An integrated method of DLC assisted stress release GaN / diamond

Abstract

The application discloses an integrated method of DLC auxiliary stress release GaN / diamond, which comprises sample pretreatment, preparation of a DLC auxiliary layer, preparation of a GaN / diamond heat dissipation module, and polishing and grinding of Si / DLC auxiliary layer to obtain a complete GaN / diamond module. The application has the beneficial effect that in the process of growing a diamond epitaxial layer, the DLC auxiliary layer is covered and wrapped with a graphite felt, heat preservation and heat gradient are generated, and stress release of GaN is assisted, so that the stability of GaN and the yield of the GaN / diamond module are improved.

Description

TECHNICAL FIELD

[0001] The application relates to a GaN / diamond integration method, in particular to a DLC-assisted stress release GaN / diamond integration method, and belongs to the technical field of semiconductor power electronic devices. BACKGROUND

[0002] The third-generation semiconductor represented by gallium nitride (GaN) has the advantages of wide band gap, high thermal conductivity, excellent electron mobility and electron saturation drift speed, and is widely used in the fields of aerospace and 5G communication. The highest temperature that the power chip prepared from GaN can withstand is up to 600°C, which not only has high energy utilization efficiency but also is stable enough to be expected to replace traditional Si-based power devices in the future.

[0003] With the industrialization, the size of the chip is continuously reduced, and the performance requirement of the power device is continuously improved. The 3D integrated circuit (3DIC) technology is considered as an important technology to cope with the "Moore's Law", and with the high-density power device and chip bonding and packaging, heat dissipation is an urgent process problem to be solved. GaN power devices generate a certain loss when working, and this part of power loss is in the form of heat energy in the internal device. Especially, the current GaN devices are mainly based on sapphire and Si substrates, and the thermal conductivity coefficients are 0.5 W / cm·K and 1.5 W / cm·K respectively, which makes the heat concentrate on the bonding surface of GaN / substrate, thereby greatly affecting the service life and service stability of the GaN power device.

[0004] In the prior art, the patent with publication number CN110838438A discloses a method for integrating diamond and gallium nitride. First, the gallium nitride epitaxial wafer and the temporary carrier are cleaned, then the two are temporarily bonded with their front surfaces facing each other, the substrate of the gallium nitride epitaxial wafer is removed after bonding, then the gallium nitride epitaxial layer supported by the temporary carrier is placed in deionized water and attached to the diamond substrate, then it is placed on a rotating table to dry, a bonding layer is formed on the attached surface, then it is placed in a bonding machine for heating and pressurizing, and finally the temporary carrier and the adhesive material are removed. Diamond has excellent thermal conductivity (22 W / cm·K), and its application in assisting GaN power device heat dissipation is a common method in the semiconductor field today. The integration of diamond and GaN power devices is mainly from two aspects: one is the heat dissipation of the device layer on the top of GaN, mainly applying diamond passivation heat dissipation technology; the other is the heat dissipation of the diamond substrate at the bottom of GaN, mainly including GaN bottom heteroepitaxial diamond, diamond surface heteroepitaxial GaN and GaN and diamond bonding technology. However, due to the large lattice mismatch between GaN and diamond, the large difference in thermal expansion coefficient, and the extremely high hardness of diamond, whether GaN or diamond is used as the base, heteroepitaxy of the other will cause serious thermal stress deformation on the interface between GaN and diamond. At the same time, in the process of heteroepitaxy, the growth environment of diamond requires extremely high temperature, which causes the GaN layer to have defects such as warping and cracking before or during the growth of the diamond layer, so that GaN and diamond cannot be well integrated together.

[0005] In the field of heteroepitaxial diamond, the thickness of GaN is also an important factor affecting the growth of diamond and the growth of other buffer layers. When heteroepitaxially growing a diamond layer on GaN, the thickness of GaN has a great influence on the surface binding energy. Thick GaN has great application potential in the preparation of double-layer structure with GaN attached on both sides. Currently, the binding energy of GaN and diamond is calculated as follows:

[0006]

[0007] Wherein, the binding energy is proportional to the square of the thickness of GaN , so preparing high-thickness GaN is an important means for heteroepitaxially growing high-quality diamond layer on GaN.

