A method for preparing a high-power diamond-based microwave load

Abstract

The present invention relates to a method for preparing a high-power diamond-based microwave load, comprising the following steps: S1, laser grooving a substrate; S2, surface treating the substrate; S3, sequentially sputtering a resistor film layer and a metal seed layer on the front surface of the substrate, sputtering the metal seed layer on the back surface, and sputtering the metal seed layer on the surface of the holes formed by the laser grooving; S4, electroplating and thickening the metal seed layer on the front, back, and side surfaces of the substrate to form a conductor layer, and heat treating the substrate after the electroplating and thickening treatment; S5, forming a metal conductor pattern on the front surface of the substrate; S6, forming a resistor pattern on the front surface of the substrate; S7, thermally oxidizing the resistor pattern on the front surface of the substrate to adjust the resistance; S8, printing a dielectric glue on the resistor pattern area on the front surface of the substrate; and S9, dividing the substrate into units, thereby completing the preparation of the diamond-based microwave load. This method can address the shortcomings of the existing technology and realize the preparation of thin-film resistors based on CVD diamond substrates.

Description

Technical Field

[0001] The present invention relates to the field of hybrid integrated electronic technology, and in particular to a method for preparing a high-power diamond-based microwave load. Background Art

[0002] High-power diamond-based microwave loads are primarily used in military equipment, particularly in phased array radars for electronic countermeasures. As specialized passive components, they often serve as the terminal device in power load circuits, primarily absorbing power from RF or microwave systems while maintaining a minimal standing wave ratio within the operating frequency range.

[0003] Compared to traditional power loads based on AlN and BeO substrates, diamond offers higher mechanical strength, greater thermal conductivity, and more reliable high-frequency characteristics. Under the same packaging conditions, it also boasts greater power capacity and improved heat dissipation. Thin-film-based diamond power loads are characterized by their compact size, light weight, excellent high-frequency performance, and high power handling capability. As military equipment evolves towards miniaturization, higher power, and higher frequency bands, high-power diamond-based microwave loads are essential as fundamental passive components.

[0004] Existing diamond-based microwave loads primarily feature a thin-film resistor layer and a metal conductor layer on the front surface, with the resistors trimmed using lasers. The metal conductors on the front surface are not connected to the back surface, leaving the load's two ports on one side. This necessitates bonding and is unsuitable for dual-port assembly, such as eutectic soldering. While maintaining the same resistance accuracy, laser trimming can disrupt and alter the resistor pattern, impacting the load's microwave performance, increasing the standing wave ratio (SWR) and worsening the characteristic impedance matching. Summary of the Invention

[0005] The object of the present invention is to provide a method for preparing a high-power diamond-based microwave load, which can solve the deficiencies in the prior art and realize the preparation of thin-film resistors based on CVD diamond substrates.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for preparing a high-power diamond-based microwave load, the method comprising the following steps:

[0008] S1. Selection of substrate and laser grooving of substrate

[0009] A CVD diamond substrate is selected as a substrate, and the substrate is grooved by laser processing;

[0010] S2. Substrate surface treatment

[0011] Performing surface treatment on the substrate after laser grooving;

[0012] S3. Sputtering of the resistance film layer and the metal seed layer

[0013] The resistor film layer and the metal seed layer are sequentially sputtered on the front side of the laser grooved substrate, the metal seed layer is sputtered on the back side, and the metal seed layer is sputtered on the surface of the hole groove formed by the laser groove;

[0014] S4, electroplating thickening treatment and heat treatment

[0015] Electroplating and thickening the metal seed layer on the front, back and side surfaces of the substrate to form a conductor layer, and heat treating the substrate after the electroplating and thickening process;

[0016] S5. Fabrication of Metal Conductor Graphics

[0017] Producing a metal conductor pattern on the front side of the substrate;

[0018] S6. Fabrication of resistor graphics

[0019] forming a resistor pattern on the front side of the substrate;

[0020] S7, thermal oxidation resistance adjustment

[0021] Performing thermal oxidation resistance adjustment on the resistor pattern on the front side of the substrate;

[0022] S8, printed medium glue

[0023] Printing dielectric glue on the resistor pattern area on the front side of the substrate;

[0024] S9. Substrate unit division

[0025] The substrate is divided into units and the diamond-based microwave load is prepared. Due to the hardness of diamond, conventional grinding wheels cannot cut it.

