Diamond window for microwave electric vacuum devices and method of manufacturing thereof

Abstract

The application discloses a method for preparing a diamond window for a microwave electron vacuum device, and has the characteristics that the method is implemented by the following steps: cleaning a diamond single crystal wafer; physically shielding a waveguide area of the diamond single crystal wafer; performing chemical vapor etching on a sealing area of the diamond single crystal wafer, and roughening and activating the diamond single crystal wafer; pre-preparing a bonding metal frame layer; assembling the bonding metal frame layer on both sides of the etching wafer sealing area and performing high-temperature bonding treatment; and finally performing packaging treatment. The diamond window comprises the bonding metal frame layer, the bonding metal frame layer is composed of a bonding contact layer, a skeleton support layer and a packaging bonding layer, the thickness ratio of the bonding contact layer to the skeleton support layer is 1:(2-4), and the thickness ratio of the bonding contact layer to the packaging bonding layer is 1:(5-10). The window obtained by the method can meet the use under the condition of a high-power microwave electron vacuum, and has excellent microwave performance, vacuum leakage rate and other technical index performances.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of vacuum electron devices, and relates to a diamond window for a microwave electric vacuum device. BACKGROUND

[0002] The microwave output window is an important component of all vacuum electron devices, and mainly plays a sealing and energy transmission role in high-power traveling wave tubes, gyrotrons, extended interaction tubes and other tube types, directly affecting the performance of the tube, and is also a hot and difficult point of research at home and abroad. The continuously increasing output power of vacuum electron devices puts higher requirements on the material of the microwave output window.

[0003] Single crystal diamond has extremely low dielectric transmission loss, extremely high thermal conductivity, the highest hardness and elastic modulus, and many other excellent properties, and has been proven to be a nearly perfect microwave output window medium material. The diamond microwave output window can achieve good matching in a wide frequency band range in the microwave, millimeter wave and even terahertz frequency bands, quickly diffuse the absorbed heat during high-frequency microwave energy output, and resist the high pressure difference on both sides of the window.

[0004] In recent years, the development of diamond film microwave output window research and application technology has been rapid, and international major high-power gyrotron manufacturers have used CVD diamond film microwave output windows. Domestic research institutions have also made great progress in the development of diamond windows. Although most companies and research institutions have test data that meet application requirements, the overall level is still in the laboratory stage. The application of diamond film in microwave vacuum devices has been developed to some extent at home and abroad, but there are few reports on the use of diamond single crystals in microwave vacuum devices. Due to the small size of the single crystal diamond, although the performance is better than that of polycrystal, the size of millimeter level directly limits its application range, and it cannot become a window material. In recent years, with the development of single crystal diamond preparation technology, whether it is high temperature and high pressure technology or CVD technology, it has the conditions for industrial production of centimeter-sized diamond single crystals. In addition, the forming and polishing ability of diamond single crystals has also been well developed in recent years, laying a solid foundation for the application of diamond single crystals in microwave electric vacuum devices. SUMMARY

[0005] The purpose of the present application is to provide a diamond window for a microwave electric vacuum device, which solves the problems of high dielectric transmission loss, low thermal conductivity, low hardness and elastic modulus of the energy transmission window in the prior art.

[0006] Another purpose of the present application is to provide a preparation method of the diamond window for a microwave electric vacuum device.

[0007] The technical scheme adopted by the present application is a diamond window preparation method for a microwave vacuum device, which is implemented according to the following steps:

[0008] Step 1: cleaning the diamond single crystal wafer;

[0009] Step 2: marking the center area of the diamond single crystal wafer as a waveguide area, the periphery of the waveguide area as a sealing area, physically shielding the waveguide area to obtain a shielding piece;

[0010] Step 3: chemically vapor etching the shielding piece in Step 2 to roughen and activate the sealing area, thereby obtaining an etched piece;

[0011] Step 4: pre-preparing a bonding metal frame layer:

[0012] Prepared metal foil, sequentially assembling the bonding contact layer, the skeleton support layer, and the encapsulation bonding layer, and denoted as the bonding metal frame layer;

[0013] Step 5: assembling the bonding metal frame layer in Step 4 on both sides of the etched piece sealing area, wherein the bonding contact layer is in contact with the sealing area, and then using a six-surface press to perform high-temperature bonding processing to obtain a diamond composite material X for the window;

[0014] Step 6: using a high-vacuum packaging device to package the diamond composite material X for the window in Step 5.

