Sapphire substrate GaN HEMT epitaxial wafer
By designing the sputtering film layer and cyclic buffer layer on a sapphire substrate, the lattice mismatch problem of the GaN epitaxial layer is solved, the crystal quality and carrier mobility are improved, the resistance is reduced, and the efficient two-dimensional electron gas concentration and mobility are achieved.
Patent Information
- Application Number
- CN202421615302.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-09
- Publication Date
- 2025-08-05
- Estimated Expiration
- 2034-07-09
AI Technical Summary
The GaN epitaxial layer has a large lattice and thermal mismatch problem on the sapphire substrate, resulting in high dislocation density, affecting crystal quality and carrier mobility, and increasing device current leakage. In particular, the crystal quality of GaN 002, 004 and 102 surfaces is poor and the square resistance is high.
The sputtering film layer on the sapphire substrate, the cyclic low-temperature InAlN layer and the low-temperature polycrystalline GaN layer are used as the buffer layer, and the growth technology of the high-temperature InAlN layer and the high-temperature AlGaN layer is combined to form a GaN HEMT epitaxial sheet of the sapphire substrate. By relieving stress adaptation and reducing dislocations, the polarization effect is enhanced and the crystal quality is improved.
The flatness of the GaN surface is improved, the polarization effect between AlGaN and GaN is enhanced, the two-dimensional electron gas concentration and mobility are increased, and the square resistance and on-resistance of the epitaxial sheet are reduced.
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Figure CN223195063U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of semiconductor devices, in particular to a sapphire substrate GaN HEMT epitaxial wafer. Background Art
[0002] GaN is one of the most important wide-bandgap semiconductor materials. Its unique excellent optoelectronic and mechanical properties make it have broad application prospects in high-power electronic devices, high-voltage electronic devices and other fields.
[0003] Currently, the most common growth method for GaN is heteroepitaxial growth on Si or SiC substrates. However, there are large lattice mismatch and thermal mismatch problems between sapphire materials and GaN materials, resulting in a high density of mismatch dislocations in the GaN epitaxial layer. Such dislocations reduce carrier mobility and aggravate device current leakage, seriously affecting the crystal quality of the GaN material. The crystal quality of GaN 002, 004, and 102 surfaces is poor, and the sheet resistance is high. Utility Model Content
[0004] The embodiments of the present application provide a sapphire substrate GaN HEMT epitaxial wafer, which can improve the crystal quality of the semiconductor epitaxial wafer as a whole, increase the flatness of the GaN surface, thereby enhancing the polarization effect between AlGaN and GaN, reducing interface scattering, and achieving the purpose of increasing the concentration and mobility of the two-dimensional electron gas and reducing the sheet resistance of the epitaxial wafer.
[0005] An embodiment of the present application provides a sapphire substrate GaN HEMT epitaxial wafer, comprising a sapphire substrate and a sputtered thin film layer, a buffer layer, an undoped GaN main layer, a high-temperature InAlN layer, and a high-temperature AlGaN layer stacked in sequence and grown on the surface of the sapphire substrate, wherein the buffer layer is a low-temperature InAlN layer and a low-temperature polycrystalline GaN layer that are cycled N times, wherein the low-temperature InAlN layer is close to the sputtered thin film layer, and N is greater than or equal to 4 and less than or equal to 8.
[0006] In a possible implementation, the sputtered thin film layer is an AlN thin film layer, and the thickness of the sputtered thin film layer is 10 nm to 25 nm.
[0007] In a possible implementation, the low-temperature InAlN layer has a thickness of 2 nm to 10 nm.
[0008] In a possible implementation, the low-temperature polycrystalline GaN layer has a thickness of 5 nm to 10 nm, and the total thickness of the buffer layer is 28 nm to 160 nm.
[0009] In a possible implementation, the thickness of the undoped GaN main layer is 1000 nm to 3000 nm.
[0010] In a possible implementation, the high-temperature InAlN layer has a thickness of 1 nm to 5 nm.
