Method for multi-scale optimization of diamond adapter plate, application of method and adapter plate product

Abstract

The invention discloses a method for multi-scale optimization of a diamond adapter plate, application of the method and an adapter plate product, and the method comprises the steps: building a laser irradiation temperature field finite element model and a carbon atom phase change process molecular dynamics model based on a laser processing process, and carrying out analysis and mutual coupling in combination with a first principle to obtain a multi-scale simulation system; and optimizing the structure and the laser process of the diamond adapter plate according to the multi-scale simulation system to obtain optimized structure parameters and optimized laser parameters. According to the method, a laser irradiation temperature field finite element model and a carbon atom phase change process molecular dynamics model are combined with first principle analysis and are mutually coupled to obtain a multi-scale simulation system, and structure parameters of the diamond adapter plate after optimization and laser parameters of machining are obtained. According to the invention, the heat dissipation performance and interconnection reliability are enhanced, and the problems of heat dissipation and interconnection in high-power semiconductor packaging are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor packaging manufacturing, and in particular to a method for multi-scale optimization of a diamond adapter plate, an application thereof, and an adapter plate product. Background Art

[0002] As semiconductor devices accelerate their development towards high-density integration, high frequency and high power, integrated packaging technology has become the core path to break through the performance bottleneck of the "post-Moore era". As the key interconnection structure between chips and packaging carriers, adapter plates need to simultaneously meet the requirements of micron-level electrical interconnection accuracy, efficient heat dissipation and mechanical support. However, traditional organic substrates and silicon-based adapter plates face severe challenges due to the limitations of the intrinsic properties of the materials. For example, the thermal conductivity of organic substrates is only 0.2-0.5W / mK, which is prone to thermal warping at high temperatures and can only carry power densities below 1W / mm 2 Consumer electronic devices; Although the silicon-based adapter board achieves high-density interconnection with a line width of 2-5μm through silicon via (TSV) technology, its actual thermal conductivity is reduced to 50-100W / mK due to copper-filled TSV and interface effects. It is difficult to cope with the heat load of 5G RF modules or automotive power devices, and it is easy to cause thermal failure risks.

[0003] Diamond, the ultimate heat dissipation material (with a thermal conductivity of approximately 2000 W / mK and a coefficient of thermal expansion of 1-1.5 ppm / K), theoretically enables the creation of a low-interfacial thermal resistance heat conduction path from the chip to the heat sink. However, its electrical insulation and chemical inertness present bottlenecks in traditional microfabrication techniques. For example, wet etching makes it difficult to form high-aspect-ratio structures on the diamond surface, physical vapor deposition (PVD) metal layers are prone to delamination due to insufficient adhesion, and the difference in thermal expansion coefficients between diamond and chip materials can induce interfacial delamination. This constellation of challenges urgently requires breakthrough processes to achieve coordinated regulation of electrical and thermal conductivity.

[0004] Ultrafast laser-induced graphitization technology uses femtosecond laser to locally reconstruct the carbon atomic bond state within the diamond lattice (sp 3 to sp 2 ), provides an innovative solution to the above contradiction. This technology can achieve a resistivity as low as 1×10 by precisely controlling the laser energy density, scanning speed and spot overlap rate. -5 The chip's continuous conductive path of 100 Ω·m is achieved while suppressing amorphization or microcracks caused by thermal accumulation. A vertical through-hole array and multi-layer graphitized surface wiring respectively create a fully diamond thermal conduction channel from chip to substrate to heat sink (reducing thermal resistance by over 80% compared to silicon-based interconnects) and a 40GHz high-frequency signal interconnect network (insertion loss <0.3dB / mm). An Al2O3 passivation layer ensures compatibility with mainstream packaging processes such as flip-chip and thermocompression bonding.

[0005] While ultrafast laser-induced diamond graphitization technology has a solid theoretical basis, and some literature has provided methods for producing diamond circuit boards using laser processing, few design methods for optimizing the structure of diamond adapter plates have been reported. Summary of the Invention

[0006] The purpose of the present invention is to use diamond as a substrate to prepare an adapter plate, and to use laser in-situ to control the diamond-carbon bonding state to simultaneously achieve high-precision three-dimensional circuit forming and ultra-high thermal management capabilities, thereby solving the problems of heat dissipation bottlenecks, insufficient interconnection reliability and excessive process complexity in high-power semiconductor device packaging.