[0026] Furthermore, the selection of the substrate and the laser grooving of the substrate include:

[0027] S11: coating laser protection liquid on the front side of the substrate;

[0028] S12: using a YLF laser device to cut off a portion of the front surface of the substrate to form a hole groove;

[0029] S13: Use YLF laser equipment to continue to open the hole groove from the front of the substrate along the edge of the hole groove, so that the hole groove diameter meets the set requirements;

[0030] S14: Ultrasonic immersion of the laser-grooved substrate in an organic solution to remove the laser protection liquid on the substrate;

[0031] S15: Bake the substrate to remove moisture on the substrate.

[0032] Furthermore, the surface treatment includes:

[0033] Pretreatment of slag and organic carbides formed on the substrate during laser processing and cleaning of hydrophilic organic dirt on the substrate surface.

[0034] Furthermore, the sputtering of the resistive film layer and the metal seed layer includes:

[0035] S31: Frontal Splash

[0036] A TaN film layer is formed on the front surface of the laser grooved substrate by magnetron sputtering; a WTi film layer and an Au film layer are formed on the front surface of the laser grooved substrate by magnetron sputtering;

[0037] S32, back sputtering

[0038] Magnetron sputtering is used to form WTi and Au films on the back of the laser-grooved substrate.

[0039] S33, sidewall sputtering

[0040] A WTi film layer and an Au film layer are formed on the sidewalls of the laser-grooved substrate by magnetron sputtering.

[0041] Furthermore, the electroplating thickening treatment and heat treatment include:

[0042] S41: Select the corresponding electroplating rack according to the shape and size of the substrate;

[0043] S42: acid-washing and activating the substrate;

[0044] S43: calculating the electroplating current and electroplating time of the electroplating rack according to the area of ​​the substrate to be electroplated, and electroplating the substrate using the electroplating rack according to the electroplating current and electroplating time;

[0045] S44: Rinse the electroplated substrate with deionized water;

[0046] S45: drying the substrate at 100° C. for 10 minutes;

[0047] S46. Heat-treating the electroplated thickened substrate and performing high-temperature annealing.

[0048] Furthermore, the production of the metal conductor pattern includes:

[0049] S51: Press a 25um thick dry film on the front of the board using a dry film laminator;

[0050] S52: performing exposure and development processing on the substrate with the dry film pressed thereon;

[0051] S53: using an oven to perform a hardening treatment on the substrate after the exposure and development treatments;

[0052] S54: Apply a protective film to the back of the substrate and etch away the unnecessary metal conductor film layer on the front side using a wet method;

[0053] S55: Use the front wet etching method to remove the unnecessary adhesion layer WTi;

[0054] S56: Soak the substrate in a 3% NaOH alkaline solution for 30 minutes to remove the dry film on the surface of the substrate.

[0055] Furthermore, the manufacturing of the resistor pattern includes:

[0056] S61: Press a 25um thick dry film on the front of the substrate using a dry film laminator;

[0057] S62: performing exposure and development processing on the CVD diamond substrate with the dry film pressed thereon;

[0058] S63: using an oven to perform a hardening treatment on the substrate after the exposure and development treatments;

[0059] S64: Apply a protective film to the back of the substrate and etch away the unnecessary resistor film layer on the front side using a dry method;

[0060] S65: Soak the substrate in a 3% NaOH alkaline solution for 30 minutes to remove the dry film on the substrate surface.

[0061] Furthermore, the thermal oxidation resistance adjustment includes:

[0062] S71: classifying substrates according to initial values ​​before resistance adjustment;

[0063] S72: performing thermal oxidation resistance adjustment under different conditions on different classified substrates;

[0064] S73: Use an 8.5-digit digital multimeter to perform a DC resistance test on the substrate after thermal oxidation resistance adjustment.

[0065] Furthermore, the printed medium glue includes:

[0066] S81: Pre-treating the substrate surface;

[0067] S82: Mix and blend AB glue according to a certain ratio, fix the screen printing plate, calibrate the position of the substrate, and print the medium glue on the substrate;

[0068] S83: The dielectric glue printed on the surface of the substrate is subjected to thermal curing treatment to catalyze the colloid to fully react, form long molecular chain aggregation, and dry out water vapor.

[0069] Furthermore, the substrate unit division includes:

[0070] S91: Laser scribing is performed on the substrate surface to form fine grooves of a certain depth;

[0071] S92: A splitting machine is used to apply pressure in the vertical direction to split the substrate along the groove, and the preparation of the diamond-based microwave load is completed.

