A symmetrical GaN-based HEMT structure and a preparation method thereof

Abstract

The application discloses a symmetrical gallium nitride (GaN) based high electron mobility transistor (HEMT) structure and a preparation method thereof. x Ga 1‑x The HEMT structure comprises a GaN layer with a non-polar face as an upward crystal face, a mask layer, a GaN stereoscopic triangular island, an Al The application utilizes selected area epitaxy and combines lateral epitaxy to obtain a GaN island with a stereoscopic structure, the GaN island naturally forms a left-right symmetrical structure due to its crystal properties, and the HEMT prepared based on the feature has atom level consistency, and the left-right symmetrical semi-polar face AlGaN / GaN heterojunction can generate a two-dimensional electron gas (2DEG) with a convenient control concentration, realizes high-quality, high-performance and high-consistency paired GaN based HEMT, and can be applied to mirror current sources, differential amplification and other circuits, and has better consistency and stability compared with traditional devices.

Description

TECHNICAL FIELD

[0001] The present application relates to a symmetrical GaN-based HEMT structure and a preparation method thereof, and belongs to the fields of semiconductor epitaxial growth, GaN-based HEMT, etc. BACKGROUND

[0002] GaN-based HEMTs are becoming increasingly important in modern electronic devices. As a wide-bandgap semiconductor material, GaN has unique physical properties that give GaN-based HEMTs significant advantages in many applications. On the one hand, the wide bandgap of GaN (about 3.4 eV) allows it to withstand higher voltages than traditional silicon materials (about 1.1 eV). This characteristic enables GaN-based HEMTs to work stably under high-voltage and high-power density conditions, making them particularly suitable for power electronics and radio frequency (RF) applications. For example, in power converters and electric vehicle charging systems, GaN-based HEMTs can provide higher switching frequencies and efficiencies, significantly improving system performance and energy utilization. On the other hand, GaN has excellent electron mobility and higher saturation electron velocity, which allows GaN-based HEMTs to achieve high-performance work at high frequencies. This characteristic is particularly suitable for high-speed RF communication systems and radar equipment, which can provide higher frequency response and greater bandwidth. Compared with silicon-based HEMTs, GaN-based HEMTs can better handle high-frequency signals, reduce signal distortion, and improve the overall performance of the system. In addition, the high thermal conductivity of GaN material allows GaN-based HEMTs to effectively manage heat and reduce the impact of overheating on device performance. High thermal conductivity helps to improve the reliability and life of the device, and reduces the complexity and cost of the heat dissipation system.

[0003] In summary, GaN-based HEMTs have significant advantages in high-voltage, high-power, and high-frequency applications due to their wide bandgap, high electron mobility, and excellent thermal performance. With the advancement of technology and improvement of manufacturing processes, GaN-based HEMTs are expected to be widely used in more fields, driving the development and innovation of electronic technology. SUMMARY

[0004] Because the traditional polar heterojunction interface of GaN-based semiconductors is perpendicular to the polar axis, the resulting 2DEG concentration is large and difficult to control. The present application provides a semi-polar AlGaN / GaN heterojunction structure formed by lattice symmetry, the angle between its interface and the polar axis is an acute angle, and the resulting 2DEG concentration depends on the angle between the heterojunction interface and the polar axis, which is smaller and easier to control than the traditional polar structure. In the present application, when Al x Ga 1-xWhen the thickness of the N layer 104 is greater than 20 nm, the positions where the A electrode 106 and the common C electrode 108 are located are etched to make the electrodes contact with the GaN island, thereby generating sufficient current. Meanwhile, the diameter of the micropore and the diameter of the circumscribed circle of the N-type GaN triangular island 103 in the plane are defined to improve the crystal quality. The GaN triangular island structure is selected to release the stress of the epitaxial material and avoid the negative impact of the etching operation on the crystal quality, thereby weakening the influence of defects and polarization on the carriers. Meanwhile, the GaN island with a three-dimensional structure is obtained by using selective epitaxy combined with lateral epitaxy. Due to the crystal properties, the left-right symmetrical structure with high consistency is naturally formed, and the HEMT with atomic level consistency can be prepared, thereby improving the consistency and stability of the HEMT in the mirror current source and differential amplifier circuit, and having a wide application prospect.

[0005] To achieve the above object, the technical scheme adopted by the present application is as follows:

[0006] In one aspect, the present application provides a symmetrical GaN-based HEMT structure, characterized in that the structure comprises, from bottom to top, a GaN layer 101 with a non-polar upward crystal face, a mask layer 102 containing a micropore array, a GaN triangular island 103, an Al x Ga 1-x N layer 104, an insulating medium layer 105, an A electrode 106 below the GaN triangular island 103, a B electrode 107 on the insulating medium layer 105, and a common C electrode 108 on the top of the GaN triangular island 103; wherein the GaN triangular island 103 is obtained by epitaxial growth upward from the micropore of the mask layer 102, and contains two left-right symmetrical triangular inclined surfaces and one triangular side surface perpendicular to the bottom surface; and the Al x Ga 1-x N layer 104, the insulating medium layer 105, the A electrode 106 and the B electrode 107 are arranged on the inclined surfaces of the GaN triangular island 103 and are left-right symmetrical, and the parameters of the same structure are completely the same; the Al x Ga 1-x N layer 104, the insulating medium layer 105, the A electrode 106, the B electrode 107 and the common C electrode 108 constitute a HEMT structure L; and the Al x Ga 1-x N layer 104, the insulating medium layer 105, the A electrode 106, the B electrode 107 and the common C electrode 108 constitute a HEMT structure R.