[0008] Diamond-like carbon (DLC) is an amorphous carbon with high hardness, ultra-low friction coefficient, excellent tribological properties, good biocompatibility, high optical transmittance, high thermal conductivity and high chemical inertness. DLC film mainly consists of sp 3 hybrid bonds and sp 2Hybrid bonds are composed of sp 3 Hybridized carbon atoms are embedded in a random network structure of sp 2 Hybrid bonds, and its structure is closely related to the performance of the DLC film, especially its thermal expansion coefficient depends on the proportion of sp 3 Hybrid bonds and sp 2 Hybrid bonds, when the proportion of sp 2 Hybrid bonds is higher, the thermal expansion coefficient of DLC is larger, by controlling the conditions of DLC preparation can control the thermal expansion coefficient of DLC layer, and assist the stress release of GaN in the high temperature condition of GaN heteroepitaxy diamond. More importantly: the preparation temperature of DLC is low, and the room temperature preparation can be realized in the industry at present. At the same time, the adhesion of DLC is very strong, which can be deposited on the surface of various metals, glass, ceramics and other materials, and the roughness requirement of the sample is not high, and the preparation cost is low, which is an ideal material for assisting GaN heteroepitaxy diamond. SUMMARY

[0009] The purpose of the present application is to provide a DLC assisted stress release GaN / diamond integration method to solve at least one of the above technical problems.

[0010] The present application realizes the above-mentioned purpose through the following technical scheme: a DLC assisted stress release GaN / diamond integration method, comprising DLC assisted stress release GaN / diamond, DLC assisted stress release GaN / diamond is composed of GaN layer, Si substrate, DLC assisted stress release layer, AlN buffer layer and diamond heat dissipation layer, GaN layer is located above Si substrate, DLC assisted stress release layer is located below Si substrate, AlN buffer layer is located above GaN layer, and diamond heat dissipation layer is located above AlN buffer layer.

[0011] The integration method comprises the following steps:

[0012] S1, sample pretreatment, after ultrasonic cleaning of Si-based GaN sample with cleaning liquid, dry with Ar gas gun, and protect GaN surface, use chemical mechanical polishing equipment to grind and polish Si substrate, leave a certain thickness of Si layer for DLC assisted layer deposition;

[0013] S2, preparation of DLC assisted layer, the treated Si-based GaN sample is prepared by ion enhanced chemical vapor deposition method on Si substrate at room temperature to prepare a layer of DLC film, and then the film is annealed;

[0014] S3, preparation of GaN / diamond heat dissipation module, a layer of AlN buffer layer is grown on GaN surface by using metal organic chemical vapor deposition method, and then high quality heat dissipation diamond is grown by using microwave plasma chemical vapor deposition method.

[0015] S4, polishing the Si / DLC auxiliary layer to obtain a complete GaN / diamond module.

[0016] As a further scheme of the present application, the sample pretreatment specifically comprises:

[0017] S11, performing cleaning pretreatment on the surface of the Si-based GaN sample, placing the Si-based GaN sample in a cleaning solution prepared from 70 vol% concentrated sulfuric acid and 30 vol% hydrogen peroxide, and performing water bath heating under an ultrasonic cleaning device, and heating from room temperature to 65℃ at a rate of 5℃ / min, and then performing ultrasonic cleaning in deionized water for 10s before taking out;

[0018] S12, drying by using an Ar gas gun and reserving, protecting the GaN surface of the Si-based GaN sample by using a chip protection film, and performing grinding on the Si substrate by using a chemical mechanical grinding method, and using 800, 1500, 2000, 3000 and 5000 mesh mechanical grinding discs until the remaining Si substrate is 0.5μm, and then performing polishing;

[0019] S13, performing grinding and polishing on the Si substrate by using a polishing cloth and a polishing liquid, wherein the polishing cloth is selected to be Sat woven fabric polishing cloth, the polishing liquid formula is 40 vol% SiO2 and 60 vol% diamond, the particle size of SiO2 is 150nm, the particle size of diamond powder is 50nm, and the polishing speed is 3500r / min.

