HEMT device and preparation method thereof

Abstract

The embodiment of the present application belongs to the technical field of semiconductor devices, and relates to a HEMT device, including a substrate, an epitaxial structure, a passivation layer, a source, a gate, a drain, and a side electrode; the epitaxial structure is arranged on the substrate; the passivation layer is coated on the outside of the epitaxial structure; the source, the gate, and the drain are all arranged in the passivation layer and in contact with the upper surface of the epitaxial structure, and the gate is located between the source and the drain; the side electrodes are arranged on opposite sides of the epitaxial structure, and the side electrodes are arranged by separating the epitaxial structure through the passivation layer; the side electrodes include a gate side electrode and a drain side electrode; the gate side electrode is electrically connected to the gate through a wire to form a large gate; the drain side electrode is electrically connected to the drain through a wire to form a large drain. The present application also relates to a method for preparing a HEMT device. The technical solution provided by the present application can make the electric field distribution inside the HEMT device uniform, improve the withstand voltage capability of the HEMT device, and improve the breakdown voltage of the HEMT device.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor devices, and more specifically, to a HEMT device and a method for preparing a HEMT device. Background Art

[0002] As a typical representative of the third-generation wide bandgap semiconductors, GaN not only has the characteristics of large bandgap width, high critical breakdown electric field, large electron saturation drift velocity, high temperature resistance, radiation resistance and good chemical stability, but also due to the polarization effect of the material, it can form a two-dimensional electron gas (2DEG) heterojunction channel with high concentration and high mobility with materials such as AlGaN, which is very suitable for power switching applications. Therefore, the third-generation wide bandgap semiconductor power electronic devices based on GaN have become the current research hotspot.

[0003] Due to the advantages of GaN materials and device structure, AlGaN / GaN HEMT (high electron mobility transistor) can achieve smaller on-resistance under the same breakdown voltage. The reported performance indicators of GaN-based devices have exceeded the theoretical limits of Si, GaAs and even SiC materials, but there is still a large gap from the theoretical limits of GaN materials. There is still huge room for further optimizing device parameters and improving device voltage resistance.

[0004] Currently, the main factor restricting the breakdown voltage is the gate electric field concentration effect. The excessively large peak electric field makes the device electric field distribution very uneven. The device is easily broken down at a relatively low source-drain voltage, and the high voltage resistance advantage of the material cannot be fully utilized. Summary of the invention

[0005] The technical problem to be solved by the embodiments of the present application is the gate electric field concentration effect of the existing HEMT device. The excessive peak electric field makes the electric field inside the device unevenly distributed, and the device is prone to breakdown.

[0006] In order to solve the above technical problems, the embodiment of the present application provides a HEMT device, which adopts the following technical solution:

[0007] A HEMT device comprises a substrate, an epitaxial structure, a passivation layer, a source electrode, a gate electrode, a drain electrode, and a side electrode;

[0008] The epitaxial structure is disposed on the substrate;

[0009] The passivation layer is coated outside the epitaxial structure;

[0010] The source electrode, the gate electrode and the drain electrode are all disposed on the passivation layer and in contact with the upper surface of the epitaxial structure, and the gate electrode is located between the source electrode and the drain electrode;

[0011] The side electrodes are arranged on opposite sides of the epitaxial structure, and the side electrodes are arranged with the epitaxial structure separated by the passivation layer;

[0012] The side electrodes include a gate side electrode and a drain side electrode;

[0013] The gate side electrode is electrically connected to the gate through a wire to form a large gate;

[0014] The drain-side electrode is electrically connected to the drain through a wire to form a large drain.

[0015] Furthermore, the horizontal distance between the source electrode and the gate side electrode is 0.5-0.8 μm;

[0016] The horizontal distance between the drain electrode and the drain-side electrode is 0.5-0.8 μm.

[0017] Furthermore, the passivation layer includes a top passivation layer and a side passivation layer;

[0018] The top passivation layer is disposed on the upper surface of the epitaxial structure and is filled between the gate and the source and between the drain and the gate;

[0019] The side passivation layer surrounds and covers the outer wall of the epitaxial structure, and fills between the side electrode and the epitaxial structure and between the side electrode and the substrate.

[0020] Furthermore, the thickness of the top passivation layer is 0.1-0.3 μm; and / or

[0021] The side passivation layer has a thickness of 2 to 3 μm, wherein the side passivation layer filled between the side electrode and the epitaxial structure has a thickness of 0.5 to 0.8 μm.

