Diamond film GaN HEMT preparation method based on intelligent cutting technology

Abstract

The invention discloses a diamond film GaN HEMT preparation method based on an intelligent cutting technology, and relates to the technical field of semiconductor devices.According to the method, a monocrystal diamond film is transferred through the intelligent cutting technology, and compared with traditional heteroepitaxial growth of polycrystalline diamond, the heat conductivity of the diamond film is increased, and the heat conductivity of the monocrystal diamond film is improved; therefore, the heat dissipation capability of the GaN HEMT is improved. By changing the injection energy and the injection dosage of hydrogen ion injection, the thickness of the monocrystal diamond film can be accurately regulated and controlled.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor devices, and in particular relates to a method for preparing a diamond thin film GaN HEMT (High electron mobility transistor) based on smart cutting technology. Background Art

[0002] Gallium nitride (GaN) is a wide-bandgap semiconductor material with higher electron mobility and breakdown voltage than silicon, giving it significant advantages in high-voltage, high-power applications. However, due to GaN's low thermal conductivity (approximately 130 W / m·K), its thermal conductivity is poor. This property prevents heat generated within the device from being quickly transferred to the heat sink, causing it to accumulate inside the device, resulting in self-heating. This self-heating effect can significantly reduce basic device performance, such as saturation current, transconductance, output power, and power-added efficiency. In severe cases, it can even cause device failure.

[0003] As gallium nitride-based microwave power devices develop towards smaller sizes, higher output powers, and higher frequencies, self-heating becomes increasingly prominent, becoming a bottleneck restricting the device's performance. Diamond, with a thermal conductivity of up to 2000 W / m·K, has broad application prospects in gallium nitride devices, serving as a heat dissipation mechanism to improve thermal conductivity.

[0004] Existing technologies typically use microwave plasma chemical vapor deposition (MPCVD) or hot-filament chemical vapor deposition (HFCVD) to grow diamond films atop GaN devices to reduce device self-heating. However, the lattice mismatch between GaN (hexagonal, lattice constants: a=0.3189nm, c=0.5185nm) and diamond (cubic, lattice constant: a=0.3567nm) is approximately 10%, resulting in numerous defects at the interface during epitaxial growth. Dislocation proliferation can lead to film cracking. Furthermore, MPCVD and HFCVD present compatibility issues with GaN device manufacturing processes. For example, high-temperature, hydrogen-rich environments easily etch the GaN layer, and plasma interaction with the GaN surface can cause surface atoms to be sputtered or generate defects. Furthermore, the thermal conductivity of diamond films grown by MPCVD or HFCVD (300-600W / m·K) is far lower than that of ideal diamond, preventing the effective utilization of diamond's thermal conductivity. Summary of the Invention

[0005] To address the above-mentioned problems in the prior art, the present invention provides a method for preparing a diamond thin film GaN HEMT based on smart cutting technology. The technical problem to be solved by the present invention is achieved through the following technical solutions: The present invention provides a method for preparing a diamond thin film GaN HEMT based on smart cutting technology, comprising: Step 1: preparing a source electrode, a drain electrode and a first SiN dielectric layer on the AlGaN barrier layer of the AlGaN / GaN epitaxial wafer, wherein the first SiN dielectric layer is located between the source electrode and the drain electrode; Step 2: etching the first SiN dielectric layer to form a gate trench in contact with the AlGaN barrier layer, and preparing a gate metal inside the gate trench and on the first SiN dielectric layer to form a gate, thereby obtaining a GaN HEMT; Step 3: preparing a second SiN dielectric layer on the upper surface of the GaN HEMT; Step 4: implanting hydrogen ions into the single crystal diamond to obtain hydrogen ion-implanted single crystal diamond, wherein the hydrogen ions are implanted into the single crystal diamond, a hydrogen ion layer is located inside the single crystal diamond, and the single crystal diamond is divided into an upper single crystal diamond film layer and a lower single crystal diamond body; Step 5: Implanting the hydrogen ions into the single crystal diamond and bonding it to a GaN HEMT having a second SiN dielectric layer to obtain a bonded device, wherein the single crystal diamond film layer is in contact with the second SiN dielectric layer; Step 6: performing thermal annealing on the bonded device to peel off the single crystal diamond body; Step 7: performing a hole-forming operation on the single crystal diamond film layer and the second SiN dielectric layer at the electrode position of the GaN HEMT to form a source hole trench contacting the source electrode, a drain hole trench contacting the drain electrode, and a gate hole trench contacting the gate electrode; Step 8: preparing interconnection metal on the bottom and inner wall of the source hole groove, the drain hole groove and the gate hole groove.