[0015] The present application is also characterized in that:

[0016] The cleaning in Step 1 specifically includes:

[0017] Chemical cleaning: ultrasonic cleaning with acetone for 15-20 min to remove organic matter attached to the surface of the diamond single crystal wafer, boiling cleaning with 10% NaOH solution for 20-30 min to remove grease substances in the surface defects of the diamond particles, and boiling cleaning with mixed acid for 20-30 min to remove metal impurities and graphite impurities;

[0018] Plasma cleaning: placing the diamond single crystal wafer in the vacuum cavity of a plasma cleaning machine, using argon to generate high-energy plasma by a radio frequency power source and a direct current power source to bombard the surface of the diamond single crystal wafer, cleaning both sides of the diamond single crystal wafer to achieve deep cleaning, and the specific parameters are a cleaning time of 60-120 min, an ion source voltage of 1500-2500 v, and a bias voltage of 300-500 v.

[0019] The physical shielding of the waveguide area of the diamond single crystal wafer in Step 2 is coating ultraviolet glue on the surface of a silicon dioxide or single crystal silicon sheet, fixing it to the center of the single crystal wafer using ultraviolet irradiation, and the thickness of the silicon dioxide or single crystal silicon sheet is not greater than 0.20 mm.

[0020] The chemical vapor etching in step 3 has the following specific parameters: the etching depth of the shielding piece is 80-120 nm, and the surface roughness of the shielding piece is 40-60 nm.

[0021] In the high-temperature bonding operation in step 5, the bonding pressure is 2.5-3.0 GPa, the bonding temperature is 750-1050 DEG C, and the holding time is 1-5 min.

[0022] In step 6, the packaging solder selection requirements are: according to the material of the window and the packaging bonding layer, the corresponding gold-based, copper-based or nickel-based solder is selected; the melting point of the solder is not higher than the diamond graphitization temperature; the melting point of the solder is lower than the melting point of the metal of the support skeleton layer;

[0023] In step 6, the packaging vacuum condition is: when the furnace cavity temperature is not less than 80 DEG C, the packaging vacuum degree is not greater than 1*10 - 3 Pa; the packaging temperature is not lower than the melting temperature of the solder, and the packaging temperature is not higher than the diamond graphitization temperature and the melting point of the window frame material; the holding time of the high-temperature point is 5-30 min to ensure that the solder is fully melted; after the packaging is completed, the cooling rate is not greater than 8 DEG C / min, and the device is opened to take out the sample after cooling to room temperature.

[0024] Another technical solution adopted by the present application is a diamond window comprising a bonding metal frame layer, which is composed of a bonding contact layer, a skeleton support layer and a packaging bonding layer, wherein the thickness ratio of the bonding contact layer to the skeleton support layer is 1:(2-4), and the thickness ratio of the bonding contact layer to the packaging bonding layer is 1:(5-10).

[0025] The feature of another technical solution of the present application is also:

[0026] The material of the bonding contact layer is one or more of tungsten, molybdenum, titanium, zirconium and chromium.

[0027] The material of the skeleton support layer is one or more of tungsten, molybdenum and chromium.

[0028] The material of the packaging bonding layer is one or more of nickel and copper.

[0029] The beneficial effects of the present application are:

[0030] 1. The diamond single crystal sheet sealing area of the diamond window for the microwave electric vacuum device of the present application is roughened and activated by gas phase etching, thereby increasing the reactivity and bonding force of the diamond single crystal sheet and the metal layer.