[0020] As a further scheme of the present application, the preparation of the DLC auxiliary layer specifically comprises:

[0021] S21, placing the treated GaN sample with the Si surface upward, and placing a layer of high-temperature-resistant graphite felt at the bottom of the sample to avoid burning or melting of the chip protection film due to excessively high temperature, and placing the sample in a PECVD sample chamber, and the gas introduced in the preparation is Ar with a purity of 99.99%, and the carbon source is CH4 with a purity of 99.99%, the flow rate of CH4 is 20sccm, the flow rate of Ar is 10sccm, the base temperature is room temperature 27℃, the internal total gas pressure is 10-12Pa, the radio frequency power is 170-175W, the sputtering current is 0.5-0.6A, and the deposition rate is 5nm / min;

[0022] S22, performing preliminary vacuum extraction by using a mechanical pump, and after 30min, the pressure in the sample chamber reaches 4Pa; when the actual vacuum degree in the sample chamber reaches the preset pressure, a molecular pump is used to perform high vacuum extraction in the sample chamber until the vacuum degree in the sample chamber reaches 2x10 -3Pa, while slowly heating the temperature in the sample chamber, maintaining at 45℃;

[0023] S23, using Ar plasma to clean and activate the Si surface for 110s;

[0024] S24, after depositing for 4h, end and backfill Ar, wait for the sample chamber to return to normal temperature and pressure, take out the sample and clean it with deionized water, and get a 1200nm DLC auxiliary layer after Ar blowing dry;

[0025] S25, place the Si-based GaN sample with the prepared DLC auxiliary layer in an atmosphere furnace and anneal at 200℃ in N2 atmosphere for 60min.

[0026] As a further scheme of the application: the preparation of GaN / diamond heat dissipation module specifically comprises:

[0027] S31, after annealing, the sample GaN surface is upward and the chip protective film is removed, and the sample is placed on the high-temperature resistant graphite felt in the MOCVD sample chamber;

[0028] S32, introduce NH3 as N source and TMAl as Al source, the flow rates are 25000sccm and 240sccm respectively, the growth temperature is 800℃, the power is 1500W, and the growth pressure is 3×10 4 Pa; after depositing for 150min, backfill Ar, take out the sample with deposited AlN buffer layer, clean it with anhydrous ethanol and deionized water for 10min, and then place it on the graphite felt in the microwave chamber of the MPCVD for the growth of the final heat dissipation diamond layer;

[0029] S33, use a mechanical pump and a molecular pump in sequence to make the vacuum degree in the microwave chamber reach 2×10 -4 Pa, then introduce H2 to generate a hydrogen-rich environment and start glow discharge, after the glow in the chamber is stable for 5min, introduce carbon source CH4 to start the growth of the heat dissipation diamond layer, and simultaneously introduce a certain flow rate of Ar for auxiliary growth; the microwave power is 2500W, the growth temperature is 850℃, the chamber pressure is 80Pa, and the atmosphere ratio is H2:CH4:Ar=20-24:2:1; after growing for 5h, introduce Ar, wait for the chamber to return to normal temperature and pressure, slowly heat to 250℃ for 60min of annealing treatment, and get a complete DLC / GaN / diamond sample.

[0030] As a further scheme of the application: the polishing and grinding of Si / DLC auxiliary layer specifically comprises:

[0031] S41, the prepared DLC / GaN / diamond sample is removed from Si / DLC auxiliary layer using a chemical mechanical polishing device, and is polished using 800, 1500, 2000, 3000 and 5000 mesh mechanical grinding discs until the GaN layer is exposed;

[0032] S42, polishing is performed by using a polishing cloth and a polishing liquid, the polishing cloth is selected from Sat woven fabric polishing cloth, the polishing liquid is prepared from 10vol% Al2O3 and 90vol% diamond, the particle size of Al2O3 is 300nm, the particle size of diamond powder is 20nm, and the polishing speed is 3500r / min.

[0033] The present application has the following beneficial effects:

[0034] 1) The Si-based GaN sample surface is first protected, the Si substrate is polished to 0.5μm by using a chemical mechanical polishing device, then a DLC film is prepared on the Si surface by using a PECVD method at room temperature, and then the film is annealed to release stress and enhance mechanical strength, thereby providing a stress release point for subsequent heteroepitaxial diamond, since the DLC film with variable thermal conductivity and thermal expansion coefficient is added, the temperature and deformation stress of the sample can be effectively assisted and controlled during the subsequent MPCVD high-temperature growth of diamond, compared with the traditional method of heteroepitaxial growth of diamond, the method is more stable, effectively reduces the failure caused by thermal stress deformation of diamond and GaN during the heteroepitaxial growth of diamond, improves the production yield of diamond and GaN modules, and has great application potential in the field of GaN / diamond integration;