[0072] Compared with the prior art, the advantages of the present invention are:

[0073] (1) The present invention utilizes laser processing to effectively clean the substrate after laser processing by physical and chemical means, thereby fabricating a metal conductor layer on the side of the diamond substrate, i.e., side metallization, thereby connecting and conducting the front, side, and back metal conductor layers. In the prior art, due to the high hardness of diamond and the difficulty in removing molten residue during laser processing, it is difficult to prepare a side metal conductor layer with sufficient adhesion strength.

[0074] (2) The present invention metallizes the side of the substrate to achieve connection and conduction of the front, side and back metal conductor layers, so that the two ends of the diamond-based microwave load can be on one side or on both sides, solving the assembly problem that the ports of the diamond-based microwave load cannot be on both sides.

[0075] (3) The present invention adjusts the resistance by performing thermal oxidation, that is, by reacting the metal Ta in the TaN film with oxygen in a high-temperature environment to form a metal oxide, which can increase the overall resistivity of the TaN film, thereby adjusting the resistance value. Compared with the existing laser resistance adjustment method, thermal oxidation resistance adjustment does not destroy the resistor pattern, and ensures the microwave characteristics and characteristic impedance matching of the diamond-based microwave load as much as possible. The difficulty of thermal oxidation resistance adjustment lies in the uniformity of the magnetron sputtering film layer of the TaN film and the control of the resistance adjustment temperature curve. The present invention overcomes this difficulty and realizes a thin film resistor that meets the precision requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] Figure 1 Schematic diagram of the process steps of the method for preparing a high-power diamond-based microwave load of the present invention;

[0077] Figure 2 Schematic diagram of the structure of each step of the method for preparing a high-power diamond-based microwave load in Example 1 of the present invention.

[0078] in:

[0079] a represents the laser groove processing process, b represents the deposition of the metal seed layer, c represents the preparation of the front conductor layer, d represents the preparation of the front resistor layer, e represents the preparation of the front dielectric layer, and f represents the processed high-power diamond-based microwave load unit. DETAILED DESCRIPTION

[0080] The present invention will be further described below with reference to the accompanying drawings:

[0081] like Figure 1 The present invention provides a method for preparing a high-power diamond-based microwave load. The diamond-based microwave load includes a conductor layer, a resistor layer and an insulating dielectric layer, such as Figure 2 As shown, from bottom to top, there are: back conductor layer, side conductor layer, front resistor layer, front conductor layer and front dielectric layer. The method for making the diamond-based microwave load includes the following steps:

[0082] S1. Selection of substrate and laser grooving of substrate

[0083] A CVD diamond substrate was selected as the substrate for laser grooving, with the grooved surface serving as the substrate's side surface. Specifically, a laser protective liquid was spin-coated onto the substrate surface to be laser processed. A YLF laser was used to create holes and grooves in the substrate according to the design. During the grooving process, coaxial nitrogen gas was used for the protective gas. After laser processing, the groove edges on the substrate were free of cracks and chipping.

[0084] The selection of the substrate and the laser grooving of the substrate include:

[0085] S11: coating laser protection liquid on the front side of the substrate;

[0086] S12: using a YLF laser device to cut off a portion of the front surface of the substrate to form a hole groove;

[0087] S13: Use YLF laser equipment to continue to open the hole groove from the front of the substrate along the edge of the hole groove, so that the hole groove diameter meets the set requirements;

[0088] S14: Ultrasonic immersion of the laser-grooved substrate in an organic solution to remove the laser protection liquid on the substrate;

[0089] S15: Bake the substrate to remove moisture on the substrate.

[0090] S2. Substrate surface treatment

[0091] The laser-grooved substrate undergoes surface treatment. This includes pre-treating slag and organic carbides formed on the substrate during laser processing and cleaning hydrophilic organic contaminants from the substrate surface. This surface treatment ensures substrate surface cleanliness, ensuring uniformity and reliable adhesion of the subsequent sputtered film.

[0092] S3. Sputtering of the resistance film layer and the metal seed layer

[0093] The resistor film layer and the metal seed layer are sequentially sputtered on the front side of the laser grooved substrate, the metal seed layer is sputtered on the back side, and the metal seed layer is sputtered on the surface of the hole groove formed by the laser groove.