[0011] In a possible implementation, the high-temperature AlGaN layer has a thickness of 15 to 30 nm.
[0012] Beneficial effects: Compared with the prior art, the sapphire substrate GaN HEMT epitaxial wafer provided in the present application can effectively alleviate the stress adaptation between the sapphire substrate and the undoped GaN main layer through the sputtered thin film layer, effectively reduce the dislocations generated by the sputtered thin film layer through the low-temperature InAlN layer, and form a transition for the subsequent growth of the high-temperature AlGaN layer through the high-temperature InAlN layer. It can also further reduce the stress between the undoped GaN main layer and the high-temperature AlGaN layer, thereby improving the crystal quality of the semiconductor epitaxial wafer as a whole, including the crystal quality of the GaN 002 plane, 004 plane, and 102 plane, enhancing the polarization effect between AlGaN and GaN, and reducing interface scattering, thereby achieving the purpose of increasing the two-dimensional electron gas concentration and mobility and reducing the square sheet resistance and on-resistance of the epitaxial wafer.
[0013] These and other purposes, features and advantages of the present invention are fully reflected in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 The schematic diagram of the structure of the sapphire substrate GaN HEMT epitaxial wafer of the present application is shown. DETAILED DESCRIPTION
[0015] The following description is intended to disclose the present invention and enable those skilled in the art to implement the present invention. The preferred embodiments described below are provided for illustrative purposes only, and those skilled in the art will readily appreciate other obvious variations. The basic principles of the present invention as defined in the following description may be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the present invention.
[0016] Those skilled in the art should understand that, in the disclosure of the specification, the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicating the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms cannot be understood as limiting the present invention.
[0017] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the elements may be multiple, and the term "one" should not be understood as a limitation on the quantity.
[0018] refer to Figure 1 An embodiment of the present application provides a sapphire substrate GaN HEMT epitaxial wafer, comprising a sapphire substrate 10 and a sputtered thin film layer 20, a buffer layer 30, an undoped GaN main layer (i.e., a U-GaN main layer) 40, a high-temperature InAlN layer 50, and a high-temperature AlGaN layer 60 stacked and grown in sequence on the surface of the sapphire substrate, wherein the buffer layer 30 is a low-temperature InAlN layer and a low-temperature polycrystalline GaN layer that are cycled N times, wherein the low-temperature InAlN layer is close to the sputtered thin film layer, and N is greater than or equal to 4 and less than or equal to 8.
[0019] In one embodiment, the sputtered thin film layer 20 is an AlN thin film layer, and the thickness of the sputtered thin film layer 20 is 10 nm to 25 nm.
[0020] In one embodiment, the low-temperature InAlN layer has a thickness of 2 nm to 10 nm.
[0021] In one embodiment, the thickness of the low-temperature polycrystalline GaN layer is 5 nm to 10 nm, and the total thickness of the buffer layer is 28 nm to 160 nm.
[0022] In one embodiment, the thickness of the undoped GaN body layer 40 is 1000 nm to 3000 nm.
[0023] In one embodiment, the high temperature InAlN layer 50 has a thickness of 1 nm to 5 nm.
[0024] In one embodiment, the high temperature AlGaN layer 60 has a thickness of 15-30 nm.