[0031] 2. The bonding metal frame layer of the diamond window for the microwave electric vacuum device is composed of a bonding contact layer, a skeleton support layer and an encapsulation bonding layer, is assembled with a diamond single crystal wafer through welding combination, has high controllability of thickness, and solves problems of non-wetting of diamond and metal, poor heat dissipation, poor air tightness, axial eccentricity and the like.

[0032] 3. The preparation method of the diamond window for the microwave electric vacuum device uses a cubic press to perform bonding treatment on the diamond single crystal wafer and the bonding metal frame layer, the high-pressure state makes the metallization layer more dense, the diamond and the metal are bonded to form stable chemical bonds under high temperature, and the transition metal layer solves the problems of high interface energy and high thermal resistance of the diamond, and improves the air tightness and the thermal cycle service life of the device.

[0033] 4. The encapsulation method of the preparation method of the diamond window for the microwave electric vacuum device solves problems of air holes existing in the solder melting, flow and pollution of the waveguide cavity and graphitization of the high-temperature diamond, and provides a mature and stable encapsulation method, which meets requirements of the solder melting state, the window frame parallelism, the air tightness and the like, and has high repeatability. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is an assembly schematic diagram of the diamond window for the microwave electric vacuum device;

[0035] Figure 2 is a bonding plane schematic diagram of the diamond window for the microwave electric vacuum device;

[0036] Figure 3 is a vector analysis monitoring result diagram of the diamond window for the microwave electric vacuum device. DETAILED DESCRIPTION

[0037] The application will be described in detail below in combination with the drawings and specific embodiments.

[0038] The preparation method of the diamond window for the microwave electric vacuum device is specifically implemented according to the following steps:

[0039] I. Diamond single crystal wafer pretreatment:

[0040] The diamond single crystal wafer is cleaned, specifically including chemical cleaning, ultrasonic cleaning with acetone for 15-20 minutes to remove organic matters attached to the surface of the diamond single crystal wafer, boiling cleaning with 10% NaOH solution for 20-30 minutes to remove grease substances in the surface defects of the diamond particles, and boiling cleaning with mixed acid for 20-30 minutes to remove metal impurities and graphite impurities; the diamond single crystal wafer is placed in a vacuum cavity of a plasma cleaning machine, argon gas is used to generate high-energy plasma by a radio frequency power supply and a direct current power supply, the diamond single crystal wafer is bombarded, both sides of the diamond single crystal wafer are cleaned, and the purpose of deep cleaning is achieved, and the specific parameters are as follows: the cleaning time is 60-120 minutes, the ion source voltage is 1500-2500v, and the bias voltage is 300-500v.

[0041] The center region of the diamond single crystal wafer is marked as a waveguide region, the periphery of the waveguide region is a sealing region, the waveguide region is subjected to physical shielding treatment, and a shielding piece is obtained; the physical shielding of the waveguide region of the diamond single crystal wafer is that ultraviolet glue is coated on the surface of a silicon dioxide or single crystal silicon sheet, and the silicon dioxide or single crystal silicon sheet is fixed to the center of the single crystal wafer by ultraviolet irradiation, and the thickness of the silicon dioxide or single crystal silicon sheet is not greater than 0.20 mm.

[0042] The shielding piece in step 2 is subjected to chemical vapor etching, so that the sealing region is roughened and activated, and an etched piece is obtained, and the reaction activity and bonding force with the metal layer are increased by the roughening and activating operation; the specific parameters of the chemical vapor etching are that the etching depth of the shielding piece is 80-120 nm, and the surface roughness of the shielding piece is 40-60 nm, so that the problems of low bonding force and high reaction temperature of the metal layer in the prior art are effectively solved.

