Manufacturing method of multicolor transmission type grating

Abstract

The invention relates to the technical field of transmission-type gratings, in particular to a manufacturing method of a multicolor transmission-type grating, which comprises the following steps of: sequentially depositing narrow bands of light with specific colors in corresponding areas of the grating in a manner of multiple photoetching overlay and vacuum evaporation coating on the basis of a bright and dark stripe grating; and it is ensured that only the light with the specific color penetrates through the specific area, so that the multi-color transmission type grating is manufactured, and the grating strip width precision of the manufactured multi-color transmission type grating is high.

Description

Technical Field

[0001] The invention relates to the technical field of transmission type gratings, and in particular to a method for manufacturing a multi-color transmission type grating. Background Art

[0002] Grating is one of the important tools in modern optics. It is an optical element that shows periodic light transmission or reflection. Multicolor (color) grating has special properties different from black and white grating. Therefore, it is widely used in color measurement, optical microscopy, and laser detection. Multicolor grating is an optical element composed of multiple gratings of different wavelengths. It can split complex white light and display multiple different color stripes at the same time. The existing method of making multicolor gratings is mainly to make them by screen printing optical inks in different areas, but this method has the following problems: optical inks have poor stability and weak adhesion, and the partition is not obvious, resulting in alternating influences between different colors. Summary of the invention

[0003] The present invention provides a method for manufacturing a multi-color transmission grating. The manufacturing method sequentially deposits narrow bands of specific color light in corresponding areas of the grating by multiple photolithography overlays and vacuum evaporation coating on the basis of a light and dark stripe grating, thereby ensuring that only specific color light is transmitted in a specific area, thereby manufacturing a multi-color transmission grating. The grating strip width accuracy of the manufactured multi-color transmission grating is high.

[0004] In order to solve the above technical problems, the technical solution of the present invention is: A method for manufacturing a multi-color transmission grating comprises the following steps: S1. Take a clean and dry optical glass substrate and plate a metal light-shielding film layer on the surface of the optical glass substrate; S2, performing photolithography on the surface of the metal light-shielding film layer to form grating stripes with equal spacing of light and dark; S3. Photolithography is performed on the optical glass substrate with grating stripes to partition and a narrow band coating that can transmit light of a specific color is completed in the designated grating area. The wavelength range of the narrow band that can transmit light of a specific color after each photolithography and coating is completed is consistent. The specific steps of photolithography and coating are as follows: S3.1. Coat photoresist on the side of the optical glass substrate with grating stripes and dry; S3.2, remove the photoresist on the surface of the grating area where a narrow band of light of a specific color is to be plated by exposure and development, and cover the remaining areas with a photoresist mask and then dry; S3.3. A light-transmitting film layer of a corresponding color light is coated on the grating area where a narrow band of a specific color light is to be coated. The light-transmitting film layer satisfies a transmittance T>90% in the wavelength range of the specific color light, and the light in the rest areas is cut off; S3.4, stripping the remaining photoresist, cleaning and drying; S4. According to the method in step S3, the optical glass substrate with grating stripes is photolithographically overlaid and coated to complete a narrow band that can transmit another specific color of light, until all the narrow bands of pre-set color lights that can transmit light on the grating are photolithographically overlaid and coated, thus obtaining a multi-color transmissive grating.

[0005] In step S1 , the metal light-shielding film layer is a chromium film, which satisfies a transmittance T<0.1% in the wavelength range of 400-700 nm.

[0006] The photolithography process in step S2 includes: coating photoresist on the surface of the metal light-shielding film layer, and then sequentially performing mask exposure, development, wet etching, and stripping of the remaining photoresist.

[0007] The wet etching solution used in wet etching is a mixed solution prepared by mixing pure water, glacial acetic acid and ammonium cerium nitrate in a dosage ratio of 30 mL: (0.8-1.2) mL: (5-8) g.

[0008] The photoresist is SUN-115P UV positive photoresist.

[0009] The solution used for development is 2.2% -2.5% TMAH solution.

[0010] The degumming solution used in the degumming and stripping process is a KOH solution with a mass concentration of 10%-15%.

[0011] The drying process in step S3.2 is baking at 100° C. for 10-15 minutes.

[0012] The coating process in step S3.3 is to perform vacuum evaporation coating by a vacuum evaporation coating machine.

[0013] The width of the narrow band in step S3 and step S4 is consistent with the width of the alternating light and dark grating stripes in step S2.

[0014] Compared with the prior art, the present invention has the following beneficial effects: (1) Based on the light and dark stripe grating, the present invention deposits narrow bands of specific color light in the corresponding area of ​​the grating in sequence by multiple photolithography and vacuum evaporation coating, ensuring that only specific color light is transmitted in a specific area, thereby producing a multi-color transmission grating. The multi-color transmission grating can achieve different transmission effects in different segments and positions in the visible light band of 400nm-700nm (2) The different light transmission partitions of the multi-color transmissive grating produced by the present invention are partitioned by photolithography, avoiding the mutual influence problem in the partitioning process, and the accuracy of the grating strip width can reach ±0.5μm.

