Preparation method of ABM ceramic substrate with metal through hole

Abstract

The invention discloses a preparation method of an ABM ceramic substrate with a metal through hole, and particularly relates to the technical field of ceramic substrates, a Si3N4 ceramic substrate is prepared through tape casting and hot pressed sintering, a conical stepped through hole is processed by using ultrafast femtosecond laser, the aperture of the through hole is 100-300 [mu] m, and the smoothness of the wall of the through hole is Rat; 1 [mu] m; performing oxygen plasma activation on the inner wall of the through hole to generate a Si-O active group; sputtering a nano titanium transition layer to enhance metal-ceramic interface bonding; the through holes are filled layer by layer through pulse electrochemical deposition, the current density is controlled, and a compact non-porous structure is achieved; in-Sn-Ag low-temperature active brazing filler metal is used, and a surface copper layer is bonded under the assistance of plasma; a fine circuit is formed through photoetching and micro-electroplating, the line width and the spacing of the circuit are the same, and the line width and the spacing of the circuit are both smaller than 20 microns; etching a micro-channel network on the back surface of the substrate by using ultraviolet laser, and filling heat-conducting silicone grease; and finally, carrying out vacuum annealing for 2 hours in an environment with the temperature of 250 DEG C.

Description

Technical Field

[0001] The present application relates to the technical field of ceramic substrates, and particularly to a preparation method of an ABM ceramic substrate with metal vias. Background Art

[0002] The ABM ceramic substrate is a high-performance ceramic substrate prepared based on the active metal brazing technology. Its core process is to wet and react the AgCu solder containing a small amount of active elements (such as Ti, Zr, etc.) at a high temperature of about 800 °C at the ceramic and metal interface, so as to realize the heterogeneous bonding of ceramics and metals. The ABM ceramic substrate is a high-performance ceramic substrate based on the active metal brazing technology, with excellent thermal management performance, mechanical stability and electrical insulation, and is widely used in fields such as advanced semiconductor packaging, automotive electronics, rail transit and smart grid. Its technical advantages and market demand make it an important development direction in the future electronic packaging field;

[0003] After retrieval, the existing application number: CN202310585452.X discloses a preparation method of a thick copper-coated ceramic substrate for improving warping; the method includes the following steps: S1, loading the ceramic sheet on the ceramic pre-bending bracket, and the ceramic pre-bending bracket supports the outer edge of the ceramic sheet; 2, heating the ceramic pre-bending bracket loaded with the ceramic sheet, and cooling to room temperature and taking out of the furnace after heating is completed to obtain a pre-bent ceramic sheet; S3, heating the thick copper sheet in an oxidation environment; S4, preparing a DBC sintering bracket, placing the concave surface of the pre-bent ceramic sheet downward on the DBC sintering bracket, and the DBC sintering bracket supports the middle part of the pre-bent ceramic for mud discharge, and then placing the pre-oxidized thick copper sheet on the pre-bent ceramic; S5, placing the structure assembled in S4 in a sintering furnace for sintering, and cooling to room temperature after sintering is completed. While realizing the thin ceramic and thick copper structure, it can eliminate the warping of the product or control the warping within a small range; the inventor found the following problems in the process of realizing the present application: the metal via ceramic substrate has limitations, such as DBC or DPC ceramic substrates, among which the ceramic substrate has problems of weak interface bonding, poor thermal cycle performance and complex process;

[0004] Therefore, in view of the above problems, a preparation method of an ABM ceramic substrate with metal vias is proposed. Summary of the Invention

[0005] The purpose of the present application is to provide a preparation method of an ABM ceramic substrate with metal vias.

[0006] The preparation method of an ABM ceramic substrate with metal vias provided by the present application adopts the following technical scheme:

[0007] A preparation method of an ABM ceramic substrate with metal vias, the preparation method includes the following steps:

[0008] Step 1: Substrate preparation and via hole machining. Prepare the Si3N4 ceramic substrate by tape casting and hot-pressing sintering, and the thickness of the Si3N4 ceramic substrate is 0.3 - 1.0 mm. Use ultrafast femtosecond laser to machine tapered stepped via holes, the aperture of the via holes is 100 - 300 μm, the taper angle of the via holes is 10°, and the surface roughness Ra of the via hole wall is < 1 μm.

[0009] Step 2: Surface functionalization treatment. Activate the inner wall of the via holes by oxygen plasma to generate Si - O active groups. Sputter a nano titanium transition layer.

[0010] Step 3: Composite metal filling. Prepare copper - graphene nano slurry by mixing copper powder with a particle size of 1 μm and graphene with a sheet diameter of 5 - 10 nm. Use pulse electrochemical deposition to fill the via holes layer by layer to form a dense and pore-free structure.

[0011] Step 4: Low-temperature bonding and surface metallization. Select In - Sn - Ag low-temperature active solder, and the melting point of the solder is 120 °C. Bond the surface copper layer under plasma assistance, and the thickness of the copper layer is 50 μm. Form a circuit with the same line width and pitch, and both the line width and pitch are less than 20 μm through photolithography and microelectroplating.

[0012] Step 5: Microchannel integration and packaging. Etch the microchannel network on the back of the substrate with ultraviolet laser and fill it with thermal grease. Anneal for 2 hours in a vacuum environment at a temperature of 250 °C.