[0006] Compared with the prior art, the present invention has the following beneficial effects: The present invention's method for fabricating a GaN HEMT with diamond thin film based on smart cutting technology utilizes this technology to transfer a single-crystal diamond film. Compared to traditional heteroepitaxial growth of polycrystalline diamond, this method increases the thermal conductivity of the diamond film, thereby enhancing the heat dissipation capability of the GaN HEMT. By varying the hydrogen ion implantation energy and dose, the thickness of the single-crystal diamond film can be precisely controlled. This method also allows for the reuse of single-crystal diamond material samples, reducing the production cost of GaN HEMTs with diamond thin films.

[0007] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the following preferred embodiments are specifically cited and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 Schematic diagram of a method for preparing a diamond thin film GaN HEMT based on smart cutting technology provided by an embodiment of the present invention; Figure 2 It is a schematic diagram of AlGaN / GaN epitaxial wafer; Figure 3 This is a schematic diagram of the sample after the source, drain and first SiN dielectric layer are prepared; Figure 4 is a schematic diagram of a GaN HEMT; Figure 5 is a schematic diagram of the sample after the second SiN dielectric layer is grown and polished; Figure 6 This is a schematic diagram of hydrogen ion implantation into single crystal diamond; Figure 7 is a schematic diagram of a bonding device; Figure 8 is a schematic diagram of a bonded device for exfoliating a single crystal diamond body; Figure 9 is a schematic diagram of the sample after opening; Figure 10 Schematic diagram of diamond thin film GaN HEMT.

[0009] Icon: 1-Si substrate; 2-AlN nucleation layer; 3-GaN buffer layer; 4-GaN channel layer; 5-AlGaN barrier layer; 6-source; 7-drain; 8-first SiN dielectric layer; 9-gate; 10-second SiN dielectric layer; 11-single crystal diamond film layer; 12-hydrogen ion layer; 13-single crystal diamond body; 14 interconnect metal. DETAILED DESCRIPTION

[0010] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the following is a detailed description of a diamond thin film GaN HEMT preparation method based on smart cutting technology proposed in accordance with the present invention, in conjunction with the accompanying drawings and specific embodiments.

[0011] The aforementioned and other technical contents, features, and effects of the present invention are clearly presented in the following detailed description of the specific embodiments in conjunction with the accompanying drawings. Through the description of the specific embodiments, a deeper and more specific understanding of the technical means and effects adopted by the present invention to achieve the intended purpose can be obtained. However, the accompanying drawings are provided for reference and illustration purposes only and are not intended to limit the technical solutions of the present invention.

[0012] In the first aspect, the present invention provides a method for preparing a diamond thin film GaN HEMT based on smart cutting technology, see Figure 1 , Figure 1 FIG is a schematic diagram of a method for preparing a diamond thin film GaN HEMT based on smart cutting technology provided by an embodiment of the present invention, such as Figure 1 As shown, the method for preparing a diamond thin film GaN HEMT based on the smart cutting technology of the present invention includes the following steps: Step 1: A source electrode 6 , a drain electrode 7 and a first SiN dielectric layer 8 are prepared on the AlGaN barrier layer 5 of the AlGaN / GaN epitaxial wafer, wherein the first SiN dielectric layer 8 is located between the source electrode 6 and the drain electrode 7 .

[0013] In this embodiment, the AlGaN / GaN epitaxial wafer includes a Si substrate 1, an AlN nucleation layer 2, a GaN buffer layer 3, a GaN channel layer 4 and an AlGaN barrier layer 5 stacked from bottom to top, and a two-dimensional electron gas is formed between the GaN channel layer 4 and the AlGaN barrier layer 5.

[0014] It should be noted that the AlGaN / GaN epitaxial wafer must be surface cleaned before step 1. Specifically, the AlGaN / GaN epitaxial wafer is placed in an acetone solution for ultrasonic cleaning for 3-5 minutes, with the ultrasonic intensity not exceeding 2.5; the AlGaN / GaN epitaxial wafer is placed in a stripping solution at a temperature of 50-60°C and heated in a water bath for 3-5 minutes; the AlGaN / GaN epitaxial wafer is placed in an acetone solution and an ethanol solution in turn for ultrasonic cleaning for 3-5 minutes, with the ultrasonic intensity not exceeding 2.5; the AlGaN / GaN epitaxial wafer is rinsed with ultrapure water and blown dry with nitrogen. The schematic diagram of the cleaned AlGaN / GaN epitaxial wafer is shown as follows Figure 2 shown.

[0015] In this embodiment, step 1 may include the following steps: Step 1.1: Photolithography source and drain electrode regions are formed on the AlGaN barrier layer 5.