[0035] 2) The physical properties of the DLC used in the present invention can be changed by controlling the concentration of the carbon source (CH4) introduced during DLC ​​deposition or the deposition power, that is, the thermal expansion coefficient of DLC can be changed by process parameters to achieve an ideal value without introducing a new auxiliary layer. Secondly, DLC is easy to adhere. Compared with other auxiliary layers, it can be well deposited and attached to the Si substrate at room temperature, thereby preparing a layer of auxiliary layer with a similar thermal expansion coefficient and easy to deposit on the Si substrate. Then, the GaN DLC auxiliary layer is placed face down on a high-temperature resistant graphite felt. When growing diamond at high temperature, due to the presence of a certain thermal gradient inside the sample, heat diffuses from top to bottom to the DLC auxiliary layer with certain heat dissipation and thermal deformation capabilities. At the same time, the DLC auxiliary layer is strengthened through annealing treatment to strengthen the interfacial bonding strength, so that the GaN that should deform during high-temperature diamond growth has mechanical support here, which greatly reduces the frequency of curling during GaN heteroepitaxial diamond heat dissipation layer. Due to the introduction of the DLC auxiliary layer, when the thermal stress is too large, the DLC auxiliary layer can provide a stress release point, ensuring the yield of GaN / diamond. Finally, when the Si / DLC auxiliary layer is polished off, it will not have a significant impact on the GaN / diamond heat dissipation module. During this process, the tensile stress of GaN can be maintained at a good level and will not cause significant deformation. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Flow chart of the DLC-assisted stress-releasing GaN / diamond integration prepared by the present invention;

[0037] Figures 2 Schematic diagram of the DLC auxiliary layer prepared in the present invention;

[0038] Figures 3 Schematic diagram of the tensile testing method for the GaN / diamond module prepared in the present invention.

[0039] In the figure, 1. GaN layer; 2. Si substrate; 3. DLC auxiliary stress release layer; 4. AlN buffer layer; 5. Diamond heat dissipation layer. DETAILED DESCRIPTION

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments 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.

[0041] Example 1, as Figure 1As shown in the figure, an integrated method of DLC assisted stress release GaN / diamond includes DLC assisted stress release GaN / diamond, which is composed of a GaN layer 1, a Si substrate 2, a DLC assisted stress release layer 3, an AlN buffer layer 4 and a diamond heat dissipation layer 5. The GaN layer 1 is above the Si substrate 2, the DLC assisted stress release layer 3 is below the Si substrate 2, the AlN buffer layer 4 is above the GaN layer 1, and the diamond heat dissipation layer 5 is above the AlN buffer layer 4.

[0042] The integrated method includes the following steps:

[0043] S1, sample pretreatment, after the Si-based GaN sample is ultrasonically cleaned with a cleaning solution, it is blown dry with an Ar gas gun, and the GaN surface is protected. The Si substrate is polished by a chemical mechanical polishing device, and a certain thickness of Si layer is reserved for deposition of the DLC assisted layer.

[0044] S2, preparation of the DLC assisted layer, a layer of DLC film is prepared on the Si substrate at room temperature by ion enhanced chemical vapor deposition (PECVD, Plasma Enhanced Chemical Vapor Deposition) method after the treated Si-based GaN sample, and then the film is annealed;

[0045] S3, preparation of GaN / diamond heat dissipation module, after growing an AlN buffer layer on the GaN surface by metal organic chemical vapor deposition (MOCVD, Metal-Organic Chemical Vapour Deposition) method, high-quality heat dissipation diamond is grown by high-temperature growth method by microwave plasma chemical vapor deposition (MPCVD, Microwave Plasma Chemical Vapor Deposition) method;

[0046] S4, polishing the Si / DLC assisted layer to obtain a complete GaN / diamond module.