[0013] Preferably, in the substrate preparation and via hole machining, main material: select α - Si3N4 powder with a particle size of 0.5 - 1.5 μm, and the purity of the α - Si3N4 powder is greater than 99.9%; sintering aids: include but are not limited to Y2O3, Al2O3, and the addition amount of the sintering aids is 3 - 10 wt%; solvents: include but are not limited to ethanol, toluene or mixed solvents, where the mixed solvents include but are not limited to ethanol and xylene mixtures; dispersants: include but are not limited to phosphate esters or fish oil, and the addition amount of the dispersants is 0.5 - 2 wt%; binders: polyvinyl butyral or acrylate esters, and the addition amount of the binders is 5 - 10 wt%; plasticizers: include but are not limited to dibutyl phthalate or polyethylene glycol; where the Si3N4 powder, sintering aids, solvents, and dispersants are ball-milled for 12 - 24 hours, and the rotation speed of the ball-milling is 200 - 400 rpm. After adding the binder and plasticizer, continue to ball-mill for 4 - 6 hours to form a slurry with a viscosity of 200 - 1000 mPa·s.

[0014] Preferably, a polyester film is used as the casting carrier, and the height of the doctor blade is adjusted, and the height is 50 - 200 μm. The green body thickness is controlled, and it is dried for 4 - 8 hours in an environment with a temperature of 25 - 40°C and a humidity of 40% - 60%. After drying, the green body shrinks by about 20% - 30%. The dried green body is peeled and cut into the required shape, and the thickness is usually 0.1 - 1.0 mm. It is densified at a temperature of 1700 - 1850°C, a pressure of 20 - 40 MPa, in a nitrogen or argon environment and for 1 - 4 hours of heat preservation. The green body is degreased and pre-sintered, slowly heated at 300 - 600°C, and the time is controlled at 1 - 2°C / min. The pre-sintered body is heated. In the initial stage, that is, when the temperature is less than 1000°C, the pressure is controlled at 5 - 10 MPa. In the high-temperature stage, that is, when the temperature is greater than 1500°C, the pressure is controlled at 20 - 40 MPa. Then it is furnace-cooled to room temperature, and the cooling rate is ≤5°C / min. The substrate is subjected to subsequent processing. First, surface processing; polished with a diamond grinding wheel to Ra < 0.1 μm, secondly, annealing treatment; annealed at 1200 - 1400°C for 2 - 4 hours, and finally performance testing; the substrate density is greater than 3.2 g / cm 3 , the flexural strength is greater than 800 MPa and the thermal conductivity is greater than 30 W / m·K. An ultrafast femtosecond laser is used to punch holes in the substrate. The parameters of the ultrafast femtosecond laser are a wavelength of 1030 nm / 515 nm, a pulse width less than 500 fs, and a repetition frequency of 10 kHz - 1 MHz.

[0015] Preferably, the surface of the substrate is cleaned. The Si3N4 substrate with through holes is ultrasonically cleaned with acetone and ethanol for 15 minutes each to remove surface grease and particles. Then it is dried with nitrogen and placed in a plasma treatment chamber. In the plasma parameters, the equipment: radio frequency or microwave plasma system, gas: high-purity oxygen, flow rate 50 - 100 sccm, power: 100 - 300 W, pressure: low vacuum environment 10 - 50 Pa, treatment time: 5 - 15 minutes, sample placement: the axis of the through hole is parallel to the plasma electric field direction, or a rotating sample holder is used; the high-energy particles O + , O2 + , electrons bombard the surface of Si3N4, and Si - O - Si and Si - OH bonds are formed on the reaction surface. Then, the activity of Ti is used to form Ti - O - Si chemical bonding with the Si - O group. The equipment is a magnetron sputtering system, the target material is a high-purity titanium target with a purity greater than 99.99%, and the sputtering parameters are a base vacuum less than 5×10 -4Pa; Working gas: argon, flow rate 20 - 40 sccm; Sputtering power: DC 100 - 200 W; Gas pressure: 0.5 - 2 Pa; Substrate temperature: room temperature or heated to 100 - 200 °C; Sputtering time: 10 - 30 minutes; Sample movement: The substrate rotates at 10 - 30 rpm, where the film deposition rate is 0.1 - 0.3 nm / s, and where Ti reacts with Si - O to form TiO2 and Ti - Si compounds, and the roughness is less than 5 nm.

[0016] Preferably, the copper - graphene nano - slurry is specifically 1 - μm copper powder with a proportion of 85 - 92 wt%; graphene with a sheet diameter of 5 - 10 nm and a proportion of 3 - 8 wt%; a PVP dispersant with a proportion of 0.5 - 2 wt%; the balance is ethylene glycol solvent; a pH regulator with a pH value of 3 - 4. Graphene and PVP are ultrasonically treated in ethylene glycol for 1 hour, and the ultrasonic cleaning agent has a power of 500 W and a frequency of 40 kHz. Then copper powder is added and ball - milled for 4 hours, using zirconia balls, with the ball - mill equipment rotating at 300 rpm and a ball - to - material ratio of 5:1. Then it is left to stand for 12 hours to defoam, and the viscosity is adjusted to 200 - 500 mPa·s. The pore walls are activated by oxygen plasma, and the contact angle is less than 10°. A 50 - nm Ti layer is magnetron - sputtered and filled by pulsed electrochemical deposition. Equipment parameters: power supply mode; pulsed square wave, peak current density; 10 - 50 mA / cm 2 , conduction time; 1 - 10 ms, turn - off time; 5 - 50 ms, temperature 25 - 40 °C, stirring method; 40 - kHz ultrasonic assistance; for hierarchical filling, and the initial layer: J p = 10 mA / cm 2 , T on / T off = 1 ms / 50 ms; the middle layer J p = 30 mA / cm 2 , T on / T of x = 5 ms / 20 ms; the surface layer and the pore orifice J p = 50 mA / cm 2 , T on / T off = 10 ms / 5 ms.