[0007] Preferably, the mask layer 102 containing the micropore array is a 5-50 nm thick dielectric film coated on the non-polar GaN layer 101, wherein the dielectric film is one of SiO2, SiN or hBN, and the micropore array is etched from the top down by a process technology, and the non-polar GaN layer 101 is exposed in the micropores; the diameter of the micropores is between 0.5-5 μm, and the micropores are arranged in a close-packed form with the center of any micropore being equidistant from the centers of the six adjacent micropores, and the distance can be adjusted according to actual needs.

[0008] Preferably, the upward crystal faces of the non-polar GaN layer 101 and the N-type GaN three-dimensional triangular island 103 are both (11-20) faces, in which case the left and right two inclined crystal faces are both one of the {1-101} or {1-102} crystal face families. Since the {1-101} or {1-102} crystal face families are lower potential energy faces, regular triangular islands can be formed, and the layer structure above can be regularly and controllably grown. Alternatively, the upward crystal faces of the non-polar GaN layer 101 and the N-type GaN three-dimensional triangular island 103 can also be both (1-100) faces, in which case the left and right two inclined crystal faces are both {20-21} crystal face families. The side faces of the N-type GaN three-dimensional triangular island 103 perpendicular to the bottom face are all (000-1) faces.

[0009] Preferably, when the micropore diameter of the mask layer 102 is not greater than 1.5 μm, the circumscribed circle diameter of the N-type GaN three-dimensional triangular island 103 in the plane is between 5-20 μm and can be adjusted according to needs. Since the micropores are small, regular islands are easy to form, and the size of the islands can be controlled according to needs. When the micropore diameter of the mask layer 102 is greater than 1.5 μm, the circumscribed circle diameter of the N-type GaN three-dimensional triangular island 103 in the plane is 3-4 times the micropore diameter, but is not greater than 15 μm. Since the micropores are large, the islands are easy to be irregular, and therefore the size of the islands is limited. The island-like structure of the N-type GaN three-dimensional triangular island 103 is beneficial to releasing the stress of the epitaxial material, improving the crystal quality of the prepared HEMT structure, and weakening the influence of defects and polarization on the carriers.

[0010] Preferably, the Al x Ga 1-x N layer 104 is on the left and right two inclined faces of the GaN three-dimensional triangular island 103, close to the side face of the GaN three-dimensional triangular island 103, extends along the

[0001] axis, and has a coverage of the GaN three-dimensional triangular island 103 of 30%-50%, wherein the

[0001] axis is perpendicular to the side face of the GaN three-dimensional triangular island 103 and is directed to the side of the inclined face of the GaN three-dimensional triangular island 103, and the description method is also applicable to the remaining

[0001] axes; when the upward crystal face of the GaN three-dimensional triangular island 103 is a (11-20) face, and the left and right two inclined crystal faces are both {1-101} crystal face families, the Al x Ga1-x The Al component of the N layer 104 is 0.15 < x < 0.4, and the thickness is 2 / x ± 5 nm. Since the angle between the (1-101) plane and the (0002) plane is about 61.9°, the polarization effect is low, and thus a higher Al component or thickness is required. When the upward crystal plane of the GaN cubic triangular island 103 is the (11-20) plane, and the left and right two inclined planes are the {1-102} crystal plane family, the Al x Ga 1-x The Al component of the N layer 104 is 0.1 < x < 0.3, and the thickness is 1.5 / x ± 5 nm. Since the angle between the (1-102) plane and the (0002) plane is 43°, the polarization effect is acceptable, and thus the Al component or thickness can be slightly smaller. When the upward crystal plane of the GaN cubic triangular island 103 is the (1-100) plane, and the left and right two inclined planes are the {20-21} crystal plane family, the Al x Ga 1-x The Al component of the N layer 104 is 0.15 < x < 0.4, and the thickness is 3 / x ± 5 nm. Since the angle between the (20-21) plane and the (0002) plane is 75°, the polarization effect is very small, and thus a higher Al component or a thicker thickness is required.

[0011] The left and right two A electrodes 106 are respectively at the bottom of the inclined planes on the left and right sides of the GaN cubic triangular island 103, close to the side surface of the GaN cubic triangular island 103, and the length extending along the

[0001] axis is consistent with the Al x Ga 1-x N layer 104; the shared C electrode 108 is at the top of the GaN cubic triangular island 103, close to the side surface of the GaN cubic triangular island 103, and the length extending along the

[0001] axis is consistent with the Al x Ga 1-x N layer 104.

[0012] Preferably, the Al x Ga 1-x N layer 104 is greater than 20 nm, the left and right two A electrodes 106 and the shared C electrode 108 simultaneously contact the GaN cubic triangular island 103, the Al x Ga 1-x N layer 104; the Al x Ga 1-x N layer 104 is less than 20 nm, the left and right two A electrodes 106 and the shared C electrode 108 simultaneously contact the Al x Ga 1-x N layer 104. When the thickness of the Al x Ga 1-x N layer 104 is less than 20 nm, the A electrode 106 and the shared C electrode 108 contact the Al x Ga 1-xN layer 104 can generate enough current, so only need to cover the A electrode 106, common C electrode 108 on Al x Ga 1-x N layer 104; Al x Ga 1-x N layer 104 thickness greater than 20 nm, A electrode 106, common C electrode 108 and Al x Ga 1-x N layer 104 contact can not generate enough current, so must etching the position of A electrode 106, common C electrode 108, expose the underlying GaN island 103, and the A electrode 106, common C electrode 108 and the triangle island 103 contact.

[0013] Preferably, the insulating medium layer 105 covers Al x Ga 1-x N layer 104, close to the side of GaN solid triangle island 103, and the length along the

[0001] axis is consistent with Al x Ga 1-x N layer 104; the left and right two B electrode 107 respectively with left and right two insulating medium layer 105 contact, close to the side of GaN solid triangle island 103, and the length along the

[0001] axis is consistent with Al x Ga 1-x N layer 104.