[0094] Specifically, a resistor film layer and a metal seed layer are deposited on the front surface of the laser-grooved substrate via vacuum magnetron sputtering. The metal seed layer is also deposited on the sidewalls of the laser-grooved holes. A metal seed layer is sputtered on the back surface of the laser-grooved substrate via vacuum magnetron sputtering. The metal seed layer is also deposited on the sidewalls of the laser-grooved holes. The resistor film layer is TaN, and the metal seed layer is a certain thickness of Au.

[0095] The sputtering of the resistive film layer and the metal seed layer includes:

[0096] S31: Frontal Splash

[0097] A TaN film layer is deposited on the front surface of the laser-grooved substrate using magnetron sputtering. WTi and Au film layers are also deposited on the front surface of the laser-grooved substrate using magnetron sputtering. The WTi film serves as an interfacial adhesion layer, transitioning between the upper and lower film layers.

[0098] S32, back sputtering

[0099] Magnetron sputtering is used to deposit a WTi film layer (200 nm thick) and an Au film layer (100 nm thick) on the back of the laser-grooved substrate. The WTi film layer serves as an interfacial adhesion layer between the substrate and the upper film layer.

[0100] S33, sidewall sputtering

[0101] Magnetron sputtering is used to deposit WTi and Au films on the sidewalls of the laser-grooved substrate. The WTi film serves as an interface adhesion layer between the substrate and the upper film layer.

[0102] S4, electroplating thickening treatment and heat treatment

[0103] The metal seed layer on the front, back, and sides of the substrate is electroplated to form a conductive layer, and the substrate undergoes heat treatment. Specifically, a gold cyanide electroplating system is used to thicken the metal seed layer on the front, back, and sides of the substrate, forming a metal film layer as a conductive layer to meet the assembly requirements of 25μm gold wire bonding and gold-tin soldering.

[0104] The electroplating thickening treatment and heat treatment include:

[0105] S41: Select the corresponding electroplating rack according to the shape and size of the substrate;

[0106] S42: acid-washing and activating the substrate;

[0107] S43: calculating the electroplating current and electroplating time of the electroplating rack according to the area of ​​the substrate to be electroplated, and electroplating the substrate using the electroplating rack according to the electroplating current and electroplating time;

[0108] S44: Rinse the electroplated substrate with deionized water;

[0109] S45: drying the substrate at 100° C. for 10 minutes;

[0110] S46. Heat treat the electroplated thickened substrate and perform high-temperature annealing. Use a high-temperature oven to bake the electroplated thickened substrate. High-temperature annealing releases and eliminates the internal stress of the metal film layer, reshapes the film layer structure, and improves the film layer adhesion. The specific heat treatment method is: baking in a vacuum state.

[0111] S5. Fabrication of Metal Conductor Graphics

[0112] A metal conductor pattern is produced on the front side of the substrate. Specifically, the front metal conductor layer undergoes photolithography, followed by dry film pressing, exposure, development, hardening, wet etching, and resist stripping, to create a metal line pattern on the substrate surface. Dry film pressing is used on substrates with slots to effectively protect the metal film layer on the sidewalls of the holes.

[0113] The production of the metal conductor pattern includes:

[0114] S51: Press a 25um thick dry film on the front of the board using a dry film laminator.

[0115] S52: performing exposure and development processing on the substrate with the dry film pressed thereon.

[0116] S53: using an oven to perform a hardening treatment on the substrate after the exposure and development treatments.

[0117] S54: Apply a protective film on the back of the substrate and use a wet method to etch away the unnecessary metal conductor film layer on the front.

[0118] S55: Use the front wet etching method to remove the unnecessary adhesion layer WTi.

[0119] S56: Soak the substrate in a 3% NaOH alkaline solution for 30 minutes to remove the dry film on the surface of the substrate.

[0120] S6. Fabrication of resistor graphics

[0121] The resistor pattern is produced on the front side of the substrate. Specifically, the front metal film layer is subjected to photolithography, and through operations such as dry film pressing, exposure, development, hardening, dry etching, and debonding, the metal line pattern of the front conductive layer is produced on the surface of the substrate.

[0122] The production of the resistor pattern includes:

[0123] S61: A dry film with a thickness of 25 μm is pressed on the front side of the substrate by a dry film laminator.

[0124] S62: performing exposure and development processing on the CVD diamond substrate with the dry film pressed thereon.

[0125] S63: using an oven to perform a hardening treatment on the substrate after the exposure and development treatments.

[0126] S64: Apply a protective film on the back of the substrate and etch away the unnecessary resistor film layer on the front using a dry method.

