Diamond through hole forming method and device based on laser coupling high pressure water jet

Abstract

Diamond through hole forming method and device based on laser coupling high pressure water jet, including the following steps: the diamond to be processed is fixed on a three-dimensional moving processing table, high energy density of an ultrashort pulse laser is used to realize non-thermal melting processing of the diamond, and an initial blind hole with a graphite residual layer is quickly formed on the diamond; a high pressure water jet mixed with a first oxidizing corrosion component is used to act on the initial blind hole, the graphite residual layer on the initial blind hole is removed, and the blind hole is reamed; a high pressure water jet containing a second oxidizing corrosion component is sprayed, and a nanosecond pulse laser is coupled to act on the reamed blind hole, a processing mode similar to water guide laser is formed, and a set through hole structure is obtained. The three-step method of laser direct drilling pretreatment, high pressure chemical water jet reaming processing and chemical assisted laser reaming polishing is adopted, rapid and high precision processing of the diamond through hole is realized, the processing efficiency, precision and quality are greatly improved, the cost can be reduced, and the method is environmentally friendly and efficient.

Description

Technical Field

[0001] This invention relates to the field of laser processing technology, and in particular to a method and apparatus for forming diamond through-holes based on laser-coupled high-pressure water jet. Background Technology

[0002] Diamond, with its ultra-high thermal conductivity (>2000 W / m·K), high insulation, and extremely low coefficient of thermal expansion, is an ideal material for heat dissipation in high-power semiconductor devices. Its unique color and rarity also make it an important precious gemstone. With the maturity of CVD (chemical vapor deposition) technology, the preparation of large-size single-crystal diamonds has been domestically produced. However, through-hole processing remains a core bottleneck in the industrialization of diamond, hindering its development in the high-end jewelry sector. Diamond has a Mohs hardness of 10, and the mechanical wear rate of traditional tools is >0.5 mm / h. Traditional mechanical drilling methods result in high tool wear and low efficiency. Diamond is chemically inert and extremely resistant to acids and alkalis at room temperature, with chemical corrosion rates generally <0.1 μm / min. Chemical corrosion methods result in slow corrosion rates and processing cycles of several weeks. Laser processing, due to insufficient energy deposition per pulse, easily induces surface graphitization (amorphous carbon layer >200 nm), reducing device reliability. Existing liquid-film assisted laser ablation technology works by continuously jetting liquid onto a diamond substrate to form a flowing liquid film (10-200 μm thick). A laser then passes through the liquid film to irradiate the surface, carrying away the spatter and reducing molten material adhesion, thus improving surface smoothness by approximately 40%. Simultaneously, the cooling effect of the liquid film reduces the depth of the heat-affected zone. However, this method lacks efficiency breakthroughs, still relying on pure laser ablation, resulting in slow removal rates and low efficiency. Furthermore, it cannot address the issue of residual amorphous carbon layers. Additionally, the fluidity of the liquid film can easily lead to uncontrolled flow fields within deep holes, limiting deep hole processing; it fails when the depth-to-diameter ratio is greater than 5:1. The depth-to-diameter ratio of holes in semiconductor devices is often greater than 10, requiring sidewall roughness of less than 10 nm and no thermal damage. Existing technologies struggle to fabricate such precise hole structures on diamond substrates, failing to meet the requirements for processing diamond-based high-power semiconductor devices. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a fast, efficient, and low-cost method and apparatus for forming diamond through holes based on laser-coupled high-pressure water jet, which can be used for processing holes with high aspect ratio and high precision.

[0004] This invention is achieved through the following technical solution:

[0005] The method for forming diamond through-holes based on laser-coupled high-pressure water jet includes the following steps:

[0006] S1. Fix the diamond to be processed on a three-dimensional moving processing stage, and use the high energy density of ultra-short pulse laser to achieve non-thermal melting processing of the diamond, and quickly form an initial blind hole with a graphite residue layer on the diamond.

[0007] S2. High-pressure water jet containing the first oxidizing and corrosive component is applied to the initial blind hole to remove the graphite residue layer on the initial blind hole and enlarge the hole;

[0008] S3. Repeat steps S1 and S2 until a set number of blind holes are formed on the diamond. The processing of a single blind hole can also be done by repeating steps S1 and S2, alternating between ultrashort pulse laser and chemical high-pressure water jet to obtain a blind hole of a set depth.

[0009] S4. Transfer the diamond with several blind holes obtained in step S3 to a nanosecond pulsed laser. Use a high-pressure water jet containing a second oxidation corrosion component coupled with the nanosecond pulsed laser to process the blind holes on the diamond one by one to obtain the set through hole structure.