[0017] Preferably, for optimizing the electric field in the through - hole; a multi - needle - shaped anode array is inserted into the through - hole, with 1 reverse pulse inserted for every 100 forward pulses, and the reverse pulse parameter is - 5 mA / cm 2, 0.1 ms. After each deposition of 50 μm thickness for the final in-situ annealing, infrared local heating is carried out at a heating temperature of 300 - 400 °C for 5 minutes, and N2 protection is used. During the densification treatment, the temperature is 600 °C, the pressure is 100 MPa, in an Ar gas environment, and the pressure is maintained for 1 hour, and the surface is polished; polished with diamond paste to Ra less than 0.1 μm.

[0018] Preferably, a vacuum hot pressing bonder with a pressure accuracy of ±0.1 N and a temperature accuracy of ±1 °C is used. First, load the wafer; align the copper layers of the upper and lower substrates with a gap of 50 μm, and vacuum adsorb and fix at a vacuum degree less than 1×10-3 Pa. Ar / H2 is introduced into the bonding chamber, and the ratio of Ar to H2 is 95:5. Treat for 2 minutes at a plasma activation power of 200 W, and then perform hot pressing bonding. The temperature curve is: 25 °C → 120 °C, with a heating rate of 10 °C / min → hold for 5 minutes → cool to 80 °C and then release the pressure. The pressure is: 0.5 - 1 MPa, and the pressure is applied in stages: 0.1 MPa @ 25 - 100 °C → 0.5 MPa @ 100 - 120 °C; Among them, a positive photoresist of AZ4620 is selected, and the spin coating parameters are: 3000 rpm × 30 s → thickness 8 μm → pre-bake at 110 °C × 2 minutes, and then exposure and development are carried out. The mask plate uses a chromium plate with a line width / spacing = 18 μm / 22 μm. Exposure is carried out using an i-line stepper, and development is carried out using AZ400K developer for 60 s → stop development with deionized water.

[0019] Preferably, an electroplating solution is prepared with 200 g / L of CuSO·5H2O, 50 g / L of H2SO4, 2 g / L of polyethylene glycol, 50 ppm of chloride ions, and 5 mL / L of brightener.

[0020] Preferably, the electroplating parameters are; mode: pulse electroplating, with a duty cycle of 30%, and a frequency of 100 Hz; current density: 1 A / dm 2 , initial 5 minutes → 2 A / dm 2 , main body deposition; the temperature is 25 ± 1 °C; the time is a deposition rate of 0.4 μm / min; and stirring is carried out; the cathode rotates, that is, the rotation is 30 rpm and air bubbling is carried out with a flow rate of 0.5 L / min. Post-treatment is carried out: 200 °C × 30 minutes, and N2 protection is used; CMP polishing is carried out with alumina polishing slurry, and the pH of the alumina polishing slurry is 4, and the polishing degree is less than 0.05 μm.

[0021] Preferably, ultraviolet laser etching is used, with parameters as follows: laser wavelength is 355 nm, pulse width is 15 ns, repetition frequency is 50 kHz, single pulse energy is 80 μJ, scanning speed is 200 mm / s, focal diameter is 10 μm, and the processing environment is nitrogen purging. Etching is carried out in layers. The rough etching depth is 200 μm, the annular spiral path spacing is 8 μm, and 5 cycles are carried out. The energy density is 8 J / cm 2 : The fine etching depth is 50 μm, the linear bidirectional scanning spacing is 2 μm, and the energy density is 3 J / cm 2 : The surface is smooth, and the low energy is 1 J / cm 2 For the side wall of the laser remelting channel: hydrofluoric acid vapor etching is carried out with HF:H2O = 1:10 for 30 seconds, and then thermal conductive silicone grease is filled. The vacuum perfusion parameters are a pressure of 0.01 Pa and a pressure holding time of 30 minutes. The silicone grease formulation parameters are silicone matrix + 40 vol% BN nanosheets. The curing condition parameters are 120 °C / 1 hour → thermal conductivity > 4 W / m·K. The channel sealing parameters are ultraviolet curing glue, and vacuum annealing stress relief is carried out. The annealing temperature is 250 °C, which is lower than the decomposition temperature of Si3N4. The heating rate is 3 °C / min, and the vacuum degree is 5×10 -3 Pa, the heat preservation time is 2 hours, and the cooling method is furnace cooling to 150 °C followed by air cooling.

[0022] In summary, the present application includes at least one of the following beneficial technical effects: Among them, the interfacial bonding strength of the traditional DBC substrate is 20 - 30 MPa, and the interfacial bonding strength of the ABM substrate in this solution is 50 - 70 MPa; for the parameter of the number of thermal cycles of the traditional DBC substrate is 500 times, and the number of thermal cycles of the ABM substrate in this solution is > 2000 times; for the parameter of the thermal resistance of the traditional DBC substrate is 0.5 K / W, and the thermal resistance of the ABM substrate in this solution is 0.2 K / W; for the parameter of the via resistance of the traditional DBC substrate is 0.5 mΩ·mm, and the via resistance of the ABM substrate in this solution is 0.3 mΩ·mm; for the parameter of the process temperature of the traditional DBC substrate is 800 - 1000 °C, and the process temperature of the ABM substrate in this solution is 200 - 300 °C. Substrate material: Silicon nitride ceramic is used, which has both high thermal conductivity of 80 - 90 W / m·K, high mechanical strength, flexural strength > 800 MPa, and low thermal expansion coefficient, CTE ≈ 3.2 ppm / °C; Via metal: Copper-graphene composite metal is used, in which 1 - 3 wt% graphene is dispersed in the copper matrix to improve electrical conductivity and thermal stress resistance, and the CTE can be adjusted to 4.5 ppm / °C; Gradient via structure: The via is designed as a tapered stepped shape with a large upper part and a small lower part to increase the metal-ceramic interfacial bonding area and reduce stress concentration; Microchannel heat dissipation layer: Laser-etched microchannels with a width of 50 - 100 μm are integrated on the back of the substrate to directly cool high-power devices; Low-temperature plasma activation bonding: Plasma-assisted active metal brazing is used to achieve ceramic-metal bonding at 200 - 300 °C, while traditional ABM requires above 800 °C; Electrochemical 3D printing filling: Nanocopper paste is used for electrochemical deposition to achieve high-density metal filling in the vias, avoiding deformation during high-temperature sintering, and solving the problems of weak interfacial bonding, poor thermal cycle performance, and complex process of metal via ceramic substrates. Description of the Drawings

[0023] Figure 1 It is a schematic diagram of the preparation process of the ABM ceramic substrate with metal vias in the embodiment of the present application. Detailed Description of the Embodiment

[0024] The following is a further detailed description of the present application in conjunction with the attached Figure 1 drawings.