[0127] S65: Soak the substrate in a 3% NaOH alkaline solution for 30 minutes to remove the dry film on the substrate surface.

[0128] S7, thermal oxidation resistance adjustment

[0129] Thermal oxidation is performed on the resistor pattern on the front of the substrate. There are two existing methods for adjusting the resistance of TaN resistors: laser ablation and thermal oxidation. Thermal oxidation involves heating TaN with O2 in the air to form a dense oxide layer of Ta2O5 on the surface of the film, which acts as a self-passivation and effectively improves the sheet resistance of the film. The advantage of thermal oxidation of TaN is that it ensures the integrity of the resistor pattern, resulting in smooth high-frequency characteristics.

[0130] The thermal oxidation resistance adjustment method includes:

[0131] S71: Classify the substrates according to the initial values ​​before resistance adjustment.

[0132] S72: Perform thermal oxidation resistance adjustment under different conditions on different classified substrates.

[0133] S73: Use an 8.5-digit digital multimeter to perform a DC resistance test on the substrate after thermal oxidation resistance adjustment.

[0134] S8, printed medium glue

[0135] A dielectric glue is printed on the resistor pattern area on the front side of the substrate. Specifically, a highly thermally conductive epoxy resin is used for screen printing on the resistor pattern area, providing protection and heat dissipation, allowing the high-power diamond-based microwave load to be used in acidic, alkaline, and high-temperature environments.

[0136] The printed medium glue comprises:

[0137] S81: Pre-treat the substrate surface to ensure that the substrate surface is clean and free of dirt that affects the adhesion of the film layer;

[0138] S82: Mix and blend AB glue according to a certain ratio, fix the screen printing plate, calibrate the position of the substrate, and print the medium glue on the substrate;

[0139] S83: The dielectric glue printed on the surface of the substrate is subjected to thermal curing treatment to catalyze the colloid to fully react, form long molecular chain aggregation, and dry out water vapor.

[0140] S9. Substrate unit division

[0141] The substrate is divided into units and the diamond-based microwave load is prepared. Due to the hardness of diamond, conventional grinding wheels cannot cut it.

[0142] The substrate unit division includes:

[0143] S91: Laser scribing is performed on the surface of the substrate to form fine grooves of a certain depth.

[0144] S92: A splitting machine is used to apply pressure in the vertical direction to split the substrate along the groove, and the preparation of the diamond-based microwave load is completed.

[0145] Compared with existing ALN-based and BeO-based microwave loads, it has unparalleled advantages in terms of mechanical properties, high-frequency characteristics, and heat dissipation performance.

[0146] Diamond has a Mohs hardness of 10, making it the hardest substance in nature. It has excellent hardness and toughness, and possesses excellent mechanical properties. Diamond has a high breakdown electric field of 10 MV / cm, approximately 26 times that of common ceramic materials, and can withstand higher electric fields without breakdown. Furthermore, its relative dielectric constant is 3.5, resulting in lower substrate parasitic capacitance at high frequencies and excellent high-frequency characteristics. The present invention utilizes a diamond substrate, which has a thermal conductivity of up to 2000 W / mK, dozens of times higher than AlO, AlN, and BeO substrates, greatly facilitating heat dissipation in the device.

[0147] The following is a specific example to illustrate the method for making the high-power diamond-based microwave load of the present invention. Figure 1 As shown in , the specific steps of the method are as follows:

[0148] Step 1: Select a CVD diamond substrate as the substrate, perform laser processing to groove the substrate, and the surface with the groove is the side surface of the substrate.

[0149] The specific laser processing methods are:

[0150] (1) Spin-coat laser protection liquid on the front side of the substrate.

[0151] (2) Use YLF laser equipment to process the groove edge path from the front with a length of 20 mm and a width of 0.2 mm, and cut off the matrix inside the hole groove.

[0152] (3) Use the YLF laser device to step along the edge of the hole from the front at a distance of 1 / 2 the diameter of the laser spot and expand outward until the hole diameter reaches 0.4 mm.

[0153] (4) Ultrasonication was performed using anhydrous ethanol for 10 minutes.

[0154] (5) Bake the substrate at 100°C for 1 hour.

[0155] Step 2: Surface treatment of the grooved CVD diamond substrate.

[0156] The specific surface treatment methods are:

[0157] (1) Heat chromic acid to 70°C and ultrasonicate for 10 minutes.

[0158] (2) Use 20% hydrofluoric acid at room temperature and perform ultrasound for 10 minutes.

