Diamond thin layer device and preparation method thereof

Abstract

The present invention discloses a thin-layer device on diamond and a method for preparing the same, comprising the following steps: growing a thin-layer device epitaxial structure on a sapphire substrate; forming an ion-buried layer using ion implantation; fabricating source and drain electrodes; fabricating a gate electrode; depositing a silicon nitride dielectric layer; depositing a diamond material layer, wherein during heating, the epitaxial material separates from the ion-buried layer to form a diamond / gallium nitride thin-layer device; and using a laser to create windows in the source, drain, and gate regions for circuit wiring, thereby forming a gallium nitride thin-layer device with a positive-mounted structure and forward-directed wiring. The present invention precisely controls the thickness of the stripped nitride epitaxial layer device, enabling the direct transfer of the thin-layer device onto the diamond material. Direct growth of the diamond material is combined with ion implantation to separate the traditional substrate, addressing the current technical issues of combining thin-layer gallium nitride materials or devices with diamond materials, such as high stress, low stripping precision, unsuitability for mass production, and poor heat dissipation.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and in particular to a diamond top thin layer device and a preparation method thereof. Background Art

[0002] Third-generation GaN semiconductor materials are primarily grown on conventional substrates, such as silicon, sapphire, silicon carbide, and GaN substrates. However, the high power density, high current, and high field strength characteristics of GaN power electronics place high demands on heat dissipation, including in device packaging. The main drawback of conventional substrates is their poor thermal conductivity. The high junction temperature of GaN devices leads to degraded performance and significant reliability challenges. Due to heat dissipation issues, the performance of GaN materials and optoelectronic devices falls far short of theoretical values. To achieve optimal optoelectronic device performance and reliability, addressing this heat dissipation bottleneck is crucial.

[0003] However, diamond has the highest thermal conductivity in nature, reaching 2000 W / m·K. However, large-scale single-crystal substrates are difficult to prepare and are still under research, leaving them a long way from commercialization. Existing technologies use bonding to combine GaN single crystals or devices with polycrystalline diamond films, which is technically challenging. There are also reports of substrates used for nitride epitaxy, which improve heat dissipation by bonding relatively high-thermal-conductivity materials such as metal sheets. Because bonding is used, the bonding medium is typically a low-thermal-conductivity material like silicon dioxide, which limits the thermal conductivity of the bonding medium. Therefore, finding a suitable mass production technology and a method for preparing GaN-diamond structures with effective heat dissipation is crucial to effectively address the thermal effects of GaN devices and promote their industrialization. Summary of the Invention

[0004] The purpose of the present invention is to address the deficiencies in the prior art and provide a thin-layer device on diamond and a preparation method thereof. The method utilizes a direct growth combined with ion implantation and stripping method, does not require a bonding process, accurately controls the thickness of the stripped nitride epitaxial layer device, and realizes the transfer of thin-layer devices. This solves the problems of high stress, low stripping precision, unsuitability for mass production, and poor heat dissipation in the existing technical route for combining thin-layer gallium nitride materials or devices with diamond materials.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] First, the present invention provides a method for preparing a thin layer device on diamond, comprising the following steps:

[0007] (1) Using the PVD method to grow a 30nm thick AlN epitaxial nucleation layer on a sapphire substrate;

[0008] (2) epitaxially growing a 200 nm thick GaN channel layer on the AlN nucleation layer using the MOCVD method;

[0009] (3) epitaxially growing an AlGaN barrier layer with a thickness of 25 nm on the GaN channel layer using the MOCVD method;

[0010] (4) injecting hydrogen ions or helium ions into the GaN channel layer using an ion implantation process to form an ion buried layer, wherein the ion buried layer is located in the gallium nitride channel layer and is 160 nm away from the AlGaN barrier layer;