[0043] II. Bonding treatment of the sealing region of the diamond single crystal wafer

[0044] The pre-bonding metal frame layer is prepared by pre-preparing a metal foil, processing it into a fixed specification, and then assembling it; the bonding contact layer, the skeleton support layer and the packaging bonding layer are sequentially assembled and denoted as a bonding metal frame layer, wherein the bonding metal frame layer is composed of the bonding contact layer, the skeleton support layer and the packaging bonding layer, the thickness ratio of the bonding contact layer to the skeleton support layer is 1:(2-4), and the thickness ratio of the bonding contact layer to the packaging bonding layer is 1:(5-10); the bonding contact layer is a metal that can form a stable chemical bond with diamond, specifically one or more of tungsten, molybdenum, titanium, zirconium and chromium; the skeleton support layer is a high-melting-point metal, specifically one or more of tungsten, molybdenum and chromium; and the packaging bonding layer is a window frame material metal, specifically one or more of nickel and copper.

[0045] Assembling the key metal frame layer on both sides of the sealing area of the etching sheet, wherein the key contact layer is connected with the sealing area, and then using a six-surface press to perform high-temperature keying treatment to obtain the diamond composite material X for the window; the keying pressure in the high-temperature keying operation is 2.5-3.0 GPa, the keying temperature is 750-1050℃, the holding time is 1-5 min, and the keying temperature cannot be higher than the diamond graphitization temperature in this environment and cannot be lower than the diamond and metal keying temperature.

[0046] III. Packaging:

[0047] Using a high-vacuum packaging device, the diamond composite material X for the window is subjected to packaging treatment. The packaging solder selection requirements are: selecting the corresponding gold-based, copper-based or nickel-based solder according to the material of the window and the packaging bonding layer; being able to be mutually soluble and wetted with the soldering surface of the diamond single crystal sheet and the window frame material; the melting point of the solder being not higher than the diamond graphitization temperature; the melting point of the solder being lower than the melting point of the support skeleton layer metal. The packaging vacuum condition is: when the furnace cavity temperature is not less than 80℃, the packaging vacuum degree is not greater than 1x10 - 3 Pa; the packaging temperature is not lower than the melting temperature of the solder, and the packaging temperature is not higher than the diamond graphitization temperature and the melting point of the window frame material; the holding time of the high-temperature point is 5-30 min to ensure that the solder is fully melted; after the packaging is completed, the cooling rate is not greater than 8℃ / min, and the device is opened to take out the sample after cooling to room temperature to prevent oxidation and contamination.

[0048] Example 1

[0049] I. Diamond single crystal sheet pretreatment:

[0050] The diamond single crystal sheet is cleaned by ultrasonic cleaning with acetone for 15 min to remove organic matter attached to the surface of the diamond single crystal sheet, boiled and cleaned with 10% NaOH solution for 20 min to remove oil substances in the surface defects of the diamond particles, boiled and cleaned with mixed acid for 20 min to remove metal impurities and graphite impurities, and the surface of the diamond single crystal sheet is bombarded by high-energy plasma generated by a radio frequency power source and a direct current power source using high-purity argon in a vacuum device. The ion source voltage is 2000v, the bias voltage is 300v, and the cleaning time is 60 min. The cleaning process is double-sided cleaning.

[0051] The sealing area of the diamond single crystal sheet is subjected to chemical vapor etching, the etching depth is 87 nm, and the roughness is 41 nm.

[0052] II. Bonding treatment of the sealing area of the diamond single crystal sheet:

[0053] The pre-prepared bonding metal frame layer is specifically a titanium layer as the bonding contact layer, a tungsten layer as the skeleton support layer, and a copper layer as the packaging bonding layer, wherein the thickness of the titanium layer is 200 μm, the thickness of the tungsten layer is 400 μm, and the thickness of the copper layer is 1000 μm, that is, the thickness ratio of the titanium layer and the tungsten layer is 1:2; the thickness ratio of the titanium layer and the copper layer is 1:5; the etching plate is assembled in the order of Ti-W-Cu on both sides of the sealing and welding area, and then high-temperature bonding treatment is performed on the etching plate by using a six-surface pressing machine, the bonding pressure is 2.6 GPa, the temperature is 890 ℃, and the holding time is 1.5 min.