[0010] Furthermore, in step S2, the high-pressure water jet is a single-channel jet, and the first oxidative corrosion component includes alkali metal hydroxide.

[0011] Furthermore, in step S2, the high-pressure water jet is a dual-channel jet corresponding to two nozzles. The dual-channel jet includes a first channel and a second channel. The first oxidizing and corrosive component in the first channel is an alkali metal hydroxide, and the first oxidizing and corrosive component in the second channel is an oxidant.

[0012] Furthermore, the alkali metal hydroxide in the first flow channel is NaOH or KOH, with a mass content of 5%-20%, and the temperature of the high-pressure water jet sprayed in the first flow channel is 60-85℃; the oxidant in the second flow channel is hydrogen peroxide (H2O2), with a mass content of 5%-20%, and the temperature of the high-pressure water jet sprayed in the second flow channel is 30-50℃.

[0013] Furthermore, in step S2, the high-pressure water jet scours the sidewall of the initial blind hole at an incident angle of 20-40°, with a water pressure of 400-800MPa and a flow velocity of 20-40m / s.

[0014] Furthermore, in step S2, the high-pressure water jet also contains 2%-10% by mass of nano-abrasives, wherein the nano-abrasives are one or a combination of alumina (Al2O3), diamond, and boron nitride, and the particle size of the nano-abrasives is 30-150 nm.

[0015] In some embodiments, the nanoabrasive is diamond microparticles with a particle size D50 = 50 nm and a weight content of 2%-4%.

[0016] In other embodiments, the nanoabrasive is Al2O3 with a particle size D50 = 40 nm and a weight content of 3%-8%. It should be noted that alumina should be avoided in high-pressure water jets of alkali metal hydroxides to prevent reactions.

[0017] Furthermore, in step S4, the nanosecond pulsed laser has a wavelength of 300-800nm, a pulse width of 10-100ns, a pulse repetition frequency of 50-150kHz, a single pulse energy of 0.01-0.2mJ, an energy density of 10-40J / cm², and adopts a spiral scanning path with a scanning speed of 100-500mm / s.

[0018] Further, in step S4, the second oxidative corrosion component is a strong base or a strong acid. The strong base is an alkali metal hydroxide KOH or NaOH, and the weight content of the strong base in the high-pressure water jet is 10%-30%. The strong acid is hydrofluoric acid HF or nitric acid HNO3, and the weight content of the strong acid in the high-pressure water jet is 10%-30%. The flow velocity of the high-pressure water jet is 20-40 m / s, the water pressure is >400 MPa, and the spray angle is 40-70°.

[0019] Furthermore, in step S1, the pulse width of the ultrashort pulse laser is 100-500 fs, its energy density is >1 J / cm², and its wavelength range is 450-1600 nm; the processing scanning path of the ultrashort pulse laser is helical, the step spacing is >0.5-2 μm, and the taper of the resulting initial blind hole is <10°.

[0020] A diamond through-hole forming device based on laser-coupled high-pressure water jet is used to realize the above-mentioned diamond through-hole forming method based on laser-coupled high-pressure water jet. It includes an ultrashort pulse laser, a nanosecond laser, a high-pressure water jet device, and a three-dimensional moving processing table.

[0021] The ultrashort pulse laser is used to generate ultrashort pulse lasers and pre-treat the diamond surface to form an initial blind hole.

[0022] The nanosecond laser is used to generate nanosecond pulse lasers, which are used to further enlarge the blind hole to obtain the final through hole.

[0023] The high-pressure water jet device includes a liquid supply module and at least one nozzle. The liquid supply module is used to supply the nozzle with a jetting liquid containing a first oxidizing and corrosive component or a second oxidizing and corrosive component. The nozzle is used to jet a high-pressure water jet containing the first oxidizing and corrosive component or the second oxidizing and corrosive component. When jetting the high-pressure water jet containing the first oxidizing and corrosive component, it is used to etch and enlarge the initial blind holes pre-treated on the diamond. When jetting the high-pressure water jet containing the second oxidizing and corrosive component, it is used to work in conjunction with the nanosecond pulse laser generated by the nanosecond laser to further process the diamond through holes.

[0024] The nozzle is equipped with a filter element to filter the sprayed liquid. The liquid supply module can be equipped with a storage tank and a high-pressure pump; the storage tank is used to hold the corresponding sprayed liquid.

[0025] The three-dimensional moving processing stage is equipped with a three-dimensional driving structure, which is used to drive the sample to be processed fixed on it to perform three-dimensional movement, so that the sample can be transferred between the ultrashort pulse laser and the nanosecond laser, and the position of the sample can be adjusted so as to process through holes in diamond.

