US20220251722A1 - Anodization apparatus and anodization method - Google Patents
Anodization apparatus and anodization method Download PDFInfo
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- US20220251722A1 US20220251722A1 US17/349,811 US202117349811A US2022251722A1 US 20220251722 A1 US20220251722 A1 US 20220251722A1 US 202117349811 A US202117349811 A US 202117349811A US 2022251722 A1 US2022251722 A1 US 2022251722A1
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- anodization
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- anode
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- 238000002048 anodisation reaction Methods 0.000 title claims abstract description 129
- 238000000034 method Methods 0.000 title claims abstract description 77
- 239000003792 electrolyte Substances 0.000 claims abstract description 154
- 239000000758 substrate Substances 0.000 claims abstract description 118
- 230000008569 process Effects 0.000 claims abstract description 72
- 239000007788 liquid Substances 0.000 claims abstract description 29
- 238000009792 diffusion process Methods 0.000 claims description 23
- 239000004615 ingredient Substances 0.000 claims description 19
- 230000007246 mechanism Effects 0.000 description 15
- 239000000463 material Substances 0.000 description 14
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- 239000002245 particle Substances 0.000 description 7
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 6
- 239000004020 conductor Substances 0.000 description 6
- 229910000040 hydrogen fluoride Inorganic materials 0.000 description 6
- WGTYBPLFGIVFAS-UHFFFAOYSA-M tetramethylammonium hydroxide Chemical compound [OH-].C[N+](C)(C)C WGTYBPLFGIVFAS-UHFFFAOYSA-M 0.000 description 6
- 238000005406 washing Methods 0.000 description 6
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 4
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- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 3
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- 238000004140 cleaning Methods 0.000 description 2
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- ZEFWRWWINDLIIV-UHFFFAOYSA-N tetrafluorosilane;dihydrofluoride Chemical compound F.F.F[Si](F)(F)F ZEFWRWWINDLIIV-UHFFFAOYSA-N 0.000 description 2
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Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
- C25D11/02—Anodisation
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
- C25D11/02—Anodisation
- C25D11/32—Anodisation of semiconducting materials
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
- C25D11/005—Apparatus specially adapted for electrolytic conversion coating
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D17/00—Constructional parts, or assemblies thereof, of cells for electrolytic coating
- C25D17/002—Cell separation, e.g. membranes, diaphragms
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D17/00—Constructional parts, or assemblies thereof, of cells for electrolytic coating
- C25D17/02—Tanks; Installations therefor
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D17/00—Constructional parts, or assemblies thereof, of cells for electrolytic coating
- C25D17/06—Suspending or supporting devices for articles to be coated
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D21/00—Processes for servicing or operating cells for electrolytic coating
- C25D21/06—Filtering particles other than ions
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D21/00—Processes for servicing or operating cells for electrolytic coating
- C25D21/12—Process control or regulation
- C25D21/14—Controlled addition of electrolyte components
Definitions
- Embodiments described herein relate generally to an anodization apparatus and an anodization method.
- a technology of forming porous film on a substrate surface by anodization is known.
- FIG. 1 is a configuration diagram of an anodization apparatus according to a first embodiment.
- FIG. 2 is a diagram describing a rotated state of an anode holder in the anodization apparatus according to the first embodiment.
- FIG. 3 is a flowchart of an anodization process in the anodization apparatus according to the first embodiment.
- FIG. 4 is an overall configuration diagram of an anodization process system according to a second embodiment.
- an anodization apparatus includes: a first process tank configured to perform an anodization process on a substrate; a holder configured to hold the substrate; and a first electrolyte supply system configured to supply a first electrolyte to the first process tank.
- the holder immerses the substrate in the first electrolyte in a state where the substrate is inclined with respect to a liquid level of the first electrolyte.
- the anodization process is executed in a state where the substrate is inclined with respect to the liquid level of the first electrolyte.
- an anodization apparatus that forms a silicon porous layer (for example, a porous Si layer) on a surface of a semiconductor substrate (hereinafter simply referred to as a “substrate”) will be described.
- a silicon porous layer for example, a porous Si layer
- substrate a semiconductor substrate
- FIG. 1 is a configuration diagram of the anodization apparatus.
- an anodization apparatus 1 includes an anodization tank 10 , an anode holder 11 , a first electrolyte supply system 13 , a concentration adjustment unit 14 , a temperature adjustment unit 15 , a second electrolyte supply system 16 , a current source 17 , and a control circuit 18 .
- the anodization tank 10 is a process tank used for anodization.
- the anodization tank 10 has a cylindrical shape, for example.
- the inner diameter of the anodization tank 10 is larger than the outer diameter of the anode holder 11 .
- An insulating material is used for the anodization tank 10 .
- a pipe 201 and a pipe 202 are coupled to the anodization tank 10 .
- the pipe 201 is used when supplying a first electrolyte from the first electrolyte supply system 13 to the anodization tank 10 .
- the first electrolyte is a liquid used for an anodization process, and is an electrolyte containing at least hydrogen fluoride (HF).
- the pipe 202 is used when refluxing the first electrolyte from the anodization tank 10 to the first electrolyte supply system 13 .
- a cathode tank 101 , a cathode 102 , a filter 103 , and a diffusion plate 104 are provided in the anodization tank 10 .
- the cathode tank 101 When the first electrolyte is supplied to the anodization tank 10 , the cathode tank 101 functions as a shower head casing in combination with the diffusion plate 104 .
- the cathode tank 101 has a cylindrical shape, for example.
- the inner diameter of the cathode tank 101 is, for example, preferably equal to or larger than the outer diameter of a substrate 110 which is a target of anodization.
- An insulating material is used for the cathode tank 101 .
- the bottom surface of the cathode tank 101 contacts the bottom surface inside the anodization tank 10 .
- An opened portion of the upper end of the cathode tank 101 is inclined with respect to the bottom surface of the cathode tank 101 and thereby the diffusion plate 104 may be attached in an inclined manner with respect to a liquid level of the first electrolyte.
- the cathode 102 functions as a cathode in the anodization process.
- the cathode 102 has a disk shape, for example.
- the cathode 102 contacts the bottom surface inside the cathode tank 101 .
- the diameter of the cathode 102 is, for example, the same as the inner diameter of the cathode tank 101 .
- the cathode 102 is made of conductive materials, and uses materials with low reactivity to the first electrolyte (with almost no dissolution in the first electrolyte).
- the cathode 102 may be a conductive material using, for example, carbon, diamond, Pt, or Au as a coating material.
- the coating material may be a glass-like fiber carbon, a diamond coat silicon or the like.
- the filter 103 is provided above the cathode 102 in the cathode tank 101 .
- the filter 103 is provided between the cathode 102 and the diffusion plate 104 .
- the filter 103 removes particles generated at the cathode 102 .
- the electrode may undergo oxidization due to aging, etc., and generate particles.