[0014] Preferably, the insulating medium layer 105 covers Al x Ga 1-x N layer 104 from the side of A electrode 106, coverage > 30%, B electrode 107 close to the side of A electrode 106; or insulating medium layer 105 covers Al x Ga 1-x N layer 104 from the side of common C electrode 108, coverage > 30%, B electrode 107 close to the side of common C electrode 108; or insulating medium layer 105 completely covers Al x Ga 1-x N layer 104, B electrode 107 close to the side of A electrode 106 or common C electrode 108.

[0015] In another aspect, the present application provides a preparation method of symmetrical GaN based HEMT structure, characterized in that: the structure comprises from bottom to top, GaN layer 101 with upward crystal face of nonpolar surface, mask layer 102 containing micro hole array, GaN solid triangle island 103, Al x Ga 1-xN layer 104, insulating medium layer 105, A electrode 106, B electrode 107 and common C electrode 108 constitute HEMT structure L; and Al x Ga 1-x N layer 104, insulating medium layer 105, A electrode 106, B electrode 107 and common C electrode 108 constitute HEMT structure L; and Al x Ga 1-x N layer 104, insulating medium layer 105, A electrode 106, B electrode 107 and common C electrode 108 constitute HEMT structure L; and Al x Ga 1-x N layer 104, insulating medium layer 105, A electrode 106, B electrode 107 and common C electrode 108 constitute HEMT structure L; and Al

[0016] a) prepare a non-polar GaN template as non-polar GaN layer 101, or epitaxially grow a non-polar GaN film on sapphire, Si or SiC substrate as non-polar GaN layer 101;

[0017] b) prepare a dielectric film on non-polar GaN layer 101, use micro-processing technology to process micro-hole structure on the dielectric layer to form mask layer 102 containing micro-hole array, and expose the underlying non-polar GaN layer 101;

[0018] c) use selective epitaxy growth technology to perform selective epitaxy using the above micro-holes, and then realize lateral epitaxy by controlling the temperature,

[0019] V / III ratio, reaction chamber pressure and carrier gas and reactant source flow and other conditions to form GaN island 103;

[0020] d) select one of chemical vapor deposition, epitaxial growth, evaporation plating, and magnetron sputtering, and combine micro-processing technology to prepare Al x Ga 1-x N layer 104 on GaN island 103;

[0021] e) select one of chemical vapor deposition, epitaxial growth, evaporation plating, and magnetron sputtering, and combine micro-processing technology to prepare insulating medium layer 105 on Al x Ga 1-x N layer 104;

[0022] f) using thin film deposition technology combined with micro-processing technology, depositing metal thin film at the corresponding positions of A electrode 106, B electrode 107 and common C electrode 108 to prepare A electrode 106, B electrode 107 and common C electrode 108, and complete the preparation of the symmetrical GaN-based HEMT structure.

[0023] The application also provides a preparation method of a symmetrical GaN-based HEMT structure, characterized in that: the structure comprises, from bottom to top, a GaN layer 101 with upward crystal face being a non-polar face, a mask layer 102 containing a micro-pore array, a GaN three-dimensional triangular island 103, an Al x Ga 1-x N layer 104 with thickness greater than 20 nm and Al composition of 0.1 < x < 0.4, an insulating medium layer 105, and A electrode 106 below the GaN three-dimensional triangular island 103, B electrode 107 on the insulating medium layer 105 and common C electrode 108 on the top of the GaN three-dimensional triangular island 103; wherein the GaN three-dimensional triangular island 103 is obtained by epitaxial growth from the micro-pore of the mask layer 102 upward, and contains, except the bottom, two left-right symmetrical triangular inclined faces and one triangular side face perpendicular to the bottom face; and the Al x Ga 1-x N layer 104, the insulating medium layer 105, the A electrode 106 and the B electrode 107 are arranged on the inclined faces of the GaN three-dimensional triangular island 103 in left-right symmetry, and the parameters of the same structure are completely the same; the Al x Ga 1-x N layer 104, the insulating medium layer 105, the A electrode 106 and the B electrode 107 and the common C electrode 108 constitute HEMT structure L; the Al x Ga 1-x N layer 104, the insulating medium layer 105, the A electrode 106 and the B electrode 107 and the common C electrode 108 constitute HEMT structure R. The preparation method of the transistor structure comprises the following steps:

[0024] a) preparing a non-polar GaN template as the non-polar GaN layer 101, or epitaxially growing a non-polar GaN film on a sapphire, Si or SiC substrate as the non-polar GaN layer 101;

[0025] b) preparing a dielectric film on the non-polar GaN layer 101, and using micro-processing technology to process a micro-pore structure on the dielectric layer to expose the underlying non-polar GaN layer 101;

[0026] c) using selective epitaxial growth technology to perform selective epitaxy by using the above micro-pore, and then controlling the temperature,

[0027] The conditions such as V / III ratio, reaction chamber pressure, carrier gas and flow rate of reactant source realize lateral epitaxy to form GaN islands 103;

[0028] d) Selecting one of chemical vapor deposition, epitaxial growth, evaporation plating, magnetron sputtering, and combining with micro-processing technology, Al x Ga 1-x N layer 104 is prepared on the GaN islands 103;

[0029] e) Selecting one of chemical vapor deposition, epitaxial growth, evaporation plating, magnetron sputtering, and combining with micro-processing technology, an insulating medium layer 105 is prepared on the Al x Ga 1-x N layer 104;

[0030] f) Using micro-processing technology, the insulating medium layer 105 and the Al x Ga 1-x N layer 104 are etched from top to bottom on the GaN three-dimensional triangular island

[0031] 103, and the position of the vertical triangular side of the bottom surface and the position where the A electrode 106 and the common C electrode 108 need to be prepared are etched to expose the underlying GaN island 103; then thin film deposition technology is selected to complete the preparation of the A electrode 106, the B electrode 107

[0032] and the common C electrode 108, and the preparation of the symmetric GaN-based HEMT structure is completed.

