US20150192702A1 - Mold, optical element and method for manufacturing the same - Google Patents
Mold, optical element and method for manufacturing the same Download PDFInfo
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- US20150192702A1 US20150192702A1 US14/663,746 US201514663746A US2015192702A1 US 20150192702 A1 US20150192702 A1 US 20150192702A1 US 201514663746 A US201514663746 A US 201514663746A US 2015192702 A1 US2015192702 A1 US 2015192702A1
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- surface roughness
- substrate
- mold
- etching
- fine surface
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- 238000000034 method Methods 0.000 title claims abstract description 67
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 34
- 230000003287 optical effect Effects 0.000 title claims abstract description 26
- 230000003746 surface roughness Effects 0.000 claims abstract description 108
- 238000005530 etching Methods 0.000 claims abstract description 107
- 239000000758 substrate Substances 0.000 claims abstract description 86
- 229910018503 SF6 Inorganic materials 0.000 claims abstract description 35
- 239000007789 gas Substances 0.000 claims abstract description 34
- SFZCNBIFKDRMGX-UHFFFAOYSA-N sulfur hexafluoride Chemical compound FS(F)(F)(F)(F)F SFZCNBIFKDRMGX-UHFFFAOYSA-N 0.000 claims abstract description 26
- 229960000909 sulfur hexafluoride Drugs 0.000 claims abstract description 26
- 239000001301 oxygen Substances 0.000 claims abstract description 16
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 16
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 15
- 229910052751 metal Inorganic materials 0.000 claims abstract description 11
- 239000002184 metal Substances 0.000 claims abstract description 11
- 239000004065 semiconductor Substances 0.000 claims abstract description 6
- 230000003667 anti-reflective effect Effects 0.000 claims description 58
- 239000011295 pitch Substances 0.000 description 41
- 238000002834 transmittance Methods 0.000 description 22
- 238000000059 patterning Methods 0.000 description 17
- 238000001816 cooling Methods 0.000 description 15
- 238000001020 plasma etching Methods 0.000 description 12
- 239000000463 material Substances 0.000 description 10
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 9
- WRQGPGZATPOHHX-UHFFFAOYSA-N ethyl 2-oxohexanoate Chemical compound CCCCC(=O)C(=O)OCC WRQGPGZATPOHHX-UHFFFAOYSA-N 0.000 description 9
- 229910052710 silicon Inorganic materials 0.000 description 9
- 239000010703 silicon Substances 0.000 description 9
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 8
- 239000000203 mixture Substances 0.000 description 6
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 4
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 4
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 4
- 229910052804 chromium Inorganic materials 0.000 description 4
- 239000011651 chromium Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 239000010408 film Substances 0.000 description 4
- 229910052731 fluorine Inorganic materials 0.000 description 4
- 239000011737 fluorine Substances 0.000 description 4
- 229910052759 nickel Inorganic materials 0.000 description 4
- 229910052719 titanium Inorganic materials 0.000 description 4
- 239000010936 titanium Substances 0.000 description 4
- 238000000609 electron-beam lithography Methods 0.000 description 3
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical compound [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 3
- 239000010409 thin film Substances 0.000 description 3
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 3
- 229910052721 tungsten Inorganic materials 0.000 description 3
- 239000010937 tungsten Substances 0.000 description 3
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 2
- XPDWGBQVDMORPB-UHFFFAOYSA-N Fluoroform Chemical compound FC(F)F XPDWGBQVDMORPB-UHFFFAOYSA-N 0.000 description 2
- 229910001069 Ti alloy Inorganic materials 0.000 description 2
- 229910001080 W alloy Inorganic materials 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 229910021418 black silicon Inorganic materials 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 229910001882 dioxygen Inorganic materials 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 229910052715 tantalum Inorganic materials 0.000 description 2
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000002019 doping agent Substances 0.000 description 1
- 238000001312 dry etching Methods 0.000 description 1
- 238000005323 electroforming Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000001459 lithography Methods 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- -1 oxygen ions Chemical class 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- WNUPENMBHHEARK-UHFFFAOYSA-N silicon tungsten Chemical compound [Si].[W] WNUPENMBHHEARK-UHFFFAOYSA-N 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- TXEYQDLBPFQVAA-UHFFFAOYSA-N tetrafluoromethane Chemical compound FC(F)(F)F TXEYQDLBPFQVAA-UHFFFAOYSA-N 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
Images
Classifications
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
- G02B1/11—Anti-reflection coatings
- G02B1/113—Anti-reflection coatings using inorganic layer materials only
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/02—Diffusing elements; Afocal elements
- G02B5/0273—Diffusing elements; Afocal elements characterized by the use
- G02B5/0294—Diffusing elements; Afocal elements characterized by the use adapted to provide an additional optical effect, e.g. anti-reflection or filter
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C33/00—Moulds or cores; Details thereof or accessories therefor
- B29C33/38—Moulds or cores; Details thereof or accessories therefor characterised by the material or the manufacturing process
- B29C33/3842—Manufacturing moulds, e.g. shaping the mould surface by machining
- B29C33/3857—Manufacturing moulds, e.g. shaping the mould surface by machining by making impressions of one or more parts of models, e.g. shaped articles and including possible subsequent assembly of the parts
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C33/00—Moulds or cores; Details thereof or accessories therefor
- B29C33/42—Moulds or cores; Details thereof or accessories therefor characterised by the shape of the moulding surface, e.g. ribs or grooves
- B29C33/424—Moulding surfaces provided with means for marking or patterning
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F4/00—Processes for removing metallic material from surfaces, not provided for in group C23F1/00 or C23F3/00
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
- G02B1/11—Anti-reflection coatings
- G02B1/118—Anti-reflection coatings having sub-optical wavelength surface structures designed to provide an enhanced transmittance, e.g. moth-eye structures
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
- G02B1/12—Optical coatings produced by application to, or surface treatment of, optical elements by surface treatment, e.g. by irradiation
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02041—Cleaning
- H01L21/02057—Cleaning during device manufacture
- H01L21/02068—Cleaning during device manufacture during, before or after processing of conductive layers, e.g. polysilicon or amorphous silicon layers
- H01L21/02071—Cleaning during device manufacture during, before or after processing of conductive layers, e.g. polysilicon or amorphous silicon layers the processing being a delineation, e.g. RIE, of conductive layers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
- H01L21/3205—Deposition of non-insulating-, e.g. conductive- or resistive-, layers on insulating layers; After-treatment of these layers
- H01L21/321—After treatment
- H01L21/3213—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer
- H01L21/32131—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer by physical means only
- H01L21/32132—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer by physical means only of silicon-containing layers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
- H01L21/3205—Deposition of non-insulating-, e.g. conductive- or resistive-, layers on insulating layers; After-treatment of these layers
- H01L21/321—After treatment
- H01L21/3213—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer
- H01L21/32133—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer by chemical means only
- H01L21/32135—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer by chemical means only by vapour etching only
- H01L21/32136—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer by chemical means only by vapour etching only using plasmas
- H01L21/32137—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer by chemical means only by vapour etching only using plasmas of silicon-containing layers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C33/00—Moulds or cores; Details thereof or accessories therefor
- B29C33/56—Coatings, e.g. enameled or galvanised; Releasing, lubricating or separating agents
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
- Y10T428/24355—Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
Definitions
- the present invention relates to a method for manufacturing a mold or an optical element provided with a fine surface roughness, the mold and the optical element.
- Anti-reflective structures having grating shapes, the pitch (or the period) of the grating being smaller than the wavelength of light are used in optical elements.
- a method for manufacturing molds for such anti-reflective structures a method in which a resist undergoes patterning by interference exposure or using an electron-beam lithography system and then etching or electroforming is carried out is known (for example, WO2006/129514).
- a pattern with a fine pitch can be formed, and lithography or pattern forming on curved surfaces can be realized.
- the required manufacturing time excessively increases as an area in which pattern is to be formed increases. Accordingly, from a practical standpoint, the maximum area in which pattern can be formed is 10 mm square at most.
- the method in which interference exposure is used carries an advantage that a large area can be patterned at a time, but in the method the resolution is restricted. Thus, the pitch cannot be made highly fine. Further, when the method is applied to patterning on curved surfaces, degree of flexibility in design is low. Accordingly, there has been a problem that anti-reflection property deteriorates in the lower wavelength area of visible light.
- black silicon for solar cells has been already developed.
- the technical field of black silicon and that of molds for optical elements completely differ from each other. The both are irrelevant to each other, and there is nothing that suggests some relationship between the both.
- a method for manufacturing a mold or an optical element provided with a fine surface roughness is a method in which the fine surface roughness has been manufactured using a reactive etching apparatus.
- a substrate or a film made of a semiconductor or a metal which reacts with sulfur hexafluoride is placed, and into which a mixed gas of sulfur hexafluoride and oxygen is introduced and tuned into plasma such that oxides are made to be scattered on a surface of the substrate or the film, the surface of the substrate or the film is made to undergo etching by the sulfur hexafluoride while the oxides function as an etching mask, and thus the fine surface roughness is formed on the surface of the substrate or the film.