- the particles may inhibit porous silicon from being forming in the anodization process.
- the size of the particles that may be removed by the filter 103 can be designed as appropriate. For example, as the filter 103 , a filter that can remove particles with a particle diameter of 0.01 ⁇ m or more may be used.
- one end of the pipe 201 is provided in a manner penetrating the bottom part of the anodization tank 10 , the bottom part of the cathode tank 101 , the cathode 102 , and the filter 103 , and the first electrolyte is supplied to the cathode tank 101 from the first electrolyte supply system 13 .
- the diffusion plate 104 is fixed to the opened portion of the upper end of the cathode tank 101 in a state of being inclined at angle ⁇ (0° ⁇ 90°) with respect to the liquid level of the first electrolyte (or the bottom surfaces of the anodization tank 10 and the cathode tank 101 ).
- the diffusion plate 104 is provided with a plurality of holes for diffusing the first electrolyte. The diameter and arrangement of the holes may be designed as appropriate.
- the first electrolyte is supplied to the surface of the substrate 110 (the surface to be anodized) that is fixed to the anode holder 11 .
- the diffusion plate 104 is made of insulating materials, and uses materials with low reactivity to the first electrolyte (with almost no dissolution in the first electrolyte). As the diffusion plate 104 , for example, it is preferable to use poly-tetra-fluoro-ethylene (PTFE), polyvinyl chloride, or materials on which antistatic measures have been taken.
- PTFE poly-tetra-fluoro-ethylene
- PVC polyvinyl chloride
- the anode holder 11 functions as a holder for fixing the substrate 110 .
- the anode holder is immersed in the first electrolyte with the substrate 110 .
- the anode holder 11 includes a base 111 , an anode 112 , and a wafer clamp 113 .
- the base 111 has a disk shape, for example.
- the diameter of the base 111 is, for example, equal to or larger than the diameter of the substrate 110 .
- An insulating material, for example, is used for the base 111 .
- the anode 112 functions as an anode in the anodization process.
- the anode 112 has a disk shape, for example.
- the diameter of the anode 112 is, for example, the same as the diameter of the base 111 .
- the anode 112 contacts the bottom surface of the base 111 in a state where at least a part of the anode holder 11 and the substrate 110 are immersed in the first electrolyte inside the anodization tank 10 .
- the anode 112 is made of conductive materials, and uses materials with low reactivity to a second electrolyte described later.
- the anode 112 may be a conductive material using, for example, carbon, diamond, Pt, or Au as a coating material.
- the coating material may be a glass-like fiber carbon, a diamond coat silicon or the like.
- the wafer clamp 113 has a cylindrical shape, for example. On the side surface of the wafer clamp 113 , for example, a groove for fixing the base 111 and the anode 112 is provided. Furthermore, the lower end of the wafer clamp 113 is provided with an edge seal for fixing the substrate 110 .
- the outer diameter of the wafer clamp 113 is larger than the outer diameters of the substrate 110 , the base 111 , and the anode 112 .
- the edge seal of the wafer clamp 113 is in contact with the entire surface of the outer circumference of the substrate 110 and fixes the substrate 110 in a manner such that the front surface of the substrate 110 faces downwards (on the diffusion plate 104 side).
- the wafer clamp 113 fixes the substrate 110 and the anode 112 in a manner such that the back surface of the substrate 110 (the surface not to be anodized) is not in contact with the anode 112 , and the substrate 110 and the anode 112 are in parallel.
- the wafer clamp 113 is made of insulating materials, and uses materials with low reactivity to the first electrolyte and the second electrolyte (with almost no dissolution in the electrolytes).
- the diffusion plate 104 for example, it is preferable to use PTFE, polyvinyl chloride, or materials on which antistatic measures have been taken.
- the second electrolyte having conductivity is supplied from the second electrolyte supply system 16 to a space defined by the back surface of the substrate 110 , the anode 112 , and the wafer clamp 113 .
- the anode holder 11 is coupled to a pipe 203 for supplying the second electrolyte from the second electrolyte supply system 16 to the anode holder 11 , and a pipe 204 for refluxing the second electrolyte to the second electrolyte supply system 16 .
- the pipes 203 and 204 are provided in a manner penetrating the base 111 and the anode 112 , and the second electrolyte is supplied to the above-described space from the second electrolyte supply system 16 .
- the second electrolyte fills the space between the anode 112 and the substrate 110 .
- the second electrolyte subjected to electrolysis may cause gas to be generated in the above-described space.
- a path may be provided in the anode holder 11 to discharge the gas.
- the back surface of the substrate 110 may be brought into contact with the anode 112 .
- a low resistive layer which is injected with a high dopant concentration, or a metal that can perform an ohmic contact with respect to the substrate 110 , may also be provided.
- An anode holder driving mechanism 12 is fixed on the center portion of the upper surface of the base 111 .
- the base 111 is made rotatable by the anode holder driving mechanism 12 in a state where at least a part of the anode holder 11 and the substrate 110 are immersed in the first electrolyte inside the anodization tank 10 .
- the anode holder driving mechanism 12 is fixed to the center portion of a surface of the base 111 facing a surface on which the anode 112 is provided, in which manner the base 111 is rotatable.
- the anode holder driving mechanism 12 has a mechanism for immersing at least a part of the base 111 in the anodization tank 10 in a state where the base 111 is inclined by angle ⁇ , and rotating the base 111 in such a state. Therefore, in the present embodiment, at least a part of the anode holder 11 and the substrate 110 are immersed in the first electrolyte in a state where they are inclined by angle ⁇ with respect to the liquid level of the first electrolyte of the anodization tank 10 .
- the anode holder driving mechanism 12 inclines the substrate 110 and the anode 112 by angle ⁇ , thereby allowing the substrate 110 , the anode 112 , and the diffusion plate 104 to be provided in a parallel state in the anodization process.
- the in-plane uniformity of the current density relating to the substrate 110 improves. It should be noted that the anode 112 and the diffusion plate 104 may or may not be provided in a parallel state.
- the in-plane uniformity of the current density relating to the substrate 110 improves by inclining the diffusion plate 104 in the same direction as the substrate 110 with respect to the bottom surface of the anodization tank 10 or the liquid level of the first electrolyte.
- FIG. 2 shows a cross-section of the anode holder 11 and an upper surface of the base 111 in the rotated state.
- the anode holder driving mechanism 12 rotates the base 111 inclined by angle ⁇ about the anode holder driving mechanism 12 serving as a rotational axis.
- angle ⁇ By inclining the base 111 by angle ⁇ the substrate 110 and the anode 112 become inclined by angle ⁇ .
- the anode holder driving mechanism 12 rotates the base 111 and the substrate 110 in the range of 10 to 100 rpm.
- the first electrolyte supply system 13 supplies the first electrolyte to the anodization tank 10 .
- the first electrolyte is a liquid to be used for the anodization process.
