Treatment method for roughening surface of three-dimensional precise control area of diamond window sheet

Abstract

The invention discloses a treatment method for roughening the surface of a three-dimensional precise control area of a diamond window piece. The treatment method comprises the steps that S1, a single crystal diamond material is cut and polished into an optical-grade single crystal diamond window piece; s2, cleaning the optical-grade single crystal diamond window sheet; s3, protecting a non-metal area in the center of the optical-grade single crystal diamond window piece; s4, the three-dimensional precise control area of the outer ring of the optical-grade single crystal diamond window piece is covered with a thin film, photoresist in a non-metal area is removed, then the window piece plated with the metal thin film is placed in an atmosphere furnace to be subjected to high-temperature etching, finally, residual metal or metal oxide on the surface is removed, and roughening treatment on the three-dimensional precise control area is completed; and 5, carrying out metallization treatment on the three-dimensional precise control area of the outer ring to complete the coverage of a metal coating. According to the surface roughening method for the three-dimensional precise control area of the diamond window piece, the problem that wettability between a diamond material and a heterogeneous material is poor is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of vacuum electronic devices and relates to a method for processing the surface roughening of a three-dimensional precision-controlled area of ​​a diamond window. Background Art

[0002] The increasing output power of vacuum electronic devices has put forward higher requirements on the materials of microwave output windows. Sapphire, boron nitride and beryllium oxide are the most commonly used energy transmission window materials in vacuum electronic devices. However, with the continuous increase in the output power of vacuum electronic devices such as traveling wave tubes, the traditional microwave energy transmission window cannot meet the requirements of high power capacity and miniaturization at the same time. Therefore, new materials are urgently needed to upgrade and improve the traditional microwave energy transmission window. Diamond single crystal has many excellent properties such as extremely low dielectric transmission loss, extremely high thermal conductivity, highest hardness and elastic modulus, and has been proven to be a nearly perfect microwave window dielectric material. Diamond-based microwave output windows can achieve good matching of wide bandwidth range in microwave, millimeter wave and even terahertz frequency bands, quickly diffuse the heat absorbed when high-frequency microwave energy is output, and resist the high pressure difference on both sides of the window. Therefore, exploring wide-band, high-power and small-volume diamond energy transmission windows is an important direction in the field of vacuum electronic devices.

[0003] However, due to the special crystal structure of diamond materials, its welding process technology has the following problems: (1) The chemical inertness of diamond materials results in a high interface energy between the diamond material and the solder metal. Whether in air or in a vacuum atmosphere, the surface of diamond is almost not wetted by ordinary solder, and it is difficult to chemically react with other metals and non-metals, let alone interpenetration. Therefore, it is difficult to form a metallurgical bond during welding; (2) The welding temperature is limited. When it exceeds 1000 K, diamond will undergo graphitization; (3) The thermal expansion coefficient of diamond materials is very different from that of other metals. The mismatch in thermodynamic properties on both sides of the interface results in large thermal stress when the welding temperature cools down, which reduces the reliability of the seal and even causes cracks.

[0004] Therefore, the metallization of the diamond dielectric window surface is the basis for ensuring the airtightness of the energy transmission window assembly. At present, manual coating and magnetron sputtering technology are mainly used to metallize the side and surface edge of the diamond single crystal energy transmission window. However, as the research frequency band becomes higher and higher, the size of the corresponding window becomes smaller and smaller. When performing manual coating, the uniformity and consistency of the coating cannot be guaranteed at the micron level, resulting in an increase in uncontrollable factors.

[0005] The nano-scale roughness and high transmittance of the window energy transmission area are key parameters to ensure low transmission loss. However, it is not conducive to improving the bonding strength between diamond and the plated metal during the magnetron sputtering metallization process. The metallization layer may peel or fall off, resulting in poor airtightness after the entire window is sealed. Summary of the invention

[0006] The purpose of the present invention is to provide a method for roughening the surface of a three-dimensional precision-controlled area of ​​a diamond window, thereby improving the bonding force between single-crystal diamond and the plated metal, meeting the high airtightness requirements of the entire window sealing process, and solving the problem of poor wettability between diamond materials and heterogeneous materials.