[0026] This invention employs a three-step method: laser direct drilling pretreatment + high-pressure chemical water jet hole enlargement + chemically assisted laser hole enlargement and polishing. First, the high energy density of an ultrashort pulse laser achieves non-thermal melting of the diamond, accurately positioning the through-hole and initially overcoming the diamond hardness barrier to form an initial blind hole. Then, high-pressure water jet chemical etching removes carbon and enlarges the hole. Finally, the synergistic effect of the high-pressure chemical water jet and the laser overcomes the limitations of traditional laser direct writing methods in processing holes with large aspect ratios and smooth, heat-damaged edges. This method can process holes with aspect ratios greater than 10, wall roughness less than 10 nm, and no heat-damaged layer on diamond substrates, achieving rapid and high-precision processing of diamond through-holes. Processing efficiency is significantly improved, and processing accuracy and surface quality are significantly enhanced. It overcomes the shortcomings of existing technologies such as slow chemical etching, laser-induced carbon layer residue, and easy damage from mechanical drilling. By combining chemical etching with laser, the laser locally activates the surface, accelerating the chemical reaction rate and reducing energy consumption. The chemical reagents can be easily filtered and recycled, reducing costs and making the process environmentally friendly and efficient. Attached Figure Description

[0027] Figure 1 This is a flowchart illustrating the process of an embodiment of the present invention.

[0028] Figure 2 This is a schematic diagram of step one of the embodiments of the present invention.

[0029] Figure 3 This is a schematic diagram of step two of the present invention.

[0030] Figure 4 This is a schematic diagram of a processing state in step four of an embodiment of the present invention.

[0031] Figure 5 This is a schematic diagram of another processing state in step four of the present invention.

[0032] Figure 6 This is a schematic diagram of a diamond through-hole forming device according to an embodiment of the present invention.

[0033] Figure reference numerals: 1-diamond; 2-blind hole; 3-ultra-short pulse laser; 4-graphite residue layer; 5-first high-pressure water jet; 6-second high-pressure water jet; 7-nanosecond pulse laser; 8-through hole; 10-ultra-short pulse laser; 20-nanosecond laser; 30-high-pressure water jet equipment; 40-three-dimensional moving processing table. Detailed Implementation

[0034] A method for forming diamond through-holes based on laser-coupled high-pressure water jet, such as Figure 1 It includes the following steps:

[0035] Step 1, such as Figure 2 The diamond 1 to be processed is fixed on a three-dimensional moving processing stage, and the diamond 1 is processed without thermal melting by using the high energy density of the ultra-short pulse laser 3, so that an initial blind hole 2 with a graphite residue layer 4 is quickly formed on the diamond.

[0036] Ultrashort pulse laser 3 refers to a pulse width of picosecond (10^30) -12 s), femtosecond (10 -15 Lasers in the picosecond range or lower have narrow pulse widths and high peak power. Compared to conventional continuous laser processing via thermal ablation, when the laser pulse time is shortened to the picosecond range, the rapid increase in pulse energy results in a high power density sufficient to strip the outer electrons from the material surface, thus removing the material. Due to the extremely short interaction time between the laser and the material, ions are ablated before transferring energy to the surrounding material, resulting in a very small heat-affected zone, hence the term "cold ablation." In this process, the material is not removed by melting but rather through a process similar to "vaporization," achieving high-precision, low-damage processing. However, ultrashort pulse lasers are expensive, and their processing depth is limited by factors such as pulse width, plasma shielding effect, and diffraction effect, making it difficult to process small-diameter deep holes in thick substrates. For example, when processing a 40μm diameter hole with an ultrashort pulse laser, the efficiency decreases when the hole depth approaches 100μm, and becomes almost impossible to process when the depth approaches 150μm, making it difficult to continue. Therefore, for processing holes with larger diameters, it is necessary to combine them with other techniques.

[0037] This invention utilizes an ultrashort pulse laser 3 to rapidly form initial blind holes 2 on diamond, achieving precise positioning of through holes 8 and initially overcoming the hardness barrier of diamond, thus creating conditions for subsequent finishing. The pulse width of the ultrashort pulse laser 3 can be 100-500 fs, its energy density is >1 J / cm², and its wavelength range is 450-1600 nm. The initial blind hole 2 can be formed using a spiral processing scanning path with a step spacing >0.5-2 μm. The resulting initial blind hole 2 has a taper <10° and is suitable for single-crystal diamonds with a thickness of 400-1000 μm. The depth-to-diameter ratio of the resulting initial blind hole 2 is greater than 1:1. The processing time for a single hole depends on the laser energy density and the processing depth of the blind hole, and can be controlled within 1-10 minutes.