[0159] (3) Rinse with deionized water for 2 minutes.

[0160] (4) Heat to 80°C with 3% alkaline surfactant and ultrasonicate for 20 minutes.

[0161] (5) QDR cycle was performed 3 times.

[0162] (6) Heat to 80°C with hot water and ultrasonicate for 20 minutes;

[0163] (7) QDR cycle was performed 6 times.

[0164] (8) Use anhydrous ethanol at room temperature and ultrasonicate for 10 minutes.

[0165] (9) The substrate was baked at 100°C for 1 hour.

[0166] (10) Pickling is used to remove the slag and organic carbides formed by laser processing.

[0167] Step 3: sputtering a resistor film layer and a metal seed layer on the front side of the slotted CVD diamond substrate.

[0168] The specific front sputtering method is:

[0169] (1) The TaN film is formed by magnetron sputtering, and the sheet resistance of the film is controlled to be 45 to 50 ohms / square, with a temperature resistance ratio of -100ppm ≤ TCR ≤ +100ppm. TCR refers to the percentage of resistance change per 1°C change in temperature, and ppm refers to one part per million.

[0170] (2) Magnetron sputtering is used to form a WTi film layer with a thickness of 100 nm and an Au film layer with a thickness of 100 nm. The WTi film layer serves as an interface adhesion layer between the upper and lower film layers.

[0171] Step 4: sputtering a metal seed layer on the back side of the grooved CVD diamond substrate.

[0172] The specific back-side sputtering method is to use magnetron sputtering to form a WTi film layer with a thickness of 200 nanometers and an Au film layer with a thickness of 100 nanometers. The WTi film layer serves as an interface adhesion layer between the substrate and the upper film layer.

[0173] Step 5: Electroplating thickens the front, back and side metal seed layers to form a conductor layer.

[0174] The specific electroplating method is:

[0175] (1) Select the corresponding 2-inch plating rack according to the shape and size of the substrate;

[0176] (2) The substrate is acid-washed and activated by heating 10% sulfuric acid to 45°C and soaking for 2 minutes;

[0177] (3) Calculate the electroplating current and time based on the area of ​​the substrate to be plated. Specific parameters are: 5000 mm² per substrate, 8 substrates per rack, 0.88 A current, 1350 seconds, and an Au plating thickness of 2-3 μm.

[0178] (4) Rinse with deionized water for 30 seconds;

[0179] (5) baking the substrate at 100°C for 10 minutes;

[0180] Step 6: Heat-treating the electroplated thickened CVD diamond substrate to perform high-temperature annealing.

[0181] The specific heat treatment method is: using a vacuum oven, at an atmospheric pressure of 150 Pa and a temperature of 300 ° C, for 2 hours;

[0182] Step 7: Fabricate a metal conductor pattern on the front side of the CVD diamond substrate.

[0183] The specific method for making the front metal conductor pattern is as follows:

[0184] (1) Press a 25um thick dry film on the front of the CVD diamond substrate using a dry film laminator. The lamination conditions are: roller pressure 0.4±0.1MPa, roller speed 0.5±0.1m / min, upper roller temperature 110±5℃, lower roller temperature 30±5℃

[0185] (2) Expose and develop the CVD diamond substrate with the dry film. The exposure energy is 5.6 mW / cm2, the exposure time is 5 seconds, and the development time is 2 minutes to 2 minutes and 30 seconds.

[0186] (3) Use an oven to harden the developed substrate. The baking temperature is 100 degrees Celsius and the baking time is 30 minutes to prevent the colloid from falling off during the corrosion process.

[0187] (4) Protect the back with a film and wet-etch the front side with the unnecessary metal conductor film. Use a potassium iodide and iodine solution etching system at room temperature of 25°C for 40 to 50 seconds.

[0188] (5) Wet-etch the unnecessary adhesive layer WTi from the front side using 70% hydrogen peroxide solution, heated to 90°C, and the etching time is controlled within 20 to 30 seconds.

[0189] (6) Soak in 3% NaOH alkaline solution for 30 minutes to remove the dry film on the surface of the substrate.

[0190] Step 8: Create a resistor pattern on the front side of the CVD diamond substrate.

[0191] The specific method for making the front resistance pattern is:

[0192] (1) A 25 μm thick dry film is pressed on the front of the CVD diamond substrate using a dry film laminator. The lamination conditions are: roller pressure 0.45 ± 0.1 MPa, roller speed 0.5 ± 0.1 m / min, upper roller temperature 110 ± 5 °C, lower roller temperature 30 ± 5 °C. Increasing the roller pressure makes the metal conductor film layer and the resistor film layer fit more closely at the step.