[0007] The technical solution adopted by the present invention is a method for roughening the surface of a three-dimensional precision-controlled area of ​​a diamond window, and the specific steps are as follows: S1, cutting and polishing the single crystal diamond material into optical grade single crystal diamond window pieces; S2. Surface cleaning of optical grade single crystal diamond window; S3. Protect the non-metallic areas in the center of the upper and lower surfaces of the optical-grade single-crystal diamond window; S4, covering the outer three-dimensional precision control area of ​​the optical-grade single-crystal diamond window with a metal or metal oxide film, and removing the photoresist in the non-metallic area in the center of the window, then placing the window coated with the metal film in an atmosphere furnace for high-temperature etching, and finally placing it in dilute hydrochloric acid to remove the metal or metal oxide remaining on the surface, completing the roughening treatment of the outer three-dimensional precision control area; S5. Metallizing the outer ring three-dimensional precision control area after the roughening treatment of the diamond window to complete the coverage of the metal coating.

[0008] The present invention is also characterized in that: The single crystal diamond material in S1 adopts optical grade single crystal material, specifically HPHT single crystal diamond, CVD single crystal diamond or natural diamond.

[0009] The diameter of the optical grade single crystal diamond window in S1 is 1-15mm, the thickness is 0.1-0.6mm, the surface roughness Ra is less than 1nm, the total thickness deviation TTV is less than 5um, and the thermal conductivity is greater than 2000W·m -1 ·K -1 , infrared transmittance>70%; The non-metallic area of ​​the optical-grade single-crystal diamond window is 0.6-12mm, and the width of the outer ring three-dimensional precision-controlled area is 0.4-3mm.

[0010] The specific method of S2 is: The optical grade single crystal diamond window is placed in a mixed acid solution and boiled for 0.5-2 hours, wherein the mixed acid solution is prepared by concentrated sulfuric acid and concentrated nitric acid in a ratio of 5-10:1, and then ultrasonically cleaned. The cleaning solution is acetone, isopropanol, anhydrous ethanol or deionized water.

[0011] The specific method of S3 is: use a photolithography mask or a stamping mask to prepare a photoresist layer with a diameter of 0.6-12mm in the central area of ​​the window, and the thickness of the photoresist layer is 100-500μm, ensuring that the center point of the photoresist coincides with the center point of the single crystal diamond wafer, and ensuring that there is no photoresist layer in the three-dimensional precision control area around the outer ring of the window.

[0012] The specific method of S4 is: The three-dimensional precision-controlled area is covered with metal or metal oxide film by magnetron sputtering, electroplating or deposition. The metal or metal oxide film is made of Fe, Ni, Co, Fe2O3, MnO2 or NiO. The process parameters are: background vacuum degree 6-9ⅹ10 -4 Pa, working pressure 1.5-2.0Pa, RF power 250-400W, sample distance to target 8-10mm, sputtering time 2-5min, film thickness of coating is 50-500nm; After coating, the sample is placed in a degumming solution or acetone to remove the photoresist in the center area of ​​the single crystal diamond wafer, and the metal or metal oxide film on its surface is removed. The window plate coated with the metal or metal oxide film is then placed in a vacuum furnace, and 50-100sccm of hydrogen is introduced. The temperature is increased at a rate of 3-8℃ / min until the temperature reaches 600-900℃, and the insulation time is 10-60min. Finally, the single crystal diamond window is placed in dilute hydrochloric acid and heated to 80℃ to remove the residual metal or metal oxide on the surface. Then, ultrasonic cleaning is performed in acetone or deionized water for 15min respectively to complete the roughening treatment of the three-dimensional precision control area of ​​the outer ring of the optical grade single crystal diamond window.

[0013] The surface roughness Ra of the outer three-dimensional precision-controlled area of ​​the optical-grade single-crystal diamond window in S4 is 0.1-0.8um after roughening treatment.

[0014] In S5, magnetron sputtering, electroplating or ion implantation is used to cover the outer ring three-dimensional precision control area with a metal coating, and the metallization coating is covered in batches and multiple times, and the coating metal includes more than three of Ti, Cu, Ni, Wu, Mo, Cr, Fe, Si or Pt; Process parameters: chamber vacuum degree 1-5ⅹ10 -3 Pa, working pressure is 0.5-3Pa, RF power is 800-1200W, the sample rotates around the target, 5-10cm away from the target, the metallized coating thickness is 2-10um, and the coating time is 10-60min.