- a mold or an optical element provided with a fine surface roughness can be manufactured by a simplified process without the necessity of patterning process for an etching mask. Further, a mold or an optical element provided with a fine surface roughness having a pitch in a wide range including a visible light region and an infrared region can be obtained.
- a mold according to another embodiment of the present invention is manufactured by the method described in the above-described first embodiment.
- the fine surface roughness on the mold is used to form an anti-reflective structure.
- the fine surface roughness on the mold is used to form a diffusing structure.
- An optical element according to another embodiment of the present invention is manufactured by the method described in the above-described first embodiment.
- FIG. 1 shows a construction of a reactive ion etching apparatus used for a method for manufacturing a mold or an optical element having a surface roughness
- FIG. 2 is a flowchart for illustrating the principle of a method for manufacturing a mold for anti-reflective structure according to the present invention
- FIGS. 3A and 3B illustrate a method for manufacturing a mold having a fine surface roughness on a flat surface
- FIGS. 4A and 4B illustrate a method for manufacturing an optical element having a fine surface roughness
- FIG. 5 is a flowchart for determining etching conditions of a method for manufacturing a mold for anti-reflective structure as an example of the method for manufacturing a mold according to the present invention
- FIG. 6 shows a relationship between etching time and pitch of the fine surface roughness in the case that the power of the high frequency power supply is set to 100 watts and the etching conditions shown in Table 1 are maintained and a relationship between etching time and pitch of the fine surface roughness in the case that the power of the high frequency power supply is set to 200 watts and the etching conditions shown in Table 1 are maintained;
- FIG. 7 shows a relationship between etching time and depth of the fine surface roughness in the case that the power of the high frequency power supply is set to 100 watts and the etching conditions shown in Table 1 are maintained and a relationship between etching time and depth of the fine surface roughness in the case that the power of the high frequency power supply is set to 200 watts and the etching conditions shown in Table 1 are maintained;
- FIG. 8 shows relationships between wavelength and transmittance of infrared rays which enter substrates having different types of surface roughness
- FIG. 9 illustrates transmittance
- FIG. 10 shows a relationship between wavelength of light transmittance of which is to be increased and pitch of fine surface roughness for increasing the transmittance
- FIG. 11 shows a photo of the substrate 1 without a fine surface roughness, the substrate 2 with a fine surface roughness for visible light, and the substrate with the fine surface roughness 3 ;
- FIG. 12 shows a scanning electron microscope photo of the fine surface roughness 3 ;
- FIG. 13 is a flowchart for determining etching conditions of the a method for manufacturing a mold for anti-reflective structure according to the present invention.
- FIGS. 14A and 14B illustrate how a mold for anti-reflective structure is formed on a flat surface
- FIGS. 15A , 15 B and 15 C illustrate how a mold for anti-reflective structure is formed on a curved surface
- FIG. 16 is a flowchart for illustrating a method for manufacturing a mold for a diffraction grating provided with an anti-reflective structure
- FIGS. 17A , 17 B and 17 C are diagrams for illustrating a method for manufacturing a mold for a diffraction grating provided with an anti-reflective structure
- FIGS. 18A , 18 B and 18 C are diagrams for illustrating patterning of an etching mask
- FIG. 19 shows a scanning electron microscope photo of a mold for anti-reflective structure manufactured by a method according to the present invention
- FIG. 20 shows a scanning electron microscope photo of a mold for a diffraction grating provided with an anti-reflective structure
- FIG. 21 shows relationships between reflectance and wavelength of a surface provided with an anti-reflective structure manufactured by the method according to the present invention, a surface provided with an anti-reflective structure manufactured by a method according to a prior art and a surface without an anti-reflective structure.
- FIG. 1 shows a construction of a reactive ion etching apparatus 200 used for manufacturing a mold or an optical element having a surface roughness.
- the reactive ion etching apparatus 200 has an etching chamber 201 . Gases are fed to the evacuated etching chamber 201 through a gas feed port 207 .
- the etching chamber 201 is further provided with a gas exhaust port 209 to which a valve 217 is attached.
- the gas pressure in the etching chamber 201 can be controlled to a desired value by a controller 215 which is configured to manipulate the valve 217 according to a measurement of a gas pressure gauge 213 installed at the etching chamber 201 .
- An upper electrode 203 and a lower electrode 205 are provided in the etching chamber 201 .
- Plasma can be generated by applying high frequency voltage between the both electrodes using high frequency power supply 211 .
- a substrate 101 which is a base material of a mold is placed.
- the lower electrode 205 can be cooled at a desired temperature by a cooling device 219 .
- the cooling device 219 may be a water-cooling chiller, for example. The reason that the lower electrode 205 is cooled is to control the etching reaction by keeping the temperature of the substrate 101 at a desired value.
- the gas to be fed to the etching chamber 201 is a mixture of sulfur hexafluoride gas and oxygen gas.
- the material of the substrate is a semiconductor or a metal which reacts with sulfur hexafluoride.
- FIG. 2 is a flowchart for illustrating the principle of a method for manufacturing a mold for anti-reflective structure according to an embodiment of the present invention.
- step S 1010 of FIG. 2 a high frequency voltage is applied to the mixture of gases such that it is turned into plasma to carry out plasma dry etching.
- step S 1020 of FIG. 2 oxygen ions in the plasma bind to ions of the metal or the semiconductor of the substrate, which have reacted with the fluorine-containing gas (sulfur hexafluoride gas), resultant oxides deposit at random positions on the surface of the substrate.
- the fluorine-containing gas sulfur hexafluoride gas
- step S 1030 of FIG. 2 portions on the surface of the substrate, which are not covered with the oxides undergo etching while the oxides function as a mask. As a result, a surface roughness is formed on the surface of the substrate.
- the used gas is a mixture of sulfur hexafluoride (SF 6 ) gas and oxygen gas.
- the material of the substrate is a semiconductor or a metal which reacts with sulfur hexafluoride. More specifically, the material is silicon, titanium, tungsten, tantalum, a titanium alloy which is made by adding other elements to titanium, a tungsten alloy which is made by adding other elements to tungsten, or the like.
- FIGS. 3A and 3B illustrate a method for manufacturing a mold having a fine surface roughness on a flat surface.
- FIG. 3A shows a cross section of a substrate 101 to which etching has not been carried out.
- FIG. 3B shows a cross section of the substrate 101 which is provided with a fine surface roughness.
- the fine surface roughness has been formed by etching carried out using the reactive ion etching apparatus.
- the size of the fine surface roughness is displayed in an enlarged view in comparison with the substrate for the sake of easier understanding.
- FIGS. 4A and 4B illustrate a method for manufacturing an optical element having a fine surface roughness.
- FIG. 4A shows a cross section of an optical element made of silicon.
- the optical element has a curved surface, which has been shaped by cutting or the like.
- the optical element made of silicon is used for infrared rays.
- FIG. 4B shows a cross section of the optical element made of silicon, which is provided with a fine surface roughness.
- the fine surface roughness has been formed by etching carried out using the reactive ion etching apparatus.
- the fine surface roughness of the optical element functions as an anti-reflective structure.
- the size of the fine surface roughness is displayed in an enlarged view in comparison with the optical element for the sake of easier understanding.
- FIG. 5 is a flowchart for determining etching conditions of a method for manufacturing a mold for anti-reflective structure as an example of the manufacturing method according to the present invention.
- step S 2010 in FIG. 5 initial values of the etching conditions are selected.
- step S 2020 in FIG. 5 etching is carried out on the substrate under the selected etching conditions using the reactive ion etching apparatus.
- step S 2030 in FIG. 5 a reflectance of the manufactured mold is evaluated.
- step S 2040 in FIG. 5 a shape of the manufactured mold is evaluated.
- the shape is evaluated using a scanning electron microscope, for example.
- step S 2050 in FIG. 5 it is determined whether or not the manufactured mold is appropriate for a mold for anti-reflective structure. If the manufactured mold is appropriate, the process is terminated. If the manufactured mold is not appropriate, the process goes to step S 2060 .
- step S 2060 in FIG. 5 the etching conditions are adjusted.
- Table 1 shows some of the etching conditions.
- the mixed gas of sulfur hexafluoride and oxygen is fed into the etching chamber 201 of the reactive etching apparatus 200 .
- An amount of feed of sulfur hexafluoride and that of oxygen are 50 milliliters per minute respectively.
- the pressure in the etching chamber 201 is controlled at 1 pascal.
- the temperature of the lower electrode 205 on which the substrate 101 is set is controlled at 3 degrees centigrade.
- the substrate 101 is made of silicon.
- FIG. 6 shows a relationship between etching time and pitch of the fine surface roughness in the case that the power of the high frequency power supply 211 is set to 100 watts and the etching conditions shown in Table 1 are maintained, and a relationship between etching time and pitch of the fine surface roughness in the case that the power of the high frequency power supply 211 is set to 200 watts and the etching conditions shown in Table 1 are maintained.
- the horizontal axis in FIG. 6 represents etching time while the vertical axis in FIG. 6 represents pitch of the fine surface roughness.
- the unit of time is minute and the unit of pitch is micrometer.
- the frequency of the high frequency power supply 211 is 13.56 MHz.