[0011] (5) Performing photolithography on the AlGaN barrier layer to expose the source and drain patterns of the ohmic contact, and performing electron beam evaporation of Ti, Al, Ni, and Au to sequentially grow a titanium deposition layer with a thickness of 20 nm, an aluminum deposition layer with a thickness of 80 nm, a nickel deposition layer with a thickness of 20 nm, and a gold deposition layer with a thickness of 60 nm on the AlGaN barrier layer. After debonding and annealing, the source and drain electrodes of the device are formed;

[0012] (6) Performing photolithography on the AlGaN barrier layer to expose the pattern of the Schottky gate, evaporating Ni / Au by electron beam, and sequentially growing a nickel deposition layer with a thickness of 20 nm and a gold deposition layer with a thickness of 60 nm on the AlGaN barrier layer, and then performing debonding and stripping to form the gate electrode of the device;

[0013] (7) using the PEVCD method to deposit a 10 nm thick silicon nitride dielectric layer on the source, gate, drain and AlGaN barrier layer;

[0014] (8) Using MPCVD equipment, a diamond material layer with a thickness of 120 μm is deposited on the silicon nitride dielectric layer. During the heating process, the ions in the ion buried layer are converted into gas due to heating, thereby separating the epitaxial material from the ion buried layer to form a diamond / gallium nitride thin layer device;

[0015] (9) Using laser method, windows are opened in the source, drain and gate regions for circuit leads, thereby forming a gallium nitride thin-layer device with a positive structure and positive leads.

[0016] Furthermore, the PVD process parameters in step (1) are: the reaction chamber pressure is 1-10 Pa, aluminum metal is used as the target material, the nitrogen flow rate is 3000-6000 sccm, and the argon flow rate is 1000-2000 sccm.

[0017] Power is 1KW-6KW

[0018] Furthermore, the MOCVD process parameters in step (2) are: reaction chamber pressure of 50-200 Torr, organic Ga source flow rate of 40-100 μmol / min, ammonia flow rate of 5000-40000 sccm, and hydrogen flow rate of 50000-80000 sccm.

[0019] Furthermore, the MOCVD process parameters in step (3) are: reaction chamber pressure of 50-200 Torr, Al source flow rate of 40-100 μmol / min, Ga source flow rate of 40-100 μmol / min, ammonia flow rate of 5000-40000 sccm, and hydrogen flow rate of 1000-2000 sccm.

[0020] Furthermore, the ion implantation process parameters in step (4) are: acceleration voltage of 200 KeV, ion concentration of 8×10 19 / cm 3 .

[0021] Furthermore, in step (5), the deposition thickness of titanium is 20 nm, the deposition thickness of aluminum is 80 nm, the deposition thickness of nickel is 20 nm, the deposition thickness of gold is 60 nm, the annealing temperature is 840-890° C., and the time is 30-70 s.

[0022] Furthermore, in step (6), the deposition thickness of nickel is 20 nm, and the deposition thickness of gold is 60 nm.

[0023] Furthermore, the PEVCD process parameters in step (7) are: the flow ratio of ammonia to silane is 3.5:1, the substrate temperature is 400 degrees, and the reaction gas pressure is 1 mbar.

[0024] Furthermore, the growth temperature of the diamond in step (8) is 700-1000°C.

[0025] Furthermore, the MOCVD process parameters in step (8) are: a flow ratio of methane to oxygen of 1:1, a growth pressure of 20 torr, a hydrogen carrier gas of 1 slm, and a thickness of the gallium nitride thin layer device of less than 200 nm.

[0026] Furthermore, the thickness of the gallium nitride thin layer device in step (8) is less than 200 nm.

[0027] Secondly, the present invention provides a diamond-on-thin-layer device, which is prepared by the above-mentioned method for preparing the diamond-on-thin-layer device.