[0025] Embodiment: A method for preparing an ABM ceramic substrate with metal vias includes the following steps:

[0026] Step 1: Substrate preparation and via processing;

[0027] Prepare an Si3N4 ceramic substrate by tape casting and hot press sintering, and the thickness of the Si3N4 ceramic substrate is 0.3 - 1.0 mm;

[0028] A tapered stepped through-hole is machined using an ultrafast femtosecond laser, the aperture of the through-hole is 100 - 300 μm, the taper angle of the through-hole is 10°, and the surface roughness Ra of the through-hole wall is < 1 μm;

[0029] Step 2: Surface functionalization treatment;

[0030] The inner wall of the through-hole is activated by oxygen plasma to generate Si - O active groups;

[0031] A nano-titanium transition layer is sputtered to enhance the metal-ceramic interface bonding;

[0032] Step 3: Composite metal filling;

[0033] A copper-graphene nano-slurry is prepared, which is made by mixing copper powder with a particle size of 1 μm and graphene with a sheet diameter of 5 - 10 nm;

[0034] Pulse electrochemical deposition is used to fill the through-hole layer by layer, and the current density is controlled to achieve a dense and pore-free structure;

[0035] Step 4: Low-temperature bonding and surface metallization;

[0036] An In-Sn-Ag low-temperature active solder is used, the melting point of the solder is 120 °C, and the surface copper layer is bonded under plasma assistance, and the thickness of the copper layer is 50 μm;

[0037] A fine circuit is formed by photolithography and micro-electroplating, the line width and pitch of the circuit are the same, and both the line width and pitch of the circuit are less than 20 μm;

[0038] Step 5: Microchannel integration and packaging;

[0039] A microchannel network is etched on the back of the substrate using ultraviolet laser and filled with thermal conductive silicone grease;

[0040] Finally, vacuum annealing is carried out at 250 °C for 2 hours to eliminate residual stress;

[0041] Among them, the interfacial bonding strength of the traditional DBC substrate is 20 - 30 MPa, while that of the ABM substrate in this solution is 50 - 70 MPa; the number of thermal cycles of the traditional DBC substrate is 500 times, while that of the ABM substrate in this solution is > 2000 times; the thermal resistance of the traditional DBC substrate is 0.5 K / W, while that of the ABM substrate in this solution is 0.2 K / W; the via resistance of the traditional DBC substrate is 0.5 mΩ·mm, while that of the ABM substrate in this solution is 0.3 mΩ·mm; the process temperature of the traditional DBC substrate is 800 - 1000 °C, while that of the ABM substrate in this solution is 200 - 300 °C. Substrate material: Silicon nitride ceramic is used, which has both high thermal conductivity of 80 - 90 W / m·K, high mechanical strength, flexural strength > 800 MPa, and low coefficient of thermal expansion, CTE ≈ 3.2 ppm / °C; Via metal: Copper-graphene composite metal is used, in which 1 - 3 wt% graphene is dispersed in the copper matrix to improve electrical conductivity and thermal stress resistance, and the CTE can be adjusted to 4.5 ppm / °C; Gradient via structure: The via is designed as a tapered stepped shape with a larger upper part and a smaller lower part to increase the metal-ceramic interface bonding area and reduce stress concentration; Microchannel heat dissipation layer: Laser-etched microchannels with a width of 50 - 100 μm are integrated on the back of the substrate to directly cool high-power devices; Low-temperature plasma activation bonding: Plasma-assisted active metal soldering is used to achieve ceramic-metal bonding at 200 - 300 °C, while traditional ABM requires a temperature above 800 °C; Electrochemical 3D printing filling: Nano-copper paste is used for electrochemical deposition to achieve high-density metal filling in the vias and avoid deformation due to high-temperature sintering;

[0042] Among them, raw materials are selected for the ceramic substrate: Main material: α-Si3N4 powder, and the powder particle size is 0.5 - 1.5 μm, and the purity of the α-Si3N4 powder is greater than 99.9%; Sintering aids: including but not limited to Y2O3, Al2O3, and the addition amount of the sintering aids is 3 - 10 wt% to promote liquid-phase sintering; Solvents: including but not limited to ethanol, toluene, or mixed solvents, where the mixed solvents include but not limited to ethanol and xylene mixtures; Dispersants: including but not limited to phosphate esters or fish oil, and the addition amount of the dispersants is 0.5 - 2 wt%; Binders: Polyvinyl butyral or acrylate esters, and the addition amount of the binders is 5 - 10 wt%; Plasticizers: including but not limited to dibutyl phthalate or polyethylene glycol; Among them, the Si3N4 powder, sintering aids, solvents, and dispersants are ball-milled for 12 - 24 hours, and the rotation speed of the ball-milling is 200 - 400 rpm. After adding the binder and plasticizer, ball-milling is continued for 4 - 6 hours to form a stable, low-viscosity slurry, and the viscosity of the slurry is 200 - 1000 mPa·s;