[0016] Specifically, the process includes: placing an AlGaN / GaN epitaxial wafer on a hot plate at 200°C and baking it for 5 minutes; then, applying and spinning off a stripping adhesive on the AlGaN / GaN epitaxial wafer, with the stripping adhesive layer having a thickness of 0.35 μm, and baking the coated sample on a hot plate at 200°C for 5 minutes; applying and spinning off a photoresist on the stripping adhesive, with the photoresist layer having a thickness of 0.77 μm, and baking the coated sample on a hot plate at 90°C for 1 minute; placing the coated and spun-off sample into a photolithography machine to expose the photoresist in the source and drain electrode area; placing the exposed sample into a developer, removing the photoresist and stripping adhesive in the source and drain electrode area, and rinsing the sample with ultrapure water and drying it with nitrogen.

[0017] Step 1.2: Prepare ohmic electrode metal in the source and drain electrode regions to form source 6 and drain 7.

[0018] Specifically, the AlGaN / GaN epitaxial wafer with active and drain electrode patterns was placed in a plasma stripper for bottom film treatment for 5 minutes; the wafer was placed in an electron beam evaporation station and the vacuum degree of the reaction chamber of the electron beam evaporation station was maintained at 2×10 -6 After the Torr process, ohmic metal is evaporated. This ohmic metal is a metal stack composed of four layers of metal, Ti, Al, Ni, and Au, in order from bottom to top. The sample after ohmic metal evaporation is stripped to remove the ohmic metal, photoresist, and stripping adhesive outside the source and drain electrode regions. The sample is rinsed with ultrapure water and blown dry with nitrogen. The sample, after ohmic metal evaporation and stripping, is placed in a rapid thermal annealing furnace for annealing. This allows the ohmic metal in the source and drain electrode regions to sink into the GaN buffer layer 3, forming an ohmic contact between the ohmic metal and the heterojunction channel, forming source 6 and drain 7. The annealing process conditions are: N2 atmosphere, annealing temperature 830°C, and annealing time 30 seconds.

[0019] Step 1.3: On the AlGaN barrier layer 5, a first SiN dielectric layer 8 is grown using a PECVD process.

[0020] Specifically, the sample with the prepared source 6 and drain 7 is placed in an acetone solution for ultrasonic cleaning for 3 minutes with an ultrasonic intensity of 3.0; the sample is placed in a water bath in a stripping solution at a temperature of 60°C for heating for 5 minutes; the sample is placed in an acetone solution and an ethanol solution for ultrasonic cleaning for 3 minutes with an ultrasonic intensity of 3.0, the sample is rinsed with ultrapure water and blown dry with nitrogen; on the AlGaN barrier layer 5, a first SiN dielectric layer 8 with a thickness of 120nm is grown using a PECVD process. The growth process conditions are: NH3 and SiH4 are used as reaction gases, the substrate temperature is 250°C, the reaction chamber pressure is 600mTorr, and the RF power is 22W. The schematic diagram of the sample after the source 6, drain 7 and the first SiN dielectric layer 8 are prepared is as shown below. Figure 3 shown.

[0021] It is understandable that after the source 6 , the drain 7 and the first SiN dielectric layer 8 are prepared, mesa photolithography and mesa etching are performed to achieve mesa isolation.

[0022] The mesa photolithography specifically includes: placing the sample with the prepared source 6, drain 7 and first SiN dielectric layer 8 on a hot plate at 200°C and baking it for 5 minutes; applying and spinning photoresist, the thickness of the photoresist layer is 0.70-0.80 μm, and baking the coated sample on a hot plate at 90°C for 1-2 minutes; placing the coated sample in a photolithography machine to expose the photoresist; placing the exposed sample in a developer to remove the photoresist in the electrical isolation area, and then rinsing it with ultrapure water and drying it with nitrogen.

[0023] The mesa etching process specifically involves using a F-based etching method to remove the first SiN dielectric layer 8 in the mesa region. The etching process conditions are: CF4 / O2 as the reaction gas, 80-100W upper electrode power, 5-15W lower electrode power, 40-50V bias, 3-5° He drain, 5-10mTorr pressure, and 30-40 / 5-15sccm gas flow rate. The AlGaN barrier layer 5 and part of the GaN buffer layer 3 in the mesa region are etched using a Cl-based etching method. The etching process conditions are: BCl3 / Cl2 as the reaction gas, 40-60W upper electrode power, 5-20W lower electrode power, 6-8° He drain, 204V bias, 15-20 / 5-20sccm gas flow rate, and 5mTorr pressure. The etched sample is then sequentially cleaned in acetone solution, stripping solution, acetone solution, and ethanol solution to remove residual photoresist. The sample is then rinsed with ultrapure water and blown dry with nitrogen.

[0024] Step 2: A gate groove is formed on the first SiN dielectric layer 8 to contact the AlGaN barrier layer 5 , and a gate metal is prepared inside the gate groove and on the first SiN dielectric layer 8 to form a gate 9 to obtain a GaN HEMT.