- Pitch of the fine surface roughness is an average of distance in the direction parallel to the substrate surface between adjacent convex portions or between adjacent concave portions in a cross section of the fine surface roughness.
- the view of the cross section can be obtained by an atomic force microscope or the like.
- the pitch can be obtained through Fourier analysis of the cross section shape of the fine surface roughness.
- pitch of the fine surface roughness increases with etching time. Further, rate of increase of pitch against time increases with power of the high frequency power supply 211 .
- FIG. 7 shows a relationship between etching time and depth of the fine surface roughness in the case that the power of the high frequency power supply 211 is set to 100 watts and the etching conditions shown in Table 1 are maintained, and a relationship between etching time and depth of the fine surface roughness in the case that the power of the high frequency power supply 211 is set to 200 watts and the etching conditions shown in Table 1 are maintained.
- the horizontal axis in FIG. 7 represents etching time while the vertical axis in FIG. 7 represents depth of the fine surface roughness.
- the unit of time is minute and the unit of depth is micrometer.
- Depth of the fine surface roughness is an average of distance in the direction perpendicular to the substrate surface between adjacent convex and concave portions in a cross section of the fine surface roughness.
- depth of the fine surface roughness increases with etching time. Further, rate of increase of depth against time increases with power of the high frequency power 211 .
- fine surface roughness having pitches and depths which correspond to visible light region and infrared region can be manufactured.
- FIG. 8 shows relationships between wavelength and transmittance of infrared rays which enter substrates having different types of surface roughness.
- the horizontal axis in FIG. 8 represents wavelength of the infrared rays which enter the substrates while the vertical axis in FIG. 8 represents transmittance of the infrared rays.
- the solid line represents the relationship between wavelength and transmittance of infrared rays which enter a substrate without fine surface roughness.
- the two-dotted line represents the relationship between wavelength and transmittance of infrared rays which enter the substrate having the fine surface roughness which has been manufactured under the etching conditions 1 which will be described below.
- the dashed line represents the relationship between wavelength and transmittance of infrared rays which enter the substrate having the fine surface roughness which has been manufactured under the etching conditions 2 which will be described below.
- FIG. 9 illustrates transmittance.
- Transmittance is a ratio of an amount of transmitted light to an amount of the incident light.
- the transmittance changes by the function of the fine surface roughness 1011 of the substrate 101 .
- Table 2 shows the etching conditions 1 and the etching conditions 2.
- the fine surface roughness which has been manufactured under the etching conditions 1 will be hereinafter referred to as the fine surface roughness 1 .
- the pitch of the fine surface roughness 1 is 1.0 micrometer while the depth of the fine surface roughness 1 is 1.21 micrometers.
- the ratio of pitch to depth of the fine surface roughness 1 is 0.83.
- the fine surface roughness which has been manufactured under the etching conditions 2 will be hereinafter referred to as the fine surface roughness 2 .
- the pitch of the fine surface roughness 2 is 3.0 micrometer while the depth of the fine surface roughness 2 is 2.79 micrometers.
- the ratio of pitch to depth of the fine surface roughness 2 is 1.1.
- transmittance of the substrate having the fine surface roughness 1 is higher than that of the substrate without fine surface roughness in the wavelength range from 2 to 15 micrometers.
- transmittance of the substrate having the fine surface roughness 1 is higher than that of the substrate without fine surface roughness by 10% or more.
- Transmittance of the substrate having the fine surface roughness 2 is higher than that of the substrate without fine surface roughness in the wavelength range from 6 to 15 micrometers.
- transmittance of the substrate having the fine surface roughness 2 is higher than that of the substrate without fine surface roughness by 7% or more.
- the pitch of fine surface roughness for increasing transmittance, that is, reducing reflectance should be from one fifth (1 ⁇ 5) to one half (1 ⁇ 2) of the wavelength of light transmittance of which is to be increased.
- FIG. 10 shows an example of a relationship between wavelength of light transmittance of which is to be increased and pitch of fine surface roughness for increasing the transmittance.
- the horizontal axis in FIG. 10 represents wavelength of light transmittance of which is to be increased while the vertical axis in FIG. 10 represents pitch of fine surface roughness for increasing the transmittance.
- Fine surface roughness having a pitch which is larger than that of the fine surface roughness 2 was manufactured.
- the fine surface roughness will be hereinafter referred to as fine surface roughness 3 .
- Table 3 shows the etching conditions for the fine surface roughness 3 .
- the pitch of the fine surface roughness 3 is 18.0 micrometers while the depth of the fine surface roughness 3 is 6.0 micrometers.
- the ratio of pitch to depth of the fine surface roughness 3 is 3.0
- the amount of feed of oxygen is smaller than that of sulfur hexafluoride.
- distances between oxides which are deposited on the substrate surface and function as an etching mask become greater.
- the ratio of pitch to depth of the fine surface roughness 3 becomes greater than those of the fine surface roughness 1 and the fine surface roughness 2 .
- FIG. 11 shows a photo of the substrate 1 without a fine surface roughness, the substrate 2 with a fine surface roughness for visible light, and the substrate with the fine surface roughness 3 .
- the pitch of the fine surface roughness of the substrate 2 is 0.2 micrometers. Reflection on the surface of the substrate 2 is reduced by the fine surface roughness, and therefore the substrate 2 looks darker than the substrate 1 .
- the pitch of the fine surface roughness 3 is much greater than wavelengths of the visible light.
- values of distance in the direction parallel to the substrate surface between adjacent convex portions or between adjacent concave portions are not constant and are distributed in a predetermined range.
- the fine surface roughness 3 of the substrate 3 causes diffracted lights of various orders of diffraction and of various wavelengths, and thus the substrate 3 looks more whitish than the substrate 1 .
- the substrate 3 with the fine surface roughness 3 causes diffusion of the visible light.
- the substrate 3 with the fine surface roughness 3 functions as a diffuser plate.
- a mold for a diffusing structure is obtained.
- FIG. 12 shows a scanning electron microscope photo of the fine surface roughness 3 .
- a method for manufacturing a mold for anti-reflective structure according to the present invention will be described using another example.
- a silicon wafer is used as the substrate.
- Table 4 shows characteristics of the silicon wafer used in the example.
- Table 5 shows etching conditions in the example.
- the frequency of the high frequency power is 13.56 MHz and the voltage is 200 V.
- the pitch of the fine structure of the mold for anti-reflective structure manufactured by the above-described manufacturing conditions is approximately 0.2 micrometers while the depth thereof is approximately 0.3 micrometers.
- the aspect ratio is approximately 1.5.
- FIG. 13 is a flowchart for determining etching conditions of the method for manufacturing a mold for anti-reflective structure according to the present invention.
- step S 3010 in FIG. 13 initial values of the etching conditions are selected. More specifically, for example, the values shown in Table 5 are selected.
- step S 3020 in FIG. 13 etching is carried out on the substrate under the selected etching conditions using the reactive ion etching apparatus.
- step S 3030 in FIG. 13 a reflectance of the manufactured mold is evaluated.
- step S 3040 in FIG. 13 a shape of the manufactured mold is evaluated.
- the shape is evaluated using a scanning electron microscope, for example.
- step S 3050 in FIG. 13 it is determined whether or not the manufactured mold is appropriate for a mold for anti-reflective structure. If the manufactured mold is appropriate, the process is terminated. If the manufactured mold is not appropriate, the process goes to step S 3060 .
- step S 3060 in FIG. 13 the etching conditions are adjusted. How to adjust the etching conditions will be described below.
- the aspect ratio of the fine structure should be 0.8 or more.
- a ratio of partial pressures of the gasses, the cooling temperature of the substrate, and etching time are mainly adjusted.
- the partial pressure of SF 6 gas in the mixed gas is raised, the etching rate becomes higher.
- the cooling temperature of the substrate is lowered, the reaction for generating silicon oxide (SiO) is promoted, and therefore formation of coated portions for preventing etching (the mask) is promoted. Accordingly, when the etching time (reaction time) is increased under the above-described conditions, the aspect ratio becomes greater.
- the pitch of the fine structure should be 0.35 micrometers or less such that the pitch is smaller than wavelengths of the visible light.
- a ratio between partial pressures of the gasses and the cooling temperature of the substrate are adjusted. When the ratio of partial pressure of oxygen is raised and the cooling temperature of the substrate is lowered, the pitch of the fine structure becomes smaller.
- Table 6 shows the ranges of adjustment of the various parameters in the above-described case (in which the material of the substrate is silicon and the mixed gas includes sulfur hexafluoride (SF 6 ) and oxygen).
- Table 7 shows the ranges of adjustment of the various parameters in the case in which the material of the substrate is one of titanium, tungsten, tantalum, a titanium alloy which is made by adding other elements to titanium, and a tungsten alloy which is made by adding other elements to tungsten silicon and the mixed gas includes sulfur hexafluoride (SF 6 ) and oxygen.
- the material of the substrate is one of titanium, tungsten, tantalum, a titanium alloy which is made by adding other elements to titanium, and a tungsten alloy which is made by adding other elements to tungsten silicon and the mixed gas includes sulfur hexafluoride (SF 6 ) and oxygen.