[0015] The beneficial effects of the present invention are: (1) The optical-grade single-crystal diamond used in the method for roughening the surface of the three-dimensional precisely controlled area of ​​the diamond window of the present invention has the advantages of low dielectric constant, high optical transmittance and high thermal conductivity, and is a key medium for vacuum electronic devices to achieve high frequency, high power and light weight. At the same time, the energy transmission area has an ultra-smooth surface, high total thickness consistency, and has the characteristics of low transmission loss; (2) The method for roughening the surface of the three-dimensional precision control area of ​​the diamond window of the present invention is to roughen the surface of the three-dimensional precision control area of ​​the outer ring of the single-crystal diamond window before metallizing it, thereby reducing the interface energy between the single-crystal diamond and the heterogeneous material, enhancing the bonding strength between the metal coating and the diamond window, and ensuring the vacuum degree of the entire energy transmission window after welding; at the same time, the nano-scale roughness and high transmittance characteristics of the energy transmission area in the center of the diamond window are controlled, thereby ensuring the low transmission loss of the energy transmission window. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the surface roughening treatment of the three-dimensional precision-controlled area of ​​the outer ring of the optical-grade diamond single crystal window of the present invention; Figure 2 This is a structural diagram of the metallized coating of the outer ring three-dimensional precision control area without roughening treatment in Example 1 of the present invention; Figure 3 This is a structural diagram of the metallized coating after roughening treatment in the outer ring three-dimensional precision control area of ​​Example 1 of the present invention. DETAILED DESCRIPTION

[0017] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] The method for roughening the surface of a three-dimensional precision-controlled area of ​​a diamond window of the present invention comprises the following specific steps: S1. Cut and polish the single crystal diamond material into optical grade single crystal diamond window pieces, the size of which is determined according to the transmission band of different application ends; among them, the single crystal diamond material adopts optical grade single crystal material, specifically HPHT single crystal diamond, CVD single crystal diamond or natural diamond, which has the advantages of low dielectric constant, high optical transmittance and high thermal conductivity, and is the key medium for vacuum electronic devices to achieve high frequency, high power and lightweight.

[0019] The polished optical grade single crystal diamond window has a diameter of 1-15mm, a thickness of 0.1-0.6mm, a surface roughness Ra<1nm, a total thickness deviation TTV<5um, and a thermal conductivity>2000W·m -1 ·K -1 , infrared transmittance>70%; the non-metallic area of ​​the optical-grade single-crystal diamond window is 0.6-12mm, and the width of the outer ring three-dimensional precision-controlled area is 0.4-3mm.

[0020] S2. Clean the surface of the optical grade single crystal diamond window. The specific method is as follows: The optical grade single crystal diamond window is placed in a mixed acid solution and boiled for 0.5-2 hours, wherein the mixed acid solution is prepared from concentrated sulfuric acid and concentrated nitric acid, and the ratio of concentrated sulfuric acid to concentrated nitric acid is 5-10:1, followed by ultrasonic cleaning, and the cleaning solution is acetone, isopropanol, anhydrous ethanol or deionized water; S3. Protect the non-metallic areas in the center of the upper and lower surfaces of the optical-grade single-crystal diamond window. The specific method is: use a photolithography mask or a stamping mask to prepare a photoresist layer with a diameter of 0.6-12 mm in the center area of ​​the window. The thickness of the photoresist layer is 100-500 μm, ensuring that the center point of the photoresist coincides with the center point of the single-crystal diamond disc, and ensuring that there is no photoresist layer in the three-dimensional precision-controlled area around the outer ring of the single-crystal diamond window; S4. Cover the outer three-dimensional precision control area (metallized area) of the optical grade single crystal diamond window with a metal or metal oxide film, and remove the photoresist in the non-metallic area in the center of the single crystal diamond window. Then place the window coated with the metal film in an atmosphere furnace for high-temperature etching. Finally, place it in dilute hydrochloric acid to remove the metal or metal oxide remaining on the surface, and complete the roughening treatment of the outer three-dimensional precision control area. The surface roughness Ra of the outer three-dimensional precision control area of ​​the optical grade single crystal diamond window after roughening treatment is 0.1-0.8um. Figure 1 As shown, the specific method is: The window with a uniform glue layer left in the central non-metallic area is covered with one or more layers of metal or metal oxide film by magnetron sputtering, electroplating or deposition. The metal or metal oxide film is made of Fe, Ni, Co, Fe2O3, MnO2 or NiO, etc. The specific process parameters are: the background vacuum degree is 6-9ⅹ10 -4 Pa, working pressure is 1.5-2.0Pa, RF power is 250-400W, sample distance to target is 8-10mm, sputtering time is 2-5min, and film thickness is 50-500nm; After the coating is completed, the sample is placed in a degumming solution or acetone solution to remove the photoresist in the center area of ​​the single crystal diamond disc, and the metal or metal oxide film on its surface is removed. Then the window plate coated with the metal or metal oxide film is placed in a vacuum furnace, 50-100sccm of hydrogen is introduced, and the temperature is increased at a rate of 3-8℃ / min until the temperature reaches 600-900℃, and the insulation time is 10-60min. Finally, the above single crystal diamond window is placed in dilute hydrochloric acid and heated to 80℃ to remove the metal or metal oxide remaining on the surface, and then ultrasonically cleaned in acetone and deionized water for 15min respectively, thereby achieving the roughening of the outer ring three-dimensional precision control area of ​​the optical grade single crystal diamond window.