[0054] III. Packaging:

[0055] The AgCuPd27-5 solder is processed into a specified size, and packaging is performed by using a high-vacuum packaging device. The melting point of the AgCuPd27-5 solder is 807 ℃, the vacuum degree is 8.4 × 10 -4 Pa, the packaging temperature is 810 ℃, the holding time is 7 min, and after the packaging is completed, the etching plate is cooled to room temperature at a cooling rate of 8 ℃ / min, and then the device is opened to obtain a window device that meets the requirements.

[0056] Example 2

[0057] I. Pretreatment of the diamond single crystal wafer:

[0058] The diamond single crystal wafer is cleaned by ultrasonic cleaning with acetone for 18 min to remove organic substances attached to the surface of the diamond single crystal wafer, boiled and cleaned with 10% NaOH solution for 25 min to remove oil substances in the surface defects of the diamond particles, and boiled and cleaned with mixed acid for 25 min to remove metal impurities and graphite impurities. In a vacuum device, high-energy plasma is generated by using high-purity argon through a radio frequency power source and a direct current power source to bombard the surface of the diamond single crystal wafer. The ion source voltage is 2200 V, the bias voltage is 350 V, and the cleaning time is 90 min. The cleaning process is double-sided cleaning.

[0059] The sealing and welding area of the diamond single crystal wafer is chemically vapor etched, the etching depth is 93 nm, and the roughness is 44 nm.

[0060] II. Bonding treatment of the sealing and welding area of the diamond single crystal wafer:

[0061] The pre-prepared bonding metal frame layer is specifically a chromium layer as the bonding contact layer, a molybdenum layer as the skeleton support layer, and a copper layer as the packaging bonding layer, wherein the thickness of the chromium layer is 200 μm, the thickness of the molybdenum layer is 600 μm, and the thickness of the copper layer is 1200 μm, that is, the thickness ratio of the chromium layer and the molybdenum layer is 1:3, and the thickness ratio of the chromium layer and the copper layer is 1:6. The etching plate is assembled in the order of Cr-Mo-Cu on both sides of the sealing and welding area, and then high-temperature bonding treatment is performed on the etching plate by using a six-surface pressing machine, the bonding pressure is 2.5 GPa, the temperature is 935 ℃, and the holding time is 1.5 min.

[0062] III. Packaging:

[0063] The AgCuin27-10 solder was processed to a specified size, and packaged using a high-vacuum packaging device. The melting point of the AgCuin27-10 is 685°C, and the vacuum degree is 7.1x10 -4 Pa. The packaging temperature was 690°C, and the holding time was 10 min. After packaging, the device was cooled to room temperature at a cooling rate of 8°C / min, and the required window device was obtained by opening the device.

[0064] Example 3

[0065] I. Pretreatment of the diamond single crystal wafer:

[0066] The diamond single crystal wafer was cleaned by ultrasonic cleaning in acetone for 20 min, and the oil-like substances in the surface defects of the diamond particles were removed by boiling cleaning in a 10% NaOH solution for 30 min. The metal and graphite impurities were removed by boiling cleaning in a mixed acid for 30 min. In a vacuum device, high-energy plasma was generated by using high-purity argon gas through a radio frequency power source and a direct current power source to bombard the surface of the diamond single crystal wafer. The ion source voltage was 1500 V, the bias voltage was 400 V, and the cleaning time was 60 min. The cleaning process was double-sided cleaning.

[0067] The sealing and welding area of the diamond single crystal wafer was subjected to chemical vapor etching, with an etching depth of 120 nm and a roughness of 60 nm.