- SF 6 sulfur hexafluoride
- An advantage of the case in which silicon is used as the material of the substrate is that machining is easier, while an advantage of the case in which a metal is used as the material of the substrate is that the mold is superior in durability.
- the mixed gas of sulfur hexafluoride and oxygen is used.
- sulfur hexafluoride other fluorine-containing gases (carbon tetrafluoride, trifluoromethane and the like) can also be used.
- FIGS. 14A and 14B illustrate how a mold for anti-reflective structure is formed on a flat surface.
- FIG. 14A shows a cross section of the substrate 1101 to which etching has not been carried out.
- FIG. 14B shows a cross section of the substrate 1101 which is provided with a shape of anti-reflective structure on a surface.
- the shape of anti-reflective structure has been formed through etching which has been carried out using the reactive ion etching apparatus.
- FIGS. 15A , 15 B and 15 C illustrate how a mold for anti-reflective structure is formed on a curved surface.
- FIG. 15A shows a cross section of a mold core 1110 which is provided with a curved surface.
- the curved surface is formed by cutting, for example.
- FIG. 15B shows a cross section of a mold core 1110 which is provided with a thin film 111 of base material formed on a surface of the core.
- the thin film 111 of base material is formed by sputtering, vapor deposition or the like.
- FIG. 15C shows a cross section of a mold core which is obtained by forming a shape of anti-reflective structure on a surface of the thin film 1111 of the substrate of what is shown in FIG. 15B .
- the shape of anti-reflective structure has been formed through etching which has been carried out using the reactive ion etching apparatus.
- a mold for anti-reflective structure can be manufactured on any curved surfaces.
- FIG. 16 is a flowchart for illustrating a method for manufacturing a mold for a diffraction grating provided with an anti-reflective fine structure.
- FIGS. 17A , 17 B and 17 C are diagrams for illustrating the method for manufacturing a mold for a diffraction grating provided with an anti-reflective fine structure.
- step S 4010 in FIG. 16 a shape of anti-reflective structure is formed on a surface of a substrate 1121 through etching which is carried out using the reactive ion etching apparatus.
- FIG. 17A shows a cross section of the substrate 1121 which has undergone etching.
- step S 4020 in FIG. 16 on the surface of the substrate 1121 , on which the shape of anti-reflective structure has been formed through etching which has been carried out using the reactive ion etching apparatus, a patterning of etching mask for a diffraction grating is carried out.
- FIG. 17B shows a cross section of the substrate 1121 , on a surface of which the patterning of an etching mask 1125 for the diffraction grating has been carried out.
- the patterning of the etching mask 1125 will be described later.
- step S 4030 in FIG. 16 the substrate 1121 , on a surface of which the patterning of the etching mask 1125 for the diffraction grating has been carried out is further made to undergo etching using the reactive ion etching apparatus.
- step S 4040 in FIG. 16 the etching mask 1125 is removed.
- the removal of the etching mask 1125 will be described later.
- FIG. 17C shows a cross section of a mold for a diffraction grating provided with an anti-reflective fine structure.
- the mold is manufactured by the method illustrated in the flowchart of FIG. 16 .
- FIGS. 18A , 18 B and 18 C are diagrams for illustrating patterning of an etching mask.
- FIG. 18A shows a cross section of a substrate 1121 , on a surface of which patterning of a resist 1123 for a diffraction grating has been carried out.
- FIG. 18B shows a cross section of the substrate 1121 , on a surface of which patterning of the resist 1123 for the diffraction grating has been carried out and then a metal 1125 which is resistant to reaction with fluorine-containing gases, such as chromium and nickel has been deposited.
- FIG. 18C shows a cross section of the substrate 121 , on a surface of which patterning of the resist 1123 for the diffraction grating has been carried out, the metal 1125 which is resistant to reaction with fluorine-containing gases, such as chromium and nickel has been deposited and then the resist 1123 has been removed.
- the metal 1125 such as chromium and nickel, shown in FIG. 18C functions as the etching mask.
- the resist 1123 shown in FIG. 18A can also be used as the etching mask.
- etch selectivity (a difference in etching rate) of the substrate against the resist is smaller than etch selectivity of the substrate against a metal such as chromium and nickel, and therefore depth of etching is smaller.
- FIG. 19 shows a scanning electron microscope photo of a mold for anti-reflective structure manufactured by a method according to the present invention.
- the pitch of the fine structure of the anti-reflective structure is approximately 0.2 micrometers.
- FIG. 20 shows a scanning electron microscope photo of a mold for a diffraction grating provided with an anti-reflective fine structure.
- the pitch of the diffraction grating is approximately 2 micrometers while the pitch of the fine structure of the anti-reflective structure is approximately 0.2 micrometers.
- FIG. 21 shows relationships between reflectance and wavelength of a surface provided with an anti-reflective structure manufactured by the method according to the present invention, a surface provided with an anti-reflective structure manufactured by a method according to a prior art (a method using an electron beam lithography system) and a surface without an anti-reflective structure.
- the horizontal axis of FIG. 21 represents wavelength while the vertical axis of FIG. 21 represents reflectance.
- Reflectance of the surface provided with the anti-reflective structure manufactured by the method according to the present invention is smaller over the whole range of wavelength than the reflectance of the surface provided with the anti-reflective structure manufactured by the method according to a prior art. This demonstrates that an anti-reflective structure having higher performance can be manufactured according to the present invention.
- an anti-reflective structure having higher performance can be manufactured without the use of patterning.
- a mold for an anti-reflective structure of a large area can be manufactured without any other constrains than the area of the reactive etching apparatus.
- a mold for an anti-reflective structure for molding an anti-reflective fine structure on any curved surface and a mold for an anti-reflective structure for molding a diffraction grating provided with an anti-reflective fine structure can be manufactured.
- a mold for an anti-reflective structure used for visible light and infrared rays, an optical element provided with an anti-reflective structure, and a mold for diffusing structure can be obtained without the necessity of patterning.
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Abstract
A method for manufacturing a mold or an optical element provided with a fine surface roughness according to an embodiment of the present invention is a method in which the fine surface roughness has been manufactured using a reactive etching apparatus. In the apparatus a substrate or a film made of a semiconductor or a metal which reacts with sulfur hexafluoride is placed, and into which a mixed gas of sulfur hexafluoride and oxygen is introduced and tuned into plasma such that oxides are made to be scattered on a surface of the substrate or the film, the surface of the substrate or the film is made to undergo etching by the sulfur hexafluoride while the oxides function as an etching mask, and thus the fine surface roughness is formed on the surface of the substrate or the film.
Description
- This is a Continuation-in-Part of International Patent Application No. PCT/JP2013/061889 filed Apr. 23, 2013, which designates the U.S. and was published under PCT Article 21(2) in English, which claims priority from U.S. Provisional Patent Application No. 61/727,284, dated Nov. 16, 2012. This Continuation-in-Part application also claims priority from U.S. Provisional Patent Application No. 61/968,629 filed on Mar. 21, 2014. The contents of these applications are hereby incorporated by reference.
- 1. Field
- The present invention relates to a method for manufacturing a mold or an optical element provided with a fine surface roughness, the mold and the optical element.
- 2. Description of the Related Art
- Anti-reflective structures having grating shapes, the pitch (or the period) of the grating being smaller than the wavelength of light, are used in optical elements. As a method for manufacturing molds for such anti-reflective structures, a method in which a resist undergoes patterning by interference exposure or using an electron-beam lithography system and then etching or electroforming is carried out is known (for example, WO2006/129514).
- By the method in which an electron-beam lithography system is used, a pattern with a fine pitch can be formed, and lithography or pattern forming on curved surfaces can be realized. However, the required manufacturing time excessively increases as an area in which pattern is to be formed increases. Accordingly, from a practical standpoint, the maximum area in which pattern can be formed is 10 mm square at most.
- The method in which interference exposure is used carries an advantage that a large area can be patterned at a time, but in the method the resolution is restricted. Thus, the pitch cannot be made highly fine. Further, when the method is applied to patterning on curved surfaces, degree of flexibility in design is low. Accordingly, there has been a problem that anti-reflection property deteriorates in the lower wavelength area of visible light.
- Thus, methods in which patterning is used are complicated in process and are time-consuming.
- On the other hand, a method for manufacturing a mold for an anti-reflective structure, which does not require patterning, has been developed (for example, U.S. Pat. No. 8,187,481B1).
- However, the method described in U.S. Pat. No. 8,187,481B1 has a problem when the method is applied to manufacture a high-performance anti-reflective structure. Concerning the problem, description will be given later in comparison with the present invention.
- Further, black silicon for solar cells has been already developed. However, the technical field of black silicon and that of molds for optical elements completely differ from each other. The both are irrelevant to each other, and there is nothing that suggests some relationship between the both.
- Recently, other methods for manufacturing anti-reflective structures without the necessity of patterning process of resist have been developed. Among the methods, there are a method in which a fine surface roughness is formed by coating nanoparticles on a surface of a substrate (for example, JP2012-40878) and a method in which a fine surface roughness is formed using anodic oxidation porous alumina as a mold (for example, JP2014-51710). These methods are supposed to be applied to a surface having a large area or a curved surface. However, because of the properties of the manufacturing methods, pitch of the surface roughness is restricted to 1 micrometer or less. Accordingly, the surface roughness can hardly be applied to optical elements functioning with infrared rays, for example.