[0038] In one embodiment, the diamond to be processed is 400 μm thick. The laser parameters for laser direct drilling pretreatment are set as follows: wavelength 1064 nm, pulse width 280 fs, repetition frequency 20 kHz, and power 30 W. The scanning path is spiral, which is more uniform than linear scanning, and the step spacing is >0.5-2 μm. The initial blind hole 2 formed has an inlet diameter <80 μm, an outlet diameter <100 μm, a taper <10°, an initial hole diameter of 80±2 μm, a depth >200 μm, a tapered initial hole depth-to-diameter ratio >1:1, and a residual graphite layer of 1-2 μm on the hole wall. The 1064nm infrared laser can match the absorption characteristics of diamond (absorption is enhanced through surface treatment) to achieve efficient energy deposition; the 280fs pulse width is less than the electron-phonon relaxation time of diamond (about 1ps), avoiding graphitization caused by thermal diffusion; the energy density of more than 1J / cm² exceeds the ablation threshold of diamond (about 0.5J / cm²), but is lower than the lattice distortion threshold (about 1.5J / cm²), ensuring processing accuracy.

[0039] Step Two, as follows Figure 3 A high-pressure water jet (named the first high-pressure water jet 5 for distinction) mixed with the first oxidizing and corrosive component is applied to the initial blind hole 2 to remove the graphite residue layer 4 on the initial blind hole 2 and enlarge the hole.

[0040] The first oxidizing and corrosive component reacts with the graphite layer on the pore wall to remove the residual graphite layer 4. This reduces the thickness of the residual graphite layer on the pore wall from over 2 μm to below 50 nm, thus enlarging the pores. The composition of the first oxidizing and corrosive component and the action of the high-pressure water jet can vary.

[0041] In some embodiments, the first oxidizing and corrosive component is a strong alkali, such as alkali metal hydroxides like NaOH and KOH. The weight concentration of the first oxidizing and corrosive component in the high-pressure water jet is 5%-20%, and the temperature is 60-85°C. Specifically, the nozzle sprays a KOH or NaOH solution with a temperature of 60-85°C and a concentration of 5%-20%. The inner diameter of the flow channel nozzle is set to 0.3 mm.

[0042] In some embodiments, the first oxidizing and corrosive component includes two components: a strong alkali and an oxidant. The strong alkali can be an alkali metal hydroxide such as NaOH or KOH, and the oxidant can be hydrogen peroxide (H₂O₂). In this case, the high-pressure water jet has a dual-channel configuration, corresponding to two nozzles. The dual-channel configuration includes a first channel and a second channel. The first oxidizing and corrosive component in the first channel is an alkali metal hydroxide, and the temperature of the high-pressure water jet containing the alkali metal hydroxide can be controlled between 60-85°C. The first oxidizing and corrosive component in the second channel is an oxidant, and the temperature of the high-pressure water jet containing the oxidant is determined based on the composition of the oxidant to avoid its rapid decomposition. For hydrogen peroxide (H₂O₂), the temperature should not exceed 50°C.

[0043] The mass content of the first oxidizing corrosion component in each flow channel is 5%-20%. In one embodiment of the dual-flow-channel implementation, one flow channel contains a 15 wt% KOH solution at 65°C, and the other flow channel contains a 20 wt% hydrogen peroxide solution at 40°C. The inner diameter of the flow channel nozzle is set to 0.3 mm.

[0044] For the first high-pressure water jet 5, the jet pressure can be controlled to be >400MPa, preferably 400-800MPa, and the flow velocity to be 20-40m / s, preferably 30m / s. The high-pressure water jet scours the sidewall of the initial blind hole 2 at an incident angle of 20-40°, aiming at the laser-pretreated initial blind hole 2. The duration of the high-pressure water jet can be controlled to be 5-30 minutes, based on removing the graphite layer covering the initial blind hole 2. The greater the thickness, the longer the jetting duration.

[0045] In the dual-channel implementation, the two nozzles can spray simultaneously or alternately. Practice has shown that alternating spraying provides better removal and saves on spraying agents; therefore, alternating spraying is preferred. In one embodiment, one nozzle sprays a 70°C, 15wt% KOH solution for 1-1.5 minutes, then the other channel begins spraying a 45°C, 20wt% hydrogen peroxide solution for 1-1.5 minutes, followed by another spraying of KOH solution. This alternation continues until the graphite carbon layer is completely removed.

[0046] In some embodiments, it is necessary to process through holes with a large aperture. In addition to the first oxidizing and corroding component, the first high-pressure water jet 5 also contains 2%-10% by mass of nano-abrasives. Under the action of the water flow, the abrasives can act on the holes, playing the role of an abrasive water jet, grinding and removing the graphite layer on the hole wall. The abrasives can be one or a combination of several of alumina (Al2O3), diamond, and boron nitride, with a particle size ranging from 30-150 nm and a weight content of 2%-10%. In the dual-channel implementation, both water jets may contain abrasives simultaneously, or only one channel may contain abrasives. In the case where both channels contain abrasives, the type and content of abrasives in the two channels may be the same or different.