[0021] S5. Perform metallization on the three-dimensional precision-controlled area of ​​the diamond window after roughening to complete the coverage of the metal coating.

[0022] Specifically, magnetron sputtering, electroplating or ion implantation is used to cover the roughened window outer ring three-dimensional precision control area with metal plating. The thickness of the metallized coating is 2-10um. The metallized coating is a multi-layer composite structure, which is covered in batches and multiple times. The coating metal includes more than three of Ti, Cu, Ni, Wu, Mo, Cr, Fe, Si or Pt. The specific process is: the cavity vacuum degree is 1-5ⅹ10 -3 Pa, working pressure 0.5-3Pa, RF power 800-1200W, sample rotates around the target, 5-10cm away from the target, coating thickness 2-10um, coating time 10-60min.

[0023] The present invention performs roughening treatment in specific areas to enhance the bonding force between the metal coating and the diamond sheet. At the same time, the central area is guaranteed to still have mirror features. Secondly, the selected material is diamond single crystal, which is relatively excellent in material properties and processing quality.

[0024] Example 1 The method for roughening the surface of a three-dimensional precision-controlled area of ​​a diamond window of the present invention comprises the following specific steps: S1. Cut and polish the HPHT single crystal diamond into discs with a diameter of 3 mm and a thickness of 0.2 mm, ensuring that its surface roughness Ra is less than 1 nm, the total thickness deviation TTV is less than 3 um, and the thermal conductivity is greater than 2000 W·m -1 ·K -1 , infrared transmittance>70%.

[0025] S2, boiling the optical grade single crystal diamond window in a mixed acid solution for 0.5 h, wherein the mixed acid solution is prepared by concentrated sulfuric acid and concentrated nitric acid in a ratio of 5:1, and then ultrasonically cleaning it in an acetone solution; S3. Prepare a photoresist layer with a diameter of 0.6 mm in the central area of ​​the window by using a photolithography mask. The thickness of the photoresist layer is 200 μm, ensuring that there is no photoresist layer in the outer three-dimensional precision control area around the single crystal diamond window; S4. Magnetron sputtering is used to cover two layers of Fe metal film on the window with a uniform glue layer in the central non-metallic area. The process parameters are: the background vacuum degree is 6×10 -4 Pa, working pressure is 1.8Pa, RF power is 300W, sample distance to target is 8mm, sputtering time is 2min, and the film thickness of the coating is 300nm; After the coating is completed, the sample is placed in a degumming solution to remove the photoresist in the center area of ​​the single crystal diamond disc, and the Fe metal film on its surface is removed. Then the window is placed in a vacuum furnace, 50sccm hydrogen is introduced, and the temperature is increased at a rate of 8℃ / min until the temperature reaches 900℃, and the holding time is 10min. Finally, the above single crystal diamond window is placed in dilute hydrochloric acid and heated to 80℃ to remove the residual metal on the surface, and then ultrasonically cleaned in acetone and deionized water for 15min respectively, completing the roughening of the outer ring three-dimensional precision control area of ​​the optical grade single crystal diamond window.

[0026] Metallized coatings without roughening treatment such as Figure 2 As shown, the roughened metallized coating is Figure 3 shown.