[0007] In order to achieve the above object, the present invention provides a method for multi-scale optimization of diamond adapter plates, comprising: Based on the laser processing process, a finite element model of the laser irradiation temperature field and a molecular dynamics model of the carbon atom phase transition process were constructed. Combined with first-principles analysis, they were coupled to obtain a multi-scale simulation system. The structure and laser process of the diamond adapter plate are optimized based on the multi-scale simulation system to obtain the optimized structural parameters and optimized laser parameters.

[0008] Furthermore, the multi-scale simulation system obtained by mutual coupling includes: Output temperature field distribution and cooling rate according to the finite element model of laser irradiation temperature field; The molecular dynamics model of the carbon atom phase transition process extracts the temperature variation curve in a certain area over time, simulates the atomic-level phase transition process of carbon atoms from diamond to graphite under laser heating, and obtains the kinetic parameters; The energy band structure, electrical conductivity and doping effect of the graphitized region are obtained based on first-principles analysis. The electrical conductivity, interface contact resistance and doping energy level are output to evaluate the graphitization degree and electrical properties of carbon atoms.

[0009] Furthermore, in the construction of the finite element model of the laser irradiation temperature field, laser parameter scanning with different wavelengths, pulse widths, energy densities, and scanning rates is combined; The simulation of the molecular dynamics model of the carbon atom phase transition process is performed using the Tersoff or ReaxFF potential function in the NVT / NPT ensemble with a time step of 0.1fs-1fs; The first principle is based on DFT theory and Boltzmann transport equation, and outputs energy band diagram, conductivity, interface contact resistance and doping energy level position.

[0010] Furthermore, the optimized structural parameters include the thickness, surface roughness, and thermal conductivity of the initial diamond adapter plate, the diameter and aspect ratio of the vertical segment of the vertical interconnect circuit formed by the graphitized carbon atoms in the processed diamond adapter plate, and the line width of the horizontal segment; The optimized laser parameters include wavelength, pulse width, energy density and scanning speed.

[0011] Furthermore, the thickness of the initial diamond adapter plate is 50-500 μm and the roughness is less than 10 nm. If the initial diamond adapter plate is single crystal, the thermal conductivity needs to be greater than or equal to 2000 / m·K; if it is polycrystalline, the thermal conductivity needs to be greater than or equal to 1500 / m·K. The laser parameters specifically include a wavelength of 515-1064 nm, a pulse width of 100-500 fs, and an energy density of 1-10 J / cm 2 , the scanning speed is 0.1-10mm / s; among them, the energy density when processing the vertical section is 5-10J / cm 2 , when processing the horizontal section, the energy density is 1-3J / cm 2 .

[0012] The present invention also provides an application of the above-mentioned multi-scale optimization method for diamond adapter plates in the preparation of diamond adapter plates, comprising: Select and pre-process the diamond adapter plate according to the optimized structural parameters; The product is obtained by processing according to the optimized laser parameters.

[0013] Furthermore, after the product is obtained, an insulating material is grown on the upper surface of the non-graphitized area to improve the electrical isolation performance of the product.

[0014] There is no need to strictly limit the growth process and type of the insulating material. For example, silicon nitride with a thickness of 100-500 nm can be grown by plasma enhanced chemical vapor deposition (PECVD).

[0015] Furthermore, after growing the insulating material, a protective layer is grown on the upper surface of the graphitized region, and the protective layer is etched to expose the graphitized region, and then a bonding metal is grown in the etched hole.

[0016] To ensure long-term, reliable circuit operation, a protective layer is grown on the upper surface of the graphitized region. The growth process and type of material for the protective layer are not strictly limited. For example, a 50-200nm thick layer of diamond-like carbon (DLC) or aluminum nitride (AlN) is grown on the upper surface of the graphitized region to enhance oxidation resistance and mechanical toughness. Reactive ion etching (RIE) can be used to precisely create windows in the protective layer, forming etched holes and exposing the graphitized region.

[0017] Furthermore, after the bonding metal is grown, it is bonded to the chip on which the conductive circuit and heat dissipation channel need to be constructed.

[0018] The present invention also provides a transfer plate product obtained by adopting the above application.