[0025] In this embodiment, step 2 may include the following steps: Step 2.1: Photolithographically form a gate trench region on the first SiN dielectric layer 8 .

[0026] Specifically, the process includes: placing the sample on a hot plate at 200°C and baking it for 5 minutes; applying and spinning photoresist on the sample surface at a spinning speed of 3500r / min, and placing the coated sample on a hot plate at 90°C and baking it for 1 minute; placing the coated sample in a photolithography machine to expose the photoresist in the gate groove area; placing the exposed sample in a developer to remove the photoresist in the gate groove area, and then rinsing it with ultrapure water and drying it with nitrogen.

[0027] Step 2.2: Etch and remove the first SiN dielectric layer 8 in the gate trench region.

[0028] Specifically, the process includes: using an ICP (Inductively Coupled Plasma) etching process to remove the first SiN dielectric layer 8 in the gate groove area. The etching conditions are: the reaction gases are CF4 and O2, the reaction chamber pressure is 10mTorr, the RF power of the upper electrode and the lower electrode are 100W and 10W respectively, and the etching depth is 120nm to the AlGaN barrier layer 5; the etched sample is sequentially placed in an acetone solution, a stripping solution, an acetone solution, and an ethanol solution for cleaning to remove the photoresist outside the gate groove area.

[0029] Step 2.3: Photolithographically forming a gate electrode region on the first SiN dielectric layer 8; Specifically, the process includes: placing a sample with a gate groove on a hot plate and baking it for 5 minutes at 200°C; applying and spinning a stripping adhesive on the surface of the sample, with the thickness of the stripping adhesive layer being 0.35 μm, and baking the coated sample on a hot plate at 200°C for 5 minutes; applying and spinning a photoresist on the stripping adhesive, with the thickness of the photoresist layer being 0.77 μm, and baking the sample on a hot plate at 90°C for 1 minute; placing the sample that has been coated and spun into a photolithography machine to expose the photoresist in the gate electrode area; placing the exposed sample in a developer to remove the photoresist and stripping adhesive in the gate electrode area, and rinsing it with ultrapure water and drying it with nitrogen.

[0030] Step 2.4: Prepare gate metal in the gate electrode region to form a gate 9.

[0031] Specifically, the sample with the gate electrode photolithography pattern is placed in a plasma stripper for bottom film treatment, and the treatment time is 5 minutes; the sample is placed in an electron beam evaporation table, and the vacuum degree of the reaction chamber of the electron beam evaporation table reaches 2×10 -6 After the Torr process, gate metal is evaporated on the photoresist inside and outside the gate electrode area. The gate metal is a metal stack structure composed of two layers of metal, Ni and Au, from bottom to top. The sample after the gate metal evaporation is stripped to remove the gate metal, photoresist and stripping glue outside the gate electrode area to form a gate 9. The sample is rinsed with ultrapure water and blown dry with nitrogen. Figure 4 shown.

[0032] Step 3: Prepare a second SiN dielectric layer 10 on the upper surface of the GaN HEMT.

[0033] In this embodiment, step 3 may include the following steps: Step 3.1: Ultrasonic cleaning of GaN HEMT.

[0034] In this embodiment, the GaN HEMT is ultrasonically cleaned in acetone, stripping solution, acetone, isopropyl alcohol, and deionized water in sequence to remove surface organic matter.

[0035] Step 3.2: A second SiN dielectric layer 10 with a thickness of 120-200 nm is grown on the upper surface of the ultrasonically cleaned GaN HEMT using a plasma enhanced chemical vapor deposition (PECVD) process.

[0036] In this embodiment, the growth process conditions are: NH 3 and SiH 4 as reaction gases, substrate temperature of 250° C., reaction chamber pressure of 600 mTorr, and RF power of 22 W. The second SiN dielectric layer 10 covers the source 6 , drain 7 , first SiN dielectric layer 8 , and gate 9 .

[0037] Step 3.3: Use a CMP (chemical mechanical polishing) process to polish the surface of the second SiN dielectric layer 10 .

[0038] In this embodiment, the surface roughness of the polished second SiN dielectric layer 10 is less than 1 nm. Figure 5 shown.

[0039] Step 4: hydrogen ion implantation is performed on the single crystal diamond to obtain hydrogen ion implanted single crystal diamond. The hydrogen ions are implanted into the single crystal diamond. The hydrogen ion layer 12 is located inside the single crystal diamond, and the single crystal diamond is divided into an upper single crystal diamond film layer 11 and a lower single crystal diamond body 13. Figure 6 shown.