- a liquid containing a hydrogen fluoride (HF) is used as the first electrolyte.
- a mixed liquid of an HF solution and ethanol or isopropyl alcohol (IPA) is used for the first electrolyte.
- the first electrolyte supply system 13 of the present embodiment has a function of circulating the first electrolyte between the anodization tank 10 and the first electrolyte supply system 13 .
- the first electrolyte supply system 13 supplies the first electrolyte for which concentration is adjusted to the cathode tank 101 via the pipe 201 , and recovers the first electrolyte from the anodization tank 10 via the pipe 202 .
- the first electrolyte supply system 13 does not necessarily have a function for circulating the first electrolyte. In such a case, the pipe 202 is omitted, and the first electrolyte in the anodization tank 10 is processed as a waste liquid.
- the first electrolyte supply system 13 includes an ingredient supply unit 131 , a mixing tank 132 , and a pump 133 .
- the ingredient supply unit 131 supplies ingredients of the first electrolyte to the mixing tank 132 based on the control of the control circuit 18 and the concentration adjustment unit 14 .
- Ingredients may be, for example, an HF solution, alcohol, and DIW (deionized water).
- materials other than liquids may be used.
- the mixing tank 132 mixes ingredients supplied from the ingredient supply unit 131 with the first electrolyte recovered from the anodization tank 10 using the pipe 202 , and produces a first electrolyte that can be used for the anodization process.
- the pump 133 compresses and transfers the first electrolyte produced in the mixing tank 132 to the cathode tank 101 via the pipe 201 .
- the pump 133 may also be used when transferring the first electrolyte in the mixing tank 132 to a waste liquid line (not shown). Furthermore, another pump may be provided for the waste liquid line.
- the concentration adjustment unit 14 adjusts the concentration of the first electrolyte.
- the concentration adjustment unit 14 includes a concentration sensor 141 .
- the concentration sensor 141 is coupled to the pipe 201 .
- the concentration sensor 141 measures an ion concentration of the first electrolyte supplied from the first electrolyte supply system 13 .
- the concentration adjustment unit 14 feeds back the measurement result of the concentration sensor 141 to the ingredient supply unit 131 , and adjusts the amount of ingredients to be supplied in the ingredient supply unit 131 . This allows the concentration of the first electrolyte supplied to the anodization tank 10 to be maintained at a certain level, and H 2 SiF 6 , etc., which is a by-product of the anodization process, to be filtered.
- the concentration adjustment unit 14 may be provided in the first electrolyte supply system 13 .
- the temperature adjustment unit 15 adjusts the temperature of the first electrolyte.
- the temperature adjustment unit 15 includes a temperature sensor 151 .
- the temperature sensor 151 is coupled to the pipe 201 , and monitors the temperature of the first electrolyte.
- the temperature adjustment unit 15 includes a tiller or a heater, and cools or heats the first electrolyte in accordance with the result of the temperature monitor.
- the temperature adjustment unit 15 maintains the temperature of the first electrolyte in the anodization tank 10 at a certain level.
- the temperature adjustment unit 15 may be provided in the first electrolyte supply system 13 .
- the second electrolyte supply system 16 supplies the second electrolyte to the anode holder 11 .
- the second electrolyte is used to bring the anode 112 and the substrate 110 into conduction.
- a liquid at least containing a conductive material is used. More specifically, for example, the conductive material may include at least one of HF, HCl, NaCl, KCl, KOH, H 3 PO 4 , or TMAH (Tetra-Methyl-Ammonium-Hydroxide).
- the second electrolyte supply system 16 of the present embodiment has a function of circulating the second electrolyte between the anode holder 11 and a mixing tank 162 .
- the second electrolyte supply system 16 supplies the second electrolyte for which concentration is adjusted to the anode holder 11 via the pipe 203 , and recovers the second electrolyte from the anode holder 11 via the pipe 204 .
- the second electrolyte supply system 16 does not necessarily have a function for circulating the second electrolyte. In such a case, the pipe 204 is omitted, and the second electrolyte in the anode holder 11 is processed as a waste liquid.
- the second electrolyte supply system 16 includes an ingredient supply unit 161 , the mixing tank 162 , and a pump 163 .
- the ingredient supply unit 161 supplies ingredients of the second electrolyte to the mixing tank 162 based on the control of the control circuit 18 .
- the ingredients may be solutions such as HF, HCl, NaCl, KCl, KOH, H 3 PO 4 , and TMAH, and DIW (deionized water), etc.
- materials other than liquids may be used.
- the mixing tank 162 mixes ingredients supplied from the ingredient supply unit 161 with the second electrolyte recovered from the anode holder 11 using the pipe 204 , and produces a second electrolyte.
- the pump 163 compresses and transfers the second electrolyte produced in the mixing tank 162 to the anode holder 11 via the pipe 203 .
- the pump 163 may also be used when transferring the second electrolyte in the mixing tank 162 to a waste liquid line. Furthermore, another pump may be provided for the waste liquid line.
- the pump 163 may set the supply pressure of the second electrolyte higher than the supply pressure of the first electrolyte so that the entire surface of the outer circumference of the substrate 110 is pressed against the edge seal of the wafer clamp 113 .
- the current source 17 is coupled to the anode 112 and the cathode 102 , and supplies a desired amount of current to the anode 112 when the anodization is performed.
- the control circuit 18 controls the entire anodization apparatus 1 . More specifically, the control circuit 18 controls the anode holder driving mechanism 12 , the first electrolyte supply system 13 , the concentration adjustment unit 14 , the temperature adjustment unit 15 , the second electrolyte supply system 16 , and the current source 17 .
- FIG. 3 is a flowchart of the anodization.
- the first electrolyte supply system 13 starts supplying the first electrolyte to the anodization tank 10 (step S 1 ).
- the substrate 110 is set on the anode holder 11 in a manner such that the back surface of the substrate 110 (the surface not to be anodized) faces the anode 112 (step S 2 ).
- the second electrolyte supply system 16 starts supplying the second electrolyte to the anode holder 11 (step S 3 ). This allows the space between the substrate 110 and the anode 112 to be filled by the second electrolyte.
- the anode holder driving mechanism 12 inclines the anode holder 11 (the base 111 ), in which the substrate 110 is set and to which the second electrolyte is supplied, by angle ⁇ .
- the anode holder driving mechanism 12 immerses at least a part of the anode holder 11 and the substrate 110 in the first electrolyte in the anodization tank 10 in a state where the anode holder 11 and the substrate 110 are inclined by angle ⁇ with respect to the liquid level (step S 4 ).
- By inclining the anode holder 11 air (bubbles) can be suppressed from being trapped upon immersion.
- the first electrolyte circulates between the anodization tank 10 and the first electrolyte supply system 13 .
- the anode holder driving mechanism 12 then starts rotating the anode holder 11 (step S 5 ).