[0043] Among them, polyester film is used as the casting carrier, and the height of the doctor blade is adjusted, and the height is 50 - 200 μm. The green body thickness is controlled, and it is dried for 4 - 8 hours in an environment with a temperature of 25 - 40 °C and a humidity of 40% - 60%. After drying, the green body shrinks by about 20% - 30%. The dried green body is peeled and cut into the required shape, and the thickness is usually 0.1 - 1.0 mm. Among them, it is densified at a temperature of 1700 - 1850 °C, a pressure of 20 - 40 MPa, in a nitrogen or argon environment and for 1 - 4 hours of heat preservation. And the green body is degreased and pre-sintered, slowly heated up at 300 - 600 °C, and the time is controlled at 1 - 2 °C / min. The pre-sintered body is heated. Among them, in the initial stage, that is, when the temperature is less than 1000 °C, the pressure is controlled at 5 - 10 MPa. In the high-temperature stage, that is, when the temperature is greater than 1500 °C, the pressure is controlled at 20 - 40 MPa. Then it is furnace-cooled to room temperature, and the cooling rate ≤ 5 °C / min. The substrate is subjected to subsequent processing. First, surface processing; polished with a diamond grinding wheel to Ra < 0.1 μm. Secondly, annealing treatment; annealed at 1200 - 1400 °C for 2 - 4 hours. Finally, performance testing; the substrate density is greater than 3.2 g / cm 3 , the flexural strength is greater than 800 MPa and the thermal conductivity is greater than 30 W / m·K. Among them, an ultrafast femtosecond laser is used to drill holes in the substrate. The parameters of the ultrafast femtosecond laser are wavelength 1030 nm / 515 nm, pulse width less than 500 fs, and repetition frequency 10 kHz - 1 MHz;

[0044] Among them, the surface of the substrate is cleaned. The Si3N4 substrate with through holes is ultrasonically cleaned with acetone and ethanol for 15 minutes each to remove surface grease and particles. Then it is dried with nitrogen and placed in a plasma treatment chamber. Among the plasma parameters, the equipment: radio frequency or microwave plasma system, gas: high-purity oxygen, flow rate 50 - 100 sccm, power: 100 - 300 W, pressure: low vacuum environment 10 - 50 Pa, treatment time: 5 - 15 minutes, sample placement: the axis of the through hole is parallel to the plasma electric field direction, or a rotating sample holder is used; Among them, the high-energy particles O + , O2 + , electrons bombard the Si3N4 surface, and Si - O - Si and Si - OH bonds are formed on the reaction surface. Then, the activity of Ti is used to form Ti - O - Si chemical bonding with the Si - O group. The equipment is a magnetron sputtering system, the target is a high-purity titanium target with a purity greater than 99.99%, and the sputtering parameters are the base vacuum less than 5×10 -4Pa; Working gas: argon, flow rate 20 - 40 sccm; Sputtering power: DC 100 - 200 W; Gas pressure: 0.5 - 2 Pa; Substrate temperature: room temperature or heated to 100 - 200 °C; Sputtering time: 10 - 30 minutes; Sample movement: The substrate rotates at 10 - 30 rpm, where the film deposition rate is 0.1 - 0.3 nm / s, and where Ti reacts with Si - O to form TiO2 and Ti - Si compounds, and the roughness is less than 5 nm;

[0045] Among them, the copper - graphene nano - slurry is specifically 1 μm copper powder with a proportion of 85 - 92 wt%; graphene with a sheet diameter of 5 - 10 nm and a proportion of 3 - 8 wt%; a PVP dispersant with a proportion of 0.5 - 2 wt%; the balance is ethylene glycol solvent; a pH regulator with a pH of 3 - 4. Among them, graphene and PVP are ultrasonically treated in ethylene glycol for 1 hour, and the ultrasonic cleaning agent power is 500 W, 40 kHz. Then copper powder is added and ball - milled for 4 hours, using zirconia balls, the ball - milling equipment rotates at 300 rpm, and the ball - to - material ratio is 5:1. Then it is left to stand for 12 hours to defoam, and the viscosity is adjusted to 200 - 500 mPa·s. Among them, the pore walls are activated by oxygen plasma, and the contact angle is less than 10°. And a 50 nm Ti layer is magnetron - sputtered and filled by pulsed electrochemical deposition, equipment parameters; power supply mode; pulsed square wave, peak current density; 10 - 50 mA / cm 2 、Conduction time; 1 - 10 ms, Turn - off time; 5 - 50 ms, Temperature 25 - 40 °C, Stirring method; 40 kHz ultrasonic assistance; Stratified filling is carried out, and the initial layer: J p = 10 mA / cm 2 , T on / T off = 1 ms / 50 ms; The middle layer J p = 30 mA / cm 2 , T on / T off = 5 ms / 20 ms; The surface layer and the pore mouth J p = 50 mA / cm 2 , T on / T off = 10 ms / 5 ms, where the electric field in the through - hole is optimized; a multi - needle - shaped anode array is inserted into the through - hole, and 1 reverse pulse is inserted every 100 positive pulses, and the reverse pulse parameter is - 5 mA / cm 2, 0.1 ms. After each deposition of 50 μm thickness for the final in-situ annealing, infrared local heating is carried out at a heating temperature of 300 - 400 °C for 5 minutes, and N2 protection is used. During the densification treatment, the temperature is 600 °C, the pressure is 100 MPa, and it is kept under pressure for 1 hour in an Ar gas environment, and the surface is polished; polished with diamond polishing paste to Ra less than 0.1 μm. The specific composition and formation mechanism of the dense and pore-free structure are the refinement of copper grains: Pulse deposition inhibits grain growth, and the copper grain size is reduced from 1 - 5 μm in traditional DC deposition to 200 - 500 nm, the grain boundary density increases, and the grain boundary pores are reduced; Graphene filling effect: Nano-graphene sheets are inserted into copper grain boundaries and lattice defects to physically block pores; Interface chemical bonding: A chemical connection is formed between the copper and graphene interfaces through a cuprous oxide transition layer to enhance the bonding strength and avoid interlayer peeling;