[0047] As one embodiment of the single-channel system, the nozzle sprays a NaOH solution at 65°C and 15wt% concentration. The NaOH solution contains nano-abrasives, which are diamond microparticles with a particle size D50=50nm and a weight content of 3% in the NaOH solution.

[0048] As one embodiment of the dual-channel system, one nozzle sprays a 60°C, 20wt% KOH solution containing no nano-abrasives, and the other nozzle sprays a 40°C, 20wt% hydrogen peroxide containing nano-abrasives. The nano-abrasives are Al2O3 with a particle size D50 = 40nm and a weight content of 5% in the hydrogen peroxide.

[0049] As another embodiment of the dual-channel system, one nozzle sprays a KOH solution at 60°C and 20wt% concentration, which contains nano-abrasives, namely diamond microparticles with a particle size D50=50nm and a weight content of 5% in the NaOH solution; the other nozzle sprays hydrogen peroxide at 40°C and 20wt% concentration, which does not contain nano-abrasives.

[0050] As another embodiment of the dual-channel system, one nozzle sprays a 60°C, 20wt% KOH solution containing nano-abrasives, which are diamond microparticles with a particle size D50 = 50nm and a weight content of 3% in the NaOH solution; the other nozzle sprays a 40°C, 20wt% hydrogen peroxide solution containing nano-abrasives, which are Al2O3 with a particle size D50 = 40nm and a weight content of 4% in the hydrogen peroxide solution.

[0051] Step 3: Repeat steps 1 and 2 until a predetermined number of blind holes 2 are formed on the diamond.

[0052] Steps one and two can be repeated to process a single blind hole 2, that is, by alternating the action of an ultrashort pulse laser 3 and a chemical high-pressure water jet (first high-pressure water jet 5), a blind hole 2 of a set depth can be obtained, which can also improve the processing efficiency of a single blind hole 2. By repeating this process, multiple blind holes 2 can be processed one by one on a diamond substrate, and the position of each blind hole 2 can be accurately located to facilitate subsequent finishing.

[0053] Step 4, as follows Figure 4 The diamond 1 with several blind holes 2 obtained in step S3 is transferred to a nanosecond pulsed laser, and a high-pressure water jet containing a second oxidation corrosion component is coupled through a nanosecond pulsed laser 7. Figure 4 and Figure 5 The second high-pressure water jet (6) processes the blind holes (2) on the diamond (1) one by one, such as... Figure 5 Thus, the structure with 8 through holes is obtained.

[0054] While water-guided laser (WJGL) can reduce the heat-affected zone and residual thermal stress during laser processing, decrease material thermal deformation and damage during high-power laser processing, and improve processing quality, it suffers from laser attenuation in the water jet, significant energy loss, coupling difficulties, complex equipment, high operational expertise, and high cost. This invention, drawing on the principles of water-guided laser, introduces a chemical etchant into a second high-pressure water jet 6. Utilizing the corrosive properties of the chemical etchant, it is applied to the processing of diamond through-holes 8. In addition to increasing the material removal rate, the high-pressure water jet provides surface scouring and cooling, thereby reducing thermal damage from laser processing and partially mimicking the functions of a water-guided laser. This results in through-holes 8 with a large aspect ratio and smooth walls. However, compared to water-guided laser, the high-pressure water jet does not need to be coaxial with the laser beam, its angle can be freely adjusted according to the processing surface, and the laser equipment and high-pressure water jet equipment are independent. Therefore, the overall device structure is simple, easy to operate and maintain, and has a lower cost.

[0055] The nanosecond pulsed laser 7 is used, which is less expensive than ultrashort pulse (picosecond, femtosecond) lasers, and can efficiently deposit energy on the surface, reducing heat diffusion and deep thermal damage. Optionally, the nanosecond pulsed laser 7 has a wavelength of 300-800 nm, a pulse width of 10-100 ns, a pulse repetition frequency of 50-150 kHz, a single pulse energy of 0.01-0.2 mJ, and an energy density of 10-40 J / cm², using a helical scanning path with a scanning speed of 100-500 mm / s. Under these laser parameters, the laser can reach the ablation threshold of diamond, effectively removing material without causing severe plasma shielding and explosion effects. The single-hole processing time depends on the laser energy density, the diameter and depth of the through-hole 8, and can be controlled within 10-60 minutes. The processed sample is then ultrasonically cleaned sequentially with acetone, ethanol, and deionized water.