- Thus, a method for manufacturing a mold or an optical element by which fine surface roughness having pitches of a wide range including infrared region can be formed on a surface having a large area or on a curved surface, has not been developed.
- Accordingly, there is a need for a method for manufacturing a mold or an optical element by which fine surface roughness having pitches of a wide range including infrared region can be formed on a surface having a large area or on a curved surface.
- A method for manufacturing a mold or an optical element provided with a fine surface roughness according to an embodiment of the present invention is a method in which the fine surface roughness has been manufactured using a reactive etching apparatus. In the apparatus a substrate or a film made of a semiconductor or a metal which reacts with sulfur hexafluoride is placed, and into which a mixed gas of sulfur hexafluoride and oxygen is introduced and tuned into plasma such that oxides are made to be scattered on a surface of the substrate or the film, the surface of the substrate or the film is made to undergo etching by the sulfur hexafluoride while the oxides function as an etching mask, and thus the fine surface roughness is formed on the surface of the substrate or the film.
- According to the present embodiment, a mold or an optical element provided with a fine surface roughness can be manufactured by a simplified process without the necessity of patterning process for an etching mask. Further, a mold or an optical element provided with a fine surface roughness having a pitch in a wide range including a visible light region and an infrared region can be obtained.
- A mold according to another embodiment of the present invention, is manufactured by the method described in the above-described first embodiment.
- In a mold according to another embodiment of the present invention, the fine surface roughness on the mold is used to form an anti-reflective structure.
- In a mold according to another embodiment of the present invention, the fine surface roughness on the mold is used to form a diffusing structure.
- An optical element according to another embodiment of the present invention, is manufactured by the method described in the above-described first embodiment.
-
FIG. 1 shows a construction of a reactive ion etching apparatus used for a method for manufacturing a mold or an optical element having a surface roughness; -
FIG. 2 is a flowchart for illustrating the principle of a method for manufacturing a mold for anti-reflective structure according to the present invention; -
FIGS. 3A and 3B illustrate a method for manufacturing a mold having a fine surface roughness on a flat surface; -
FIGS. 4A and 4B illustrate a method for manufacturing an optical element having a fine surface roughness; -
FIG. 5 is a flowchart for determining etching conditions of a method for manufacturing a mold for anti-reflective structure as an example of the method for manufacturing a mold according to the present invention; -
FIG. 6 shows a relationship between etching time and pitch of the fine surface roughness in the case that the power of the high frequency power supply is set to 100 watts and the etching conditions shown in Table 1 are maintained and a relationship between etching time and pitch of the fine surface roughness in the case that the power of the high frequency power supply is set to 200 watts and the etching conditions shown in Table 1 are maintained; -
FIG. 7 shows a relationship between etching time and depth of the fine surface roughness in the case that the power of the high frequency power supply is set to 100 watts and the etching conditions shown in Table 1 are maintained and a relationship between etching time and depth of the fine surface roughness in the case that the power of the high frequency power supply is set to 200 watts and the etching conditions shown in Table 1 are maintained; -
FIG. 8 shows relationships between wavelength and transmittance of infrared rays which enter substrates having different types of surface roughness; -
FIG. 9 illustrates transmittance; -
FIG. 10 shows a relationship between wavelength of light transmittance of which is to be increased and pitch of fine surface roughness for increasing the transmittance; -
FIG. 11 shows a photo of thesubstrate 1 without a fine surface roughness, thesubstrate 2 with a fine surface roughness for visible light, and the substrate with thefine surface roughness 3; -
FIG. 12 shows a scanning electron microscope photo of thefine surface roughness 3; -
FIG. 13 is a flowchart for determining etching conditions of the a method for manufacturing a mold for anti-reflective structure according to the present invention; -
FIGS. 14A and 14B illustrate how a mold for anti-reflective structure is formed on a flat surface; -
FIGS. 15A , 15B and 15C illustrate how a mold for anti-reflective structure is formed on a curved surface; -
FIG. 16 is a flowchart for illustrating a method for manufacturing a mold for a diffraction grating provided with an anti-reflective structure; -
FIGS. 17A , 17B and 17C are diagrams for illustrating a method for manufacturing a mold for a diffraction grating provided with an anti-reflective structure; -
FIGS. 18A , 18B and 18C are diagrams for illustrating patterning of an etching mask; -
FIG. 19 shows a scanning electron microscope photo of a mold for anti-reflective structure manufactured by a method according to the present invention; -
FIG. 20 shows a scanning electron microscope photo of a mold for a diffraction grating provided with an anti-reflective structure; and -
FIG. 21 shows relationships between reflectance and wavelength of a surface provided with an anti-reflective structure manufactured by the method according to the present invention, a surface provided with an anti-reflective structure manufactured by a method according to a prior art and a surface without an anti-reflective structure. -
FIG. 1 shows a construction of a reactiveion etching apparatus 200 used for manufacturing a mold or an optical element having a surface roughness. The reactiveion etching apparatus 200 has anetching chamber 201. Gases are fed to the evacuatedetching chamber 201 through agas feed port 207. Theetching chamber 201 is further provided with agas exhaust port 209 to which avalve 217 is attached. The gas pressure in theetching chamber 201 can be controlled to a desired value by acontroller 215 which is configured to manipulate thevalve 217 according to a measurement of agas pressure gauge 213 installed at theetching chamber 201. Anupper electrode 203 and alower electrode 205 are provided in theetching chamber 201. Plasma can be generated by applying high frequency voltage between the both electrodes using highfrequency power supply 211. On the lower electrode 205 asubstrate 101 which is a base material of a mold is placed. Thelower electrode 205 can be cooled at a desired temperature by acooling device 219. Thecooling device 219 may be a water-cooling chiller, for example. The reason that thelower electrode 205 is cooled is to control the etching reaction by keeping the temperature of thesubstrate 101 at a desired value. - The gas to be fed to the
etching chamber 201 is a mixture of sulfur hexafluoride gas and oxygen gas. The material of the substrate is a semiconductor or a metal which reacts with sulfur hexafluoride. -
FIG. 2 is a flowchart for illustrating the principle of a method for manufacturing a mold for anti-reflective structure according to an embodiment of the present invention. - In step S1010 of
FIG. 2 , a high frequency voltage is applied to the mixture of gases such that it is turned into plasma to carry out plasma dry etching. - In step S1020 of
FIG. 2 , oxygen ions in the plasma bind to ions of the metal or the semiconductor of the substrate, which have reacted with the fluorine-containing gas (sulfur hexafluoride gas), resultant oxides deposit at random positions on the surface of the substrate. The above-described oxides are hardy etched by sulfur hexafluoride, and therefore function as an etching mask. - In step S1030 of
FIG. 2 , portions on the surface of the substrate, which are not covered with the oxides undergo etching while the oxides function as a mask. As a result, a surface roughness is formed on the surface of the substrate. - As described above, the used gas is a mixture of sulfur hexafluoride (SF6) gas and oxygen gas.
- The material of the substrate is a semiconductor or a metal which reacts with sulfur hexafluoride. More specifically, the material is silicon, titanium, tungsten, tantalum, a titanium alloy which is made by adding other elements to titanium, a tungsten alloy which is made by adding other elements to tungsten, or the like.
-
FIGS. 3A and 3B illustrate a method for manufacturing a mold having a fine surface roughness on a flat surface. -
FIG. 3A shows a cross section of asubstrate 101 to which etching has not been carried out. -
FIG. 3B shows a cross section of thesubstrate 101 which is provided with a fine surface roughness. The fine surface roughness has been formed by etching carried out using the reactive ion etching apparatus. InFIG. 3B , the size of the fine surface roughness is displayed in an enlarged view in comparison with the substrate for the sake of easier understanding. -
FIGS. 4A and 4B illustrate a method for manufacturing an optical element having a fine surface roughness. -
FIG. 4A shows a cross section of an optical element made of silicon. The optical element has a curved surface, which has been shaped by cutting or the like. The optical element made of silicon is used for infrared rays. -
FIG. 4B shows a cross section of the optical element made of silicon, which is provided with a fine surface roughness. The fine surface roughness has been formed by etching carried out using the reactive ion etching apparatus. The fine surface roughness of the optical element functions as an anti-reflective structure. InFIG. 4B , the size of the fine surface roughness is displayed in an enlarged view in comparison with the optical element for the sake of easier understanding. -
FIG. 5 is a flowchart for determining etching conditions of a method for manufacturing a mold for anti-reflective structure as an example of the manufacturing method according to the present invention. - In step S2010 in
FIG. 5 , initial values of the etching conditions are selected. - In step S2020 in
FIG. 5 , etching is carried out on the substrate under the selected etching conditions using the reactive ion etching apparatus. - In step S2030 in
FIG. 5 , a reflectance of the manufactured mold is evaluated. - In step S2040 in
FIG. 5 , a shape of the manufactured mold is evaluated. The shape is evaluated using a scanning electron microscope, for example. - In step S2050 in
FIG. 5 , it is determined whether or not the manufactured mold is appropriate for a mold for anti-reflective structure. If the manufactured mold is appropriate, the process is terminated. If the manufactured mold is not appropriate, the process goes to step S2060. - In step S2060 in
FIG. 5 , the etching conditions are adjusted. - The etching conditions will be described in detail below.