[0019] Compared with the prior art, the present invention has the following beneficial effects: This paper utilizes a finite element model of the laser irradiation temperature field and a molecular dynamics model of the carbon atom phase transition process, combined with first-principles analysis, to create a multi-scale simulation system. This system then determines the optimized structural parameters of the diamond adapter plate and the laser processing parameters. This method enhances heat dissipation performance and interconnect reliability, resolving heat dissipation and interconnection issues encountered in high-power semiconductor packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 The schematic diagram of the multi-scale simulation system obtained by mutual coupling in Example 1 is shown; Figure 2 A flow chart showing a method for preparing a transfer plate product according to Example 2 is shown; Figure 3 A schematic structural diagram showing the product of each step of the method for preparing the adapter plate product of Example 2; Description of reference numerals: 1. Diamond substrate; 2. Vertical segment; 3. Horizontal segment; 4. Insulation material; 5. Etched hole; 6. Power chip; 7. Bonding metal. DETAILED DESCRIPTION

[0022] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to form one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed in the present invention.

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the specific embodiments of the present invention and the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] Example 1 A method for multi-scale optimization of a diamond adapter plate comprises the following steps: T1. Based on the laser processing process, a finite element model of the laser irradiation temperature field and a molecular dynamics model of the carbon atom phase change process are constructed, and combined with the first principle analysis, such as Figure 1 As shown in Figure 3, a multi-scale simulation system is obtained by mutual coupling.

[0025] The overall analysis process includes laser irradiation finite element temperature field simulation, atomic-level phase transition molecular dynamics simulation, and first-principles electrical performance calculation. The three are interrelated, forming a closed-loop research framework from macroscopic temperature distribution to microscopic phase transition mechanism, and then to electronic transmission performance, providing a scientific basis for subsequent process design and reliability verification.

[0026] In the construction of the finite element model of the laser irradiation temperature field, the absorptivity, reflectivity and thermal radiation boundary conditions of the laser beam on the diamond adapter plate are introduced into the 2D / 3D finite element solver, and the optical and thermal processes are simulated simultaneously based on the heat conduction equation. With the help of the parameter sweep method, the typical wavelength, ns to μs pulse width and different energy densities (J / cm 2 ), systematically calculated the temperature distribution evolution under different combinations of scan rates and repetition frequencies, obtaining the maximum temperature, temperature gradient, and cooling rate distribution on and within the diamond adapter plate. Mesh refinement and time-step independence were used to verify the accuracy of the results and ensure computational convergence. This phase of research revealed how key process parameters affect temperature field changes during laser heating and cooling, providing accurate boundary condition input for subsequent carbon atomic-level simulations.

[0027] In the construction of the molecular dynamics model of the carbon atom phase transition process, the temperature-time curve of a specific area in the laser irradiation temperature field finite element model is used as the MD boundary condition, and the Tersoff or ReaxFF potential function including multi-body interaction is selected to simulate the sp 3 The bonding paradigm of diamond is sp 2The graphitization transition process is simulated using an NVT or NPT ensemble with a time step range of 0.1 fs to 1 fs to realistically reproduce the atomic-level evolution under laser heating and rapid cooling. By analyzing the changes in atomic coordination numbers, radial distribution functions (RDFs), and the evolution of local cluster structures, the phase transition rate and threshold temperature are accurately extracted, and the degree of graphitization is quantitatively assessed, providing key kinetic parameters for subsequent studies of the material's electrical properties.

[0028] First-principles calculations utilize density functional theory (DFT) combined with plane-wave pseudopotentials to construct local models of the graphitized region and the diamond / graphitized layer interface, performing K-point sampling and band structure and density of states (DOS) calculations. Furthermore, based on linear response theory and the Boltzmann transport equation, conductivity changes under different doping conditions (such as nitrogen and boron) can be evaluated. Interface models are constructed to calculate contact resistance and the impact of interface states on carrier transport. The final output includes a band diagram, a table of conductivity and mobility, the location of doping energy levels, and interface contact resistance, providing a direct basis for quantifying the relationship between the degree of graphitization and electrical properties.

[0029] T2. Optimize the structure and laser process of the diamond adapter plate based on the multi-scale simulation system to obtain the optimized structural parameters and optimized laser parameters.

[0030] The optimized structural parameters include the thickness, surface roughness, and thermal conductivity of the initial diamond adapter plate; the diameter and aspect ratio of the vertical segments of the graphitized carbon atoms forming the vertical interconnect circuits; and the line width of the horizontal segments. Specifically, the initial diamond adapter plate has a thickness of 50-500μm and a roughness of less than 10nm. If the initial diamond adapter plate is single crystal, the thermal conductivity must be greater than or equal to 2000 / m·K; if it is polycrystalline, the thermal conductivity must be greater than or equal to 1500 / m·K.