[0056] As one embodiment, the laser wavelength is 355nm, the pulse width is 20ns, the pulse frequency is 80kHz, the single pulse energy is 0.05-0.1mJ, the spot diameter is about 20μm, the energy density is controlled at about 25J / cm², and the spiral scanning path is matched with a scanning speed of 150-250mm / s.

[0057] In another embodiment, the laser wavelength is 532nm (matching the KOH absorption peak), the pulse width is 12ns, the pulse frequency is 200kHz, the single pulse energy is 0.05-0.08mJ, the spot diameter is about 15μm, the energy density is controlled at about 30J / cm², and the spiral scanning path is combined with a high scanning speed of 200-300mm / s.

[0058] The role of the second oxidizing and corrosive component is to react promptly with the laser-processed products to accelerate material removal. In some embodiments, the second oxidizing and corrosive component is a strong alkali, such as alkali metal hydroxide KOH or NaOH, and its weight content in the high-pressure water jet is 10%-30%.

[0059] In other embodiments, the second oxidative corrosion component is a strong acid, such as hydrofluoric acid HF solution or nitric acid HNO3 solution, and its weight content in the high-pressure water jet is 10%-30%.

[0060] The second oxidative corrosion component may also include other corrosive components.

[0061] Preferably, the high-pressure water jet has a flow velocity of 100-200 m / s and a water pressure >400 MPa. The nozzle diameter is 25-100 µm, and the spray angle can be set to an angle of 40-70° with the diamond surface. Under these parameters, the high-pressure water jet and laser work together to process through holes. Under ultra-high pressure, the high-pressure water jet performs waterjet cutting on one hand and flushing away debris on the other, preventing deposition on the processed surface, maintaining the cleanliness of the cut surface, reducing the roughness of the processed surface, and also playing a cooling role, reducing thermal effects and avoiding thermal damage.

[0062] The second high-pressure water jet 6 in step four and the first high-pressure water jet 5 in step two can use the same jetting equipment for high-pressure water jetting. The chemical agents can also be shared. For example, a 15% KOH solution can be prepared and sprayed in step two, and the agent can be continuously sprayed in step four. If both KOH solution and hydrogen peroxide need to be sprayed in step two, the hydrogen peroxide can be stopped in step four, and the KOH solution can be sprayed continuously. The spraying pressure and flow rate can remain unchanged or be adjusted according to the laser processing parameters.

[0063] Employing a laser-chemical synergistic approach, the laser simultaneously irradiates the orifice during high-pressure water jet processing. The transparent high-pressure water jet guides the laser transmission, while the laser activates the reactivity of the second oxidative corrosion component in the high-pressure water jet, accelerating the selective corrosion of the amorphous carbon layer (graphite residue) on the hole wall (temperature 80℃, pH=12). Etching occurs concurrently with laser processing, following a process of L [laser irradiation] → P [activation of solution free radicals] → O [graphite oxide layer] → R [water jet erosion products]. The water jet simultaneously etches and washes away processing residues, maximizing the processing effect of water-guided laser. Compared to conventional water-guided laser processes, this method further improves processing efficiency and reduces overall energy consumption by 40%. The final hole diameter tolerance is <±0.5μm, surface roughness Ra<0.1μm, and processing efficiency is ≥100μm / min, representing a 35-fold improvement over traditional pure chemical etching methods.

[0064] The processing time in step four depends on the processing depth and diameter of the through hole 8. The greater the processing depth and the larger the diameter, the longer the processing time. It is also closely related to the laser processing parameters, the high-pressure water jet spray parameters, and the type and concentration of the reagent.

[0065] Practice has proven that using the method of this invention to process diamond through-holes 8 achieves a material removal rate of 2.5 mm³ / min, reducing processing time to several hours. The hole diameter error can be controlled within ±0.5 μm, and the hole wall roughness Ra < 5 nm, which meets the requirements for diamond MEMS resonators (Q value > 10). 6 The high precision requirements of heat dissipation substrates for high-power devices (thermal conductivity > 2000 W / m·K) can be met, and the cost per hole can be controlled within 100 yuan, achieving high efficiency, high quality and low cost.

[0066] Comparative Example 1

[0067] Chemical etching method: using molten KNO3 as the etchant, the etching rate is <0.1μm / min. It takes several weeks, about 120 hours, to process a 400μm thick diamond through hole.

[0068] The method of the present invention achieves a material removal rate of 2.5 mm³ / min, and only requires 4.5 hours to process a 400 μm thick diamond through hole, reducing the processing time to 3.75% of the traditional method.