[0040] In this embodiment, before hydrogen ion implantation, the surface of the single crystal diamond is cleaned. The single crystal diamond can be ultrasonically cleaned in acetone, stripping solution, acetone, isopropyl alcohol and deionized water in sequence to remove surface organic matter.

[0041] Optionally, the energy of hydrogen ion implantation is 150-200 KeV and the dose is 5×10 16 -3×10 17 cm -2 The thickness of the single crystal diamond film layer in the single crystal diamond implanted with hydrogen ions is 500-800nm.

[0042] In this embodiment, the thickness of the single crystal diamond film can be precisely controlled by changing the implantation energy and implantation dose of hydrogen ions.

[0043] In this embodiment, hydrogen ion implantation forms a hydrogen ion layer 12 parallel to the surface of the single-crystal diamond within the single-crystal diamond material. The thickness tolerance of the single-crystal diamond film layer 11 formed by the hydrogen ion layer 12 does not exceed 5% of the thickness of the single-crystal diamond film layer 11, thereby ensuring consistent heat dissipation performance when the single-crystal diamond film layer 11 is transferred to the GaN HEMT.

[0044] It should be noted that the thermal conductivity of single crystal diamond is 2000W / m·K. When the implantation energy is 16.5MeV and the implantation dose is the same, C 3+ 、N 3+ and O 3+ After ion implantation, its thermal conductivity decreases significantly. With the increase of implantation dose, when the implantation dose is 4×10 14 cm -2 , the thermal conductivity is reduced to 718-599W / m·K. In addition, the thermal conductivity is proportional to the mass of the implanted ions, C 3+ The injected samples maintained the highest overall thermal conductivity, while O 3+ The thermal conductivity is the lowest. Compared with the above three ions, H + The mass is lower, the injection energy is 150-200KeV, and the ion injection has less impact on the thermal conductivity of diamond.

[0045] Step 5: Implant hydrogen ions into the single crystal diamond and bond it to the GaN HEMT with the second SiN dielectric layer 10 to obtain a bonded device, wherein the single crystal diamond film layer 11 is in contact with the second SiN dielectric layer 10. The schematic diagram of the bonded device is shown in FIG. Figure 7 shown.

[0046] In this embodiment, step 5 may include the following steps: Step 5.1: Pre-treating the hydrogen ion implanted single crystal diamond.

[0047] Specifically, the process includes: ultrasonically cleaning the hydrogen ion-implanted single-crystal diamond, wherein the hydrogen ion-implanted single-crystal diamond is sequentially ultrasonically cleaned in acetone, stripping solution, acetone, isopropyl alcohol, and deionized water to remove surface organic matter; activating the surface of the single-crystal diamond film layer 11 using an argon atomic beam, sputtering a Si nanolayer with a thickness of less than 5 nm on the surface of the single-crystal diamond film layer 11 using a magnetron sputtering process, and activating the Si nanolayer using an argon atomic beam.

[0048] Step 5.2: Pre-treating the GaN HEMT with the second SiN dielectric layer.

[0049] Specifically, the process includes activating the surface of the second SiN dielectric layer 10 with an argon atomic beam, sputtering a Si nanolayer with a thickness of less than 5 nm on the surface of the second SiN dielectric layer 10 with a magnetron sputtering process, and activating the Si nanolayer with an argon atomic beam.

[0050] Step 5.3: Place the pretreated hydrogen ion implanted single crystal diamond and the pretreated GaN HEMT with the second SiN dielectric layer 10 in a bonding machine, and apply a pressure of 1-10 MPa at room temperature to obtain a bonded device, wherein the Si nanolayer on the surface of the single crystal diamond film layer 11 is placed opposite to the Si nanolayer on the surface of the second SiN dielectric layer 10.

[0051] In this embodiment, surface contaminants are removed by activation with an argon atomic beam. The prepared Si nanolayer can reduce the interfacial thermal resistance between the single-crystal diamond film 11 and the second SiN dielectric layer 10, while also strengthening the bonding strength between the single-crystal diamond film 11 and the second SiN dielectric layer 10.

[0052] Step 6: Perform thermal annealing on the bonded device to peel off the single crystal diamond body 13 .

[0053] In this embodiment, step 6 may include the following steps: Step 6.1: Perform a first thermal annealing treatment on the bonded device to peel off the single crystal diamond body 13.

[0054] Specifically, the bonded device is placed in an annealing furnace and annealed at 1000-1200°C for 1-2 hours. Through this thermal annealing process, the chemical bonds between the upper and lower molecules of the hydrogen ion layer 12 in the single-crystal diamond are all broken, so that the single-crystal diamond film layer 11 and the single-crystal diamond body 13 are separated, and the transfer of the diamond film is completed on the GaN HEMT. The schematic diagram of the bonded device with the single-crystal diamond body peeled off is shown in FIG. Figure 8 shown.

