Diamond microwave millimeter wave power heat sink substrate and processing method
By using diamond microwave millimeter wave power heat sink substrates, combined with magnetron sputtering, electroplating and laser processing technology, the problem of insufficient thermal conductivity of traditional heat sink materials is solved, and efficient heat dissipation and high power load capacity are achieved, which is suitable for the integrated development of microwave millimeter wave devices.
Patent Information
- Application Number
- CN202510325048.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-19
- Publication Date
- 2025-06-20
AI Technical Summary
Traditional heat sink materials such as molybdenum copper alloys have insufficient thermal conductivity, resulting in insufficient heat dissipation capabilities of microwave millimeter-wave power devices, affecting device performance and integrated development.
Diamond microwave millimeter-wave power heat sink substrate is used to form a solderable coating through magnetron sputtering and electroplating, and conduction holes are prepared by laser processing. Combined with vacuum annealing, the thermal conductivity and electrical properties of the substrate are improved.
It significantly improves thermal conductivity, which increases it by 5 to 10 times compared with traditional molybdenum copper materials, reduces the chip junction temperature, improves power load capacity, and reduces the volume. It is suitable for high-power GaN devices and DC-40GHz frequency band.
Smart Images
Figure CN120184113A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of semiconductor materials, in particular to a diamond microwave and millimeter-wave power heat sink substrate and a processing method thereof. Background Art
[0002] With the miniaturization and high power of microwave and millimeter-wave power devices, the thermal conductivity of traditional heat sink materials (such as molybdenum-copper alloy, aluminum nitride, etc.) (usually lower than 400 W / (m·K)) can no longer meet the heat dissipation requirements, resulting in an increase in the junction temperature of the device and limited performance. For example, the thermal conductivity of molybdenum-copper alloy (MoCu30) is only 185 W / (m·K), and it is necessary to increase the volume to compensate for the heat dissipation capacity, which hinders the development of integration.
[0003] Diamond has become an ideal heat sink material due to its ultra-high thermal conductivity (theoretical value up to 2200 W / (m·K)), low coefficient of thermal expansion (1×10⁻ 6 / K), and insulating properties. However, in the prior art, diamond substrates have problems such as high surface roughness (affecting the adhesion of the coating), poor process compatibility (requiring additional grinding), and high cost. For example, the cost of preparing large-size single-crystal diamond by the CVD method is high, and it is not compatible with silicon-based processes. Summary of the Invention
[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a diamond microwave and millimeter-wave power heat sink substrate and a processing method thereof, effectively solving the deficiencies of the prior art.
[0005] To achieve the above purpose, an embodiment of one aspect of the present invention provides a diamond microwave and millimeter-wave power heat sink substrate, including a diamond substrate, the thermal conductivity of the diamond substrate is 1500~2000 W / (m·K), the surface roughness ≤20 nm, and the thickness is selected from any one of 0.127 mm, 0.2 mm, 0.254 mm, 0.3 mm, 0.381 mm; A solderable coating formed by magnetron sputtering and electroplating is provided on the surface of the diamond substrate, including a bottom metal, a back electrode, and a matching electrode; The substrate is provided with a via hole processed by laser, and the hole is filled with metal by electroplating to achieve vertical conduction, and the welding void ratio with Au80Sn20 solder ≤5%.
[0006] Preferably, according to any of the above solutions, the bottom metal is any one of nickel and a nickel-titanium-tungsten alloy layer, the thickness of the bottom metal is 1000 Å, and the bottom metal is used to enhance the adhesion and stability of the coating.
[0007] Preferably, according to any of the above solutions, the surface metal of the solderable coating is a gold layer, the solderable coating is thickened by magnetron sputtering and electroplating, and the thickness of the solderable coating is uniform and the conductivity is excellent.
[0008] Preferably, any of the above schemes has a dielectric constant of ≤5.7, which is suitable for the DC-40 GHz frequency band.
[0009] Preferably, any of the above schemes is that the substrate is applied to microwave and millimeter wave power devices, TR components or satellite communication systems, its operating frequency covers DC-40GHz, its power load capacity is ≥150W, and its volume is 1 / 2~1 / 5 of that of traditional molybdenum-copper substrates.