[0068] II. Bonding treatment of the sealing and welding area of the diamond single crystal wafer:

[0069] A pre-bonding metal frame layer was prepared, specifically, the bonding contact layer was a molybdenum layer, the skeletal support layer was a chromium layer, and the packaging bonding layer was a nickel layer. The thickness of the molybdenum layer was 200 μm, the thickness of the chromium layer was 400 μm, and the thickness of the nickel layer was 1.2 mm. That is, the thickness ratio of the molybdenum layer and the chromium layer was 1:2, and the thickness ratio of the molybdenum layer and the nickel layer was 1:6. The etched wafer was assembled in the order of Mo-Cr-Ni on both sides of the sealing and welding area, and then subjected to high-temperature bonding treatment using a six-surface press. The bonding pressure was 2.6 GPa, the temperature was 870°C, and the holding time was 3 min.

[0070] III. Packaging:

[0071] The AgCu23in1.5Ni2.5 solder was processed to a specified size, and packaged using a high-vacuum packaging device. The melting point of the AgCu23in1.5Ni2.5 is 779°C, and the vacuum degree is 6.5x10 -4 Pa. The packaging temperature was 802°C, and the holding time was 18 min. After packaging, the device was cooled to room temperature at a cooling rate of 8°C / min, and the required window device was obtained by opening the device.

[0072] Example 4

[0073] I. Pretreatment of the diamond single crystal wafer:

[0074] The diamond single crystal wafer surface was cleaned by ultrasonic cleaning with acetone for 18 min, and the grease in the surface defects of the diamond particles was removed by boiling cleaning with 10% NaOH solution for 25 min. The metal and graphite impurities were removed by boiling cleaning with mixed acid for 25 min. In a vacuum device, high-energy plasma was generated by using high-purity argon through a radio frequency power supply and a direct current power supply to bombard the surface of the diamond single crystal wafer. The ion source voltage was 2500 V, the bias voltage was 500 V, and the cleaning time was 120 min. The cleaning process was double-sided cleaning.

[0075] The sealing area of the diamond single crystal wafer was subjected to chemical vapor etching, with an etching depth of 106 nm and a roughness of 49 nm.

[0076] II. Bonding treatment of the sealing area of the diamond single crystal wafer:

[0077] A pre-bonding metal frame layer was prepared, which included a tungsten layer as the bonding contact layer and the skeleton support layer, and a nickel layer as the packaging bonding layer. The thickness of the tungsten layer was 400 μm, and the thickness of the nickel layer was 700 μm, i.e., the thickness ratio of the tungsten layer to the nickel layer was 4:7. The thickness ratio of the bonding contact layer to the skeleton support layer was 1:3, and the thickness ratio of the bonding contact layer to the packaging bonding layer was 1:7. The etched wafer was assembled in the sealing area on both sides in the order of tungsten-nickel, and then subjected to high-temperature bonding treatment using a six-surface press, with a bonding pressure of 2.8 GPa and a temperature of 1040°C for 1 min.

[0078] III. Packaging:

[0079] AgCuPd27-5 solder was used, and the solder was processed to a specified size. High-vacuum packaging equipment was used for packaging. The melting point of AgCuPd27-5 was 807°C, the vacuum degree was 7.7 x 10 -4 Pa, the packaging temperature was 810°C, and the holding time was 4.5 min. After packaging, the device was cooled to room temperature at a cooling rate of 8°C / min, and the required window device was obtained.

[0080] Example 5

[0081] I. Pretreatment of the diamond single crystal wafer:

[0082] The diamond single crystal wafer surface is cleaned by acetone ultrasonic cleaning for 15 min, the oil substance in the surface defects of the diamond particles is removed by using 10% NaOH solution to boil for 20 min, the metal impurities and graphite impurities are removed by mixed acid boiling cleaning for 20 min, in a vacuum device, high-energy plasma is generated by using high-purity argon through a radio frequency power supply and a direct current power supply to bombard the surface of the diamond single crystal wafer, the ion source voltage is 2000v, the bias voltage is 300v, and the cleaning time is 60 min, and the cleaning process is double-sided cleaning.