[0193] (2) Expose and develop the CVD diamond substrate with the dry film. The exposure energy is 5.6 mW / cm2, the exposure time is 5 seconds, and the development time is 2 minutes to 2 minutes and 30 seconds.

[0194] (3) Use an oven to harden the developed substrate. The baking temperature is 100 degrees Celsius and the baking time is 30 minutes to prevent the colloid from falling off during the corrosion process.

[0195] (4) Protect the back with a film and etch away the unnecessary resistor film layer on the front using a dry etching method. Use plasma etching equipment, Ar gas as the process gas, and control the time to be 80 to 120 minutes.

[0196] (5) Soak in 3% NaOH alkaline solution for 30 minutes to remove the dry film on the surface of the substrate.

[0197] Step 9: Thermally oxidize the front resistor of the CVD diamond substrate. The TaN resistor requires a precision of 50Ω±5%. As the core region of the high-power diamond-based microwave load, it is a critical dissipation region of the component. Resistance accuracy also affects the matching of the microwave characteristic impedance. Thermal oxidation trimming ensures resistance accuracy while maintaining stable resistance.

[0198] The specific thermal oxidation resistance adjustment method is:

[0199] (1) Classification based on the initial resistance value before resistance adjustment. Category 1 includes substrates with an average resistance of 45 to 47.5Ω; Category 2 includes substrates with an average resistance of 47.5 to 52Ω;

[0200] (2) Thermal oxidation resistance adjustment is performed under different conditions for different types of substrates. For type 1 substrates, each time they are baked in an air environment at 300°C for 2 hours until the average resistance is ≥47.5Ω, and then they are classified as type 2. For type 2 substrates, each time they are baked in an air environment at 200°C for 2 hours.

[0201] (3) Use an 8-bit and a half digital multimeter to test the DC resistance of the substrate after thermal oxidation resistance adjustment.

[0202] Step 10: Print dielectric glue on the resistor pattern area on the front side of the CVD diamond substrate.

[0203] The specific method for making the printed medium glue is as follows:

[0204] (1) Pre-treat the substrate surface. Wipe the substrate surface with anhydrous ethanol, rinse with deionized water for 30 seconds, and then blow it clean with a nitrogen gun to remove any water stains.

[0205] (2) Use AB epoxy resin glue with good thermal conductivity and stir it in a ratio of 1:10 for 10 minutes.

[0206] (3) Fix the screen printing plate, calibrate the position of the CVD diamond substrate, and then print.

[0207] (4) Now let it stand at room temperature of 25℃ for 6 hours, and then bake it in an oven at 80℃ for 1 hour.

[0208] Dielectric glue is a key factor in resistor heat dissipation and environmental protection.

[0209] Step 11: Divide the CVD diamond substrate into units. Due to the hardness of diamond, conventional grinding wheels cannot cut it.

[0210] The specific method for making the printed medium glue is as follows:

[0211] (1) Laser scribing is performed on the surface of the CVD substrate to form a cutting groove with a width of 0.04 mm and a depth of 0.3 mm along the center of the unit size edge line.

[0212] (2) Use a splitting machine to apply a pressure of 16 kg / cm2 in a direction perpendicular to the substrate surface, so that the substrate is split along the groove.