[0010] An embodiment of one aspect of the present invention provides a method for processing a diamond microwave millimeter wave power heat sink substrate, comprising the following steps: S1. Provide diamond wafers of standard thickness and perform double-sided polishing; S2. Grooving and drilling holes on the substrate by laser processing; S3. Using magnetron sputtering to sequentially deposit nickel / titanium-tungsten alloy bottom metal, back electrode and matching electrode; S4. Prepare metal thin films layer by layer by photolithography and mask patterning technology; S5. Electroplating metal in the via hole to achieve vertical conduction; S6. The coating is subjected to vacuum annealing at a temperature of 450 to 550° C. for 1 to 2 hours; S7. Test the electrical properties and thermal conductivity of the substrate.
[0011] Preferably, any of the above schemes is that the parameters of the laser processing in step S2 are: wavelength 1064nm, pulse width ≤20ns, aperture accuracy ±5μm.
[0012] Preferably, in any of the above schemes, the annealing treatment in step S5 is performed under nitrogen protection, and the void ratio of the film after annealing is ≤5%.
[0013] Preferably, in any of the above schemes, the process conditions of magnetron sputtering in step S3 are: vacuum degree ≤ 5×10⁻ 6 Torr, sputtering power 200~400W, substrate temperature ≤80℃.
[0014] Preferably, any of the above schemes further includes performing a thermal performance test on the substrate after step g: soldering the power device to the surface of the substrate, and verifying that the heat dissipation efficiency is improved by ≥20% through simulation and actual measurement of the junction temperature.
[0015] The present invention has the following advantages: The diamond microwave and millimeter-wave power heat sink substrate and its processing method can increase the thermal conductivity by 5 to 10 times compared with traditional molybdenum-copper materials, reduce the chip junction temperature by 28 °C, and the power load capacity reaches 150 W. It is suitable for high-power GaN devices, and its volume is reduced to 1 / 5 of the traditional material, with improved integration, meeting the requirements of radar and satellite communication modules, supporting the DC-40 GHz frequency band, and expanding the application range of microwave and millimeter-wave devices. Brief Description of the Drawings
[0016] Figure 1 It is a schematic structural diagram of the diamond heat sink substrate of the present invention; Figure 2 It is a test diagram of the heat sink substrate of the present invention; Figure 3 It is a process flow chart of the present invention; Figure 4 It is an external view of the present invention. Detailed Embodiments
[0017] The following further describes the present invention with reference to the accompanying drawings, but the protection scope of the present invention is not limited to the following.
[0018] As Figures 1 to 2 shown, the diamond microwave and millimeter-wave power heat sink substrate includes a diamond substrate. The thermal conductivity of the diamond substrate is 1500 - 2000 W / (m·K), the surface roughness ≤ 20 nm, and the thickness is selected from any one of 0.127 mm, 0.2 mm, 0.254 mm, 0.3 mm, and 0.381 mm; A solderable coating formed by magnetron sputtering and electroplating is provided on the surface of the diamond substrate, which includes a bottom metal, a back electrode, and a matching electrode; The substrate is provided with via holes processed by laser, and the holes are electroplated with metal to achieve vertical conduction, and the welding void ratio with Au80Sn20 solder ≤ 5%.
[0019] As an optional technical solution of the present invention, the bottom metal is any one of nickel and a titanium-tungsten alloy layer, and the thickness of the bottom metal is 1000 Å. The bottom metal is used to enhance the adhesion and stability of the coating.
[0020] As an optional technical solution of the present invention, the surface metal of the solderable coating is a gold layer. The solderable coating is thickened by magnetron sputtering and electroplating, and the thickness of the solderable coating is uniform and the conductivity is excellent.
[0021] As an optional technical solution of the present invention, the dielectric constant of the substrate ≤ 5.7, which is suitable for the DC-40 GHz frequency band.
[0022] As an optional technical solution of the present invention, the substrate is applied to microwave and millimeter wave power devices, TR components or satellite communication systems, with an operating frequency covering DC-40GHz, a power load capacity ≥150W, and a volume of 1 / 2~1 / 5 of a traditional molybdenum-copper substrate.
[0023] like Figure 3 As shown, the method for processing a diamond microwave millimeter wave power heat sink substrate comprises the following steps: S1. Provide diamond wafers of standard thickness and perform double-sided polishing; S2. Grooving and drilling holes on the substrate by laser processing; S3. Using magnetron sputtering to sequentially deposit nickel / titanium-tungsten alloy bottom metal, back electrode and matching electrode; S4. Prepare metal thin films layer by layer by photolithography and mask patterning technology; S5. Electroplating metal in the via hole to achieve vertical conduction; S6. The coating is subjected to vacuum annealing at a temperature of 450 to 550° C. for 1 to 2 hours; S7. Test the electrical properties and thermal conductivity of the substrate.