[0047] Example two, as Figures 2 to 3 shown, an integrated method of DLC assisted stress release GaN / diamond, the thickness of GaN is 450 μm, the integrated method includes the following steps:

[0048] Sample pretreatment, cleaning and pretreatment on the surface of Si-based GaN sample, the Si-based GaN sample is placed in a cleaning solution prepared from 70vol% concentrated sulfuric acid and 30vol% hydrogen peroxide, and heated in a water bath under ultrasonic cleaning device, the temperature is raised from room temperature to 65℃ at a rate of 5℃ / min, after ultrasonic cleaning for 10min, it is placed in deionized water for ultrasonic cleaning for 10s, then taken out; dry with Ar gas gun and standby, protect the GaN surface of Si-based GaN sample with chip protection film, use chemical mechanical polishing method to polish Si substrate, use 800, 1500, 2000, 3000 and 5000 mesh mechanical polishing disc until the remaining Si substrate is 0.5μm, then polish; use polishing cloth and polishing liquid to polish Si substrate, the polishing cloth is Sat woven fabric polishing cloth, the polishing liquid formula is 40vol% SiO2 and 60vol% diamond, the particle size of SiO2 is 150nm, the particle size of diamond powder is 50nm, and the polishing speed is 3500r / min.

[0049] Preparation of DLC auxiliary layer, the treated GaN sample is placed with Si surface upward, and a layer of high-temperature resistant graphite felt is placed on the bottom of the sample to avoid burning or melting of the chip protection film due to high temperature; the sample is placed in the PECVD sample chamber; the gas introduced in the preparation is Ar with a purity of 99.99%, and the carbon source is CH4 with a purity of 99.99%; the flow rate of CH4 is 20sccm, the flow rate of Ar is 10sccm, the base temperature is room temperature 27℃, the internal total gas pressure is 12Pa, the radio frequency power is 175W, the sputtering current is 0.5A, and the deposition rate is 5nm / min; a mechanical pump is used for preliminary vacuum extraction, and after 30min, the pressure in the sample chamber reaches 4Pa; when the actual vacuum degree in the sample chamber reaches the preset pressure, a molecular pump is used to extract high vacuum in the sample chamber until the vacuum degree in the sample chamber reaches 2×10 -3 Pa, and the temperature in the sample chamber is slowly heated and maintained at 45℃; the Si surface is cleaned and activated by Ar plasma for 110s; the deposition is completed after 4h, and Ar is filled, the sample chamber is restored to room temperature and normal pressure, the sample is taken out and cleaned with deionized water, and the 1200nm DLC auxiliary layer is obtained after Ar drying; the Si-based GaN sample with DLC auxiliary layer is placed in an atmosphere furnace and annealed at 200℃ in N2 atmosphere for 60min.

[0050] A GaN / diamond heat dissipation module was prepared. The sample after annealing was placed on a high-temperature resistant graphite felt in a MOCVD sample chamber with the GaN surface facing up and the chip protective film removed. NH3 was introduced as the N source and TMAl was introduced as the Al source. The flow rates were 25000 sccm and 240 sccm, respectively. The growth temperature was 800°C. The power was 1500 W. The growth pressure was 3x10 4 Pa. After 150 min of deposition, the sample was removed and cleaned with anhydrous ethanol and deionized water for 10 min. The sample was then placed on a graphite felt in a microwave chamber of a MPCVD. The sample was subjected to a final growth of a heat dissipation diamond layer. The vacuum degree in the microwave chamber was increased to 2x10 -4 Pa by using a mechanical pump and a molecular pump. H2 was introduced to generate a hydrogen-rich environment. The microwave power was 2500 W. The growth temperature was 850°C. The pressure in the chamber was 80 Pa. The atmosphere ratio was H2:CH4:Ar=20:2:1. After 5 h of growth, Ar was introduced. After the chamber returned to normal temperature and pressure, the sample was slowly heated to 250°C for 60 min of annealing to obtain a complete DLC / GaN / diamond sample.

[0051] The Si / DLC auxiliary layer was polished. The prepared DLC / GaN / diamond sample was polished using a chemical mechanical polishing device to remove the Si / DLC auxiliary layer. The sample was ground using 800, 1500, 2000, 3000 and 5000 mesh mechanical grinding discs until the GaN layer was exposed. The sample was then polished using a polishing cloth and a polishing liquid. The polishing cloth was Sat woven fabric polishing cloth. The polishing liquid was prepared by mixing 10 vol% Al2O3 and 90 vol% diamond. The particle size of the Al2O3 was 300 nm. The particle size of the diamond powder was 20 nm. The polishing speed was 3500 r / min.

[0052] The GaN / diamond module prepared in the above example was subjected to tensile stress testing using a universal material testing machine. The testing method is shown in Figure 3 . The two ends of the GaN / diamond module were labeled. The module was clamped at the two ends using the clamps of the universal material testing machine. The tensile stress was applied at a speed of 1 mm / s. The tensile stress test result was 0.41 GPa.