- the anode holder 11 is rotated in a state of being inclined by angle ⁇ with respect to the liquid level. Furthermore, as long as the anode holder is rotated in a state of being inclined with respect to the liquid level, it does not have to be in the same inclination angle as that at the time of immersing.
- the current source 17 supplies a current between the anode 112 and the cathode 102 (step S 6 ). While the current source 17 supplies the current, the anodization process is executed. As a result, porous layer is created on the front surface of the substrate 110 .
- the anode holder driving mechanism 12 stops rotating the anode holder 11 (step S 7 ).
- the anode holder driving mechanism 12 then takes the anode holder 11 out from the anodization tank 10 (step S 8 ).
- the second electrolyte supply system 16 stops supplying the second electrolyte to the anode holder 11 (step S 9 ).
- the substrate 110 is recovered from the anode holder (step S 10 ).
- anodization apparatus which can form a porous film with excellent in-plane uniformity on a substrate surface. Such advantageous effects will be explained in detail.
- the concentration of HF in the electrolyte decreases, and hydrogen gas or H 2 SiF 6 (SiF 6 2 ⁇ ion) is produced as a by-product.
- this may cause the composition (ion concentration) of the electrolyte to change, and deteriorate the uniformity of the porous layer in the substrate surface or in each substrate.
- a pair of positive and negative charged particles is formed on the substrate surface, causing an electric field double layer to occur side by side in layers, which delays the supply of ions to the substrate surface and the draining of the by-products.
- the anodization apparatus 1 can immerse the substrate 110 in a state where it is inclined with respect to the first electrolyte. Furthermore, the anodization apparatus 1 can execute the anodization process while rotating the substrate 110 in an inclined state. This allows the anodization apparatus 1 to suppress air (bubbles) from being trapped when immersing the substrate 110 in the first electrolyte. Furthermore, when performing the anodization process, the anodization apparatus 1 can efficiently drain the gas (for example, hydrogen) generated on the substrate surface or the by-product (for example, SiF 6 2 ⁇ ) from the substrate surface.
- the gas for example, hydrogen
- the by-product for example, SiF 6 2 ⁇
- the anodization apparatus 1 can also increase the flow rate of the first electrolyte on the substrate surface, and reduce the thickness of the electric field double layer formed near the front surface of the substrate 110 . Therefore, the anodization apparatus 1 can improve the uniformity of the ion supplied to the substrate surface, and improve the in-plane uniformity of the formed porous layer (the film-thickness uniformity of the porous layer and in-plane uniformity of porosity).
- the anodization apparatus 1 when performing the anodization process, can provide the diffusion plate 104 in parallel with the substrate 110 between the anode 112 and the cathode 102 . This allows the uniformity of the current density in the plane of the substrate 110 to be improved. Therefore, the in-plane uniformity of the formed porous layer can be improved.
- the anodization apparatus 1 has a first electrolyte supply system. Since this allows the concentration of the first electrolyte in the anodization tank 10 to be maintained at a certain level, the concentration of the first electrolyte can be suppressed from changing during the anodization process and in each of the substrates. Thus, the uniformity of film quality in a depth direction of the porous layer formed on the substrate 110 , and the film quality uniformity between the substrates, can be improved.
- the anodization apparatus 1 supplies the second electrolyte between the anode 112 and the substrate 110 . It is thereby possible to prevent the anode 112 and the substrate 110 from coming into contact. Thus, it is possible to reduce metal contamination of the substrate 110 caused by the anode 112 .
- FIG. 4 is a plan view of a configuration of an anodization process system 300 .
- the anodization process system 300 includes a process module 301 , a transfer module 302 , a load port 303 , and a load module 304 .
- the process module 301 is a module for performing various processes on the substrate 110 .
- the process module 301 includes three anodization tanks 310 to 312 and two washing tanks 313 and 314 .
- the anodization tanks 310 to 312 correspond to the anodization tank 10 described in the first embodiment.
- each composition of a first electrolyte in the anodization tanks 310 to 312 may be different, and the anodization process can be executed under different conditions.
- the washing tanks 313 and 314 are used for pre-cleaning or post-cleaning of the anodization process.
- the washing tanks 313 and 314 may be, for example, a sheet-type spin washing apparatus.
- process module 301 is not limited to this.
- process units that are different from the anodization tank and the washing tank may be provided.
- the number of the anodization tanks and the washing tanks is optional.
- the transfer module 302 is provided in the process module 301 .
- the transfer module 302 includes a handler 320 .
- the handler 320 is configured to be driven to carry the substrate 110 to each tank in the process module 301 .
- the load port 303 opens and closes a front opening unified pod (FOUP) 330 .
- the FOUP 330 is set on the load port 303 .
- the FOUP 330 is a sealed container for carrying the substrates 110 .
- the FOUP 330 is able to store a plurality of substrates 110 . It should be noted that although the example of FIG. 4 shows a case in which four load ports 303 are provided, the number of load ports 303 may be at least one.
- the load module 304 includes a handler 340 .
- the handler 340 is configured to be driven to carry the substrate 110 between the FOUP 330 and the transfer module 302 .
- the anodization apparatus described in the first embodiment can be adopted in the anodization process system of the present embodiment.
- An anodization apparatus includes: a first process tank ( 10 ) configured to perform an anodization process on a substrate; a holder ( 11 ) configured to hold the substrate; and a first electrolyte supply system ( 13 ) configured to supply a first electrolyte to the first process tank.
- the holder immerses the substrate in the first electrolyte in a state where the substrate is inclined with respect to a liquid level of the first electrolyte.
- the anodization process is executed in a state where the substrate is inclined with respect to the liquid level of the first electrolyte.
- the substrate may be a substrate for heterogeneous computing, a substrate for micro electro mechanical systems (MEMS), a semiconductor wafer for a three-dimensional integrated circuit, a biometric/medical substrate, or an optical waveguide substrate, etc.
- MEMS micro electro mechanical systems
- the substrate may be a substrate for heterogeneous computing, a substrate for micro electro mechanical systems (MEMS), a semiconductor wafer for a three-dimensional integrated circuit, a biometric/medical substrate, or an optical waveguide substrate, etc.
- the state of being “coupled” in the foregoing embodiments includes a state of being coupled with something else indirectly interposed.
Abstract
Description
- This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2021-019756, filed Feb. 10, 2021, the entire contents of which are incorporated herein by reference.
- Embodiments described herein relate generally to an anodization apparatus and an anodization method.
- A technology of forming porous film on a substrate surface by anodization is known.
-
FIG. 1 is a configuration diagram of an anodization apparatus according to a first embodiment. -
FIG. 2 is a diagram describing a rotated state of an anode holder in the anodization apparatus according to the first embodiment. -
FIG. 3 is a flowchart of an anodization process in the anodization apparatus according to the first embodiment. -
FIG. 4 is an overall configuration diagram of an anodization process system according to a second embodiment. - In general, according to one embodiment, an anodization apparatus includes: a first process tank configured to perform an anodization process on a substrate; a holder configured to hold the substrate; and a first electrolyte supply system configured to supply a first electrolyte to the first process tank. The holder immerses the substrate in the first electrolyte in a state where the substrate is inclined with respect to a liquid level of the first electrolyte. The anodization process is executed in a state where the substrate is inclined with respect to the liquid level of the first electrolyte.