[0213] The above-described embodiments are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A method for preparing a high-power diamond-based microwave load, characterized in that: The method comprises the following steps: S1. Selection of substrate and laser grooving of substrate A CVD diamond substrate is selected as a substrate, and the substrate is grooved by laser processing; S2. Substrate surface treatment Performing surface treatment on the substrate after laser grooving; S3. Sputtering of the resistance film layer and the metal seed layer The resistor film layer and the metal seed layer are sequentially sputtered on the front side of the laser grooved substrate, the metal seed layer is sputtered on the back side, and the metal seed layer is sputtered on the surface of the hole groove formed by the laser groove; S4, electroplating thickening treatment and heat treatment Electroplating and thickening the metal seed layer on the front, back and side surfaces of the substrate to form a conductor layer, and heat treating the substrate after the electroplating and thickening process; S5. Fabrication of Metal Conductor Graphics Producing a metal conductor pattern on the front side of the substrate; S6. Fabrication of resistor graphics Fabricating a resistor pattern on the front side of the substrate; S7, thermal oxidation resistance adjustment Performing thermal oxidation resistance adjustment on the resistor pattern on the front side of the substrate; S8, printed medium glue Printing dielectric glue on the resistor pattern area on the front side of the substrate; S9. Substrate unit division The substrate is divided into units and the diamond-based microwave load is prepared; The sputtering of the resistive film layer and the metal seed layer includes: S31: Frontal Splash A TaN film layer is formed on the front surface of the laser grooved substrate by magnetron sputtering; a WTi film layer and an Au film layer are formed on the front surface of the laser grooved substrate by magnetron sputtering; S32, back sputtering Magnetron sputtering is used to form WTi and Au films on the back of the laser-grooved substrate. S33, sidewall sputtering Magnetron sputtering is used to form WTi film layers and Au film layers on the sidewalls of the laser-grooved substrate. The electroplating thickening treatment and heat treatment include: S41: Select the corresponding electroplating rack according to the shape and size of the substrate; S42: acid-washing and activating the substrate; S43: calculating the electroplating current and electroplating time of the electroplating rack according to the area of ​​the substrate to be electroplated, and electroplating the substrate using the electroplating rack according to the electroplating current and electroplating time; S44: Rinse the electroplated substrate with deionized water; S45: drying the substrate at 100° C. for 10 minutes; S46. Heat-treating the electroplated thickened substrate and performing high-temperature annealing.

2. The method according to claim 1, characterized in that The selection of the substrate and the laser grooving of the substrate include: S11: coating laser protection liquid on the front side of the substrate; S12: using a YLF laser device to cut off a portion of the front surface of the substrate to form a hole groove; S13: Use YLF laser equipment to continue to open the hole groove from the front of the substrate along the edge of the hole groove, so that the hole groove diameter meets the set requirements; S14: Ultrasonic immersion of the laser-grooved substrate in an organic solution to remove the laser protection liquid on the substrate; S15: Bake the substrate to remove moisture on the substrate.

3. The method according to claim 1, characterized in that The surface treatment includes: Pretreatment of slag and organic carbides formed on the substrate during laser processing and cleaning of hydrophilic organic dirt on the substrate surface.

4. The method according to claim 1, wherein The production of the metal conductor pattern includes: S51: Press a 25um thick dry film on the front of the board using a dry film laminator; S52: performing exposure and development processing on the substrate with the dry film pressed thereon; S53: using an oven to perform a hardening treatment on the substrate after the exposure and development treatments; S54: Apply a protective film to the back of the substrate and etch away the unnecessary metal conductor film layer on the front side using a wet method; S55: Use the front wet etching method to remove the unnecessary adhesion layer WTi; S56: Soak the substrate in a 3% NaOH alkaline solution for 30 minutes to remove the dry film on the surface of the substrate.

5. The method according to claim 1, wherein The production of the resistor pattern includes: S61: Press a 25um thick dry film on the front of the substrate using a dry film laminator; S62: performing exposure and development processing on the CVD diamond substrate with the dry film pressed thereon; S63: using an oven to perform a hardening treatment on the substrate after the exposure and development treatments; S64: Apply a protective film to the back of the substrate and etch away the unnecessary resistor film layer on the front side using a dry method; S65: Soak the substrate in a 3% NaOH alkaline solution for 30 minutes to remove the dry film on the substrate surface.

6. The method according to claim 1, characterized in that The thermal oxidation resistance adjustment method includes: S71: classifying substrates according to initial values ​​before resistance adjustment; S72: performing thermal oxidation resistance adjustment under different conditions on different classified substrates; S73: Use an 8.5-digit digital multimeter to perform a DC resistance test on the substrate after thermal oxidation resistance adjustment.

7. The method according to claim 1, characterized in that The printed medium glue comprises: S81: Pre-treating the substrate surface; S82: Mix and blend AB glue according to a certain ratio, fix the screen printing plate, calibrate the position of the substrate, and print the medium glue on the substrate; S83: The dielectric glue printed on the surface of the substrate is subjected to thermal curing treatment to catalyze the colloid to fully react, form long molecular chain aggregation, and dry out water vapor.

8. The method according to claim 1, characterized in that The substrate unit division includes: S91: Laser scribing is performed on the substrate surface to form fine grooves of a certain depth; S92: A splitting machine is used to apply pressure in the vertical direction to split the substrate along the groove, and the preparation of the diamond-based microwave load is completed.

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