[0033] Advantages:

[0034] The present application utilizes selective epitaxy and combines lateral epitaxy to obtain a three-dimensional GaN island structure. The GaN island naturally forms a left-right symmetric structure due to its crystal properties. Based on this feature, the pair of prepared HEMT has atomic layer consistency, and the left-right symmetric semipolar AlGaN / GaN heterojunction produces 2DEG with convenient concentration control, which can realize high-quality, high-performance and highly consistent paired GaN-based HEMT. In mirror current source, differential amplification and other circuit applications, compared with traditional devices, the present application has better consistency and stability.

[0035] Meanwhile, the present application sets the thickness of the Al x Ga 1-x N layer 104 to be greater than 20 nm, etches the positions of the A electrode 106 and the common C electrode 108 and makes the electrodes contact with the GaN island, so that sufficient current is generated. When the thickness of the Al x Ga 1-x N layer 104 is less than 20 nm, the positions of the A electrode 106 and the common C electrode 108 do not need to be etched, thereby reducing the process operation.

[0036] When the diameter of the micro-hole of the mask layer 102 is not greater than 1.5 μm, the diameter of the circumscribed circle of the N-type GaN stereoscopic triangular island 103 in the plane is adjusted as required between 5-20 μm, because when the micro-hole is small, the island is easy to form regularly, and at this time, the size of the island can be controlled as required; when the diameter of the micro-hole of the mask layer 102 is greater than 1.5 μm, the diameter of the circumscribed circle of the N-type GaN stereoscopic triangular island 103 in the plane is 3-4 times the diameter of the micro-hole, but is not greater than 15 μm, because when the micro-hole is large, the island is easy to be irregular, and therefore the size of the island is limited. And the island structure is beneficial to release the stress of the epitaxial material, improve the crystal quality of the prepared HEMT structure, and weaken the influence of defects and polarization on the carriers. When the upward crystal face of the GaN stereoscopic triangular island 103 is the (11-20) face, and the left and right two inclined faces are the {1-101} crystal face family, because the angle between (1-101) and (0002) is 61.9°, the polarization effect is low, and therefore a higher Al component (0.15 < x < 0.4) or thickness (2 / x ± 5 nm) is required; when the upward crystal face of the GaN stereoscopic triangular island 103 is the (11-20) face, and the left and right two inclined faces are the {1-102} crystal face family, because the angle between (1-102) and (0002) is 43°, the polarization effect is acceptable, and therefore a lower Al component (0.1 < x < 0.3) or thickness (1.5 / x ± 5 nm) is required; when the upward crystal face of the GaN stereoscopic triangular island 103 is the (1-100) face, and the left and right two inclined faces are the {20-21} crystal face family, because the angle between (20-21) and (0002) is 75°, the polarization effect is very small, and therefore a higher Al component (0.15 < x < 0.4) or a thicker thickness (3 / x ± 5 nm) is required. By adjusting the Al component and thickness of the GaN layer 104 with different components and thicknesses, the influence of the polarization effect can be reduced, the crystal quality can be improved, and the stability of the HEMT structure can be strengthened. x Ga 1-x N layer 104, the influence of the polarization effect can be reduced, the crystal quality can be improved, and the stability of the HEMT structure can be strengthened. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 A cross-sectional view of a symmetric GaN-based HEMT structure provided by the present application is shown in FIG. 1, in which the upward crystal face of the GaN layer is the (11-20) face, and the B electrode is placed on the top of the Al x Ga 1-x N layer.

[0038] Figure 2 A top view of a symmetric GaN-based HEMT structure provided by the present application is shown in FIG. 2, in which the upward crystal face of the GaN layer is the (11-20) face, and the B electrode is placed on the top of the Al x Ga 1-x N layer.

[0039] Figure 3 A cross-sectional view of a typical structure of a conventional GaN-based HEMT is shown in FIG. 3.

[0040] Figure 4 The present invention provides a GaN layer with an upward crystal plane of (1-100) and a B electrode placed on an Al. x Ga 1-x Cross-sectional view of the symmetrical GaN-based HEMT structure at the bottom of the N-layer.

[0041] Figure 5 The present invention provides a GaN layer with an upward crystal plane of (1-100) and a B electrode placed on an Al. x Ga 1-x A top view of a symmetrical GaN-based HEMT structure at the bottom of the N-layer.

[0042] Among them, 101 is a GaN layer with a non-polar upward crystal plane; 102 is a mask layer containing a micropore array; 103 is a GaN three-dimensional triangular island; and 104 is an Al layer. x Ga 1-x N layer; 105 is the insulating dielectric layer; 106 is the A electrode; 107 is the B electrode; 108 is the common C electrode; 201 is the substrate; 202 is the buffer layer; 203 is GaN; 204 is AlGaN; 205 is the source electrode; 206 is the gate electrode; 207 is the drain electrode. Detailed Implementation

[0043] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0044] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0045] Example 1:

[0046] Embodiment 1 of the present invention provides a GaN layer with an upward crystal plane of (11-20) and a B electrode placed on an Al layer. x Ga 1-x A cross-sectional view of the symmetrical GaN-based HEMT structure at the top of the N-layer is shown below. Figure 1 As shown in the top view diagram Figure 2As shown, the symmetrical GaN-based HEMT structure includes, from bottom to top, a non-polar GaN layer 101 with upward crystal face (11-20), a mask layer 102 containing a micro-pore array, a GaN stereoscopic triangular island 103, an Al x Ga 1-x N layer 104 with Al composition x=0.15, an insulating medium layer 105, and an A electrode 106 under the GaN stereoscopic triangular island 103, a B electrode 107 on the insulating medium layer 105, and a common C electrode 108 on the top of the GaN stereoscopic triangular island 103; wherein the GaN stereoscopic triangular island 103 is obtained by epitaxial growth upward from the micro-pores of the mask layer 102, and contains, in addition to the bottom, two left-right symmetrical triangular inclined surfaces and a triangular side surface perpendicular to the bottom surface; and the Al x Ga 1-x N layer 104, the insulating medium layer 105, the A electrode 106, and the B electrode 107 are arranged on the inclined surfaces of the GaN stereoscopic triangular island 103 in left-right symmetry, and the parameters of the same structure are completely the same; the Al x Ga 1-x N layer 104, the insulating medium layer 105, the A electrode 106, the B electrode 107, and the common C electrode 108 constitute an HEMT structure L; and the Al x Ga 1-x N layer 104, the insulating medium layer 105, the A electrode 106, the B electrode 107, and the common C electrode 108 constitute an HEMT structure R.

[0047] The upward crystal face of the GaN layer 101 and the GaN stereoscopic triangular island 103 is (11-20) face, the crystal faces of the left and right inclined surfaces are {1-102} crystal face family, and the circumscribed circle diameter of the GaN stereoscopic triangular island 103 in the plane is 10 μm.

[0048] A 30-nm-thick SiO2 medium film is plated on the GaN layer 101 with upward crystal face (11-20) as the mask layer 102, a micro-pore array is etched from top to bottom by process technology, the lower GaN layer 101 is exposed in the micro-pores, and the micro-pore diameter of the mask layer 102 is 1 μm.

[0049] The Al x Ga 1-x N layer 104 covers the left and right two inclined surfaces of the GaN stereoscopic triangular island 103, and has Al composition x=0.15 and thickness of 15 nm.

[0050] The left and right two A electrodes 106 are respectively at the bottom of the left and right two inclined surfaces of the GaN stereoscopic triangular island 103, the common C electrode 108 is at the top of the GaN stereoscopic triangular island 103, and the left and right two A electrodes 106 and the common C electrode 108 are simultaneously connected to the Al x Ga 1-xN-layer 104 contact.

[0051] Insulating dielectric layer 105 covers Al x Ga 1-x On layer N 104, the two B electrodes 107 on the left and right sides are in contact with the insulating dielectric layers 105 on the left and right sides, respectively. The insulating dielectric layers 105 cover Al from the side of the common C electrode 108. x Ga 1-x N layer 104, with a coverage of 50%, B electrode 107 is located near the common C electrode 108.

[0052] Embodiment 1 of the present invention provides a GaN layer with an upward crystal plane of (11-20) and a B electrode placed on an Al layer. x Ga 1-x The method for preparing the symmetrical GaN-based HEMT structure at the top of the N-layer includes the following steps:

[0053] a) Prepare a non-polar (11-20) GaN template as the non-polar GaN layer 101.

[0054] The upward-facing crystal plane of the 101 and N-type GaN three-dimensional triangular island 103 is the (11-20) plane, and the two left and right inclined planes are the {1-102} crystal plane family;

[0055] b) A SiO2 dielectric film is prepared on the GaN layer 101 on the non-polar surface. Micro-fabrication technology is used to process a micro-pore structure on the dielectric layer to form a mask layer 102 containing a micro-pore array. The micro-pore diameter is 1 μm, exposing the underlying non-polar GaN layer 101.

[0056] c) Selective epitaxy is performed using the aforementioned micropores, followed by controlling the epitaxial growth temperature,

[0057] Lateral epitaxy is achieved by conditions such as V / III ratio, reaction chamber pressure, carrier gas and reactant source flow rate to form GaN island 103. The diameter of the circumscribed circle of this N-type GaN three-dimensional triangular island 103 in the plane is 10 μm.

[0058] d) Using epitaxial growth technology combined with microfabrication processes, an Al composition of x = 0.15 and a thickness of [missing information] were prepared on GaN island 103.

[0059] 15nm Al x Ga 1-x Nth floor 104;

[0060] e) Using chemical vapor deposition technology combined with microfabrication processes, on Al x Ga 1-x An insulating dielectric layer is prepared on layer N104.

[0061] 105. The insulating medium layer 105 covers the Al x Ga 1-x N layer 104 with a coverage of 50%, and the B electrode 107 is close to the common C electrode 108 side.

[0062] f) Using thin film deposition technology combined with microfabrication technology, metal thin film deposition is performed at the positions corresponding to the A electrode 106, the B electrode 107, and the common C electrode 108 to prepare the A electrode 106, the B electrode 107, and the common C electrode 108, thereby completing the preparation of the symmetric GaN-based HEMT structure.