[0046] Among them, a vacuum hot pressing bonder with a pressure accuracy of ±0.1 N and a temperature accuracy of ±1 °C is used. First, the wafers are loaded; the copper layers of the upper and lower substrates are aligned with a gap of 50 μm, and vacuum adsorption fixation is carried out at a vacuum degree less than 1×10-3 Pa. Ar / H2 is introduced into the bonding chamber, and the ratio of Ar to H2 is 95:5. It is processed for 2 minutes at a plasma activation power of 200 W, and then hot pressing bonding is carried out. The temperature curve is: 25 °C → 120 °C, and the heating rate is 10 °C / min → keep warm for 5 minutes → cool to 80 °C and then release the pressure. The pressure is: 0.5 - 1 MPa, and it is pressurized in stages: 0.1 MPa @ 25 - 100 °C → 0.5 MPa @ 100 - 120 °C; Among them, a positive photoresist of AZ4620 is selected, and the spin coating parameters are: 3000 rpm × 30 s → thickness 8 μm → pre-baking at 110 °C × 2 minutes, and then exposure and development are carried out. The mask plate uses a chromium plate with a line width / spacing = 18 μm / 22 μm. Exposure is carried out using an i-line stepper, and development is carried out using AZ400K developer. The development time is 60 s → stop development with deionized water. Among them, an electroplating solution is prepared with 200 g / L of CuSO·5H2O, 50 g / L of H2SO4, 2 g / L of polyethylene glycol, 50 ppm of chloride ions, and 5 mL / L of brightener. The electroplating parameters are; Mode: Pulse electroplating, and the duty cycle is 30%, the frequency is 100 Hz; Current density: 1 A / dm 2 , initial 5 minutes → 2 A / dm 2 , the main body is deposited; the temperature is 25 ± 1 °C; the time is a deposition rate of 0.4 μm / min; and stirring is carried out; the cathode rotates, that is, the rotation is 30 rpm and air bubbling is carried out, and the flow rate is 0.5 L / min. Post-treatment is carried out: 200 °C × 30 minutes, and N2 protection is used; CMP polishing is carried out using alumina polishing liquid, and the pH of the alumina polishing liquid is 4, and the polishing degree is less than 0.05 μm;

[0047] Among them, ultraviolet laser etching; parameters; the laser wavelength is 355 nm, the pulse width is 15 ns, the repetition frequency is 50 kHz, the single pulse energy is 80 μJ, the scanning speed is 200 mm / s, the focal diameter is 10 μm, and the processing environment is nitrogen purging; etching is carried out in layers; among them, the rough etching depth is 200 μm: the annular spiral path spacing is 8 μm, and 5 cycles are carried out: the energy density is 8 J / cm 2 : among them, the fine etching depth is 50 μm; the linear bidirectional scanning spacing is 2 μm: the energy density is 3 J / cm 2 : among them, the surface is smooth; the low energy is 1 J / cm 2 Laser remelting of the channel sidewall: hydrofluoric acid vapor etching with HF:H2O = 1:10 for 30 seconds, filled with thermal conductive silicone grease, where the vacuum infusion parameters are a pressure of 0.01 Pa and a pressure holding time of 30 minutes; the silicone grease formulation parameters are silicone matrix + 40 vol% BN nanosheets; the curing condition parameters are 120 °C / 1 hour → thermal conductivity > 4 W / m·K; the channel sealing parameters are ultraviolet curing glue, and vacuum annealing stress relief is carried out; the annealing temperature is 250 °C, which is less than the decomposition temperature of Si3N4; the heating rate is 3 °C / min; the vacuum degree is 5×10 -3 Pa; the heat preservation time is 2 hours; the cooling method is furnace cooling to 150 °C and then air cooling.

[0048] The working process of this application is as follows: First, substrate preparation and through-hole processing: Prepare the Si3N4 ceramic substrate by tape casting + hot press sintering, and use an ultrafast femtosecond laser to process tapered stepped through-holes to ensure that the hole wall is smooth with Ra less than 1 μm; second, surface functionalization treatment: perform oxygen plasma activation on the inner wall of the through-hole to generate Si-O active groups, and sputter a nano-titanium transition layer to enhance the metal-ceramic interface bonding; second, composite metal filling: prepare a copper-graphene nano-slurry, and use pulse electrochemical deposition to fill it layer by layer in the through-hole, control the current density, and achieve a dense and pore-free structure; second, low-temperature bonding and surface metallization: use In-Sn-Ag low-temperature active solder to bond the surface copper layer under plasma assistance, and form a fine circuit through photolithography + microelectroplating. Finally, microchannel integration and packaging: Use ultraviolet laser to etch the microchannel network on the back of the substrate, fill it with thermal conductive silicone grease or directly pass coolant, and finally perform vacuum annealing to eliminate residual stress, solving the problems of weak metal through-hole ceramic substrate interface bonding, poor thermal cycling performance, and complex processes.

[0049] The embodiments of this specific implementation manner are all preferred embodiments of this application, and do not limit the protection scope of this application accordingly. Among them, the same components are represented by the same reference numerals. Therefore, all equivalent changes made according to the structure, shape, and principle of this application should be covered within the protection scope of this application.