[0069] Comparative Example 2

[0070] Pure laser direct writing method: Using ultraviolet picosecond laser, the thickness of the amorphous carbon layer on the hole wall is >200nm during processing, requiring additional plasma etching for further processing. The carbon layer can easily lead to a decrease in device reliability, such as reduced heat dissipation efficiency. The taper of the through hole is >10°, and the hole wall roughness Ra is >100nm. Due to the characteristics of the laser beam, it is difficult to process holes with a depth-to-diameter ratio >10:1, which cannot meet the requirements of high-power semiconductor devices (such as heat dissipation substrates) in terms of depth-to-diameter ratio and roughness.

[0071] The method of this invention can process through-holes with a diameter of 50 μm and a depth of 500 μm on a diamond substrate. Specifically, firstly, an initial blind hole with a diameter of approximately 40 μm and a depth of approximately 100 μm is processed according to step one. The graphite layer thickness of the initial blind hole wall is <2 μm, and the graphite carbon layer has a loose structure. In step two, the graphite layer is further removed, increasing the diameter of the blind hole to 50 μm. Then, according to step four, a nanosecond pulsed laser coupled with a high-pressure water jet is used to further process the blind hole until a through-hole with a diameter of 50 μm and a depth of 500 μm is obtained. Finally, ultrasonic cleaning (40 kHz, 100 W) is used to completely remove processing residues. The above method, combining the Gaussian beam energy distribution of the laser with the uniform scouring of the high-pressure water jet, achieves a through-hole taper of <5°, a hole wall roughness Ra <5 nm, a depth-to-diameter ratio of over 10, and a hole diameter error of ±0.5 μm, meeting the requirements of diamond MEMS resonators (Q value >10). 6 High precision requirements for heat dissipation substrates for high-power devices (thermal conductivity > 2000 W / m·K).

[0072] Comparative Example 3

[0073] Mechanical drilling method: Drilling is carried out using diamond-coated drill bits. The tool wear rate is >0.5mm / h, and the tool needs to be replaced after processing about 100 through holes. The cost per hole is greater than 1,000 yuan, and it is easy to cause chipping of the hole edge (chipping rate >30%), with a hole diameter error of ±10μm.

[0074] The method of this invention adopts a non-contact processing method of laser + water jet, which eliminates mechanical tool wear and reduces the processing cost of a single hole to 100, which is only 7.5% of that of traditional mechanical methods. Furthermore, the hole edge chipping rate is <5%, and the hole diameter error can be ±0.5μm, meeting the requirements for heat dissipation substrates of high-power devices.

[0075] A diamond through-hole forming device based on laser-coupled high-pressure water jet is provided to realize the aforementioned diamond through-hole forming method based on laser-coupled high-pressure water jet, such as... Figure 6 As shown, it includes an ultrashort pulse laser 10, a nanosecond laser 20, a high-pressure water jet device 30, and a three-dimensional moving processing table 40.

[0076] The ultrashort pulse laser 10 is used to generate ultrashort pulse laser 3 and to pre-treat the diamond surface to form an initial blind hole 2.

[0077] The nanosecond laser 20 is used to generate nanosecond pulse lasers for further enlarging the blind hole to obtain the final through hole 8.

[0078] The high-pressure water jet device 30 includes a liquid supply module and at least one nozzle. The liquid supply module supplies a jetting liquid containing a first oxidizing and corrosive component or a second oxidizing and corrosive component to the nozzle. The nozzle is used to jet a high-pressure water jet containing the first oxidizing and corrosive component or the second oxidizing and corrosive component. When jetting the high-pressure water jet containing the first oxidizing and corrosive component, it is used to etch and enlarge the pre-treated initial blind hole 2 on the diamond. When jetting the high-pressure water jet containing the second oxidizing and corrosive component, it is used to cooperate with the nanosecond pulse laser generated by the nanosecond laser to further process the diamond through hole 8. In some embodiments, to achieve dual-channel jetting, two nozzles can be configured to jet two different components of the first oxidizing and corrosive component.

[0079] The nozzle is equipped with a filter element to filter the sprayed liquid. The liquid supply module can be equipped with a storage tank and a high-pressure pump; the storage tank is used to hold the corresponding sprayed liquid. For dual-channel systems, to avoid cross-contamination of substances with different chemical components, two independent storage tanks and high-pressure pumps can be configured.

[0080] The three-dimensional moving processing stage 40 is equipped with a three-dimensional driving structure for driving the sample to be processed, which is fixed on it, to perform three-dimensional movement, allowing the sample to be transferred between the ultrashort pulse laser 10 and the nanosecond laser 20, and to adjust the position of the sample so as to process through holes 8 in diamond. The three-dimensional driving structure can be constructed from X-axis linear motion modules, Y-axis linear motion modules, and Z-axis linear motion modules. These linear motion modules can adopt existing electric cylinder or pneumatic cylinder driven structures, which will not be described in detail here.