[0028] The beneficial effects of the present invention are:

[0029] The method of direct growth combined with ion implantation and stripping eliminates the need for a bonding process. Secondly, the ion implantation method can precisely control the thickness of the stripped nitride epitaxial layer device, enabling the direct transfer of thin-layer devices to diamond materials. Diamond materials are directly grown and separated from traditional substrates by ion implantation. This solves the problems of high stress, low stripping precision, unsuitability for mass production, and poor heat dissipation in the current thin-layer gallium nitride material or device-diamond material bonding technology route. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the epitaxial structure of the thin-layer device of the present invention;

[0031] Figure 2 Schematic diagram of the ion implantation process in step (4) of the present invention;

[0032] Figure 3 This is a schematic diagram of the structure of an ion buried layer formed in the epitaxial material of the present invention;

[0033] Figure 4 Schematic diagram of the process for preparing ohmic contacts of source and drain electrodes in step (5) of the present invention;

[0034] Figure 5 This is a schematic diagram of the Schottky gate preparation process in step (6) of the present invention;

[0035] Figure 6 Schematic diagram of the process for preparing the silicon nitride dielectric layer in step (7) of the present invention;

[0036] Figure 7 This is a schematic diagram of the self-separation of the diamond material epitaxial layer and the substrate in step (8) of the present invention;

[0037] Figure 8 This is step (9) of the present invention, in which the source, drain and gate of the diamond substrate are opened.

[0038] Figure numerals: 1-sapphire substrate, 2-AlN nucleation layer, 3-GaN channel layer, 4-AlGaN barrier layer, 5-implanted ions, 6-ion buried layer, 7-source and drain electrodes, 8-gate electrode, 9-silicon nitride dielectric layer, 10-direct diamond material layer, 11-source, drain and gate electrode opening windows. DETAILED DESCRIPTION

[0039] In order to further understand the present invention, the following examples and the accompanying drawings specifically describe a method for preparing a thin layer device on diamond of the present invention. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0040] In this embodiment, a method for preparing a thin layer device on diamond is provided, which specifically includes the following steps:

[0041] Figure 1 Schematic diagram of the epitaxial structure of a thin-layer device in an embodiment of the present invention.

[0042] Step (1): Soak the sapphire substrate in an HF acid solution for 30 seconds, then ultrasonically clean it in an acetone solution, an anhydrous ethanol solution, and deionized water for 2 minutes each. Blow dry the cleaned sapphire substrate with nitrogen. Place the treated sapphire substrate in a PVD system with a reaction chamber pressure of 5 Pa, aluminum metal as the target, a nitrogen flow rate of 4000 sccm, an argon flow rate of 1500 sccm, and a power of 2 kW. Use the PVD method to grow a 30 nm thick AlN epitaxial nucleation layer 2 on the sapphire substrate 1.

[0043] Step (2) epitaxially grows a 200 nm thick GaN channel layer 3 on the AlN nucleation layer 2 using a MOCVD method; no buffer layer of a conventional device structure is required. In the MOCVD system, the reaction chamber pressure is 100 Torr, the Ga source flow rate is 100 μmol / min, the ammonia flow rate is 6000 sccm, and the hydrogen flow rate is 80,000 sccm.

[0044] Step (3): epitaxially grow an AlGaN barrier layer 4 with a thickness of 25 nm on the GaN channel layer 3 using a MOCVD method. In the MOCVD system, the reaction chamber pressure is 100 Torr, the Al source flow rate is 100 μmol / min, the Ga source flow rate is 100 μmol / min, the ammonia flow rate is 40,000 sccm, and the hydrogen flow rate is 80,000 sccm.

[0045] Figure 2 、 3 Schematic diagram of ion implantation in step (4) of the embodiment of the present invention.

[0046] Step (4): hydrogen ions are injected into the GaN channel layer 3 using an ion implantation process 5, with an acceleration voltage of 200 KeV and an ion concentration of 8×10 19 / cm 3 , forming an ion buried layer 6 , the ion buried layer 6 is located in the gallium nitride channel layer 3 and is 160 nm away from the AlGaN barrier layer 4 .