Claims

1. A method for preparing an ABM ceramic substrate with metal through holes, characterized in that: The preparation method comprises the following steps: Step 1: Substrate preparation and through-hole processing: a Si3N4 ceramic substrate is prepared by tape casting and hot pressing sintering, and the thickness of the Si3N4 ceramic substrate is 0.3-1.0 mm; an ultrafast femtosecond laser is used to process a tapered stepped through hole, the aperture of the through hole is 100-300 μm, the cone angle of the through hole is 10°, and the smoothness of the through hole wall is Ra<1 μm; Step 2: Surface functionalization treatment, oxygen plasma activation of the inner wall of the through hole to generate Si-O active groups; sputtering of nano-titanium transition layer; Step 3: Composite metal filling, preparing copper-graphene nano-slurry, using copper powder with a particle size of 1 μm and graphene with a flake size of 5-10 nm to mix; using pulse electrochemical deposition to fill the through holes layer by layer to form a dense and non-porous structure; Step 4: Low-temperature bonding and surface metallization: In-Sn-Ag low-temperature active solder with a melting point of 120°C is selected, and the surface copper layer is bonded under plasma assistance, with a thickness of 50 μm; circuits with the same line width and spacing, and the line width and spacing are both less than 20 μm, are formed by photolithography and micro-electroplating; Step 5: Microchannel integration and packaging: use ultraviolet laser to etch the microchannel network on the back of the substrate and fill it with thermal grease; anneal in a vacuum environment at 250°C for 2 hours.

2. The method for preparing an ABM ceramic substrate with metal through holes according to claim 1, characterized in that: In the preparation of substrate and through-hole processing, the main material is: α-Si3N4 powder with a particle size of 0.5-1.5μm, and the purity of α-Si3N4 powder is greater than 99.9%; sintering aids include but are not limited to Y2O3 and Al2O3, and the addition amount of sintering aids is 3-10wt%; solvents include but are not limited to ethanol, toluene or mixed solvents, wherein the mixed solvents include but are not limited to ethanol and xylene mixtures; dispersants include but are not limited to phosphates or fish oil, and the dispersants The addition amount is 0.5-2wt%; binder: polyvinyl butyral or acrylate, and the addition amount of the binder is 5-10wt%; plasticizer: including but not limited to dibutyl phthalate or polyethylene glycol; wherein Si3N4 powder, sintering aid, solvent, and dispersant are ball-milled for 12-24 hours, and the ball-milling speed is 200-400rpm, after adding the binder and plasticizer, continue ball-milling for 4-6 hours to form a slurry with a viscosity of 200-1000mPa·s.

3. The method for preparing an ABM ceramic substrate with metal through holes according to claim 2, characterized in that: A polyester film is used as a casting carrier, and the height of the scraper is adjusted to 50-200 μm. The thickness of the green body is controlled, and the green body is dried for 4-8 hours at a temperature of 25-40°C and a humidity of 40% to 60%. The green body shrinks by about 20% to 30% after drying. The dried green body is peeled and cut into a desired shape, and the thickness is usually 0.1-1.0 mm. The green body is densified at a temperature of 1700-1850°C, a pressure of 20-40 MPa, a nitrogen or argon environment, and a heat preservation time of 1 to 4 hours, and the green body is degreased and pre-sintered. -600℃ slowly heating, and the time is controlled at 1-2℃ / min, pre-sintering is heated, wherein the initial stage, i.e., the temperature is less than 1000℃, the pressure is controlled at 5-10MPa, the high temperature stage, i.e., the temperature is greater than>1500℃, the pressure is controlled at 20-40MPa, and then the furnace is cooled to room temperature, and the cooling rate is ≤5℃ / min, the substrate is subsequently processed, first surface processing; diamond grinding wheel polishing to Ra<0.1μm, followed by annealing; 1200-1400℃ annealing for 2-4 hours, and finally performance testing; the substrate density is greater than 3.2g / cm 3 , flexural strength greater than 800MPa and thermal conductivity greater than 30W / m·K, wherein an ultrafast femtosecond laser is used to drill holes in the substrate, wherein the ultrafast femtosecond laser parameters are a wavelength of 1030nm / 515nm, a pulse width of less than 500fs, and a repetition frequency of 10kHz-1MHz.

4. The method for preparing an ABM ceramic substrate with metal through holes according to claim 1, characterized in that: The surface of the substrate is cleaned, and the Si3N4 substrate containing the through hole is ultrasonically cleaned with acetone and ethanol for 15 minutes each to remove surface grease and particles, and then dried with nitrogen and placed in a plasma processing chamber, wherein the plasma parameters include equipment: radio frequency or microwave plasma system, gas: high-purity oxygen, flow rate 50-100sccm, power: 100-300W, pressure: low vacuum environment 10-50Pa, processing time: 5-15 minutes, sample placement: the through hole axis is parallel to the plasma electric field direction, or a rotating sample holder is used; wherein the high-energy particles O in the oxygen plasma + 、O2 + , electrons bombard the surface of Si3N4, and a reaction occurs on the surface to form Si-O-Si and Si-OH bonds; then the activity of Ti is used to form Ti-O-Si chemical bonds with Si-O groups. The equipment is a magnetron sputtering system, the target material is a high-purity titanium target with a purity greater than 99.99%, and the sputtering parameters are a background vacuum of less than 5×10 -4 Pa; working gas: argon, flow rate 20-40sccm; sputtering power: DC100-200W; Gas pressure: 0.5-2Pa; substrate temperature: room temperature or heated to 100-200℃; sputtering time: 10-30 minutes; sample movement: substrate rotation is 10-30rpm, where the film passing rate is 0.1-0.3nm / s, and Ti reacts with Si-O to generate TiO2 and Ti-Si compounds, and the roughness is less than 5nm.