[0031] The optimized laser parameters include wavelength, pulse width, energy density and scanning speed. Specifically, the wavelength is 515-1064nm, the pulse width is 100-500fs, and the energy density is 1-10J / cm 2 , the scanning speed is 0.1-10mm / s; among them, the energy density when processing the vertical section is 5-10J / cm 2 , when processing the horizontal section, the energy density is 1-3J / cm 2 .

[0032] Based on the multi-scale simulation system constructed in this embodiment, structural parameters and laser parameters suitable for diamond adapter plate processing can be obtained. These parameters can be applied to the actual processing of diamond adapter plates to obtain various products.

[0033] Example 2 A method for preparing a transfer plate product, based on the parameters obtained in Example 1, such as Figure 2 and Figure 3 As shown, it includes the following steps, S101, Diamond substrate selection and pretreatment A single-crystal or polycrystalline diamond substrate 1 grown by chemical vapor deposition (CVD) is selected, with a thickness controlled within the range of 50-500μm. After mechanical polishing and plasma cleaning, the surface roughness of the diamond substrate 1 should be less than 10nm to ensure micron-level precision in laser processing. To meet high thermal conductivity requirements, the thermal conductivity of single-crystal substrates must reach 2000W / m·K, and that of polycrystalline substrates must reach 1500W / m·K. The thermal performance of selected samples is verified using the laser flash method. For substrates whose high reflectivity reduces energy utilization, a silicon nitride anti-reflection film can be selectively deposited on the surface to improve the efficiency of laser energy absorption.

[0034] S102, Laser Induced Graphitization Processing A femtosecond laser system (wavelength 515-1064nm, pulse width 100-500fs) is used to form three-dimensional circuits on diamond substrates. By dynamically adjusting the laser energy density (1-10J / cm 2 ) and scanning speed (0.1-10mm / s), achieving differentiated processing, high energy density (5-10J / cm 2 ) is used to drill vertical through holes and simultaneously graphitize the hole walls. It forms vertical segments with a hole diameter of 5-50μm and an aspect ratio of up to 15:1. Low energy density (1-3J / cm 2 ) is used to generate the surface redistribution layer, namely the horizontal segment 3. The line width of the horizontal segment 3 can be controlled to be 1-10 μm, and the resistivity is less than 1×10 -5 During the processing, a galvanometer scanning system and a dynamic focusing module are used to ensure a spot positioning accuracy of ±0.5μm, and real-time power monitoring is used to stabilize energy output.

[0035] S103, multi-layer circuit integration and insulation processing In traditional back-end processes, interconnect layers are deposited layer by layer (dielectric layer, metal interconnect layer, isolation layer). The present invention uses laser graphitization to form a three-dimensional interconnect structure layer by layer. This three-dimensional interconnect structure is composed of multiple layers. Each layer of interconnect structure can be divided into a vertical interconnect layer (cross-layer vias) and a horizontal interconnect layer. Depending on the design requirements, multi-layer circuits with different three-dimensional interconnect structures can be obtained. In the final step, a 100-500nm thick layer of insulating material, silicon nitride, is grown on the upper surface of the graphitized interconnect layer to further enhance the electrical isolation strength between the layers. This multi-layer integration process and protective layer deposition enhance heat dissipation performance and interconnect reliability.

[0036] After completing steps S101-S103, a diamond adapter plate was essentially fabricated. A vacuum fixture was used to systematically verify the performance and reliability of the resulting diamond adapter plate. The four-probe method was used to measure the resistivity of the graphite layer on the vertical through-hole walls; insertion loss was measured at 40 GHz; and resistance drift was measured after 5000 cycles of thermal cycling from -65°C to 175°C. All tests were conducted at an ambient temperature of 23±1°C and a relative humidity of <40%, with multiple parallel measurements to ensure data repeatability and reliability.

[0037] The results show that the resistivity of the graphite layer on the vertical through-hole wall of the diamond adapter plate is ≤1×10 -5 Ω·m; insertion loss at 40GHz is less than 0.2dB / mm; after thermal cycle testing, resistance drift is within 2%.

[0038] S104, protective layer deposition and chip integration To ensure long-term, reliable circuit operation, a 50-200nm thick protective layer of diamond-like carbon (DLC) or aluminum nitride (AlN) is deposited on the upper surface of the graphitized region to enhance oxidation resistance and mechanical toughness. Subsequently, reactive ion etching (RIE) is used to precisely create windows in the protective layer, forming etched holes 5 to expose the graphitized region. Bonding metal 7 is then grown within these etched holes.