- Hereinafter, embodiments will be described with reference to the drawings. In the following description, structural elements having approximately the same function and configuration will be assigned the same reference symbol, and a repeat description will be given only where necessary. The embodiments to be described below are given as an example of an apparatus or a method for embodying the technical idea of the embodiments, and are not intended to limit the material, shape, structure, arrangement, etc. of components to those described below.
- An anodization apparatus according to a first embodiment will be described. In the present embodiment, an anodization apparatus that forms a silicon porous layer (for example, a porous Si layer) on a surface of a semiconductor substrate (hereinafter simply referred to as a “substrate”) will be described.
- 1.1 Basic Configuration of Anodization Apparatus
- An example of a basic configuration of an anodization apparatus will be described with reference to
FIG. 1 .FIG. 1 is a configuration diagram of the anodization apparatus. - As shown in
FIG. 1 , ananodization apparatus 1 includes ananodization tank 10, ananode holder 11, a firstelectrolyte supply system 13, aconcentration adjustment unit 14, atemperature adjustment unit 15, a secondelectrolyte supply system 16, acurrent source 17, and acontrol circuit 18. - The
anodization tank 10 is a process tank used for anodization. Theanodization tank 10 has a cylindrical shape, for example. The inner diameter of theanodization tank 10 is larger than the outer diameter of theanode holder 11. An insulating material is used for theanodization tank 10. - A
pipe 201 and apipe 202 are coupled to theanodization tank 10. Thepipe 201 is used when supplying a first electrolyte from the firstelectrolyte supply system 13 to theanodization tank 10. The first electrolyte is a liquid used for an anodization process, and is an electrolyte containing at least hydrogen fluoride (HF). Thepipe 202 is used when refluxing the first electrolyte from theanodization tank 10 to the firstelectrolyte supply system 13. - A
cathode tank 101, acathode 102, afilter 103, and adiffusion plate 104 are provided in theanodization tank 10. - When the first electrolyte is supplied to the
anodization tank 10, thecathode tank 101 functions as a shower head casing in combination with thediffusion plate 104. Thecathode tank 101 has a cylindrical shape, for example. The inner diameter of thecathode tank 101 is, for example, preferably equal to or larger than the outer diameter of asubstrate 110 which is a target of anodization. An insulating material is used for thecathode tank 101. The bottom surface of thecathode tank 101 contacts the bottom surface inside theanodization tank 10. An opened portion of the upper end of thecathode tank 101 is inclined with respect to the bottom surface of thecathode tank 101 and thereby thediffusion plate 104 may be attached in an inclined manner with respect to a liquid level of the first electrolyte. - The
cathode 102 functions as a cathode in the anodization process. Thecathode 102 has a disk shape, for example. Thecathode 102 contacts the bottom surface inside thecathode tank 101. The diameter of thecathode 102 is, for example, the same as the inner diameter of thecathode tank 101. Thecathode 102 is made of conductive materials, and uses materials with low reactivity to the first electrolyte (with almost no dissolution in the first electrolyte). Thecathode 102 may be a conductive material using, for example, carbon, diamond, Pt, or Au as a coating material. Furthermore, the coating material may be a glass-like fiber carbon, a diamond coat silicon or the like. - The
filter 103 is provided above thecathode 102 in thecathode tank 101. In other words, thefilter 103 is provided between thecathode 102 and thediffusion plate 104. In the anodization process, thefilter 103 removes particles generated at thecathode 102. For example, even when a material that is hard to dissolve in the first electrolyte is used for the electrode material of thecathode 102, the electrode may undergo oxidization due to aging, etc., and generate particles. When the particles are generated, they may inhibit porous silicon from being forming in the anodization process. The size of the particles that may be removed by thefilter 103 can be designed as appropriate. For example, as thefilter 103, a filter that can remove particles with a particle diameter of 0.01 μm or more may be used. - In the present embodiment, one end of the
pipe 201 is provided in a manner penetrating the bottom part of theanodization tank 10, the bottom part of thecathode tank 101, thecathode 102, and thefilter 103, and the first electrolyte is supplied to thecathode tank 101 from the firstelectrolyte supply system 13. - The
diffusion plate 104 is fixed to the opened portion of the upper end of thecathode tank 101 in a state of being inclined at angle θ (0°<θ<90°) with respect to the liquid level of the first electrolyte (or the bottom surfaces of theanodization tank 10 and the cathode tank 101). Thediffusion plate 104 is provided with a plurality of holes for diffusing the first electrolyte. The diameter and arrangement of the holes may be designed as appropriate. After being diffused by thediffusion plate 104, the first electrolyte is supplied to the surface of the substrate 110 (the surface to be anodized) that is fixed to theanode holder 11. Hereinafter, a surface on which a porous layer is to be formed by anodization will be referred to as a front surface of thesubstrate 110, and a surface on which the porous layer is not to be formed will be referred to as a back surface of thesubstrate 110. Thediffusion plate 104 is made of insulating materials, and uses materials with low reactivity to the first electrolyte (with almost no dissolution in the first electrolyte). As thediffusion plate 104, for example, it is preferable to use poly-tetra-fluoro-ethylene (PTFE), polyvinyl chloride, or materials on which antistatic measures have been taken. - The anode holder 11 functions as a holder for fixing the
substrate 110. When performing anodization, the anode holder is immersed in the first electrolyte with thesubstrate 110. - The
anode holder 11 includes abase 111, ananode 112, and awafer clamp 113. - The
base 111 has a disk shape, for example. The diameter of thebase 111 is, for example, equal to or larger than the diameter of thesubstrate 110. An insulating material, for example, is used for thebase 111. - The
anode 112 functions as an anode in the anodization process. Theanode 112 has a disk shape, for example. The diameter of theanode 112 is, for example, the same as the diameter of thebase 111. Theanode 112 contacts the bottom surface of the base 111 in a state where at least a part of theanode holder 11 and thesubstrate 110 are immersed in the first electrolyte inside theanodization tank 10. Theanode 112 is made of conductive materials, and uses materials with low reactivity to a second electrolyte described later. Theanode 112 may be a conductive material using, for example, carbon, diamond, Pt, or Au as a coating material. Furthermore, the coating material may be a glass-like fiber carbon, a diamond coat silicon or the like. - The
wafer clamp 113 has a cylindrical shape, for example. On the side surface of thewafer clamp 113, for example, a groove for fixing thebase 111 and theanode 112 is provided. Furthermore, the lower end of thewafer clamp 113 is provided with an edge seal for fixing thesubstrate 110. The outer diameter of thewafer clamp 113 is larger than the outer diameters of thesubstrate 110, thebase 111, and theanode 112. In a state where at least a part of theanode holder 11 and thesubstrate 110 are immersed in the first electrolyte inside theanodization tank 10, the edge seal of thewafer clamp 113 is in contact with the entire surface of the outer circumference of thesubstrate 110 and fixes thesubstrate 110 in a manner such that the front surface of thesubstrate 110 faces downwards (on thediffusion plate 104 side). - The