[0047] In other embodiments, helium ions may be further implanted into the GaN channel layer 3 using an ion implantation process.

[0048] like Figure 4As shown, in step (5), photolithography is performed on the AlGaN barrier layer 4 to expose the source and drain level patterns of the ohmic contact, and Ti, Al, Ni, and Au electron beam evaporation is performed to sequentially grow a titanium deposition layer with a thickness of 20 nm, an aluminum deposition layer with a thickness of 80 nm, a nickel deposition layer with a thickness of 20 nm, and a gold deposition layer with a thickness of 60 nm on the AlGaN barrier layer. After debonding and annealing at an annealing temperature of 860°C for 40 seconds, the source electrode 7 and the drain electrode 7 of the device are formed.

[0049] like Figure 5 As shown, in step (6), photolithography is performed on the AlGaN barrier layer to expose the pattern of the Schottky gate, Ni / Au is evaporated by electron beam, and a nickel deposition layer with a thickness of 20nm and a gold deposition layer with a thickness of 60nm are grown on the AlGaN barrier layer in sequence. After debonding and peeling, the gate electrode 8 of the device is formed.

[0050] like Figure 6 As shown, in step (7), a 10 nm thick silicon nitride dielectric layer 9 is deposited on the source, gate, drain, and AlGaN barrier layers using the PEVCD method. In the PEVCD system, the flow ratio of ammonia to silane is 3.5:1, the substrate temperature is 400 degrees, and the reaction gas pressure is 1 mbar.

[0051] like Figure 7 As shown, in step (8), a diamond material layer 10 with a thickness of 120 μm is deposited on the silicon nitride dielectric layer 9 using MPCVD equipment. During the heating process, the ions in the ion-buried layer 6 are heated to gas, thereby separating the epitaxial material from the ion-buried layer 6, forming a diamond / gallium nitride thin layer device. In the MPCVD system, the flow ratio of methane and oxygen is 1:1, the growth pressure is 20 Torr, and the hydrogen carrier gas is 1 slm. Since the growth temperature of diamond is 900 degrees, during this process, the ions in the ion-buried layer in the epitaxial material are heated to gas, thereby separating the epitaxial material from the ion-buried layer, thereby forming a diamond material / gallium nitride thin layer device. The thickness of the entire gallium nitride thin layer device is less than 200 nm (160 nm gallium nitride channel layer + 25 nm AlGaN barrier layer). Finally, a laser method is used to open windows in the source, drain, and gate regions for circuit leads. Finally, a gallium nitride thin-layer device with a positive structure and positive leads is formed.

[0052] (9) A laser method is used to open windows 11 in the source, drain and gate regions for circuit leads, ultimately forming a gallium nitride thin-layer device with a positive structure and positive leads.

[0053] This invention utilizes a direct growth combined with ion implantation and exfoliation method, eliminating the need for a bonding process. Furthermore, the ion implantation method allows for precise control of the thickness of the exfoliated nitride epitaxial layer device, enabling the direct transfer of thin-layer devices onto diamond materials. Diamond materials are directly grown and separated from traditional substrates using ion implantation. This addresses the current challenges of combining thin-layer gallium nitride materials or devices with diamond materials, such as high stress, low exfoliation precision, unsuitability for mass production, and poor heat dissipation.

[0054] Based on the disclosure of the above description, those skilled in the art may also make appropriate changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and any modifications and variations of the present invention should also fall within the scope of protection of the claims of the present invention. In addition, although certain specific terms are used in this description, these terms are merely for convenience of description and do not constitute any limitation to the present invention.