[0027] S5. Use magnetron sputtering to cover the roughened window outer ring three-dimensional precision control area with metal coating, specifically, Ti is first covered on diamond, then Ni is covered on Ti, and then Mo is covered on Ni. The process parameters are: chamber vacuum degree 1x10 -3 Pa, working pressure 2Pa, RF power 800W, sample rotates around the target, 8cm away from the target, coating thickness 2um, coating time 30min.

[0028] Example 2 S1. Cut and polish the CVD single crystal diamond into a disc with a diameter of 15 mm and a thickness of 0.6 mm, ensuring that its surface roughness Ra is less than 1 nm, the total thickness deviation TTV is less than 3 um, and the thermal conductivity is greater than 2000 W·m -1 ·K -1 , infrared transmittance>70%.

[0029] S2, boiling the optical grade single crystal diamond window in a mixed acid solution for 2 hours, wherein the mixed acid solution is prepared by concentrated sulfuric acid and concentrated nitric acid in a ratio of 10:1, and then ultrasonically cleaning it in an isopropanol solution; S3. Prepare a photoresist layer with a diameter of 12 mm in the central area of ​​the window by using a stamping mask. The thickness of the photoresist layer is 500 μm, ensuring that there is no photoresist layer in the outer three-dimensional precision control area around the single crystal diamond window; S4. Two layers of Ni metal film are coated on the window with a uniform glue layer in the central non-metallic area by electroplating. The process parameters are: the background vacuum degree is 9ⅹ10 -4 Pa, working pressure is 2.0Pa, RF power is 400W, sample distance to target is 10mm, sputtering time is 5min, and film thickness is 500nm; After the coating is completed, the sample is placed in an acetone solution to remove the photoresist in the center area of ​​the single crystal diamond disc, and the Ni metal film on its surface is removed. Then the window is placed in a vacuum furnace, 100 sccm of hydrogen is introduced, and the temperature is increased at a rate of 3°C / min until the temperature reaches 600°C, and the holding time is 60 minutes. Finally, the above single crystal diamond window is placed in dilute hydrochloric acid and heated to 80°C to remove the residual metal on the surface, and then ultrasonically cleaned in acetone and deionized water for 15 minutes respectively, completing the roughening treatment of the outer ring three-dimensional precision control area of ​​the optical grade single crystal diamond window.

[0030] S5. The roughened window outer ring three-dimensional precision control area is covered with metal plating by electroplating. Specifically, Ti is first covered on diamond, then Cu is covered on Ti, and then Wu is covered on Cu. The process parameters are: chamber vacuum degree 5x10 -3 Pa, working pressure 3Pa, RF power 1200W, sample rotates around the target, 10cm away from the target, coating thickness 10um, coating time 60min.

[0031] Example 3 S1. Cut and polish natural diamonds into discs with a diameter of 0.1 mm and a thickness of 1 mm, so that their surface roughness Ra is less than 1 nm, the total thickness deviation TTV is less than 3 um, and the thermal conductivity is greater than 2000 W·m -1 ·K -1 , infrared transmittance>70%.

[0032] S2, boiling the optical grade single crystal diamond window in a mixed acid solution for 1 hour, wherein the mixed acid solution is prepared by concentrated sulfuric acid and concentrated nitric acid in a ratio of 8:1, and then ultrasonically cleaning it in an anhydrous ethanol solution; S3. Prepare a photoresist layer with a diameter of 1 mm in the central area of ​​the window by using a stamping mask. The thickness of the photoresist layer is 100 μm, ensuring that there is no photoresist layer in the outer three-dimensional precision control area around the single crystal diamond window; S4. Two layers of Fe2O3 metal oxide film are deposited on the window with a uniform glue layer in the central non-metallic area. The process parameters are: the background vacuum is 7x10 -4 Pa, working pressure is 1.5Pa, RF power is 250W, sample distance to target is 9mm, sputtering time is 4min, and film thickness of coating is 50nm; After the coating is completed, the sample is placed in an acetone solution to remove the photoresist in the center area of ​​the single crystal diamond disc, and the metal or metal oxide film on its surface is removed. Then the window is placed in a vacuum furnace, 80sccm of hydrogen is introduced, and the temperature is increased at a rate of 5℃ / min until the temperature reaches 700℃, and the insulation time is 30min. Finally, the above single crystal diamond window is placed in dilute hydrochloric acid and heated to 80℃ to remove the residual metal oxide on the surface, and then ultrasonically cleaned in acetone and deionized water for 15min respectively, completing the roughening treatment of the outer ring three-dimensional precision control area of ​​the optical grade single crystal diamond window.