wafer clamp 113 fixes thesubstrate 110 and theanode 112 in a manner such that the back surface of the substrate 110 (the surface not to be anodized) is not in contact with theanode 112, and thesubstrate 110 and theanode 112 are in parallel. Thewafer clamp 113 is made of insulating materials, and uses materials with low reactivity to the first electrolyte and the second electrolyte (with almost no dissolution in the electrolytes). As thediffusion plate 104, for example, it is preferable to use PTFE, polyvinyl chloride, or materials on which antistatic measures have been taken. - In the present embodiment, in order to bring the
substrate 110 and theanode 112 into conduction, the second electrolyte having conductivity is supplied from the secondelectrolyte supply system 16 to a space defined by the back surface of thesubstrate 110, theanode 112, and thewafer clamp 113. More specifically, theanode holder 11 is coupled to apipe 203 for supplying the second electrolyte from the secondelectrolyte supply system 16 to theanode holder 11, and apipe 204 for refluxing the second electrolyte to the secondelectrolyte supply system 16. Thepipes base 111 and theanode 112, and the second electrolyte is supplied to the above-described space from the secondelectrolyte supply system 16. In other words, the second electrolyte fills the space between theanode 112 and thesubstrate 110. - In the anodization process, in some cases, the second electrolyte subjected to electrolysis may cause gas to be generated in the above-described space. In such a case, a path may be provided in the
anode holder 11 to discharge the gas. - It should be noted that, in the present example, although a case of bringing the
substrate 110 and theanode 112 into conduction by supplying the second electrolyte to the space between thesubstrate 110 and theanode 112 is described, it is not limited thereto. For example, the back surface of thesubstrate 110 may be brought into contact with theanode 112. On the surface of theanode 112 with which thesubstrate 110 is to be in contact, a low resistive layer which is injected with a high dopant concentration, or a metal that can perform an ohmic contact with respect to thesubstrate 110, may also be provided. - An anode
holder driving mechanism 12 is fixed on the center portion of the upper surface of thebase 111. Thebase 111 is made rotatable by the anodeholder driving mechanism 12 in a state where at least a part of theanode holder 11 and thesubstrate 110 are immersed in the first electrolyte inside theanodization tank 10. In other words, the anodeholder driving mechanism 12 is fixed to the center portion of a surface of the base 111 facing a surface on which theanode 112 is provided, in which manner thebase 111 is rotatable. The anodeholder driving mechanism 12 has a mechanism for immersing at least a part of the base 111 in theanodization tank 10 in a state where thebase 111 is inclined by angle θ, and rotating the base 111 in such a state. Therefore, in the present embodiment, at least a part of theanode holder 11 and thesubstrate 110 are immersed in the first electrolyte in a state where they are inclined by angle θ with respect to the liquid level of the first electrolyte of theanodization tank 10. The anodeholder driving mechanism 12 inclines thesubstrate 110 and theanode 112 by angle θ, thereby allowing thesubstrate 110, theanode 112, and thediffusion plate 104 to be provided in a parallel state in the anodization process. By arranging thesubstrate 110, theanode 112, and thediffusion plate 104 in a parallel state, the in-plane uniformity of the current density relating to thesubstrate 110 improves. It should be noted that theanode 112 and thediffusion plate 104 may or may not be provided in a parallel state. Even in a case where theanode 112 and thecathode 102 are not provided in a parallel state, and the distance between theanode 112 and thecathode 102 is uneven, it is possible to improve the in-plane uniformity of the current density relating to thesubstrate 110 by arranging thesubstrate 110 and thediffusion plate 104 in a parallel state. Furthermore, the in-plane uniformity of the current density relating to thesubstrate 110 improves by inclining thediffusion plate 104 in the same direction as thesubstrate 110 with respect to the bottom surface of theanodization tank 10 or the liquid level of the first electrolyte. - A specific example of a rotated state of the
anode holder 11 will be described with reference toFIG. 2 .FIG. 2 shows a cross-section of theanode holder 11 and an upper surface of the base 111 in the rotated state. - As shown in
FIG. 2 , the anodeholder driving mechanism 12 rotates the base 111 inclined by angle θ about the anodeholder driving mechanism 12 serving as a rotational axis. By inclining thebase 111 by angle θ thesubstrate 110 and theanode 112 become inclined by angle θ. For example, the anodeholder driving mechanism 12 rotates thebase 111 and thesubstrate 110 in the range of 10 to 100 rpm. - The first
electrolyte supply system 13 will now be described with reference toFIG. 1 . The firstelectrolyte supply system 13 supplies the first electrolyte to theanodization tank 10. The first electrolyte is a liquid to be used for the anodization process. As the first electrolyte, for example, a liquid containing a hydrogen fluoride (HF) is used. More specifically, for example, a mixed liquid of an HF solution and ethanol or isopropyl alcohol (IPA) is used for the first electrolyte. The firstelectrolyte supply system 13 of the present embodiment has a function of circulating the first electrolyte between theanodization tank 10 and the firstelectrolyte supply system 13. The firstelectrolyte supply system 13 supplies the first electrolyte for which concentration is adjusted to thecathode tank 101 via thepipe 201, and recovers the first electrolyte from theanodization tank 10 via thepipe 202. The firstelectrolyte supply system 13 does not necessarily have a function for circulating the first electrolyte. In such a case, thepipe 202 is omitted, and the first electrolyte in theanodization tank 10 is processed as a waste liquid. - The first
electrolyte supply system 13 includes aningredient supply unit 131, amixing tank 132, and apump 133. - The
ingredient supply unit 131 supplies ingredients of the first electrolyte to themixing tank 132 based on the control of thecontrol circuit 18 and theconcentration adjustment unit 14. Ingredients may be, for example, an HF solution, alcohol, and DIW (deionized water). As for the ingredients, materials other than liquids may be used. - The
mixing tank 132 mixes ingredients supplied from theingredient supply unit 131 with the first electrolyte recovered from theanodization tank 10 using thepipe 202, and produces a first electrolyte that can be used for the anodization process. - The
pump 133 compresses and transfers the first electrolyte produced in themixing tank 132 to thecathode tank 101 via thepipe 201. Thepump 133 may also be used when transferring the first electrolyte in themixing tank 132 to a waste liquid line (not shown). Furthermore, another pump may be provided for the waste liquid line. - The