[0053] Example Three, as shown in Figures 2 to 3 , an integrated method for releasing stress of a GaN / diamond using a DLC auxiliary layer, the thickness of the GaN was 450 μm. The integrated method included the following steps:

[0054] The sample is pretreated, and the Si-based GaN sample is placed in a cleaning solution prepared from 70 vol% concentrated sulfuric acid and 30 vol% hydrogen peroxide, and is heated in a water bath under ultrasonic cleaning device at a rate of 5 ℃ / min from room temperature to 65 ℃. After ultrasonic cleaning for 10 min, the sample is placed in deionized water and ultrasonic cleaned for 10 s, then taken out. The Si-based GaN sample is dried by using an Ar gas gun and is ready for use. The GaN surface of the Si-based GaN sample is protected by a chip protection film. The Si substrate is ground by using a chemical mechanical grinding method. The mechanical grinding discs with a mesh size of 800, 1500, 2000, 3000 and 5000 are used until the remaining Si substrate is 0.5 μm, and then polishing is performed. The polishing is performed by using a polishing cloth and a polishing liquid. The Sat woven fabric polishing cloth is selected, and the polishing liquid is prepared from 40 vol% SiO2 and 60 vol% diamond. The particle size of SiO2 is 150 nm, the particle size of diamond powder is 50 nm, and the polishing speed is 3500 r / min.

[0055] The prepared DLC auxiliary layer is prepared. The treated GaN sample is placed with the Si surface facing upward, and a layer of high-temperature-resistant graphite felt is placed on the bottom of the sample to prevent the chip protection film from burning or melting due to excessive temperature. The sample is placed in a PECVD sample chamber. In the preparation, the gas introduced is Ar with a purity of 99.99%, and the carbon source is CH4 with a purity of 99.99%. The flow rate of CH4 is 20 sccm, the flow rate of Ar is 10 sccm, the base temperature is room temperature 27 ℃, the internal total gas pressure is 10 Pa, the radio frequency power is 170 W, the sputtering current is 0.6 A, and the deposition rate is 5 nm / min. A mechanical pump is used for preliminary vacuum extraction, and after 30 min, the pressure in the sample chamber reaches 4 Pa. When the actual vacuum degree in the sample chamber reaches the preset pressure, a molecular pump is used to extract high vacuum in the sample chamber until the vacuum degree in the sample chamber reaches 2×10 -3 Pa, and the temperature in the sample chamber is slowly heated and maintained at 45 ℃. The Si surface is cleaned and activated by using Ar plasma for 110 s. After 4 h of deposition, the process is ended, Ar is charged, the sample chamber is allowed to return to room temperature and normal pressure, the sample is taken out, washed with deionized water, dried by Ar, and a 1200 nm DLC auxiliary layer is obtained. The Si-based GaN sample with the prepared DLC auxiliary layer is placed in an atmosphere furnace and is annealed at 200 ℃ under N2 atmosphere for 60 min.

[0056] A GaN / diamond heat dissipation module was prepared. The sample after annealing was placed on a high-temperature resistant graphite felt in a MOCVD sample chamber with the GaN surface facing up and the chip protective film removed; NH3 was introduced as the N source and TMAl was introduced as the Al source, the flow rates were 25000 sccm and 240 sccm respectively, the growth temperature was 800°C, the power was 1500W, and the growth pressure was 3x10 4 Pa; after 150 min of deposition, the sample chamber was returned to normal temperature and pressure, the sample with the deposited AlN buffer layer was removed, cleaned with anhydrous ethanol and deionized water for 10 min, and then placed on a graphite felt in a microwave chamber of a MPCVD for growth of the final heat dissipation diamond layer; the vacuum degree in the microwave chamber was increased to 2x10 -4 Pa by using a mechanical pump and a molecular pump, H2 was introduced to generate a hydrogen-rich environment and start glow discharge, CH4 was introduced to start growth of the heat dissipation diamond layer after the glow discharge in the chamber was stable for 5 min, and Ar was introduced to assist the growth; the microwave power was 2500W, the growth temperature was 850°C, the pressure in the chamber was 80Pa, and the atmosphere ratio was H2:CH4:Ar=24:2:1; after 5h of growth, Ar was introduced, the chamber was returned to normal temperature and pressure, and the sample was annealed at 250°C for 60 min to obtain a complete DLC / GaN / diamond sample.