5. The method for preparing an ABM ceramic substrate with metal through holes according to claim 1, characterized in that: The copper-graphene nano-slurry is specifically 1 μm copper powder and accounts for 85-92wt%; graphene with a sheet diameter of 5-10nm and accounts for 3-8wt%; PVP dispersant with a ratio of 0.5-2wt%; the balance is ethylene glycol solvent; pH regulator at 3-4, wherein graphene and PVP are ultrasonically treated in ethylene glycol for 1 hour, and the power of the ultrasonic cleaning agent is 500W, 40kHz, and then copper powder is added, ball milled for 4 hours, and zirconium oxide balls are used, the ball milling equipment speed is 300rpm, the ball-to-material ratio is 5:1, and then it is left to stand for 12 hours to defoam, and the viscosity is adjusted to 200-500mPa·s, wherein oxygen plasma is used to activate the pore wall, and the contact angle is less than 10°, and a 50nmTi layer is magnetron sputtered, and filled by pulse electrochemical deposition, equipment parameters; power mode; pulse square wave, peak current density; 10-50mA / cm 2 , on time: 1-10ms, off time: 5-50ms, temperature: 25-40℃, stirring method: 40kHz ultrasonic assisted; layered filling, and the initial layer: J p =10mA / cm 2 , T on / T off =1ms / 50ms; middle layer J p =30mA / cm 2 , T on / T o ff=5ms / 20ms; surface and orifice J p =50mA / cm 2 , T on / T o ff=10ms / 5ms.

6. The method for preparing an ABM ceramic substrate with metal through holes according to claim 1, characterized in that: The electric field in the through hole is optimized; a multi-needle anode array is inserted into the through hole, and one reverse pulse is inserted for every 100 forward pulses, and the reverse pulse parameter is -5mA / cm 2 , 0.1ms, and finally in-situ annealing. After each deposition of 50μm thickness, infrared local heating is performed, and the heating temperature is 300-400℃, the heating time is 5 minutes, and N2 protection is used. In the densification treatment, the temperature is 600℃, the pressure is 100MPa, and the Ar gas environment is maintained for 1 hour, and the surface is polished; polished with diamond paste to Ra less than 0.1μm.

7. The method for preparing an ABM ceramic substrate with metal through holes according to claim 1, characterized in that: A vacuum hot press bonding machine with a pressure accuracy of ±0.1N and a temperature accuracy of ±1°C was used. The wafer was loaded first. The copper layers of the upper and lower substrates were aligned with a gap of 50μm and the vacuum degree was less than 1×10 -3 Pa is used for vacuum adsorption and fixation, Ar / H2 is introduced into the bonding chamber, and the ratio of Ar to H2 is 95:5, and it is treated for 2 minutes under the condition of plasma activation power of 200W for hot pressing bonding, wherein the temperature curve is: 25℃→120℃, and the heating rate is 10℃ / min→keep warm for 5 minutes→cool to 80℃ and then release the pressure, the pressure is: 0.5-1MPa, and the pressurization is applied in stages: 0.1MPa@25-100℃→0.5MPa@100-120℃; wherein AZ4620 positive photoresist is selected, and the spin coating parameters are: 3000rpm×30s→thickness 8μm→pre-bake 110℃×2 minutes, and then exposure and development are carried out, wherein the mask plate adopts a chrome plate with line width / spacing = 18μm / 22μm, the exposure adopts an i-line stepper lithography machine for exposure, and AZ400K developer is used for development, the development time is 60s→deionized water stops development.

8. The method for preparing an ABM ceramic substrate with metal through holes according to claim 1, characterized in that: The plating solution is prepared by using 200 g / L of CuSO·5H2O, 50 g / L of H2SO4, 2 g / L of polyethylene glycol, 50 ppm of chloride ions and 5 mL / L of brightener.

9. The method for preparing an ABM ceramic substrate with metal through holes according to claim 1, characterized in that: The electroplating parameters are: Mode: Pulse plating, duty cycle 30%, frequency 100Hz; current density: 1A / dm 2 , initial 5 minutes → 2A / dm 2 , main body deposition; temperature is 25±1℃; time is deposition rate 0.4μm / min; and stirring is performed; cathode rotation, i.e. rotation is 30rpm and air bubbling, and the flow rate is 0.5L / min, post-treatment is performed: 200℃×30 minutes, and N2 protection is used; CMP polishing is performed using alumina polishing liquid, and the pH of the alumina polishing liquid is 4, and the polishing degree is less than 0.05μm.

10. The method for preparing an ABM ceramic substrate with metal through holes according to claim 1, characterized in that: The parameters of ultraviolet laser etching are as follows: laser wavelength is 355nm, pulse width is 15ns, repetition frequency is 50kHz, single pulse energy is 80μJ, scanning speed is 200mm / s, focal diameter is 10μm, and processing environment is nitrogen purging; etching is performed in layers; the rough etching depth is 200μm; the spacing of the annular spiral path is 8μm, and 5 cycles are performed; the energy density is 8J / cm 2 :The finishing etching depth is 50μm; Linear bidirectional scanning pitch is 2μm: energy density is 3J / cm 2 : The surface is smooth; Low energy 1J / cm 2 Laser remelting channel sidewall: hydrofluoric acid vapor etching, and HF:H2O=1:10, for 30 seconds, thermal conductive silicone grease filling, wherein the vacuum infusion parameters are pressure 0.01Pa, pressure holding for 30 minutes; silicone grease formula parameters are silicone matrix + BN nanosheet 40vol%; curing condition parameters are 120℃ / 1hour→thermal conductivity>4W / m·K; channel sealing parameters are UV curing glue, vacuum annealing stress elimination; annealing temperature is 250℃, which is lower than the decomposition temperature of Si3N4; heating rate is 3℃ / min; vacuum degree is 5×10 -3 Pa; the holding time is 2 hours; the cooling method is furnace cooling to 150℃ and then air cooling.

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