- Table 1 shows some of the etching conditions.
-
TABLE 1 Operation Mixture ratio of Cooling pressure SF6 and O2 temperature 1 Pa 50 mL/min:50 mL/ min 3° C. - Into the
etching chamber 201 of thereactive etching apparatus 200, the mixed gas of sulfur hexafluoride and oxygen is fed. An amount of feed of sulfur hexafluoride and that of oxygen are 50 milliliters per minute respectively. The pressure in theetching chamber 201 is controlled at 1 pascal. The temperature of thelower electrode 205 on which thesubstrate 101 is set is controlled at 3 degrees centigrade. Thesubstrate 101 is made of silicon. -
FIG. 6 shows a relationship between etching time and pitch of the fine surface roughness in the case that the power of the highfrequency power supply 211 is set to 100 watts and the etching conditions shown in Table 1 are maintained, and a relationship between etching time and pitch of the fine surface roughness in the case that the power of the highfrequency power supply 211 is set to 200 watts and the etching conditions shown in Table 1 are maintained. The horizontal axis inFIG. 6 represents etching time while the vertical axis inFIG. 6 represents pitch of the fine surface roughness. The unit of time is minute and the unit of pitch is micrometer. The frequency of the highfrequency power supply 211 is 13.56 MHz. - Pitch of the fine surface roughness is an average of distance in the direction parallel to the substrate surface between adjacent convex portions or between adjacent concave portions in a cross section of the fine surface roughness. The view of the cross section can be obtained by an atomic force microscope or the like. The pitch can be obtained through Fourier analysis of the cross section shape of the fine surface roughness.
- According to
FIG. 6 , pitch of the fine surface roughness increases with etching time. Further, rate of increase of pitch against time increases with power of the highfrequency power supply 211. -
FIG. 7 shows a relationship between etching time and depth of the fine surface roughness in the case that the power of the highfrequency power supply 211 is set to 100 watts and the etching conditions shown in Table 1 are maintained, and a relationship between etching time and depth of the fine surface roughness in the case that the power of the highfrequency power supply 211 is set to 200 watts and the etching conditions shown in Table 1 are maintained. The horizontal axis inFIG. 7 represents etching time while the vertical axis inFIG. 7 represents depth of the fine surface roughness. The unit of time is minute and the unit of depth is micrometer. - Depth of the fine surface roughness is an average of distance in the direction perpendicular to the substrate surface between adjacent convex and concave portions in a cross section of the fine surface roughness.
- According to
FIG. 7 , depth of the fine surface roughness increases with etching time. Further, rate of increase of depth against time increases with power of thehigh frequency power 211. - As described above, by adjusting the etching conditions including power of the high
frequency power supply 211 and etching time, fine surface roughness having pitches and depths which correspond to visible light region and infrared region can be manufactured. -
FIG. 8 shows relationships between wavelength and transmittance of infrared rays which enter substrates having different types of surface roughness. The horizontal axis inFIG. 8 represents wavelength of the infrared rays which enter the substrates while the vertical axis inFIG. 8 represents transmittance of the infrared rays. InFIG. 8 the solid line represents the relationship between wavelength and transmittance of infrared rays which enter a substrate without fine surface roughness. InFIG. 8 the two-dotted line represents the relationship between wavelength and transmittance of infrared rays which enter the substrate having the fine surface roughness which has been manufactured under theetching conditions 1 which will be described below. InFIG. 8 the dashed line represents the relationship between wavelength and transmittance of infrared rays which enter the substrate having the fine surface roughness which has been manufactured under theetching conditions 2 which will be described below. -
FIG. 9 illustrates transmittance. Transmittance is a ratio of an amount of transmitted light to an amount of the incident light. The transmittance changes by the function of thefine surface roughness 1011 of thesubstrate 101. - Table 2 shows the
etching conditions 1 and theetching conditions 2. -
TABLE 2 Etching Operation Mixture ratio of Cooling conditions pressure SF6 and O2 Power Time temperature 1 1 Pa 50 mL/min:50 mL/ min 100 W 120 minutes 3° C. 2 1 Pa 50 mL/min:50 mL/min 200 W 120 minutes 3° C. - The fine surface roughness which has been manufactured under the
etching conditions 1 will be hereinafter referred to as thefine surface roughness 1. The pitch of thefine surface roughness 1 is 1.0 micrometer while the depth of thefine surface roughness 1 is 1.21 micrometers. The ratio of pitch to depth of thefine surface roughness 1 is 0.83. The fine surface roughness which has been manufactured under theetching conditions 2 will be hereinafter referred to as thefine surface roughness 2. The pitch of thefine surface roughness 2 is 3.0 micrometer while the depth of thefine surface roughness 2 is 2.79 micrometers. The ratio of pitch to depth of thefine surface roughness 2 is 1.1. - According to
FIG. 8 , transmittance of the substrate having thefine surface roughness 1 is higher than that of the substrate without fine surface roughness in the wavelength range from 2 to 15 micrometers. Particularly, in the wavelength range from 3 to 7 micrometers, transmittance of the substrate having thefine surface roughness 1 is higher than that of the substrate without fine surface roughness by 10% or more. Transmittance of the substrate having thefine surface roughness 2 is higher than that of the substrate without fine surface roughness in the wavelength range from 6 to 15 micrometers. Particularly, in the wavelength range from 7 to 12 micrometers, transmittance of the substrate having thefine surface roughness 2 is higher than that of the substrate without fine surface roughness by 7% or more. From the above, the pitch of fine surface roughness for increasing transmittance, that is, reducing reflectance should be from one fifth (⅕) to one half (½) of the wavelength of light transmittance of which is to be increased. -
FIG. 10 shows an example of a relationship between wavelength of light transmittance of which is to be increased and pitch of fine surface roughness for increasing the transmittance. The horizontal axis inFIG. 10 represents wavelength of light transmittance of which is to be increased while the vertical axis inFIG. 10 represents pitch of fine surface roughness for increasing the transmittance. - Fine surface roughness having a pitch which is larger than that of the
fine surface roughness 2 was manufactured. The fine surface roughness will be hereinafter referred to asfine surface roughness 3. - Table 3 shows the etching conditions for the
fine surface roughness 3. -
TABLE 3 Operation Mixture ratio of Cooling pressure SF6 and O2 Power Time temperature 1 Pa 50 mL/min:40 mL/min 300 W 120 minutes 3° C. - The pitch of the
fine surface roughness 3 is 18.0 micrometers while the depth of thefine surface roughness 3 is 6.0 micrometers. The ratio of pitch to depth of thefine surface roughness 3 is 3.0 - In the etching conditions shown in Table 3, the amount of feed of oxygen is smaller than that of sulfur hexafluoride. As a result, distances between oxides which are deposited on the substrate surface and function as an etching mask become greater. Accordingly, the ratio of pitch to depth of the
fine surface roughness 3 becomes greater than those of thefine surface roughness 1 and thefine surface roughness 2. As described above, by changing the ratio of the amount of feed of sulfur hexafluoride and the amount of feed of oxygen, the ratio of pitch to depth of the fine surface roughness can be changed. -
FIG. 11 shows a photo of thesubstrate 1 without a fine surface roughness, thesubstrate 2 with a fine surface roughness for visible light, and the substrate with thefine surface roughness 3. The pitch of the fine surface roughness of thesubstrate 2 is 0.2 micrometers. Reflection on the surface of thesubstrate 2 is reduced by the fine surface roughness, and therefore thesubstrate 2 looks darker than thesubstrate 1. The pitch of thefine surface roughness 3 is much greater than wavelengths of the visible light. On the other hand, values of distance in the direction parallel to the substrate surface between adjacent convex portions or between adjacent concave portions are not constant and are distributed in a predetermined range. Accordingly, thefine surface roughness 3 of thesubstrate 3 causes diffracted lights of various orders of diffraction and of various wavelengths, and thus thesubstrate 3 looks more whitish than thesubstrate 1. This means that thesubstrate 3 with thefine surface roughness 3 causes diffusion of the visible light. - Thus, the
substrate 3 with thefine surface roughness 3 functions as a diffuser plate. Thus, a mold for a diffusing structure is obtained. -
FIG. 12 shows a scanning electron microscope photo of thefine surface roughness 3. - A method for manufacturing a mold for anti-reflective structure according to the present invention will be described using another example. A silicon wafer is used as the substrate.
- Table 4 shows characteristics of the silicon wafer used in the example.
-
TABLE 4 Type of electric conductivity N or P Dopant Phosphorus or Boron Crystallographic axis (100) ± 1.0° Resistivity 1.0-10.0 Ω · cm - Table 5 shows etching conditions in the example.