[0025] The manufacturing method of the sapphire substrate GaN HEMT epitaxial wafer provided in this application is roughly as follows:
[0026] First, a sapphire substrate 10 is selected;
[0027] Then, a sputtered thin film layer 20 of a predetermined thickness, such as an AlN thin film layer, is sputtered on the sapphire substrate 10 using a PVD method, wherein the thickness of the sputtered thin film layer 20 is 10 nm to 25 nm, and then placed in an MOCVD reaction chamber for regrowth;
[0028] High-temperature pretreatment of the AlN film layer / sapphire substrate surface in a hydrogen atmosphere at 900°C to 1000°C for 4 to 6 minutes;
[0029] Cooling to 400° C. to 500° C., and growing a low-temperature InAlN layer of a predetermined thickness in a reaction chamber under a pressure of 25 kPa to 35 kPa, wherein the thickness of the low-temperature InAlN layer is 2 nm to 10 nm;
[0030] Growing a low-temperature polycrystalline GaN layer of a predetermined thickness in a reaction chamber at a temperature of 400° C. to 500° C. and a pressure of 80 kPa to 90 kPa, wherein the thickness of the low-temperature polycrystalline GaN layer is 5 nm to 10 nm, and the low-temperature InAlN layer and the low-temperature polycrystalline GaN layer are grown cyclically 4 to 8 times, and the total thickness of the low-temperature InAlN layer and the low-temperature polycrystalline GaN layer is controlled to be 28 nm to 160 nm, constituting a buffer layer 30 of the epitaxial wafer;
[0031] The temperature is raised to 900°C to 1000°C, and the buffer layer is recrystallized for 3 to 5 minutes in a reaction chamber under a pressure of 80 kPa to 90 kPa;
[0032] Raising the temperature to 1050° C. to 1100° C., and growing an undoped GaN main layer 40 with a thickness of 1000 nm to 3000 nm under a pressure of 20 kPa to 40 kPa;
[0033] Under the temperature condition of 1000° C. to 1050° C., growing a high-temperature InAlN layer 50 with a thickness of 1 nm to 5 nm;
[0034] Finally, under the temperature conditions of 1000℃~1050℃ and the pressure conditions of 20kPa~40kPa, a high-temperature AlGaN layer 60 with a thickness of 15nm~30nm is grown, in which the Al component is controlled at about 25% and the Ga component is about 75%, that is, Al(25%)Ga(75%)N layer, and then cooled in the furnace.
[0035] The sapphire substrate GaN HEMT epitaxial wafer provided in this application can effectively improve the crystal quality of semiconductor epitaxial wafers, enhance the polarization effect between AlGaN and GaN, and reduce interface scattering, while also achieving the purpose of increasing the two-dimensional electron gas concentration and mobility and reducing the square sheet resistance and on-resistance.
[0036] Those skilled in the art will appreciate that the embodiments of the present invention described above and shown in the accompanying drawings are provided for illustrative purposes only and do not limit the present invention. The advantages of the present invention have been fully and effectively realized. The functional and structural principles of the present invention have been demonstrated and illustrated in the embodiments. Any variations or modifications may be made to the embodiments of the present invention without departing from the principles described.
Claims
1. Sapphire substrate GaN HEMT epitaxial wafer, characterized by: The invention comprises a sapphire substrate and a sputtered thin film layer, a buffer layer, an undoped GaN main layer, a high-temperature InAlN layer and a high-temperature AlGaN layer stacked in sequence on the surface of the sapphire substrate, wherein the buffer layer is a low-temperature InAlN layer and a low-temperature polycrystalline GaN layer that are cycled N times, wherein the low-temperature InAlN layer is close to the sputtered thin film layer, and N is greater than or equal to 4 and less than or equal to 8, wherein the sputtered thin film layer is an AlN thin film layer, and the thickness of the sputtered thin film layer is 10nm to 25nm, wherein the thickness of the low-temperature InAlN layer is 2nm to 10nm, the thickness of the low-temperature polycrystalline GaN layer is 5nm to 10nm, and the total thickness of the buffer layer is 28nm to 160nm.
2. The sapphire substrate GaN HEMT epitaxial wafer according to claim 1, wherein: The thickness of the undoped GaN main layer is 1000nm to 3000nm.
3. The sapphire substrate GaN HEMT epitaxial wafer according to claim 1, wherein: The thickness of the low-temperature InAlN layer is 1 nm to 5 nm.
4. The sapphire substrate GaN HEMT epitaxial wafer according to claim 1, wherein: The thickness of the high-temperature AlGaN layer is 15-30 nm.