[0024] Preferably, any of the above schemes is that the parameters of the laser processing in step S2 are: wavelength 1064nm, pulse width ≤20ns, aperture accuracy ±5μm.
[0025] As an optional technical solution of the present invention, the annealing treatment in step S5 is performed under nitrogen protection, and the void ratio of the film after annealing is ≤5%.
[0026] As an optional technical solution of the present invention, the process conditions of magnetron sputtering in step S3 are: vacuum degree ≤ 5×10⁻ 6 Torr, sputtering power 200~400W, substrate temperature ≤80℃.
[0027] As an optional technical solution of the present invention, it also includes performing a thermal performance test on the substrate after step g: welding the power device to the surface of the substrate, and verifying that the heat dissipation efficiency is improved by ≥20% through simulation and actual measurement of the junction temperature.
[0028] Example 1: Substrate preparation The diamond film was grown by CVD method with a thickness of 0.254 mm, a thermal conductivity of 2000 W / (m·K) and a surface roughness of 15 nm6.
[0029] Laser processing of through holes with an aperture of 0.1 mm, magnetron sputtering of the nickel / titanium-tungsten alloy base layer, and sputtering of the gold layer to a thickness of 5 μm512 after photolithography masking.
[0030] Tested after vacuum annealing (500 °C, 1 hour), compared with the MoCu30 substrate, the chip junction temperature decreased from 125 °C to 97 °C7.
[0031] Example 2: Verification of high-frequency applications Integrated the substrate into an X-band power amplifier (8 - 12 GHz). The test showed that the signal distortion rate decreased by 30%, and the power density increased to 2 W / mm², meeting the requirements of the radar TR module37.
[0032] Experimental Example 1: Comparison of heat dissipation performance of diamond substrates with different thicknesses Experimental design Substrate parameters: Thermal conductivity of diamond: 2000 W / (m·K) Thickness: 0.127 mm, 0.254 mm, 0.381 mm Comparative material: MoCu30 (thermal conductivity 185 W / (m·K), thickness 0.5 mm) Test conditions: Chip heat dissipation: 20 W (continuous wave, X-band) Ambient temperature: 65 °C (GJB548B standard thermal test fixture) Experimental results: Conclusion: When the thickness of the diamond substrate is 0.127 mm, the junction temperature decreases by 28 °C, and the volume is only 25.6% of MoCu30; When the thickness increases to 0.381 mm, the junction temperature further decreases to 93 °C, but the volume is still less than 80% of the traditional material.
[0033] Experimental Example 4: Verification of high-frequency millimeter-wave (Ka-band) applications Experimental design Application scenario: Ka-band (26.5 - 40 GHz) power amplifier module Substrate parameters: Diamond thickness: 0.2 mm, surface roughness 10 nm Coating: nickel / titanium tungsten alloy (1000 Å) + gold layer (5 μm) Test indicators: Power capacity: 150 W (pulse power) Signal linearity (ACPR: adjacent channel power ratio) Experimental results: Conclusion: The power capacity of the diamond substrate increases by 3 times in the Ka-band, and the signal linearity is optimized by 12 dBc; The thermal resistance is reduced to 25% of the traditional material, and the module area is reduced to 16%.
[0034] Example 5: Influence of Annealing Process on Coating Performance Experimental Design Annealing Conditions: Temperature: 400°C, 500°C, 600°C (nitrogen protection) Time: 1 hour Test Indicators: Coating Void Ratio (detected by SEM) Adhesion (scratch test, critical load) Experimental Results: Conclusion: After annealing at 500°C, the void ratio drops to 3%, and the adhesion increases by 86%; At 600°C, microcracks are caused by thermal stress. The preferred annealing temperature is 450 - 550°C.
[0035] Example 6: Thermal Simulation Comparison with Traditional Materials Simulation Model Software: ANSYS Icepak Boundary Conditions: Chip Size: 3mm × 3mm, heat dissipation 20W Ambient Temperature: 25°C, natural convection Material Parameters: Diamond Substrate (thermal conductivity 2000W / (m·K)) Comparative Materials: MoCu30, AlN, BeO Simulation Results: Conclusion: The maximum junction temperature of the diamond substrate is 56°C lower than that of MoCu30, and the thermal gradient is only 18.4% of that of traditional materials.