[0033] S5. Use ion implantation to cover the roughened window outer ring three-dimensional precision control area with metal plating, specifically, first cover Cu on diamond, then cover Wu on Cu, then cover Cr on Wu, and finally cover Pt on Cr. Process parameters are: chamber vacuum degree 3x10 -3 Pa, working pressure 0.5Pa, RF power 1000W, sample rotates around the target, 5cm away from the target, coating thickness 5um, coating time 10min.

[0034] Example 4 S1. Cut and polish the HPHT single crystal diamond into discs with a diameter of 8 mm and a thickness of 0.3 mm, ensuring that its surface roughness Ra is less than 1 nm, the total thickness deviation TTV is less than 3 um, and the thermal conductivity is greater than 2000 W·m -1 ·K -1 , infrared transmittance>70%.

[0035] S2, boiling the optical grade single crystal diamond window in a mixed acid solution for 1.5 hours, wherein the mixed acid solution is prepared by concentrated sulfuric acid and concentrated nitric acid in a ratio of 7:1, and then ultrasonically cleaning it in deionized water; S3. Prepare a photoresist layer with a diameter of 5 mm in the central area of ​​the window by using a photolithography mask. The thickness of the photoresist layer is 300 μm, ensuring that there is no photoresist layer in the outer three-dimensional precision control area around the single crystal diamond window; S4. Two layers of MnO2 metal oxide film are coated on the window with a uniform glue layer in the central non-metallic area by electroplating. The process parameters are: the background vacuum degree is 8x10 -4 Pa, working pressure is 1.8Pa, RF power is 350W, sample distance to target is 8mm, sputtering time is 3min, and film thickness of coating is 300nm; After the coating is completed, the sample is placed in an acetone solution to remove the photoresist in the center area of ​​the single crystal diamond disc, and the metal oxide film on its surface is removed. Then the window is placed in a vacuum furnace, 50sccm of hydrogen is introduced, and the temperature is increased at a rate of 8℃ / min until the temperature reaches 800℃, and the holding time is 25min. Finally, the above single crystal diamond window is placed in dilute hydrochloric acid and heated to 80℃ to remove the residual metal or metal oxide on the surface, and then ultrasonically cleaned in acetone and deionized water for 15min respectively to complete the roughening of the outer ring three-dimensional precision control area of ​​the optical grade single crystal diamond window.

[0036] S5. Use ion implantation to cover the roughened window outer ring three-dimensional precision control area with metal plating, specifically, Ti is first covered on diamond, then Wu is covered on Ti, then Mo is covered on Wu, and finally Si is covered on Mo. The process parameters are: chamber vacuum degree 1x10 -3 Pa, working pressure 2Pa, RF power 800W, sample rotates around the target, 8cm away from the target, coating thickness 2um, coating time 30min.

[0037] Example 5 The method steps are the same as those in Example 1, and the difference from Example 1 is that: the single crystal diamond material selected in S1 is CVD single crystal diamond; in S3, a photoresist layer is prepared in the central area of ​​the window by using a stamping mask; The metal coating structure in S5 is: Wu is first covered on diamond, then Fe is covered on Wu, then Pt is covered on Fe, and finally Si is covered on Pt.

[0038] The remaining steps and parameters are the same as in Example 1.

[0039] Example 6 The method steps are the same as those in Example 2, except that the single crystal diamond material selected in S1 is natural diamond; a layer of NiO metal oxide film is covered on the window plate by magnetron sputtering in S4, and the remaining steps and parameters are the same as those in Example 2.

Claims

1. A method for roughening the surface of a three-dimensional precision-controlled area of ​​a diamond window, characterized in that: The specific steps are as follows: S1, cutting and polishing the single crystal diamond material into optical grade single crystal diamond window pieces; S2. Surface cleaning of optical grade single crystal diamond window; S3. Protect the non-metallic areas in the center of the upper and lower surfaces of the optical-grade single-crystal diamond window; S4, covering the outer three-dimensional precision control area of ​​the optical-grade single-crystal diamond window with a metal or metal oxide film, and removing the photoresist in the non-metallic area in the center of the window, then placing the window coated with the metal film in an atmosphere furnace for high-temperature etching, and finally placing it in dilute hydrochloric acid to remove the metal or metal oxide remaining on the surface, completing the roughening treatment of the outer three-dimensional precision control area; S5. Metallizing the outer ring three-dimensional precision control area after the roughening treatment of the diamond window to complete the coverage of the metal coating.