[0055] Step 6.2: Perform a second thermal annealing treatment on the bonded device from which the single crystal diamond body 13 is peeled off.

[0056] Specifically, the bonded device after the single crystal diamond body 13 is peeled off is subjected to high temperature rapid thermal annealing at 600-1000° C. for 5-10 minutes to enhance the bonding strength and form a stable structure between the GaN HEMT and the single crystal diamond film layer 11 .

[0057] It should be noted that injecting hydrogen ions into single-crystal diamond will damage the single-crystal diamond and reduce its thermal conductivity. Through thermal annealing treatment, the vacancies and interstitial carbon are recombined at high temperature, and the ion-implanted hydrogen escapes, reducing the scattering of phonons by C-H bonds. In addition, high temperature promotes the phase transition of amorphous carbon to diamond, recrystallization repairs lattice distortion, and annealing inhibits the formation of graphite. After thermal annealing, its thermal conductivity can be restored to 70-80% of the thermal conductivity of single-crystal diamond.

[0058] Step 6.3: Use a CMP process to perform surface polishing on the single crystal diamond film layer 11 of the bonding device after the second thermal annealing treatment of the peeled single crystal diamond body 13.

[0059] In this embodiment, the surface roughness of the polished single crystal diamond film layer is less than 1 nm. The amorphous layer portion of the single crystal diamond film layer 11 can be removed by a CMP process.

[0060] Step 7: Perform hole drilling on the single crystal diamond film layer 11 and the second SiN dielectric layer 10 at the electrode position of the GaN HEMT to form a source hole groove contacting the source electrode 6, a drain hole groove contacting the drain electrode 7, and a gate hole groove contacting the gate electrode 9. The schematic diagram of the sample after hole drilling is shown in FIG. Figure 9 shown.

[0061] In this embodiment, step 7 may include the following steps: Step 7.1: Grow a SiN mask layer on the single crystal diamond film layer 11 using a PECVD process.

[0062] Specifically, a SiN mask layer with a thickness of 200 nm was grown on the diamond film using a PECVD process. The growth process conditions were: NH3 and SiH4 were used as reaction gases, the substrate temperature was 250°C, the reaction chamber pressure was 600mTorr, and the RF power was 22W.

[0063] Step 7.2: Photolithographically form an opening area on the SiN mask layer.

[0064] Specifically, the process includes: placing a sample with a SiN mask layer on a hot plate at 200°C and baking it for 5 minutes; coating and spinning photoresist on the SiN mask layer at a spinning speed of 3500r / min, and baking the coated sample on a hot plate at 90°C for 1 minute; placing the coated and spun sample into a photolithography machine to expose the photoresist in the opening area; placing the exposed sample into a developer to remove the photoresist in the opening area, and then rinsing it with ultrapure water and drying it with nitrogen.

[0065] Step 7.3: Etch and remove the SiN mask layer, the single crystal diamond film layer 11 and the second SiN dielectric layer 10 in the opening area.

[0066] Specifically, the process includes: removing the SiN mask layer in the opening area using an ICP etching process, wherein the etching conditions are: CF4 and O2 as the reaction gases, a reaction chamber pressure of 10 mTorr, and 100 W and 10 W RF powers for the upper and lower electrodes, respectively, until the single crystal diamond film layer 11 is etched. Removing the single crystal diamond film layer 11 in the opening area using an ICP etching process, wherein the etching conditions are: O2 as the reaction gases, O2:Ar=150 sccm:100 sccm, until the second SiN dielectric layer 10 is etched. Removing the second SiN dielectric layer 10 in the opening area using an ICP etching process, wherein the etching conditions are: CF4 and O2 as the reaction gases, a reaction chamber pressure of 10 mTorr, and 100 W and 10 W RF powers for the upper and lower electrodes, respectively, until the electrode metal is etched away, and simultaneously removing the SiN mask layer grown on the surface of the single crystal diamond film layer 11. The etched sample was sequentially placed in acetone solution, stripping solution, acetone solution and ethanol solution for cleaning to remove the photoresist outside the opening area. The sample was rinsed with ultrapure water and dried with nitrogen gas.

[0067] Step 8: Prepare interconnect metal 14 on the bottom and inner wall of the source hole groove, the drain hole groove and the gate hole groove.

[0068] In this embodiment, the interconnect metal 14 is prepared by interconnect metal photolithography and interconnect metal evaporation.

[0069] The interconnect metal lithography specifically includes: placing the sample after opening on a hot plate at 200°C and baking it for 5 minutes; applying and spinning stripping glue on the surface of the sample, the thickness of the stripping glue layer is 0.52μm, and baking the coated sample on a hot plate at 200°C for 5 minutes; applying and spinning photoresist on the stripping glue, the thickness of the photoresist layer is 0.70μm, and baking the coated sample on a hot plate at 90°C for 1 minute; placing the sample after coating and spinning into a photolithography machine for exposure; placing the exposed sample into a developer to remove the photoresist and stripping glue in the etched area, and rinsing it with ultrapure water and blowing it dry with nitrogen.