[0083] The sealing area of the diamond single crystal wafer is subjected to chemical vapor etching, the etching depth is 80 nm, and the roughness is 40 nm.

[0084] II. Bonding treatment of the sealing area of the diamond single crystal wafer:

[0085] A pre-bonding metal frame layer is prepared, specifically, the bonding contact layer and the skeleton support layer are both zirconium layers, and the packaging bonding layer is a copper layer, wherein the thickness of the zirconium layer is 800 μm, the thickness of the copper layer is 2 mm, that is, the thickness ratio of the zirconium layer and the copper layer is 1:2.5, the thickness ratio of the bonding contact layer and the skeleton support layer is 1:3, and the thickness ratio of the bonding contact layer and the packaging bonding layer is 1:10, the etched wafer is assembled in the sealing area on both sides in the order of zirconium-copper, and then high-temperature bonding treatment is performed on the etched wafer by using a six-surface press, the bonding pressure is 3.0 GPa, the temperature is 750°C, and the holding time is 5 min.

[0086] III. Packaging:

[0087] The AgCu23in1.5Ni2.5 solder is processed into a specified size, high-vacuum packaging equipment is used for packaging, the melting point of the AgCu23in1.5Ni2.5 solder is 779°C, the vacuum degree is 8.0×10 -4 Pa, the packaging temperature is 802°C, the holding time is 30 min, after the packaging is completed, the device is cooled to room temperature at a cooling rate of 8°C / min, and the window device meeting the requirements can be obtained by opening the device.

[0088] In the method, the diamond single crystal wafer is subjected to chemical cleaning and plasma cleaning to clean the surface, then the waveguide area is shielded, the sealing area is subjected to chemical gas etching and roughening and activation to increase the surface activity and improve the bonding force, the six-surface press is used for bonding treatment, so that the diamond and the bonding metal layer form a stable chemical bond, the support metal layer can withstand high temperature and play a supporting role, and the sealing metal is solid-solution sealed with the window frame, different operating processes are used for different windows, and the window device with high transmission performance and low vacuum leakage rate and meeting the requirements of high-power microwave transmission can be obtained.

[0089] The diamond window of Example 1 of the present application is subjected to 220GHz vector analysis monitoring, and the results are as follows:Figure 3 As shown, the 220GHz energy transmission window is detected using a vector analyzer, and the result shows that the bandwidth is greater than or equal to 20GHz, S21 is -1.06dB, S11 is -19.69dB, and the window projection loss meets the use requirement.

[0090] The window electric vacuum device with high transmission performance and low vacuum leakage rate to meet the requirement of high-power microwave transmission can be obtained by adopting the application, and the quality of the device is effectively controlled by adjusting the roughening activation degree of the non-waveguide area, the structure and material of the diamond single crystal wafer sealing area and the sealing process parameters, and the vacuum leakage rate is lower than 5*10 -10 Pa, S21>-1.5dB, S11<-15dB@220GHz.

Claims

1. A method for the production of a diamond window for a microwave electric vacuum device, characterized in that, The method is implemented according to the following steps: Step 1, cleaning the diamond single crystal wafer; Step 2, marking the center area of the diamond single crystal wafer as a waveguide area, and the periphery of the waveguide area as a sealing area, and performing physical shielding treatment on the waveguide area to obtain a shielding wafer; Step 3, performing chemical vapor etching on the shielding wafer in step 2 to roughen and activate the sealing area, and obtaining an etched wafer; Step 4, pre-preparing a metal frame layer: Assembling the bonding contact layer, the skeleton support layer and the encapsulation bonding layer in sequence to obtain a metal frame layer; Step 5, assembling the metal frame layer in step 4 on both sides of the etched wafer sealing area, wherein the bonding contact layer is in contact with the sealing area, and then using a six-surface press to perform high-temperature bonding treatment to obtain a diamond composite material X for a window; Step 6, using a high-vacuum packaging device to package the diamond composite material X for a window in step 5.