Claims

1. A method for preparing a thin layer device on diamond, characterized in that: The steps include: (1) Using the PVD method to grow a 30nm thick AlN epitaxial nucleation layer on a sapphire substrate; (2) epitaxially growing a 200 nm thick GaN channel layer on the AlN nucleation layer using the MOCVD method; (3) epitaxially growing an AlGaN barrier layer with a thickness of 25 nm on the GaN channel layer using the MOCVD method; (4) using an ion implantation process to implant hydrogen ions or helium ions into the GaN channel layer to form an ion buried layer, wherein the ion buried layer is located in the gallium nitride channel layer and is 160 nm away from the AlGaN barrier layer; (5) Performing photolithography on the AlGaN barrier layer to expose the source and drain patterns of the ohmic contact, and performing electron beam evaporation of Ti, Al, Ni, and Au. After stripping and annealing, the source and drain electrodes of the device are formed; (6) Perform photolithography on the AlGaN barrier layer to expose the pattern of the Schottky gate, evaporate Ni and Au using an electron beam, and then strip the adhesive to form the gate electrode of the device; (7) using the PEVCD method to deposit a 10 nm thick silicon nitride dielectric layer on the source, gate, drain and AlGaN barrier layer; (8) Using MPCVD equipment, a diamond material layer with a thickness of 120 μm is deposited on the silicon nitride dielectric layer. During the heating process, the ions in the ion buried layer are converted into gas due to heating, thereby separating the epitaxial material from the ion buried layer to form a diamond / gallium nitride thin layer device; (9) Using laser method, windows are opened in the source, drain and gate regions for circuit leads, thereby forming a gallium nitride thin-layer device with a positive structure and positive leads.

2. The method for preparing a thin layer device on diamond according to claim 1, characterized in that: The PVD process parameters in step (1) are: reaction chamber pressure of 1-10 Pa, aluminum metal as target material, nitrogen flow rate of 3000-6000 sccm, argon flow rate of 1000-2000 sccm, and power of 1-6 KW.

3. The method for preparing a thin layer device on diamond according to claim 1, wherein: The MOCVD process parameters in step (2) are: reaction chamber pressure of 50-200 Torr, organic Ga source flow rate of 40-100 μmol / min, ammonia flow rate of 5000-40000 sccm, and hydrogen flow rate of 50000-80000 sccm.

4. The method for preparing a thin-layer device on diamond according to claim 1, wherein: The MOCVD process parameters in step (3) are: reaction chamber pressure of 50-200 Torr, Al source flow rate of 40-100 μmol / min, Ga source flow rate of 40-100 μmol / min, ammonia flow rate of 5000-40000 sccm, and hydrogen flow rate of 1000-2000 sccm.

5. The method for preparing a thin layer device on diamond according to claim 1, characterized in that: The ion implantation process parameters in step (4) are: acceleration voltage of 200 KeV, ion concentration of 8×10 19 / cm 3 .

6. The method for preparing a thin layer device on diamond according to claim 1, characterized in that: In the step (5), the deposition thickness of titanium is 20 nm, the deposition thickness of aluminum is 80 nm, the deposition thickness of nickel is 20 nm, the deposition thickness of gold is 60 nm, the annealing temperature is 840-890° C., and the time is 30-70 s.

7. The method for preparing a thin-layer device on diamond according to claim 1, wherein: In the step (6), the deposition thickness of nickel is 20 nm, and the deposition thickness of gold is 60 nm.

8. The method for preparing a thin-layer device on diamond according to claim 1, wherein: The PEVCD process parameters in step (7) are: the flow ratio of ammonia to silane is 3.5:1, the substrate temperature is 400 degrees, and the reaction gas pressure is 1 mbar.

9. The method for preparing a thin layer device on diamond according to claim 1, characterized in that: In step (8), the growth temperature of diamond is 700-1000° C., the MOCVD process parameters are: a flow ratio of methane to oxygen of 1:1, a growth pressure of 20 torr, a hydrogen carrier gas of 1 slm, and a thickness of the gallium nitride thin layer device of less than 200 nm.

10. A diamond top thin layer device, characterized in that: The compound is prepared by the preparation method according to any one of claims 1 to 9.

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