[0070] The interconnect metal evaporation specifically includes: placing the sample with completed interconnect metal lithography into the plasma stripper for bottom film treatment, and the treatment time is 5 minutes; placing the sample into the electron beam evaporation table, and waiting for the reaction chamber vacuum of the electron beam evaporation table to reach 2×10 -6 After the Torr process, interconnect metal is evaporated on the photoresist inside and outside the opening area. The interconnect metal is a metal stack structure composed of two layers of metal, Ni and Au, from bottom to top. The sample after the metal interconnect evaporation is peeled off, rinsed with ultrapure water and blown dry with nitrogen to obtain a diamond film GaN HEMT. The schematic diagram of the diamond film GaN HEMT is shown below. Figure 10 shown.

[0071] The present invention discloses a method for fabricating a GaN HEMT using a diamond thin film based on smart cutting technology. This method transfers a single-crystal diamond film using smart cutting technology. Compared to traditional heteroepitaxial growth of polycrystalline diamond, the present method increases the thermal conductivity of the diamond film, thereby enhancing the heat dissipation capability of the GaN HEMT. By varying the injection energy and dosage of hydrogen ion implantation, the thickness of the single-crystal diamond film can be precisely controlled. A two-step thermal annealing process effectively restores the thermal conductivity of the transferred single-crystal diamond film and strengthens the bonding strength. During the bonding process, a Si nanolayer less than 10 nanometers thick is used as the bonding layer, significantly reducing the interfacial thermal resistance between the GaN HEMT and the single-crystal diamond film and fully leveraging the high thermal conductivity of single-crystal diamond. During the diamond film transfer process, polishing removes the amorphous layer on the surface of the single-crystal diamond film, improving the thermal transport properties of the single-crystal diamond film.

[0072] The method for preparing a diamond thin film GaN HEMT based on the smart cutting technology according to the embodiment of the present invention can reuse single crystal diamond material samples multiple times, thereby reducing the production cost of the diamond thin film GaN HEMT.

[0073] In a second aspect, an embodiment of the present invention provides a diamond thin film GaN HEMT, which is prepared using the diamond thin film GaN HEMT preparation method based on smart cutting technology provided in the first aspect. The diamond thin film GaN HEMT of the embodiment of the present invention transfers a high-quality single crystal diamond film onto the GaN HEMT through smart cutting technology, thereby increasing the heat dissipation path of the device, improving the heat dissipation capability of the device, and realizing a diamond / GaN heterostructure with high thermal conductivity and low interface thermal resistance.

[0074] For the specific content and corresponding beneficial effects of the diamond thin film GaN HEMT, please refer to the relevant content of the diamond thin film GaN HEMT preparation method based on smart cutting technology provided in the first aspect, which will not be repeated here.

[0075] It should be noted that, in this document, relational terms such as first and second are used solely to distinguish one entity or operation from another, and do not necessarily require or imply any actual relationship or order between these entities or operations. Furthermore, the terms "comprise," "include," or any other variations thereof are intended to encompass non-exclusive inclusion, such that an article or device comprising a list of elements includes not only those elements but also other elements not explicitly listed. Without further limitation, an element defined by the phrase "comprising a..." does not preclude the presence of additional identical elements in the article or device comprising the element. Terms such as "connected" or "connected" are not limited to physical or mechanical connections but may include electrical connections, whether direct or indirect. References to orientations or positional relationships, such as "upper," "lower," "left," and "right," are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate description and simplify the description of the present invention. They do not indicate or imply that the device or element referred to must have, be constructed, or operate in a specific orientation, and are therefore not to be construed as limiting the present invention.

[0076] In the description of this specification, the reference terms "one embodiment," "some embodiments," "example," "specific example," or "some examples" mean that the specific features or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features or characteristics described can be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification.