-
TABLE 5 High frequency Gas Feed of Feed of power Cooling Reaction pressure SF6 oxygen (RF power) temperature time 2 Pa 50 ml/ min 50 ml/min 200 W 5° C. 20 minutes - The frequency of the high frequency power is 13.56 MHz and the voltage is 200 V.
- The pitch of the fine structure of the mold for anti-reflective structure manufactured by the above-described manufacturing conditions is approximately 0.2 micrometers while the depth thereof is approximately 0.3 micrometers. The aspect ratio is approximately 1.5.
-
FIG. 13 is a flowchart for determining etching conditions of the method for manufacturing a mold for anti-reflective structure according to the present invention. - In step S3010 in
FIG. 13 , initial values of the etching conditions are selected. More specifically, for example, the values shown in Table 5 are selected. - In step S3020 in
FIG. 13 , etching is carried out on the substrate under the selected etching conditions using the reactive ion etching apparatus. - In step S3030 in
FIG. 13 , a reflectance of the manufactured mold is evaluated. - In step S3040 in
FIG. 13 , a shape of the manufactured mold is evaluated. The shape is evaluated using a scanning electron microscope, for example. - In step S3050 in
FIG. 13 , it is determined whether or not the manufactured mold is appropriate for a mold for anti-reflective structure. If the manufactured mold is appropriate, the process is terminated. If the manufactured mold is not appropriate, the process goes to step S3060. - In step S3060 in
FIG. 13 , the etching conditions are adjusted. How to adjust the etching conditions will be described below. - The aspect ratio of the fine structure should be 0.8 or more. In order to change the aspect ratio, a ratio of partial pressures of the gasses, the cooling temperature of the substrate, and etching time are mainly adjusted. When the partial pressure of SF6 gas in the mixed gas is raised, the etching rate becomes higher. When the cooling temperature of the substrate is lowered, the reaction for generating silicon oxide (SiO) is promoted, and therefore formation of coated portions for preventing etching (the mask) is promoted. Accordingly, when the etching time (reaction time) is increased under the above-described conditions, the aspect ratio becomes greater.
- The pitch of the fine structure should be 0.35 micrometers or less such that the pitch is smaller than wavelengths of the visible light. In order to change the pitch of the fine structure, a ratio between partial pressures of the gasses and the cooling temperature of the substrate are adjusted. When the ratio of partial pressure of oxygen is raised and the cooling temperature of the substrate is lowered, the pitch of the fine structure becomes smaller.
- Functions of various parameters can be summarized as below.
- When the ratio of partial pressure of sulfur hexafluoride (SF6) in the mixed gas is raised, the etching rate becomes higher.
- When the cooling temperature of the substrate is lowered, the reaction for generating silicon oxide (SiO) is promoted, and therefore formation of coated portions for preventing etching (the mask) is promoted.
- When reaction time is increased, etching is promoted.
- When the gas pressure of the mixed gas is raised, the etching rate becomes higher.
- When the power of the high frequency power supply is raised, the etching rate becomes higher.
- However, when the ratio of partial pressure of sulfur hexafluoride (SF6) in the mixed gas is too high, silicon oxide (SiO) is not generated, and therefore coated portions for preventing etching (the mask) are not formed. Accordingly, the grating like structure is not formed. Further, when the ratio of partial pressure of oxygen in the mixed gas is too high, or the cooling temperature of the substrate is too low, coated portions for preventing etching (the mask) are excessively generated, and therefore etching is not carried out. Accordingly, the grating like structure is not formed.
- Accordingly, the above-described various parameters should be adjusted in predetermined ranges.
- Table 6 shows the ranges of adjustment of the various parameters in the above-described case (in which the material of the substrate is silicon and the mixed gas includes sulfur hexafluoride (SF6) and oxygen).
-
TABLE 6 High frequency Gas Ratio of oxygen power Cooling Reaction pressure in mixed gas (RF power) temperature time 1-5 Pa 30-70% 50-5000 W 30° C. or less 5-300 minutes - Table 7 shows the ranges of adjustment of the various parameters in the case in which the material of the substrate is one of titanium, tungsten, tantalum, a titanium alloy which is made by adding other elements to titanium, and a tungsten alloy which is made by adding other elements to tungsten silicon and the mixed gas includes sulfur hexafluoride (SF6) and oxygen.
-
TABLE 7 High frequency Gas Ratio of oxygen power Cooling Reaction pressure in mixed gas (RF power) temperature time 1-5 Pa 30-70% 50-5000 W 30° C. or less 5-600 minutes - An advantage of the case in which silicon is used as the material of the substrate is that machining is easier, while an advantage of the case in which a metal is used as the material of the substrate is that the mold is superior in durability.
- In the above-described embodiment, the mixed gas of sulfur hexafluoride and oxygen is used. In place of sulfur hexafluoride, other fluorine-containing gases (carbon tetrafluoride, trifluoromethane and the like) can also be used.
-
FIGS. 14A and 14B illustrate how a mold for anti-reflective structure is formed on a flat surface. -
FIG. 14A shows a cross section of thesubstrate 1101 to which etching has not been carried out. -
FIG. 14B shows a cross section of thesubstrate 1101 which is provided with a shape of anti-reflective structure on a surface. The shape of anti-reflective structure has been formed through etching which has been carried out using the reactive ion etching apparatus. -
FIGS. 15A , 15B and 15C illustrate how a mold for anti-reflective structure is formed on a curved surface. -
FIG. 15A shows a cross section of amold core 1110 which is provided with a curved surface. The curved surface is formed by cutting, for example. -
FIG. 15B shows a cross section of amold core 1110 which is provided with athin film 111 of base material formed on a surface of the core. Thethin film 111 of base material is formed by sputtering, vapor deposition or the like. -
FIG. 15C shows a cross section of a mold core which is obtained by forming a shape of anti-reflective structure on a surface of thethin film 1111 of the substrate of what is shown inFIG. 15B . The shape of anti-reflective structure has been formed through etching which has been carried out using the reactive ion etching apparatus. According to the method illustrated byFIGS. 15A , 15B and 15C, a mold for anti-reflective structure can be manufactured on any curved surfaces. -
FIG. 16 is a flowchart for illustrating a method for manufacturing a mold for a diffraction grating provided with an anti-reflective fine structure. -
FIGS. 17A , 17B and 17C are diagrams for illustrating the method for manufacturing a mold for a diffraction grating provided with an anti-reflective fine structure. - In step S4010 in
FIG. 16 , a shape of anti-reflective structure is formed on a surface of asubstrate 1121 through etching which is carried out using the reactive ion etching apparatus. -
FIG. 17A shows a cross section of thesubstrate 1121 which has undergone etching. - In step S4020 in
FIG. 16 , on the surface of thesubstrate 1121, on which the shape of anti-reflective structure has been formed through etching which has been carried out using the reactive ion etching apparatus, a patterning of etching mask for a diffraction grating is carried out. -
FIG. 17B shows a cross section of thesubstrate 1121, on a surface of which the patterning of anetching mask 1125 for the diffraction grating has been carried out. The patterning of theetching mask 1125 will be described later. - In step S4030 in
FIG. 16 , thesubstrate 1121, on a surface of which the patterning of theetching mask 1125 for the diffraction grating has been carried out is further made to undergo etching using the reactive ion etching apparatus. - In step S4040 in
FIG. 16 , theetching mask 1125 is removed. The removal of theetching mask 1125 will be described later. -
FIG. 17C shows a cross section of a mold for a diffraction grating provided with an anti-reflective fine structure. The mold is manufactured by the method illustrated in the flowchart ofFIG. 16 . -
FIGS. 18A , 18B and 18C are diagrams for illustrating patterning of an etching mask. -
FIG. 18A shows a cross section of asubstrate 1121, on a surface of which patterning of a resist 1123 for a diffraction grating has been carried out. -
FIG. 18B shows a cross section of thesubstrate 1121, on a surface of which patterning of the resist 1123 for the diffraction grating has been carried out and then ametal 1125 which is resistant to reaction with fluorine-containing gases, such as chromium and nickel has been deposited. -
FIG. 18C shows a cross section of the substrate 121, on a surface of which patterning of the resist 1123 for the diffraction grating has been carried out, themetal 1125 which is resistant to reaction with fluorine-containing gases, such as chromium and nickel has been deposited and then the resist 1123 has been removed. Themetal 1125 such as chromium and nickel, shown inFIG. 18C functions as the etching mask. - The resist 1123 shown in
FIG. 18A can also be used as the etching mask. However, etch selectivity (a difference in etching rate) of the substrate against the resist is smaller than etch selectivity of the substrate against a metal such as chromium and nickel, and therefore depth of etching is smaller. -
FIG. 19 shows a scanning electron microscope photo of a mold for anti-reflective structure manufactured by a method according to the present invention. The pitch of the fine structure of the anti-reflective structure is approximately 0.2 micrometers. -
FIG. 20 shows a scanning electron microscope photo of a mold for a diffraction grating provided with an anti-reflective fine structure. The pitch of the diffraction grating is approximately 2 micrometers while the pitch of the fine structure of the anti-reflective structure is approximately 0.2 micrometers. -
FIG. 21 shows relationships between reflectance and wavelength of a surface provided with an anti-reflective structure manufactured by the method according to the present invention, a surface provided with an anti-reflective structure manufactured by a method according to a prior art (a method using an electron beam lithography system) and a surface without an anti-reflective structure. The horizontal axis ofFIG. 21 represents wavelength while the vertical axis ofFIG. 21 represents reflectance. Reflectance of the surface provided with the anti-reflective structure manufactured by the method according to the present invention is smaller over the whole range of wavelength than the reflectance of the surface provided with the anti-reflective structure manufactured by the method according to a prior art. This demonstrates that an anti-reflective structure having higher performance can be manufactured according to the present invention. - By the method for manufacturing a mold for an anti-reflective structure according to the present invention, an anti-reflective structure having higher performance can be manufactured without the use of patterning. According to the present method, a mold for an anti-reflective structure of a large area can be manufactured without any other constrains than the area of the reactive etching apparatus. Further, according to the present method, a mold for an anti-reflective structure for molding an anti-reflective fine structure on any curved surface and a mold for an anti-reflective structure for molding a diffraction grating provided with an anti-reflective fine structure can be manufactured.