concentration adjustment unit 14 adjusts the concentration of the first electrolyte. Theconcentration adjustment unit 14 includes aconcentration sensor 141. Theconcentration sensor 141 is coupled to thepipe 201. Theconcentration sensor 141 measures an ion concentration of the first electrolyte supplied from the firstelectrolyte supply system 13. Theconcentration adjustment unit 14 feeds back the measurement result of theconcentration sensor 141 to theingredient supply unit 131, and adjusts the amount of ingredients to be supplied in theingredient supply unit 131. This allows the concentration of the first electrolyte supplied to theanodization tank 10 to be maintained at a certain level, and H2SiF6, etc., which is a by-product of the anodization process, to be filtered. Theconcentration adjustment unit 14 may be provided in the firstelectrolyte supply system 13. - The
temperature adjustment unit 15 adjusts the temperature of the first electrolyte. Thetemperature adjustment unit 15 includes atemperature sensor 151. Thetemperature sensor 151 is coupled to thepipe 201, and monitors the temperature of the first electrolyte. For example, thetemperature adjustment unit 15 includes a tiller or a heater, and cools or heats the first electrolyte in accordance with the result of the temperature monitor. Thus, thetemperature adjustment unit 15 maintains the temperature of the first electrolyte in theanodization tank 10 at a certain level. Thetemperature adjustment unit 15 may be provided in the firstelectrolyte supply system 13. - The second
electrolyte supply system 16 supplies the second electrolyte to theanode holder 11. The second electrolyte is used to bring theanode 112 and thesubstrate 110 into conduction. As the second electrolyte, a liquid at least containing a conductive material is used. More specifically, for example, the conductive material may include at least one of HF, HCl, NaCl, KCl, KOH, H3PO4, or TMAH (Tetra-Methyl-Ammonium-Hydroxide). - The second
electrolyte supply system 16 of the present embodiment has a function of circulating the second electrolyte between theanode holder 11 and amixing tank 162. The secondelectrolyte supply system 16 supplies the second electrolyte for which concentration is adjusted to theanode holder 11 via thepipe 203, and recovers the second electrolyte from theanode holder 11 via thepipe 204. The secondelectrolyte supply system 16 does not necessarily have a function for circulating the second electrolyte. In such a case, thepipe 204 is omitted, and the second electrolyte in theanode holder 11 is processed as a waste liquid. - The second
electrolyte supply system 16 includes aningredient supply unit 161, themixing tank 162, and apump 163. - The
ingredient supply unit 161 supplies ingredients of the second electrolyte to themixing tank 162 based on the control of thecontrol circuit 18. The ingredients may be solutions such as HF, HCl, NaCl, KCl, KOH, H3PO4, and TMAH, and DIW (deionized water), etc. As for the ingredients, materials other than liquids may be used. - The
mixing tank 162 mixes ingredients supplied from theingredient supply unit 161 with the second electrolyte recovered from theanode holder 11 using thepipe 204, and produces a second electrolyte. - The
pump 163 compresses and transfers the second electrolyte produced in themixing tank 162 to theanode holder 11 via thepipe 203. Thepump 163 may also be used when transferring the second electrolyte in themixing tank 162 to a waste liquid line. Furthermore, another pump may be provided for the waste liquid line. Thepump 163 may set the supply pressure of the second electrolyte higher than the supply pressure of the first electrolyte so that the entire surface of the outer circumference of thesubstrate 110 is pressed against the edge seal of thewafer clamp 113. - The
current source 17 is coupled to theanode 112 and thecathode 102, and supplies a desired amount of current to theanode 112 when the anodization is performed. - The
control circuit 18 controls theentire anodization apparatus 1. More specifically, thecontrol circuit 18 controls the anodeholder driving mechanism 12, the firstelectrolyte supply system 13, theconcentration adjustment unit 14, thetemperature adjustment unit 15, the secondelectrolyte supply system 16, and thecurrent source 17. - 1.2 Flow of Anodization Process
- An example of the flow of the anodization process will be described with reference to
FIG. 3 .FIG. 3 is a flowchart of the anodization. - As shown in
FIG. 3 , first, the firstelectrolyte supply system 13 starts supplying the first electrolyte to the anodization tank 10 (step S1). - The
substrate 110 is set on theanode holder 11 in a manner such that the back surface of the substrate 110 (the surface not to be anodized) faces the anode 112 (step S2). - The second
electrolyte supply system 16 starts supplying the second electrolyte to the anode holder 11 (step S3). This allows the space between thesubstrate 110 and theanode 112 to be filled by the second electrolyte. - The anode
holder driving mechanism 12 inclines the anode holder 11 (the base 111), in which thesubstrate 110 is set and to which the second electrolyte is supplied, by angle θ. The anodeholder driving mechanism 12 immerses at least a part of theanode holder 11 and thesubstrate 110 in the first electrolyte in theanodization tank 10 in a state where theanode holder 11 and thesubstrate 110 are inclined by angle θ with respect to the liquid level (step S4). By inclining theanode holder 11, air (bubbles) can be suppressed from being trapped upon immersion. The first electrolyte circulates between theanodization tank 10 and the firstelectrolyte supply system 13. - The anode
holder driving mechanism 12 then starts rotating the anode holder 11 (step S5). Theanode holder 11 is rotated in a state of being inclined by angle θ with respect to the liquid level. Furthermore, as long as the anode holder is rotated in a state of being inclined with respect to the liquid level, it does not have to be in the same inclination angle as that at the time of immersing. - The
current source 17 supplies a current between theanode 112 and the cathode 102 (step S6). While thecurrent source 17 supplies the current, the anodization process is executed. As a result, porous layer is created on the front surface of thesubstrate 110. - When the
current source 17 stops supplying the current, the anodeholder driving mechanism 12 stops rotating the anode holder 11 (step S7). - The anode
holder driving mechanism 12 then takes theanode holder 11 out from the anodization tank 10 (step S8). - The second
electrolyte supply system 16 stops supplying the second electrolyte to the anode holder 11 (step S9). - The
substrate 110 is recovered from the anode holder (step S10). - 1.3 Advantageous Effects of Present Embodiment
- According to the configuration of the present embodiment, it is possible to provide an anodization apparatus which can form a porous film with excellent in-plane uniformity on a substrate surface. Such advantageous effects will be explained in detail.
- For example, when an anodization process is performed and HF in an electrolyte reacts with a silicon substrate, the concentration of HF in the electrolyte decreases, and hydrogen gas or H2SiF6 (SiF6 2− ion) is produced as a by-product. In some cases, this may cause the composition (ion concentration) of the electrolyte to change, and deteriorate the uniformity of the porous layer in the substrate surface or in each substrate. Furthermore, when the anodization process is performed, in some cases, a pair of positive and negative charged particles is formed on the substrate surface, causing an electric field double layer to occur side by side in layers, which delays the supply of ions to the substrate surface and the draining of the by-products.