[0036] Summary of Experimental Comparison Heat Dissipation Performance: For the diamond substrate with the same volume, the thermal conductivity is increased by 5 - 10 times, and the junction temperature is reduced by 28 - 56°C; High - Frequency Adaptability: Supports DC - 40GHz applications, and the power density can reach 2W / mm² (for traditional materials ≤ 0.5W / mm²); Process Advantages: Laser vias have an accuracy of ±5μm, the coating void ratio ≤ 5%, and the annealing process significantly improves reliability; Economy: The substrate thickness is reduced by 50% - 75%, and the system heat dissipation cost is reduced by 40% (no additional radiator is required).
[0037] In summary, the diamond microwave and millimeter-wave power heat sink substrate and its processing method can increase the thermal conductivity by 5 to 10 times compared with traditional molybdenum-copper materials, reduce the chip junction temperature by 28 °C, and have a power load capacity of 150 W. It is suitable for high-power GaN devices, and its volume is reduced to 1 / 5 of the traditional material, with improved integration, meeting the requirements of radar and satellite communication modules, supporting the DC-40 GHz band, and expanding the application scope of microwave and millimeter-wave devices.
[0038] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. Diamond microwave millimeter wave power heat sink substrate, characterized by: A diamond substrate having a thermal conductivity of 1500-2000 W / (m·K), a surface roughness of ≤20 nm, and a thickness selected from any one of 0.127 mm, 0.2 mm, 0.254 mm, 0.3 mm, and 0.381 mm; The surface of the diamond substrate is provided with a weldable coating formed by magnetron sputtering and electroplating, comprising a bottom metal, a back electrode and a matching electrode; The substrate is provided with a laser-processed via hole, in which a metal is electroplated to achieve vertical conduction, and the welding void rate with Au80Sn20 solder is ≤5%.
2. The diamond microwave millimeter wave power heat sink substrate according to claim 1, characterized in that: The bottom layer metal is any one of nickel and titanium-tungsten alloy layer, the bottom layer metal thickness is 1000 angstroms, and the bottom layer metal is used to enhance the adhesion and stability of the coating.
3. The diamond microwave millimeter wave power heat sink substrate according to claim 1, characterized in that: The surface metal of the solderable coating is a gold layer, and the solderable coating is formed by magnetron sputtering and electroplating thickening. The solderable coating has uniform thickness and excellent electrical conductivity.
4. The diamond microwave millimeter wave power heat sink substrate according to claim 1, characterized in that: The dielectric constant of the substrate is ≤5.7 and is suitable for the DC-40GHz frequency band.
5. The diamond microwave millimeter wave power heat sink substrate according to any one of claims 1 to 4, characterized in that: The substrate is applied to microwave and millimeter wave power devices, TR components or satellite communication systems, with an operating frequency covering DC-40GHz, a power load capacity of ≥150W, and a volume of 1 / 2 to 1 / 5 of a traditional molybdenum-copper substrate.
6. A method for processing a diamond microwave millimeter wave power heat sink substrate, used for processing the diamond microwave millimeter wave power heat sink substrate according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Provide diamond wafers of standard thickness and perform double-sided polishing; S2. Grooving and drilling holes on the substrate by laser processing; S3. Using magnetron sputtering to sequentially deposit nickel / titanium-tungsten alloy bottom metal, back electrode and matching electrode; S4. Prepare metal thin films layer by layer by photolithography and mask patterning technology; S5. Electroplating metal in the via hole to achieve vertical conduction; S6. The coating is subjected to vacuum annealing at a temperature of 450 to 550° C. for 1 to 2 hours; S7. Test the electrical properties and thermal conductivity of the substrate.
7. The method for processing a diamond microwave millimeter wave power heat sink substrate according to claim 6, characterized in that: The parameters of the laser processing in step S2 are: wavelength 1064nm, pulse width ≤20ns, and aperture accuracy ±5μm.
8. The method for processing a diamond microwave millimeter wave power heat sink substrate according to claim 6, characterized in that: The annealing treatment in step S5 is performed under nitrogen protection, and the void ratio of the film after annealing is ≤5%.
9. The method for processing a diamond microwave millimeter wave power heat sink substrate according to claim 6, characterized in that: The process conditions of magnetron sputtering in step S3 are: vacuum degree ≤ 5×10⁻ 6 Torr, sputtering power 200~400W, substrate temperature ≤80℃.
10. The method for processing a diamond microwave millimeter wave power heat sink substrate according to claim 6, characterized in that: It also includes conducting a thermal performance test on the substrate after step g: soldering the power device to the surface of the substrate, and verifying that the heat dissipation efficiency is improved by ≥20% through simulation and actual measurement of the junction temperature.