- According to the present invention, a mold for an anti-reflective structure used for visible light and infrared rays, an optical element provided with an anti-reflective structure, and a mold for diffusing structure can be obtained without the necessity of patterning.
Claims (5)
1. A method for manufacturing a mold or an optical element provided with a fine surface roughness, wherein the fine surface roughness has been manufactured using a reactive etching apparatus, in which a substrate or a film made of a semiconductor or a metal which reacts with sulfur hexafluoride is placed, and into which a mixed gas of sulfur hexafluoride and oxygen is introduced and tuned into plasma such that oxides are made to be scattered on a surface of the substrate or the film, the surface of the substrate or the film is made to undergo etching by the sulfur hexafluoride while the oxides function as an etching mask, and thus the fine surface roughness is formed on the surface of the substrate or the film.
2. A mold manufactured by the method according to claim 1 .
3. A mold according to claim 2 , wherein the fine surface roughness on the mold is used to form an anti-reflective structure.
4. A mold according to claim 2 , wherein the fine surface roughness on the mold is used to form a diffusing structure.
5. An optical element manufactured by the method according to claim 1 .
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US14/663,746 US20150192702A1 (en) | 2012-11-16 | 2015-03-20 | Mold, optical element and method for manufacturing the same |
US15/808,321 US10353119B2 (en) | 2012-11-16 | 2017-11-09 | Method for manufacturing mold or optical element |
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US201261727284P | 2012-11-16 | 2012-11-16 | |
PCT/JP2013/061889 WO2014076983A1 (en) | 2012-11-16 | 2013-04-23 | Method for manufacturing mold for antireflective structures, and method of use as mold for antireflective structures |
US201461968629P | 2014-03-21 | 2014-03-21 | |
US14/663,746 US20150192702A1 (en) | 2012-11-16 | 2015-03-20 | Mold, optical element and method for manufacturing the same |
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10363687B2 (en) | 2015-09-03 | 2019-07-30 | Nalux Co., Ltd. | Mold and method for manufacturing the same |
US11978642B2 (en) | 2019-06-11 | 2024-05-07 | Nalux Co., Ltd. | Method for producing plastic element provided with fine surface roughness |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3377681B1 (en) * | 2015-11-20 | 2020-12-30 | Ecole Polytechnique Federale de Lausanne (EPFL) | Fabrication method of functional micro/nano structures over large-area, flexible and high curvature surfaces, by drawing a fiber from a preform |
US10278785B2 (en) | 2015-12-18 | 2019-05-07 | Novartis Ag | Method of making diverging-light fiber optics illumination delivery system |
US11141942B2 (en) | 2016-02-10 | 2021-10-12 | Ecole polytechnique fédérale de Lausanne (EPFL) | Multi-material stretchable optical, electronic and optoelectronic fibers and ribbons composites via thermal drawing |
US11579523B2 (en) | 2019-02-08 | 2023-02-14 | Ecole Polytechnique Federale De Lausanne (Epfl) | Method and system for fabricating glass-based nanostructures on large-area planar substrates, fibers, and textiles |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20030178057A1 (en) * | 2001-10-24 | 2003-09-25 | Shuichi Fujii | Solar cell, manufacturing method thereof and electrode material |
WO2012173122A1 (en) * | 2011-06-15 | 2012-12-20 | 東京エレクトロン株式会社 | Plasma etching method |
WO2013089473A1 (en) * | 2011-12-16 | 2013-06-20 | 주성엔지니어링(주) | Method for manufacturing a solar cell |
Family Cites Families (18)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH09232482A (en) | 1996-02-23 | 1997-09-05 | Denso Corp | Surface processing of semiconductor and semiconductor device |
JP2002022911A (en) | 2000-07-05 | 2002-01-23 | Nikon Corp | Method for producing microprism array and mold material |
JP2005303255A (en) | 2004-03-17 | 2005-10-27 | Shinryo Corp | Low-reflectance processing method of silicon substrate for solar cells |
US8187481B1 (en) | 2005-05-05 | 2012-05-29 | Coho Holdings, Llc | Random texture anti-reflection optical surface treatment |
WO2006129514A1 (en) | 2005-06-03 | 2006-12-07 | Nalux Co., Ltd. | Fine mesh and mold therefor |
CN101479031B (en) * | 2006-06-30 | 2012-11-14 | 王子制纸株式会社 | Monoparticulate-film etching mask and process for producing the same, process for producing fine structure with the monoparticulate-film etching mask, and fine structure obtained by the production pro |
JP2008112036A (en) | 2006-10-31 | 2008-05-15 | Osaka Prefecture | Manufacturing method of microstructure |
JP4986137B2 (en) | 2006-12-13 | 2012-07-25 | 独立行政法人産業技術総合研究所 | Method for producing mold for optical element or nanostructure having nanostructure |
US8928121B2 (en) * | 2007-11-12 | 2015-01-06 | Nxp B.V. | Thermal stress reduction |
JP2009128543A (en) | 2007-11-21 | 2009-06-11 | Panasonic Corp | Method for manufacturing antireflection structure |
JP5010445B2 (en) | 2007-11-29 | 2012-08-29 | パナソニック株式会社 | Manufacturing method of mold for microlens array |
JP2010013337A (en) | 2007-12-05 | 2010-01-21 | Hitachi Maxell Ltd | Surface processing method, method of manufacturing mold for imprint, optical device, and imprint method |
WO2009125769A1 (en) | 2008-04-08 | 2009-10-15 | 株式会社ニコン | Optical element, process for producing the optical element, and optical device |
JP4596072B2 (en) | 2008-12-26 | 2010-12-08 | ソニー株式会社 | Manufacturing method of fine processed body and etching apparatus |
JP5893252B2 (en) * | 2011-02-15 | 2016-03-23 | キヤノン株式会社 | Manufacturing method of fine structure |
JP5423758B2 (en) | 2011-09-29 | 2014-02-19 | 王子ホールディングス株式会社 | Single particle film and microstructure |
JP5548997B2 (en) | 2012-03-23 | 2014-07-16 | 独立行政法人産業技術総合研究所 | Silicon carbide mold having fine periodic structure and manufacturing method thereof |
JP2014051710A (en) | 2012-09-07 | 2014-03-20 | Mitsubishi Rayon Co Ltd | Production method of anodic oxidation porous alumina, production method of mold, and compact with fine uneven structures on the surface |
-
2015
- 2015-03-20 US US14/663,746 patent/US20150192702A1/en not_active Abandoned
-
2017
- 2017-11-09 US US15/808,321 patent/US10353119B2/en active Active
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20030178057A1 (en) * | 2001-10-24 | 2003-09-25 | Shuichi Fujii | Solar cell, manufacturing method thereof and electrode material |
WO2012173122A1 (en) * | 2011-06-15 | 2012-12-20 | 東京エレクトロン株式会社 | Plasma etching method |
US20140113450A1 (en) * | 2011-06-15 | 2014-04-24 | Tokyo Electron Limited | Plasma etching method |
WO2013089473A1 (en) * | 2011-12-16 | 2013-06-20 | 주성엔지니어링(주) | Method for manufacturing a solar cell |
US20140302620A1 (en) * | 2011-12-16 | 2014-10-09 | Jusung Engineering Co., Ltd. | Method for manufacturing solar cell |
Non-Patent Citations (2)
Title |
---|
Infrared, Wikipedia The Free Encyclopedia via https://web.archive.org/web/20131013151148/https://en.wikipedia.org/wiki/Infrared ; pages 1-12; 2013 * |
Sunlight, "Wikipedia, the Free Encyclopedia via https://web.archive.org/web/20121224144748/http://en.wikipedia.org/wiki/Sunlight ; pages 1-9, 2012. * |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10363687B2 (en) | 2015-09-03 | 2019-07-30 | Nalux Co., Ltd. | Mold and method for manufacturing the same |
US11978642B2 (en) | 2019-06-11 | 2024-05-07 | Nalux Co., Ltd. | Method for producing plastic element provided with fine surface roughness |
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US20180088258A1 (en) | 2018-03-29 |
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