[0077] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A method for preparing a diamond thin film GaN HEMT based on smart cutting technology, characterized in that: include: Step 1: preparing a source electrode, a drain electrode and a first SiN dielectric layer on the AlGaN barrier layer of the AlGaN / GaN epitaxial wafer, wherein the first SiN dielectric layer is located between the source electrode and the drain electrode; Step 2: etching the first SiN dielectric layer to form a gate trench in contact with the AlGaN barrier layer, and preparing a gate metal inside the gate trench and on the first SiN dielectric layer to form a gate, thereby obtaining a GaN HEMT; Step 3: preparing a second SiN dielectric layer on the upper surface of the GaN HEMT; Step 4: implanting hydrogen ions into the single crystal diamond to obtain hydrogen ion-implanted single crystal diamond, wherein the hydrogen ions are implanted into the single crystal diamond, a hydrogen ion layer is located inside the single crystal diamond, and the single crystal diamond is divided into an upper single crystal diamond film layer and a lower single crystal diamond body; Step 5: Implanting the hydrogen ions into the single crystal diamond and bonding it to a GaN HEMT having a second SiN dielectric layer to obtain a bonded device, wherein the single crystal diamond film layer is in contact with the second SiN dielectric layer; Step 6: performing thermal annealing on the bonded device to peel off the single crystal diamond body; Step 7: performing a hole-forming operation on the single crystal diamond film layer and the second SiN dielectric layer at the electrode position of the GaN HEMT to form a source hole trench contacting the source electrode, a drain hole trench contacting the drain electrode, and a gate hole trench contacting the gate electrode; Step 8: preparing interconnection metal on the bottom and inner wall of the source hole groove, the drain hole groove and the gate hole groove.

2. The method for preparing a diamond thin film GaN HEMT based on smart cutting technology according to claim 1, characterized in that: The step 3 comprises: Step 3.1: Ultrasonic cleaning of the GaN HEMT; Step 3.2: Using a plasma enhanced chemical vapor deposition process, a second SiN dielectric layer with a thickness of 120-200 nm is grown on the upper surface of the ultrasonically cleaned GaN HEMT; Step 3.3: Use a CMP process to polish the surface of the second SiN dielectric layer.

3. The method for preparing a diamond thin film GaN HEMT based on smart cutting technology according to claim 2, characterized in that: The surface roughness of the polished second SiN dielectric layer is less than 1 nm.

4. The method for preparing a diamond thin film GaN HEMT based on smart cutting technology according to claim 1, characterized in that: In step 4, the energy of hydrogen ion implantation is 150-200 KeV, and the dose is 5×10 16 -3×10 17 cm -2 .

5. The method for preparing a diamond thin film GaN HEMT based on smart cutting technology according to claim 1, characterized in that: The thickness of the single crystal diamond film layer in the hydrogen ion implanted single crystal diamond is 500-800 nm, and the thickness tolerance of the single crystal diamond film layer does not exceed 5% of the thickness of the single crystal diamond film layer.

6. The method for preparing a diamond thin film GaN HEMT based on smart cutting technology according to claim 1, characterized in that: The step 5 comprises: Step 5.1: Pre-treating the hydrogen ion-implanted single-crystal diamond, comprising: ultrasonically cleaning the hydrogen ion-implanted single-crystal diamond, activating the surface of the single-crystal diamond film layer using an argon atomic beam, sputtering a Si nanolayer having a thickness of less than 5 nm on the surface of the single-crystal diamond film layer using a magnetron sputtering process, and activating the Si nanolayer using an argon atomic beam; Step 5.2: Pre-treating the GaN HEMT having the second SiN dielectric layer, including: activating the surface of the second SiN dielectric layer using an argon atomic beam, sputtering a Si nanolayer having a thickness of less than 5 nm on the surface of the second SiN dielectric layer using a magnetron sputtering process, and activating the Si nanolayer using an argon atomic beam; Step 5.3: Place the pretreated hydrogen ion implanted single crystal diamond and the pretreated GaN HEMT with the second SiN dielectric layer in a bonding machine, and apply a pressure of 1-10 MPa at room temperature to obtain the bonded device, wherein the Si nanolayer on the surface of the single crystal diamond film layer and the Si nanolayer on the surface of the second SiN dielectric layer are placed opposite to each other.

7. The method for preparing a diamond thin film GaN HEMT based on smart cutting technology according to claim 1, characterized in that: The step 6 comprises: Step 6.1: performing a first thermal annealing treatment on the bonded device to peel off the single crystal diamond body; Step 6.2: performing a second thermal annealing treatment on the bonded device from which the single crystal diamond body is peeled; Step 6.3: Use a CMP process to perform surface polishing on the single crystal diamond film layer of the bonded device after the second thermal annealing treatment of the peeled single crystal diamond body.

8. The method for preparing a diamond thin film GaN HEMT based on smart cutting technology according to claim 7, characterized in that: The temperature of the first thermal annealing treatment is 1000-1200° C., and the annealing time is 1-2 hours.

9. The method for preparing a diamond thin film GaN HEMT based on smart cutting technology according to claim 7, characterized in that: The temperature of the second thermal annealing treatment is 600-1000° C., and the annealing time is 5-10 minutes.

10. The method for preparing a diamond thin film GaN HEMT based on smart cutting technology according to claim 7, characterized in that: The surface roughness of the polished single crystal diamond film layer is less than 1 nm.

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