 Substrate processing apparatus 10,210 Apparatus main body 11,211 Control device 13,213 Inkjet head 14,214 Stage 16 RF power supply 20,21,220,221 Electrode 50,250 Droplet 60,260 Catalyst layer 215 Electrode group 216 Pulse power supply P Atmospheric pressure plasma W Substrate

Claims

1. A substrate processing method comprising: applying atmospheric pressure plasma to an aqueous solution containing a precious metal to form a catalyst layer containing fine particles of the precious metal on a silicon substrate; and etching the silicon substrate with the catalyst layer formed thereon using an etching solution containing an oxidizing agent and hydrogen fluoride.

2. The substrate processing method according to claim 1, wherein the aqueous solution contains a compound of gold as the noble metal, and the catalyst layer contains fine particles of gold.

3. The substrate processing method according to claim 2, wherein the compound is gold chloride.

4. The substrate processing method according to claim 2, wherein the compound is chloroauric acid.

5. A substrate processing method according to any one of claims 1 to 4, wherein the particle diameter of the fine particles is 0.6 μm or less.

6. The substrate processing method according to claim 5, wherein the particle diameter of the fine particles is 0.3 μm or more.

7. The substrate processing method according to any one of claims 1 to 3, wherein the atmospheric pressure plasma acts on droplets of the aqueous solution generated by an inkjet method.

8. The substrate processing method according to any one of claims 1 to 3, wherein the atmospheric pressure plasma is applied to the aqueous solution dropped onto the silicon substrate.

9. The substrate processing method according to any one of claims 1 to 3, wherein the oxidizing agent is hydrogen peroxide.

10. The substrate processing method according to any one of claims 1 to 3, wherein the catalyst layer is a discontinuous layer formed of the noble metal.

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