[0057] The Si / DLC auxiliary layer was polished. The prepared DLC / GaN / diamond sample was polished using a chemical mechanical polishing device to remove the Si / DLC auxiliary layer. The grinding was performed using 800, 1500, 2000, 3000 and 5000 mesh mechanical grinding discs until the GaN layer was exposed. The polishing was performed using a polishing cloth and a polishing liquid. The polishing cloth was Sat woven fabric polishing cloth. The polishing liquid was prepared by mixing 10vol% Al2O3 and 90vol% diamond. The particle size of the Al2O3 was 300nm, the particle size of the diamond powder was 20nm, and the polishing speed was 3500r / min.

[0058] The GaN / diamond module prepared in the above example was subjected to tensile stress testing using a universal material testing machine. The testing method was as shown in Figure 3 The two ends of the GaN / diamond module were labeled, the module was clamped at the two ends using the clamp of the universal material testing machine, and the tensile stress was applied at a speed of 1mm / s. The tensile stress test result was 0.48GPa.

[0059] After the Si-based GaN sample is cleaned by using a cleaning solution and dried by using an argon gun, the Si substrate 2 is polished by using a chemical mechanical polishing device, a DLC film is prepared on the Si surface by using PECVD at room temperature, and then the DLC film is annealed to form a DLC auxiliary stress release layer 3; the treated sample GaN surface is prepared with an AlN buffer layer 4 by using MOCVD, and then a diamond heat dissipation layer 5 is epitaxied by using MPCVD.

[0060] It is apparent to a person skilled in the art that the present application is not limited to the details of the above-described exemplary embodiments, but can be implemented in other concrete forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all aspects as illustrative and not restrictive, and the scope of the present application is defined by the appended claims rather than the above description, and it is intended to include all changes falling within the meaning and range of equivalents of the claims. Any reference signs in the claims should not be considered as limiting the claims involved.

[0061] Furthermore, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the present specification is described in this way only for the sake of clarity, and a person skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by a person skilled in the art.

Claims

1. A DLC-assisted stress-released GaN / diamond integration method, comprising DLC-assisted stress-released GaN / diamond, characterized in that: The DLC-assisted stress-releasing GaN / diamond is composed of a GaN layer (1), a Si substrate (2), a DLC-assisted stress-releasing layer (3), an AlN buffer layer (4), and a diamond heat dissipation layer (5); the GaN layer (1) is located above the Si substrate (2), the DLC-assisted stress-releasing layer (3) is located below the Si substrate (2), the AlN buffer layer (4) is located above the GaN layer (1), and the diamond heat dissipation layer (5) is located above the AlN buffer layer (4); The integration method comprises the following steps: S1. Sample pretreatment: After ultrasonic cleaning of the Si-based GaN sample with a cleaning solution, it was dried with an Ar air gun, and the GaN surface was protected. The Si substrate was polished using a chemical mechanical polishing device, and the Si layer was retained for the deposition of the DLC auxiliary layer. S2, preparing a DLC auxiliary layer, using an ion-enhanced chemical vapor deposition method to deposit a DLC film on a Si substrate at room temperature on the treated Si-based GaN sample, and then annealing the DLC film; S3. Prepare a GaN / diamond heat dissipation module by growing an AlN buffer layer on the GaN surface using a metal organic chemical vapor deposition method, and then growing high-quality heat dissipation diamond using a microwave plasma chemical vapor deposition method at high temperature; S4. Polish the Si / DLC auxiliary layer to obtain a complete GaN / diamond module.

2. The integration method according to claim 1, characterized in that In S1, sample pretreatment specifically includes: S11. Perform a cleaning pretreatment on the surface of the Si-based GaN sample by placing the Si-based GaN sample in a cleaning solution prepared by 70 vol% concentrated sulfuric acid and 30 vol% hydrogen peroxide, heating the sample in a water bath under an ultrasonic cleaning device at a rate of 5°C / min to 65°C, ultrasonically cleaning the sample for 10 minutes, and then placing the sample in deionized water for ultrasonic cleaning for 10 seconds before taking it out. S12. Blow dry with an Ar air gun and set aside. Protect the GaN surface of the Si-based GaN sample with a chip protection film. Grind the Si substrate using a chemical mechanical polishing method. Use 800, 1500, 2000, 3000, and 5000 mesh mechanical grinding wheels until 0.5 μm of Si substrate remains, and then polish; S13. The Si substrate is ground and polished using a polishing cloth and a polishing liquid. The polishing cloth is a Sat woven fabric polishing cloth, and the polishing liquid formula is: 40 vol% SiO2 and 60 vol% diamond; the particle size of SiO2 is 150 nm, the particle size of diamond powder is 50 nm, and the polishing speed is 3500 r / min.