- In contrast, according to the configuration of the present embodiment, the
anodization apparatus 1 can immerse thesubstrate 110 in a state where it is inclined with respect to the first electrolyte. Furthermore, theanodization apparatus 1 can execute the anodization process while rotating thesubstrate 110 in an inclined state. This allows theanodization apparatus 1 to suppress air (bubbles) from being trapped when immersing thesubstrate 110 in the first electrolyte. Furthermore, when performing the anodization process, theanodization apparatus 1 can efficiently drain the gas (for example, hydrogen) generated on the substrate surface or the by-product (for example, SiF6 2−) from the substrate surface. By rotating thesubstrate 110, theanodization apparatus 1 can also increase the flow rate of the first electrolyte on the substrate surface, and reduce the thickness of the electric field double layer formed near the front surface of thesubstrate 110. Therefore, theanodization apparatus 1 can improve the uniformity of the ion supplied to the substrate surface, and improve the in-plane uniformity of the formed porous layer (the film-thickness uniformity of the porous layer and in-plane uniformity of porosity). - Furthermore, according to the configuration of the present embodiment, when performing the anodization process, the
anodization apparatus 1 can provide thediffusion plate 104 in parallel with thesubstrate 110 between theanode 112 and thecathode 102. This allows the uniformity of the current density in the plane of thesubstrate 110 to be improved. Therefore, the in-plane uniformity of the formed porous layer can be improved. - Furthermore, according to the configuration of the present embodiment, the
anodization apparatus 1 has a first electrolyte supply system. Since this allows the concentration of the first electrolyte in theanodization tank 10 to be maintained at a certain level, the concentration of the first electrolyte can be suppressed from changing during the anodization process and in each of the substrates. Thus, the uniformity of film quality in a depth direction of the porous layer formed on thesubstrate 110, and the film quality uniformity between the substrates, can be improved. - Furthermore, according to the configuration of the present embodiment, the
anodization apparatus 1 supplies the second electrolyte between theanode 112 and thesubstrate 110. It is thereby possible to prevent theanode 112 and thesubstrate 110 from coming into contact. Thus, it is possible to reduce metal contamination of thesubstrate 110 caused by theanode 112. - Furthermore, according to the configuration of the present embodiment, by supplying the second electrolyte between the
anode 112 and thesubstrate 110, bad conduction caused by a warp, etc., in theanode 112 or thesubstrate 110 can be suppressed between theanode 112 and thesubstrate 110. - A second embodiment will now be described. In the second embodiment, a specific example of an anodization process system in which a plurality of
anodization tanks 10 described in the first embodiment are provided will be described. - 2.1 Configuration of Anodization Process System
- An example of the anodization process system will be described with reference to
FIG. 4 .FIG. 4 is a plan view of a configuration of ananodization process system 300. - As shown in
FIG. 4 , theanodization process system 300 includes aprocess module 301, atransfer module 302, aload port 303, and aload module 304. - The
process module 301 is a module for performing various processes on thesubstrate 110. In the example ofFIG. 4 , theprocess module 301 includes threeanodization tanks 310 to 312 and twowashing tanks anodization tanks 310 to 312 correspond to theanodization tank 10 described in the first embodiment. For example, each composition of a first electrolyte in theanodization tanks 310 to 312 may be different, and the anodization process can be executed under different conditions. Thewashing tanks washing tanks process module 301 is not limited to this. For example, process units that are different from the anodization tank and the washing tank may be provided. It should also be noted that the number of the anodization tanks and the washing tanks is optional. - The
transfer module 302 is provided in theprocess module 301. Thetransfer module 302 includes ahandler 320. Thehandler 320 is configured to be driven to carry thesubstrate 110 to each tank in theprocess module 301. - The
load port 303, for example, opens and closes a front opening unified pod (FOUP) 330. TheFOUP 330 is set on theload port 303. TheFOUP 330 is a sealed container for carrying thesubstrates 110. TheFOUP 330 is able to store a plurality ofsubstrates 110. It should be noted that although the example ofFIG. 4 shows a case in which fourload ports 303 are provided, the number ofload ports 303 may be at least one. - The
load module 304 includes ahandler 340. Thehandler 340 is configured to be driven to carry thesubstrate 110 between theFOUP 330 and thetransfer module 302. - 2.2 Advantageous Effects of Present Embodiment
- The anodization apparatus described in the first embodiment can be adopted in the anodization process system of the present embodiment.
- An anodization apparatus according to above embodiments includes: a first process tank (10) configured to perform an anodization process on a substrate; a holder (11) configured to hold the substrate; and a first electrolyte supply system (13) configured to supply a first electrolyte to the first process tank. The holder immerses the substrate in the first electrolyte in a state where the substrate is inclined with respect to a liquid level of the first electrolyte. The anodization process is executed in a state where the substrate is inclined with respect to the liquid level of the first electrolyte.
- The embodiments are not limited to the above-described aspects, and various modifications may be adopted therein.
- For example, the substrate may be a substrate for heterogeneous computing, a substrate for micro electro mechanical systems (MEMS), a semiconductor wafer for a three-dimensional integrated circuit, a biometric/medical substrate, or an optical waveguide substrate, etc.
- The state of being “coupled” in the foregoing embodiments includes a state of being coupled with something else indirectly interposed.
- The expression “approximately the same” or “parallel” in the foregoing embodiments includes errors to the extent that the formation of porous layers when the anodization process is performed is not affected.
- While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be implemented in a variety of other forms. Furthermore, various omissions, substitutions, and changes in the form of the embodiments may be made without departing from the spirit of the inventions.
Claims (14)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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JP2021-019756 | 2021-02-10 | ||
JP2021019756A JP2022122494A (en) | 2021-02-10 | 2021-02-10 | Anodization apparatus and anodization method |
Publications (1)
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US17/349,811 Abandoned US20220251722A1 (en) | 2021-02-10 | 2021-06-16 | Anodization apparatus and anodization method |
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US (1) | US20220251722A1 (en) |
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CN107326418B (en) * | 2017-06-28 | 2019-03-01 | 中国航发南方工业有限公司 | It is filled for hard anodized and hangs shield jig and hard anodized processing method |
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2021
- 2021-02-10 JP JP2021019756A patent/JP2022122494A/en active Pending
- 2021-06-16 US US17/349,811 patent/US20220251722A1/en not_active Abandoned
- 2021-06-24 TW TW110123129A patent/TWI783550B/en active
- 2021-06-24 TW TW111137957A patent/TW202305191A/en unknown
- 2021-07-19 CN CN202110811116.3A patent/CN114908392A/en active Pending
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Also Published As
Publication number | Publication date |
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TWI783550B (en) | 2022-11-11 |
TW202231936A (en) | 2022-08-16 |
JP2022122494A (en) | 2022-08-23 |
TW202305191A (en) | 2023-02-01 |
CN114908392A (en) | 2022-08-16 |
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