[0015] (3) The present invention manufactures grating stripes by depositing and etching chromium. The chromium metal is stable and not easily damaged, thus ensuring the stability of the grating shading area under various conditions for a long time.

[0016] (4) The multi-color transmissive grating produced by the present invention can be applied in the field of medical endoscopy. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of equidistant light and dark grating stripes obtained in step S2 of the present invention; Figure 2 It is a schematic diagram of the present invention after sequentially photolithography and overlaying a blue light-transmitting narrow band and a green light-transmitting narrow band on equidistant light and dark grating stripes. DETAILED DESCRIPTION

[0018] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0019] The method for manufacturing a multi-color transmission grating provided by the present invention comprises the following steps: S1. Take a clean and dry optical glass substrate and coat a metal light-shielding film layer on the surface of the optical glass substrate by a magnetron sputtering coating device; The present invention preferably selects a suitable corresponding optical glass substrate according to the optical performance and external dimensions required by the corresponding product and for specific optical performance requirements; Specifically, before the metal light-shielding film layer is plated, the optical glass substrate is cleaned and dried by ultrasonic wave; further, it is first cleaned by ultrasonic wave with a solvent and then rinsed with pure water, and the solvent used for ultrasonic cleaning is preferably a strong alkaline solution. After the cleaning is completed, the cleaned optical glass substrate is preferably evaporated by IPA to ensure that the optical glass substrate is clean and dry; Preferably, the metal light-shielding film layer is a chromium film, which satisfies a transmittance T of less than 0.1% in the wavelength range of 400-700nm. Preferably, the thickness of the chromium film is 120nm. Preferably, the conditions of magnetron sputtering include: the sputtering power of the Cr target is 5kW, and the Ar gas flow rate is 30sccm / s when sputtering the Cr film. After the metal light-shielding film layer is plated, ultrasonic cleaning is performed again.

[0020] S2, photolithography is performed on the surface of the metal light-shielding film layer to form grating stripes with equal spacing of light and dark, such as Figure 1 As shown; Specifically, the photolithography process includes: coating a photoresist on the surface of the metal light-shielding film layer, and then sequentially performing mask exposure, development, wet etching, and stripping of the remaining photoresist. Preferably, the photoresist is SUN-115P UV positive photoresist with a viscosity of 25CP. Preferably, the solution used for development is a 2.38% TMAH solution. Preferably, the wet etching solution used in wet etching is a mixed solution prepared by mixing pure water, glacial acetic acid and ammonium cerium nitrate in a dosage ratio of 30mL:1.1mL:6g. Preferably, the stripping solution used in the stripping treatment is a KOH solution with a mass concentration of 10%. The present invention preferably also includes cleaning the optical glass substrate after stripping, and the cleaning method is preferably sequentially soaking in concentrated sulfuric acid and ultrasonic cleaning.

[0021] S3. After the film performance is tested and qualified by the Olympus reflectivity tester, the optical glass substrate with grating stripes is partitioned by photolithography overlay and a narrow band coating that can transmit a specific color of light is completed in the designated grating area. The wavelength range of the narrow band that can transmit the specific color of light after each photolithography overlay and coating is consistent; specifically, the width of the narrow band is consistent with the width of the light and dark alternating grating stripes in step S2; the specific steps of photolithography overlay and coating are: S3.1. Coat photoresist on the side of the optical glass substrate with grating stripes and dry; Preferably, the photoresist is SUN-115P UV positive photoresist with a viscosity of 25CP; the thickness of the photoresist coating is preferably 1 μm; the coating process is preferably spin coating, and the spin coating speed is preferably 2500 rpm / min; S3.2, removing the photoresist on the surface of the grating area to be plated with a narrow band of light of a specific color by exposure and development, exposing the grating strip area to be plated with a narrow band of light of a specific color, and shielding the remaining area with a photoresist mask, and then drying; The exposure method is preferably UV exposure; the exposure machine light source band is 365nm, the exposure light intensity is preferably 12mW / cm2, and the exposure time is preferably 10s; preferably, the solution used for development is 2.38% TMAH solution, and the developer is soaked for 30s. Preferably, the drying process is baking at 100°C for 10 minutes; during the exposure process, the mask and the optical glass substrate with grating stripes have alignment marks, and the two are aligned before exposure; S3.3. A light-transmitting film layer of a corresponding color light is coated on the grating area where a narrow band of a specific color light is to be coated. The light-transmitting film layer satisfies a transmittance T>90% in the wavelength range of the specific color light, and the light in the rest areas is cut off; Preferably, the coating process is vacuum evaporation coating by a vacuum evaporation coating machine; S3.4, remove the remaining photoresist, clean and dry it, and only keep the light-transmitting film layer coated on the optical glass; Preferably, the degumming solution used in the degumming and stripping process is a KOH solution with a mass concentration of 10%.