3. The integration method according to claim 1, characterized in that: In S2, preparing the DLC auxiliary layer specifically includes: S21. Place the processed GaN sample Si side up and place a layer of high-temperature resistant graphite felt on the bottom of the sample to prevent the chip protection film from burning or melting due to excessive temperature. Place the sample in the PECVD sample chamber. The gas introduced during the preparation is 99.99% pure Ar and the carbon source is 99.99% pure CH4; the flow rate of CH4 is 20 sccm, the flow rate of Ar is 10 sccm, the base temperature is 27°C, the internal total pressure is 10-12 Pa, the RF power is 170-175 W, the sputtering current is 0.5-0.6 A, and the deposition rate is 5 nm / min. S22, use a mechanical pump to perform preliminary vacuum extraction. After 30 minutes, the pressure in the sample chamber reaches a high vacuum degree. Then, perform high vacuum extraction until the vacuum degree in the sample chamber reaches 2×10 -3 Pa, and at the same time slowly heat the temperature in the sample chamber to maintain it at 45°C; S23, using Ar plasma to clean and activate the Si surface for 110s; S24, the deposition is terminated after 4 hours, and Ar is refilled, and the sample chamber is allowed to return to normal temperature and pressure. The sample is taken out and washed with deionized water, and dried with Ar to obtain a 1200 nm DLC auxiliary layer; S25. Place the Si-based GaN sample with the DLC auxiliary layer prepared in an atmosphere furnace and anneal it at 200° C. in an N 2 atmosphere for 60 minutes.

4. The integration method according to claim 1, characterized in that: In S3, preparing the GaN / diamond heat dissipation module specifically includes: S31, facing the GaN surface of the annealed sample upwards, removing the chip protective film, and placing the sample on a high-temperature resistant graphite felt in the MOCVD sample chamber; S32, NH3 was introduced as the N source and TMAl was introduced as the Al source, with flow rates of 25000 sccm and 240 sccm respectively, the growth temperature was 800 °C, the power was 1500 W, and the growth pressure was 3×10 4 Pa, after 150 minutes of deposition, Ar is backfilled, and when the sample chamber returns to normal temperature and pressure, the sample with the AlN buffer layer deposited is taken out, ultrasonically cleaned with anhydrous ethanol and deionized water for 10 minutes, blown dry with an Ar air gun, and placed on the graphite felt in the microwave chamber of the MPCVD for the final growth of the heat dissipation diamond layer; S33, use the mechanical pump and molecular pump in sequence to make the vacuum degree in the microwave chamber reach 2×10 -4 After Pa, H2 was introduced to generate a hydrogen-rich environment and ignite at the same time. After the glow in the chamber was stable for 5 minutes, the carbon source CH4 was introduced to start the growth of the heat dissipation diamond layer. At the same time, Ar was filled in for auxiliary growth. The microwave power was 2500W, the growth temperature was 850℃, the pressure in the chamber was 80Pa, and the atmosphere ratio was H2:CH4:Ar=20-24:2:

1. After 5 hours of growth, Ar was introduced. After the chamber returned to room temperature and pressure, the temperature was slowly raised to 250℃ and annealing treatment was carried out for 60 minutes to obtain a complete DLC / GaN / diamond sample.

5. The integration method according to claim 1, characterized in that In S4, polishing the Si / DLC auxiliary layer specifically includes: S41, using a chemical mechanical polishing device to remove the Si / DLC auxiliary layer from the prepared DLC / GaN / diamond sample, grinding using 800, 1500, 2000, 3000 and 5000 mesh mechanical grinding discs until the GaN layer is exposed and then polishing; S42. Polishing is performed using a polishing cloth and a polishing liquid. The polishing cloth is a Sat woven fabric polishing cloth. The polishing liquid formula is: 10 vol% Al2O3 and 90 vol% diamond. The particle size of Al2O3 is 300 nm, the particle size of the diamond powder is 20 nm, and the polishing speed is 3500 r / min.

Images