[0063] Embodiment 2:

[0064] The GaN layer provided in Embodiment 2 of the present application has an upward crystal face of (1-100) plane, and the B electrode is arranged on the Al x Ga 1-x N layer bottom. The cross-sectional view of the symmetric GaN-based HEMT structure is shown in Figure 4 , and the top view is shown in Figure 5 . The symmetric GaN-based HEMT structure includes, from bottom to top, a non-polar GaN layer 101 with an upward crystal face of (1-100) plane, a mask layer 102 containing a micro-pore array, a GaN three-dimensional triangular island 103, an Al x Ga 1-x N layer 104 with a composition of x = 0.16, an insulating medium layer 105, an A electrode 106 below the GaN three-dimensional triangular island 103, a B electrode 107 on the insulating medium layer 105, and a common C electrode 108 on the top of the GaN three-dimensional triangular island 103. The GaN three-dimensional triangular island 103 is obtained by epitaxial growth from the micro-pores of the mask layer 102, and contains, in addition to the bottom, two left and right symmetric triangular inclined surfaces and a triangular side surface perpendicular to the bottom surface. Moreover, the Al x Ga 1-x N layer 104, the insulating medium layer 105, the A electrode 106, and the B electrode 107 are symmetrically arranged on the inclined surfaces of the GaN three-dimensional triangular island 103, and the parameters of the same structure are completely the same. The Al x Ga 1-x N layer 104, the insulating medium layer 105, the A electrode 106, and the B electrode 107, and the common C electrode 108 constitute the HEMT structure L. The Al x Ga 1-x N layer 104, the insulating medium layer 105, the A electrode 106, and the B electrode 107, and the common C electrode 108 constitute the HEMT structure R.

[0065] The upward crystal surface of the GaN layer 101 and the upward crystal surface of the GaN pyramid island 103 are both (1-100) surfaces, the left and right two inclined surfaces are both {20-21} crystal surface families, and the diameter of the circumscribed circle of the GaN pyramid island 103 in the surface is 10 microns.

[0066] A 30-nm-thick SiO2 dielectric film is plated on the GaN layer 101 with the upward crystal surface being (1-100) as a mask layer 102, and a micropore array is etched from top to bottom by a process technology, the GaN layer 101 in the micropore is exposed, and the micropore diameter of the mask layer 102 is 1 micron.

[0067] Al x Ga 1-x The GaN layer 104 covers the left and right two inclined surfaces of the GaN pyramid island 103, the Al component x=0.16, and the thickness is 22 nm.

[0068] The left and right two A electrodes 106 are respectively at the bottom of the left and right two inclined surfaces of the GaN pyramid island 103, the common C electrode 108 is at the top of the GaN pyramid island 103, the left and right two A electrodes 106 and the common C electrode 108 are in contact with the GaN pyramid island 103, the Al x Ga 1-x N layer 104 at the same time.

[0069] The insulating dielectric layer 105 covers the Al x Ga 1-x N layer 104, the left and right two B electrodes 107 are respectively in contact with the left and right two insulating dielectric layers 105, the insulating dielectric layer 105 covers the Al x Ga 1-x N layer 104 from the side of the A electrode 106, the coverage rate is 50%, and the B electrode 107 is close to the side of the A electrode 106.

[0070] The preparation method of the symmetric GaN-based HEMT structure provided by the embodiment 2 of the present application, in which the upward crystal surface of the GaN layer is (1-100) and the B electrode is placed at the bottom of the Al x Ga 1-x N layer, comprises the following steps:

[0071] a) preparing a non-polar (1-100) GaN template as a non-polar GaN layer 101, the upward crystal surface of the non-polar GaN layer 101 and the upward crystal surface of the N-type GaN pyramid island 103 are both (1-100) surfaces, the left and right two inclined surfaces are both {20-21} crystal surface families;

[0072]

[0073] ​b) A SiO2 dielectric film is prepared on the non-polar GaN layer 101, and a micro-hole structure is formed on the dielectric film using micro-processing technology, with a micro-hole diameter of 1 μm, exposing the underlying non-polar GaN layer 101;

[0074] c) Using selective epitaxy growth technology, selective epitaxy is performed using the micro-hole described above, and then lateral epitaxy is achieved by controlling the temperature,

[0075] V / III ratio, reaction chamber pressure, and flow rate of carrier gas and reactant source, etc. to form GaN islands 103. The N-type GaN triangular islands 103 have an in-plane circumscribed circle diameter of 10 μm;

[0076] d) Using epitaxial growth technology, an Al x Ga 1-x N layer 104 with Al composition x = 0.16 and thickness of 22 nm is prepared on the GaN islands 103 in combination with micro-processing technology;

[0077] e) Using chemical vapor deposition technology, an insulating dielectric layer 105 is prepared on the Al x Ga 1-x N layer 104 in combination with micro-processing technology. The insulating dielectric layer 105 covers the Al x Ga 1-x N layer 104 from the side of the A electrode 106 with a coverage rate of 50%, and the B electrode 107 is close to the side of the A electrode 106;

[0078] f) Using micro-processing technology, the insulating dielectric layer 105 and the Al x Ga 1-x N layer 104 are etched from top to bottom on the side of the GaN triangular islands 103 perpendicular to the base, and the positions where the A electrode 106 and the common C electrode 108 are to be prepared are etched, exposing the underlying GaN islands 103; then thin film deposition technology is used to complete the preparation of the A electrode 106, the B electrode 107

[0079] and the common C electrode 108, and the preparation of the symmetric GaN-based HEMT structure is completed.

Claims

1. A symmetric GaN-based HEMT structure, characterized by: GaN layer (101) with upward crystal face being non-polar face, mask layer (102) containing micro-pore array, GaN stereoscopic triangular island (103), Al x Ga 1-x N layer (104) with 0.1 < x < 0.4, insulating medium layer (105), A electrode (106) under GaN stereoscopic triangular island (103), B electrode (107) on insulating medium layer (105) and common C electrode (108) on top of GaN stereoscopic triangular island (103); wherein, GaN stereoscopic triangular island (103) is obtained by epitaxial growth from micro-pore of mask layer (102), containing two left-right symmetrical triangular inclined planes and one triangular side plane vertical to bottom surface; and, Al x Ga 1-x N layer (104), insulating medium layer (105), A electrode (106), B electrode (107) are all left-right symmetrical arranged on inclined planes of GaN stereoscopic triangular island (103), and parameters of same structure are completely same; Al x Ga 1-x N layer (104), insulating medium layer (105), A electrode (106), B electrode (107) and common C electrode (108) constitute HEMT structure L; Al x Ga 1-x N layer (104), insulating medium layer (105), A electrode (106), B electrode (107) and common C electrode (108) constitute HEMT structure R.