2. The method for roughening the surface of a three-dimensional precision-controlled area of ​​a diamond window according to claim 1, characterized in that: The single crystal diamond material in S1 is an optical grade single crystal material, specifically HPHT single crystal diamond, CVD single crystal diamond or natural diamond.

3. The method for roughening the surface of a three-dimensional precision-controlled area of ​​a diamond window according to claim 2, characterized in that: The optical grade single crystal diamond window in S1 has a diameter of 1-15 mm, a thickness of 0.1-0.6 mm, a surface roughness Ra < 1 nm, a total thickness deviation TTV < 5 um, and a thermal conductivity > 2000 W·m -1 ·K -1 , infrared transmittance>70%; The non-metallic area of ​​the optical-grade single-crystal diamond window is 0.6-12 mm, and the width of the outer ring three-dimensional precision-controlled area is 0.4-3 mm.

4. The method for roughening the surface of a three-dimensional precision-controlled area of ​​a diamond window according to claim 1, characterized in that: The specific method of S2 is: The optical grade single crystal diamond window is placed in a mixed acid solution and boiled for 0.5-2 hours, wherein the mixed acid solution is prepared by concentrated sulfuric acid and concentrated nitric acid in a ratio of 5-10:1, and then ultrasonically cleaned, and the cleaning solution is acetone, isopropanol, anhydrous ethanol or deionized water.

5. The method for roughening the surface of a three-dimensional precision-controlled area of ​​a diamond window according to claim 1, characterized in that: The specific method of S3 is: using a photolithography mask or a stamping mask to prepare a photoresist layer with a diameter of 0.6-12mm in the central area of ​​the window, the thickness of the photoresist layer is 100-500μm, ensuring that the center point of the photoresist coincides with the center point of the single crystal diamond disc, and ensuring that there is no photoresist layer in the three-dimensional precision control area around the outer ring of the window.

6. The method for roughening the surface of a three-dimensional precision-controlled area of ​​a diamond window according to claim 1, characterized in that: The specific method of S4 is: The three-dimensional precision-controlled area is covered with a metal or metal oxide film by magnetron sputtering, electroplating or deposition. The metal or metal oxide film is made of Fe, Ni, Co, Fe2O3, MnO2 or NiO. The process parameters are: background vacuum degree 6-9ⅹ10 -4 Pa, working pressure 1.5-2.0Pa, RF power 250-400W, sample distance to target 8-10mm, sputtering time 2-5min, film thickness of coating is 50-500nm; After coating, the sample is placed in a degumming solution or acetone to remove the photoresist in the center area of ​​the single crystal diamond wafer, and the metal or metal oxide film on its surface is removed. The window plate coated with the metal or metal oxide film is then placed in a vacuum furnace, and 50-100sccm of hydrogen is introduced. The temperature is increased at a rate of 3-8℃ / min until the temperature reaches 600-900℃, and the insulation time is 10-60min. Finally, the single crystal diamond window is placed in dilute hydrochloric acid and heated to 80℃ to remove the residual metal or metal oxide on the surface. Then, it is ultrasonically cleaned in acetone or deionized water for 15min respectively to complete the roughening treatment of the three-dimensional precision control area of ​​the outer ring of the optical grade single crystal diamond window.

7. The method for roughening the surface of a three-dimensional precision-controlled area of ​​a diamond window according to claim 1, characterized in that: The surface roughness Ra of the outer three-dimensional precision-controlled area of ​​the optical-grade single-crystal diamond window in S4 after roughening treatment is 0.1-0.8 um.

8. The method for roughening the surface of a three-dimensional precision-controlled area of ​​a diamond window according to claim 1, characterized in that: In S5, the outer ring three-dimensional precision control area is covered with a metal coating by magnetron sputtering, electroplating or ion implantation, and the metallized coating is covered in batches and multiple times, and the coating metal includes three or more of Ti, Cu, Ni, Wu, Mo, Cr, Fe, Si or Pt; Process parameters: chamber vacuum degree 1-5ⅹ10 -3 Pa, working pressure is 0.5-3Pa, RF power is 800-1200W, the sample rotates around the target, 5-10cm away from the target, the metallized coating thickness is 2-10um, and the coating time is 10-60min.

Images