2. The method of claim 1, wherein the diamond window for a microwave electrical vacuum device is prepared by the steps of: The cleaning of the diamond single crystal wafer in step 1 specifically includes: Chemical cleaning: ultrasonic cleaning with acetone for 15-20 min to remove organic matter attached to the surface of the diamond single crystal wafer, boiling cleaning with 10% NaOH solution for 20-30 min to remove grease in the surface defects of the diamond particles, and boiling cleaning with mixed acid for 20-30 min to remove metal and graphite impurities; Plasma cleaning: placing the diamond single crystal wafer in the vacuum cavity of a plasma cleaning machine, using argon gas to generate high-energy plasma by radio frequency power and direct current power to bombard the surface of the diamond single crystal wafer, cleaning both sides of the diamond single crystal wafer to achieve deep cleaning, and the specific parameters are: cleaning time of 60-120 min, ion source voltage of 1500-2500 v, and bias voltage of 300-500 v.

3. The method of claim 1, wherein the diamond window is prepared by a method comprising: The physical shielding treatment of the waveguide area in step 2 is to coat ultraviolet glue on the surface of a silicon dioxide or single crystal silicon sheet, and fix it to the center of the single crystal wafer by ultraviolet irradiation, and the thickness of the silicon dioxide or single crystal silicon sheet is not greater than 0.20 mm.

4. The method of claim 1, wherein the diamond window for a microwave electrical vacuum device is prepared by the steps of: The specific parameters of the chemical vapor etching in step 3 are that the etching depth of the shielding wafer is 80-120 nm, and the surface roughness of the shielding wafer is 40-60 nm.

5. The method of claim 1, wherein the diamond window for a microwave electrical vacuum device is prepared by the steps of: The high-temperature bonding treatment in step 5 is specifically a bonding pressure of 2.5-3.0 GPa, a bonding temperature of 750-1050℃, and a holding time of 1-5 min.

6. The method of claim 1, wherein the diamond window for a microwave electrical vacuum device is prepared by, The packaging treatment in step 6 includes packaging solder selection, which requires that: according to the material of the window and the encapsulation bonding layer, select the corresponding gold-based, copper-based or nickel-based solder; the melting point of the solder is not higher than the graphitization temperature of diamond; the melting point of the solder is lower than the melting point of the support skeleton layer metal; The encapsulation process in step 6 includes encapsulation vacuum selection, and the encapsulation vacuum condition is that when the furnace cavity temperature is not less than 80℃, the encapsulation vacuum degree is not greater than 1×10 -3 Pa; the encapsulation temperature is not lower than the solder melting temperature, and the encapsulation temperature is not higher than the diamond graphitization temperature and the melting point of the window frame material. The holding time of the high-temperature point is 5-30 min to ensure that the solder is fully melted; after packaging is completed, the cooling rate is not greater than 8℃ / min, and the device is opened to take out the sample after cooling to room temperature.

7. A diamond window for a microwave electrical vacuum device, characterized in that, The method for preparing a diamond window for a microwave electron vacuum device according to any one of claims 1-6, wherein the diamond window comprises a bonding metal frame layer, the bonding metal frame layer is composed of a bonding contact layer, a skeleton support layer and a packaging bonding layer, wherein the thickness ratio of the bonding contact layer to the skeleton support layer is 1:(2-4), and the thickness ratio of the bonding contact layer to the packaging bonding layer is 1:(5-10).

8. The diamond window for a microwave electrical vacuum device of claim 7, wherein, The material of the bonding contact layer is one or more of tungsten, molybdenum, titanium, zirconium and chromium.

9. The diamond window for a microwave electrical vacuum device of claim 7, wherein, The material of the skeleton support layer is one or more of tungsten, molybdenum and chromium.

10. The diamond window for a microwave electrical vacuum device of claim 7, wherein, The material of the packaging bonding layer is one or more of nickel and copper.

Images