2. A symmetric GaN-based HEMT structure as claimed in claim 1, characterized in that: The mask layer (102) containing the micropore array is a micropore array etched from top to bottom by a process after a 5-50 nm thick medium film of SiO2, SiN or hBN is plated on the GaN layer (101) with a non-polar upward crystal face, and the GaN layer (101) is exposed in the micropores; the diameter of the micropores is between 0.5-5 μm, the micropores are arranged in a close-packed form with the center of any micropore being equidistant from the centers of the six adjacent micropores, and the distance can be adjusted according to actual needs.

3. A symmetric GaN-based HEMT structure as claimed in claim 1, characterized in that: The upward crystal faces of the GaN layer (101) and the GaN stereoscopic triangular island (103) are both (11-20) faces, at this time, the crystal faces of the left and right two inclined planes are both one of the {1-101} or {1-102} crystal face families; or, the upward crystal faces of the GaN layer (101) and the GaN stereoscopic triangular island (103) are both (1-100) faces, at this time, the crystal faces of the left and right two inclined planes are both the {20-21} crystal face family; the side faces of the GaN stereoscopic triangular island (103) perpendicular to the bottom face are all (000-1) faces; when the diameter of the micropores of the mask layer (102) is not greater than 1.5 μm, the diameter of the circumscribed circle of the GaN stereoscopic triangular island (103) in the plane is between 5-20 μm and can be adjusted according to needs; when the diameter of the micropores of the mask layer (102) is greater than 1.5 μm, the diameter of the circumscribed circle of the GaN stereoscopic triangular island (103) in the plane is 3-4 times the diameter of the micropores, but is not greater than 15 μm.

4. A symmetric GaN-based HEMT structure as claimed in claim 1, characterized in that: Al x Ga 1-x N layer (104) is on two inclined planes left and right of the GaN stereographic triangle island (103), close to the side of the GaN stereographic triangle island (103), and extends along the [0001] axis and covers the GaN stereographic triangle island (103) with a coverage of 30% to 50%; when the upward crystal plane of the GaN stereographic triangle island (103) is a (11-20) plane, and the left and right two inclined planes are a {1-101} crystal plane family, the Al x Ga 1-x N layer (104) has an Al component of 0.15 < x < 0.4 and a thickness of 2 / x ± 5 nm; when the upward crystal plane of the GaN stereographic triangle island (103) is a (11-20) plane, and the left and right two inclined planes are a {1-102} crystal plane family, the Al x Ga 1-x N layer (104) has an Al component of 0.1 < x < 0.3 and a thickness of 1.5 / x ± 5 nm; when the upward crystal plane of the GaN stereographic triangle island (103) is a (1-100) plane, and the left and right two inclined planes are a {20-21} crystal plane family, the Al x Ga 1-x N layer (104) has an Al component of 0.15 < x < 0.4 and a thickness of 3 / x ± 5 nm.

5. A symmetric GaN-based HEMT structure as claimed in claim 1, characterized in that: The left and right A electrodes (106) are respectively at the bottom of the inclined surface on the left and right sides of the GaN triangular island (103), close to the side of the GaN triangular island (103), and extend along the [0001] axis with a length consistent with the Al x Ga 1-x N layer (104); the shared C electrode (108) is on the top of the GaN triangular island (103), close to the side of the GaN triangular island (103), and extends along the [0001] axis with a length consistent with the Al x Ga 1-x N layer (104); when the thickness of the Al x Ga 1-x N layer (104) is greater than 20 nm, the left and right A electrodes (106) and the shared C electrode (108) simultaneously contact the GaN triangular island (103), the Al x Ga 1-x N layer (104); when the thickness of the Al x Ga 1-x N layer (104) is less than 20 nm, the left and right A electrodes (106) and the shared C electrode (108) simultaneously contact the Al x Ga 1-x N layer (104).

6. A symmetric GaN-based HEMT structure as claimed in claim 1, wherein: The insulating medium layer (105) covers the Al x Ga 1-x N layer (104) and is close to the side of the GaN stereoscopic triangular island (103) and extends along the [0001] axis with the same length as the Al x Ga 1-x N layer (104); the left and right two B electrodes (107) are respectively in contact with the left and right two insulating medium layers (105) and are close to the side of the GaN stereoscopic triangular island (103) and extend along the [0001] axis with the same length as the Al x Ga 1-x N layer (104); the insulating medium layer (105) covers the Al x Ga 1-x N layer (104) from one side of the A electrode (106) with a coverage rate of >30%, and the B electrode (107) is close to one side of the A electrode (106); or the insulating medium layer (105) covers the Al x Ga 1-x N layer (104) from one side of the common C electrode (108) with a coverage rate of >30%, and the B electrode (107) is close to one side of the common C electrode (108); or the insulating medium layer (105) completely covers the Al x Ga 1-x N layer (104), and at this time, the B electrode (107) is close to any one side of the A electrode (106) or the common C electrode (108).