[0039] The power chip 6 is flip-chipped and soldered to the adapter board using either gold-tin eutectic soldering or copper-copper thermocompression bonding. A microchannel copper heat sink is integrated on the back of the board, and high-temperature diffusion soldering technology is used to achieve an ultra-low thermal resistance interface connection, ensuring the module's thermal management performance.

[0040] In summary, this paper proposes a laser-induced circuit design method for diamond interposers. Through thermal field simulation, molecular dynamics phase transition simulation, and first-principles electrical calculations, laser parameters are optimized to achieve graphitized conductive channels and surface rewiring of through-holes. By utilizing a diamond substrate, a multi-layer integration process, and protective layer deposition, this method enhances heat dissipation and interconnect reliability, resolving heat dissipation and interconnect issues encountered in high-power semiconductor packaging.

[0041] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for multi-scale optimization of a diamond adapter plate, characterized in that: include, Based on the laser processing process, a finite element model of the laser irradiation temperature field and a molecular dynamics model of the carbon atom phase transition process were constructed. Combined with first-principles analysis, they were coupled to obtain a multi-scale simulation system. The structure and laser process of the diamond adapter plate are optimized based on the multi-scale simulation system to obtain the optimized structural parameters and optimized laser parameters.

2. The method for multi-scale optimization of diamond adapter plates according to claim 1, characterized in that: The multi-scale simulation system obtained by mutual coupling includes: Output temperature field distribution and cooling rate according to the finite element model of laser irradiation temperature field; The molecular dynamics model of the carbon atom phase transition process extracts the temperature variation curve in a certain area over time, simulates the atomic-level phase transition process of carbon atoms from diamond to graphite under laser heating, and obtains the kinetic parameters; The energy band structure, electrical conductivity and doping effect of the graphitized region are obtained based on first-principles analysis. The electrical conductivity, interface contact resistance and doping energy level are output to evaluate the graphitization degree and electrical properties of carbon atoms.

3. The method for multi-scale optimization of diamond adapter plate according to claim 1, characterized in that: In constructing the finite element model of the laser irradiation temperature field, laser parameter scanning with different wavelengths, pulse widths, energy densities, and scanning rates is combined; The simulation of the molecular dynamics model of the carbon atom phase transition process is performed using the Tersoff or ReaxFF potential function in the NVT / NPT ensemble with a time step of 0.1fs-1fs; The first principle is based on DFT theory and Boltzmann transport equation, and outputs energy band diagram, conductivity, interface contact resistance and doping energy level position.

4. The method for multi-scale optimization of a diamond adapter plate according to claim 1, characterized in that: The optimized structural parameters include the thickness, surface roughness, and thermal conductivity of the initial diamond adapter plate, the diameter and aspect ratio of the vertical segment of the vertical interconnect circuit formed by graphitized carbon atoms in the processed diamond adapter plate, and the line width of the horizontal segment; The optimized laser parameters include wavelength, pulse width, energy density and scanning speed.

5. The method for multi-scale optimization of diamond adapter plate according to claim 4, characterized in that: The initial diamond adapter plate has a thickness of 50-500 μm and a roughness of less than 10 nm. If the initial diamond adapter plate is single crystal, the thermal conductivity needs to be greater than or equal to 2000 / m·K; if it is polycrystalline, the thermal conductivity needs to be greater than or equal to 1500 / m·K. The laser parameters specifically include a wavelength of 515-1064 nm, a pulse width of 100-500 fs, and an energy density of 1-10 J / cm 2 , the scanning speed is 0.1-10mm / s; among them, the energy density when processing the vertical section is 5-10J / cm 2 , when processing the horizontal section, the energy density is 1-3J / cm 2 .

6. An application of the method for multi-scale optimization of a diamond adapter plate according to any one of claims 1 to 5 in the preparation of a diamond adapter plate, characterized in that: include, Select and pre-process the diamond adapter plate according to the optimized structural parameters; The product is obtained by processing according to the optimized laser parameters.

7. The use according to claim 6, characterized in that After the product is obtained, insulating material is grown on the upper surface of the non-graphitized area to improve the electrical isolation performance of the product.

8. The use according to claim 7, characterized in that After growing the insulating material, a protective layer is grown on the upper surface of the graphitized region, and the protective layer is etched to expose the graphitized region, and then a bonding metal is grown in the etched hole.

9. The use according to claim 8, characterized in that After the bonding metal is grown, it is bonded to the chip where the conductive circuit and heat dissipation channel need to be built.

10. A transfer plate product, characterized in that: Obtained by the application according to any one of claims 6 to 9.

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