[0081] The above detailed description is a specific description of feasible embodiments of the present invention. These embodiments are not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included in the patent scope of this case.

Claims

1. A method for forming diamond through-holes based on laser-coupled high-pressure water jet, characterized in that, Includes the following steps: S1. Fix the diamond to be processed on a three-dimensional moving processing stage, and use the high energy density of ultra-short pulse laser to achieve non-thermal melting processing of the diamond, and quickly form an initial blind hole with a graphite residue layer on the diamond. S2. High-pressure water jet containing the first oxidizing and corrosive component is applied to the initial blind hole to remove the graphite residue layer on the initial blind hole and enlarge the hole; S3. Repeat steps S1 and S2 until a set number of blind holes are formed on the diamond. S4. Transfer the diamond with several blind holes obtained in step S3 to a nanosecond pulsed laser. Use a high-pressure water jet containing a second oxidation corrosion component coupled with the nanosecond pulsed laser to process the blind holes on the diamond one by one to obtain the set through hole structure. In step S1, the pulse width of the ultrashort pulse laser is 100-500 fs; In step S2, the high-pressure water jet is a dual-channel jet corresponding to two nozzles. The dual-channel jet includes a first channel and a second channel. The first oxidizing and corrosive component in the first channel is an alkali metal hydroxide, and the first oxidizing and corrosive component in the second channel is an oxidant. The alkali metal hydroxide in the first flow channel is NaOH or KOH, with a mass content of 5%-20%, and the temperature of the high-pressure water jet sprayed in the first flow channel is 60-85℃; the oxidant in the second flow channel is hydrogen peroxide H2O2, with a mass content of 5%-20%, and the temperature of the high-pressure water jet sprayed in the second flow channel is 30-50℃. In step S2, the high-pressure water jet also contains 2%-10% by mass of nano-abrasives, wherein the nano-abrasives are one or a combination of alumina (Al2O3), diamond, and boron nitride, and the particle size of the nano-abrasives is 30-150 nm. In step S4, the nanosecond pulsed laser has a wavelength of 300-800 nm, a pulse width of 10-100 ns, a pulse repetition frequency of 50-150 kHz, a single pulse energy of 0.01-0.2 mJ, an energy density of 10-40 J / cm², and adopts a spiral scanning path with a scanning speed of 100-500 mm / s. In step S4, the second oxidative corrosion component is a strong base or a strong acid. The strong base is an alkali metal hydroxide KOH or NaOH, and the weight content of the strong base in the high-pressure water jet is 10%-30%. The strong acid is hydrofluoric acid HF or nitric acid HNO3, and the weight content of the strong acid in the high-pressure water jet is 10%-30%.

2. The method for forming diamond through-holes based on laser-coupled high-pressure water jet according to claim 1, characterized in that, In step S2, the high-pressure water jet scours the sidewall of the initial blind hole at an incident angle of 20-40°, with a water pressure of 400-800MPa and a flow velocity of 20-40m / s.

3. The method for forming diamond through-holes based on laser-coupled high-pressure water jet according to claim 1, characterized in that, In step S4 The high-pressure water jet has a flow velocity of 20-40 m / s, a water pressure of >400MPa, and a jet angle of 40-70°.

4. The method for forming diamond through-holes based on laser-coupled high-pressure water jet according to claim 1, characterized in that, In step S1, the energy density of the ultrashort pulse laser is >1 J / cm², and the wavelength range is 450-1600 nm; the processing scanning path of the ultrashort pulse laser is spiral, with a step spacing of 0.5-2 μm, and the taper of the resulting initial blind hole is <10°.

5. A diamond through-hole forming device based on laser-coupled high-pressure water jet, characterized in that, The method for forming diamond through-holes based on laser-coupled high-pressure water jet as described in any one of claims 1 to 4 includes an ultrashort pulse laser, a nanosecond laser, a high-pressure water jet device, and a three-dimensional moving processing stage. The ultrashort pulse laser is used to generate ultrashort pulse lasers; The nanosecond laser is used to generate nanosecond pulsed lasers; The high-pressure water jet device includes a liquid supply module and at least one nozzle. The liquid supply module is used to supply the nozzle with a jetting liquid containing a first oxidizing and corrosive component or a second oxidizing and corrosive component. The nozzle is used to jet a high-pressure water jet containing the first oxidizing and corrosive component or the second oxidizing and corrosive component. The three-dimensional moving processing stage is equipped with a three-dimensional driving structure, which is used to drive the sample to be processed fixed on it to perform three-dimensional movement, so that the sample can be transferred between the ultrashort pulse laser and the nanosecond laser, and the position of the sample can be adjusted for processing.

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