7. A method of fabricating a symmetric GaN-based HEMT structure, characterized by: The structure comprises, from bottom to top, a GaN layer (101) with upward crystal face being non-polar face, a mask layer (102) containing micro-pore array, a GaN stereoscopic triangular island (103), an Al x Ga 1-x N layer (104) with thickness less than 20 nm and Al component 0.1 < x < 0.4, an insulating medium layer (105), and an A electrode (106) below the GaN stereoscopic triangular island (103), a B electrode (107) on the insulating medium layer (105) and a common C electrode (108) on the top of the GaN stereoscopic triangular island (103); wherein, the GaN stereoscopic triangular island (103) is obtained by epitaxial growth from the micro-pore of the mask layer (102) upward, and comprises, except the bottom, two left-right symmetrical triangular inclined surfaces and one triangular side surface vertical to the bottom surface; and, the Al x Ga 1-x N layer (104), the insulating medium layer (105), the A electrode (106) and the B electrode (107) are arranged on the inclined surfaces of the GaN stereoscopic triangular island (103) left-right symmetrically, and the parameters of the same structure are completely same; the Al x Ga 1-x N layer (104), the insulating medium layer (105), the A electrode (106), the B electrode (107) and the common C electrode (108) constitute a HEMT structure L; and the Al x Ga 1-x N layer (104), the insulating medium layer (105), the A electrode (106), the B electrode (107) and the common C electrode (108) constitute a HEMT structure R; the preparation method of the transistor structure comprises the following steps: a) a GaN template with a non-polar upward crystal face is prepared as the GaN layer (101), or a non-polar GaN film is epitaxially grown on a sapphire, Si or SiC substrate as the GaN layer (101); b) a medium film is prepared on the GaN layer (101), and a micropore structure is processed on the medium layer by a microprocessing process to form a mask layer (102) containing a micropore array, and the underlying GaN layer (101) is exposed; c) a selective epitaxy technique is used to perform selective epitaxy by using the micropores, and then lateral epitaxy is realized by controlling the temperature, V / III ratio, reaction chamber pressure and flow rate of the carrier gas and reactant source to form a GaN stereoscopic triangular island (103); d) Selecting one of the techniques of chemical vapor deposition, epitaxial growth, evaporation plating, and magnetron sputtering, in combination with microprocessing technology, to prepare Al x Ga 1-x N layer (104) on the GaN island (103); e) Selecting one of the techniques of chemical vapor deposition, epitaxial growth, evaporation plating, and magnetron sputtering, and combining with micro-processing technology, an insulating medium layer (105) is prepared on the Al x Ga 1-x N layer (104). f) a thin film deposition technique is used in combination with a microprocessing technique to deposit a metal thin film at positions corresponding to the A electrode (106), B electrode (107) and common C electrode (108) to prepare the A electrode (106), B electrode (107) and common C electrode (108), and the preparation of the symmetric GaN-based HEMT structure is completed.

8. A method of fabricating a symmetric GaN-based HEMT structure, characterized by: The structure comprises, from bottom to top, a GaN layer (101) with upward crystal face being non-polar face, a mask layer (102) containing micro-pore array, a GaN stereoscopic triangular island (103), an Al x Ga 1-x N layer (104) with thickness greater than 20 nm and Al component 0.1 < x < 0.4, an insulating dielectric layer (105), and an A electrode (106) below the GaN stereoscopic triangular island (103), a B electrode (107) on the insulating dielectric layer (105) and a common C electrode (108) on the top of the GaN stereoscopic triangular island (103), the positions of the A electrode (106) and the common C electrode (108) need to be etched to expose the underlying GaN island (103); wherein, the GaN stereoscopic triangular island (103) is obtained by epitaxial growth from the micro-pore of the mask layer (102) upward, and comprises, except the bottom, two left-right symmetrical triangular inclined surfaces and one triangular side surface perpendicular to the bottom surface; and, the Al x Ga 1-x N layer (104), the insulating dielectric layer (105), the A electrode (106) and the B electrode (107) are arranged on the inclined surface of the GaN stereoscopic triangular island (103) left-right symmetrically, and the parameters of the same structure are completely the same; the Al x Ga 1-x N layer (104), the insulating dielectric layer (105), the A electrode (106), the B electrode (107) and the common C electrode (108) constitute a HEMT structure L; and the Al x Ga 1-x N layer (104), the insulating dielectric layer (105), the A electrode (106), the B electrode (107) and the common C electrode (108) constitute a HEMT structure R; the preparation method of the transistor structure comprises the following steps: a) a GaN template with a non-polar upward crystal face is prepared as the GaN layer (101), or a non-polar GaN film is epitaxially grown on a sapphire, Si or SiC substrate as the GaN layer (101); b) a medium film is prepared on the GaN layer (101), and a micropore structure is processed on the medium layer by a microprocessing process to form a mask layer (102) containing a micropore array, and the underlying GaN layer (101) is exposed; c) using the above-mentioned micropores to perform selective epitaxy by using selective epitaxial growth technology, and then forming a GaN cubic triangular island (103) by controlling the conditions of epitaxial growth, such as temperature, V / III ratio, reaction chamber pressure, and flow rate of carrier gas and reactant source, and lateral epitaxy; d) Selecting one of the techniques of chemical vapor deposition, epitaxial growth, evaporation plating, and magnetron sputtering, in combination with microprocessing technology, to prepare an Al x Ga 1-x N layer (104) on the GaN island (103); e) Selecting one of the techniques of chemical vapor deposition, epitaxial growth, evaporation plating, and magnetron sputtering, and combining with micro-processing technology, an insulating medium layer (105) is prepared on the Al x Ga 1-x N layer (104). f) Using microfabrication technology, the insulating dielectric layer (105) and Al x Ga 1-x N layer (104) is etched on the side of the triangle side of the GaN stereoscopic triangle island (103) perpendicular to the bottom surface, and the position where A electrode (106) and common C electrode (108) need to be prepared is exposed to the underlying GaN island (103); then select thin film deposition technology to complete the preparation of A electrode (106), B electrode (107) and common C electrode (108), and complete the preparation of this symmetrical GaN-based HEMT structure.

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