[0022] S4. According to the method in step S3, photolithography is performed on the optical glass substrate with grating stripes to complete the narrow band coating that can transmit another specific color of light, until all the pre-set narrow bands of color light that can transmit light on the grating are photolithographically overlaid, thus obtaining a multi-color transmission grating.

[0023] In this embodiment, the multi-color transmission grating is preset with narrow bands that can transmit visible light (white light), blue light and green light respectively, wherein the equidistant light and dark grating stripes prepared in step S2 can transmit visible light. Figure 1 In step S3, a narrow band that can transmit blue light is overlaid on the basis of the grating that can transmit visible light. In step S4, a narrow band that can transmit green light is overlaid on the basis of the grating that can transmit visible light and blue light, so that a three-color transmission grating that can transmit visible light, blue light and green light is obtained. Figure 2 As shown. Specifically, the light-transmitting film layer coated on the narrow band that can transmit blue light satisfies the transmittance T>90% in the blue light wavelength range (450±12nm), and the light in other areas is cut off; the light-transmitting film layer coated on the narrow band that can transmit green light satisfies the transmittance T>90% in the green light wavelength range (550±12nm), and the light in other areas is cut off. If in actual production, a color-transmitting grating that can transmit visible light, blue light, green light and orange light is required, then on the basis of the grating that can transmit visible light, blue light and green light, the narrow band that can transmit orange light is over-engraved by photolithography. The grating strip width accuracy of the multi-color transmissive grating prepared by the above method in the present invention can reach ±0.5μm.

Claims

1. A method for manufacturing a multi-color transmission grating, characterized in that The following steps are involved: S1. Take a clean and dry optical glass substrate and plate a metal light-shielding film layer on the surface of the optical glass substrate; S2, performing photolithography on the surface of the metal light-shielding film layer to form grating stripes with equal spacing of light and dark; S3. Photolithography is performed on the optical glass substrate with grating stripes to partition and a narrow band coating that can transmit light of a specific color is completed in the designated grating area. The wavelength range of the narrow band that can transmit light of a specific color after each photolithography and coating is completed is consistent. The specific steps of photolithography and coating are as follows: S3.

1. Coat photoresist on the side of the optical glass substrate with grating stripes and dry; S3.2, remove the photoresist on the surface of the grating area where a narrow band of light of a specific color is to be plated by exposure and development, and cover the remaining areas with a photoresist mask and then dry; S3.

3. A light-transmitting film layer of a corresponding color light is coated on the grating area where a narrow band of a specific color light is to be coated. The light-transmitting film layer satisfies a transmittance T>90% in the wavelength range of the specific color light, and the light in the rest areas is cut off; S3.4, stripping the remaining photoresist, cleaning and drying; S4. According to the method in step S3, the optical glass substrate with grating stripes is photolithographically overlaid and coated to complete a narrow band that can transmit another specific color of light, until all the narrow bands of pre-set color lights that can transmit light on the grating are photolithographically overlaid and coated, thus obtaining a multi-color transmissive grating.

2. The method for manufacturing a multi-color transmission grating according to claim 1, characterized in that: In step S1 , the metal light-shielding film layer is a chromium film, which satisfies a transmittance T<0.1% in the wavelength range of 400-700 nm.

3. The method for manufacturing a multi-color transmission grating according to claim 1, characterized in that: The photolithography process in step S2 includes: coating photoresist on the surface of the metal light-shielding film layer, and then sequentially performing mask exposure, development, wet etching, and stripping of the remaining photoresist.

4. The method for manufacturing a multi-color transmission grating according to claim 3, characterized in that: The wet etching solution used in wet etching is a mixed solution prepared by mixing pure water, glacial acetic acid and ammonium cerium nitrate in a dosage ratio of 30 mL: (0.8-1.2) mL: (5-8) g.

5. The method for manufacturing a multi-color transmission grating according to claim 1 or 3, characterized in that: The photoresist is SUN-115P UV positive photoresist.

6. The method for manufacturing a multi-color transmission grating according to claim 1 or 3, characterized in that: The solution used for development is 2.2% -2.5% TMAH solution.

7. The method for manufacturing a multi-color transmission grating according to claim 1 or 3, characterized in that: The degumming solution used in the degumming and stripping process is a KOH solution with a mass concentration of 10%-15%.

8. The method for manufacturing a multi-color transmission grating according to claim 1, characterized in that: The drying process in step S3.2 is baking at 100° C. for 10-15 minutes.

9. The method for manufacturing a multi-color transmission grating according to claim 1, characterized in that: The coating process in step S3.3 is to perform vacuum evaporation coating by a vacuum evaporation coating machine.

10. The method for manufacturing a multi-color transmission grating according to claim 1, characterized in that: The width of the narrow band in step S3 and step S4 is consistent with the width of the alternating light and dark grating stripes in step S2.

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