[0022] Furthermore, the epitaxial structure includes a buffer layer, a GaN channel layer and an AlGaN barrier layer which are stacked;

[0023] The side electrode extends downward from the upper surface of the passivation layer to the horizontal position where the buffer layer is located, and the bottom of the side electrode is spaced from the substrate by the passivation layer.

[0024] Furthermore, the material of the substrate is selected from one of Si, SiC, and GaN; and / or

[0025] The material of the buffer layer is selected from one or more of C-doped GaN and AlGaN; and / or

[0026] The doping method of the GaN channel layer is unintentional doping; and / or

[0027] The doping method of the AlGaN barrier layer is unintentional doping.

[0028] Furthermore, the thickness of the buffer layer is 2.0-3.0 μm; and / or

[0029] The thickness of the GaN channel layer is 0.05-0.10 μm; and / or

[0030] The thickness of the AlGaN barrier layer is 0.04-0.15 μm.

[0031] In order to solve the above technical problems, the present application also provides a method for preparing a HEMT device, which adopts the following technical solution:

[0032] A method for preparing a HEMT device, for preparing the HEMT device as described above, comprises the following steps:

[0033] Providing a substrate, and preparing an epitaxial structure on the substrate;

[0034] preparing a passivation layer on the periphery of the epitaxial structure;

[0035] Etching a source electrode preparation region and a drain electrode preparation region on the passivation layer to prepare a source electrode and a drain electrode;

[0036] Etching the side wall of the passivation layer close to the drain electrode to form a drain side electrode preparation area to prepare a drain side electrode;

[0037] etching a gate preparation region on the passivation layer to prepare a gate;

[0038] Etching the side wall of the passivation layer close to the source electrode to form a gate side electrode preparation area to prepare a gate side electrode;

[0039] The gate and the gate-side electrode are electrically connected through a wire to form a large gate, and the drain and the drain-side electrode are electrically connected through a wire to form a large drain.

[0040] Furthermore, after preparing a passivation layer on the periphery of the epitaxial structure and before etching a source electrode preparation region and a drain electrode preparation region on the passivation layer, the method further includes the following steps:

[0041] The passivation layer on the upper surface of the epitaxial structure is thinned.

[0042] Furthermore, the drain side electrode preparation region and the gate side electrode preparation region are both spaced apart from the upper surface of the substrate.

[0043] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0044] The embodiment of the present application provides a HEMT device, in which a gate side electrode and a drain side electrode are arranged outside the epitaxial structure, and part of the electric field is introduced into the epitaxial structure through the side electrodes, thereby effectively avoiding the premature breakdown phenomenon caused by the high electric field concentration effect of the gate biased to the drain side under high off-state leakage voltage, and by making the electric field distribution in the channel of the HEMT device uniform, the breakdown voltage of the HEMT device is increased, and the brightness of the HEMT device is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the scheme of the present application, a brief introduction is given below to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0046] Figure 1 is a cross-sectional view of a HEMT device according to an embodiment of the present application;

[0047] Figure 2 is a flow chart of a method for preparing a HEMT device according to an embodiment of the present application;

[0048] Figure 3a to 3d Schematic diagram of structural changes at various stages in the preparation process of the HEMT device according to the embodiment of the present application;

[0049] Figure 4 It is a comparison chart of the breakdown characteristics of the HEMT device of the embodiment of the present application and the conventional device.

[0050] Reference numerals:

[0051] 1. Substrate; 2. Epitaxial structure; 21. Buffer layer; 22. GaN channel layer; 23. AlGaN barrier layer; 3. Passivation layer; 31. Top passivation layer; 32. Side passivation layer; 4. Source; 5. Gate; 51. Gate side electrode; 6. Drain; 61. Drain side electrode. DETAILED DESCRIPTION

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by technicians in the technical field of this application; the terms used in the specification of the application herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, not to describe a specific order.

[0053] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0054] Embodiments of the HEMT device of the present application

[0055] See also Figure 1 As shown, the embodiment of the present application provides a HEMT device (High Electron Mobility Transistor) including: a substrate 1, an epitaxial structure 2, a passivation layer 3, a source 4, a gate 5, a drain 6, and a side electrode;

[0056] The epitaxial structure 2 is arranged on the substrate 1, and the passivation layer 3 is coated on the outside of the epitaxial structure 2. The source 4, the gate 5 and the drain 6 are all arranged in the passivation layer and in contact with the upper surface of the epitaxial structure 2. The gate 5 is located between the source 4 and the drain 6. In this embodiment, a gate preparation area, a source preparation area and a drain preparation area are etched on the passivation layer. The gate preparation area, the source preparation area and the drain preparation area all penetrate the passivation layer and expose the upper surface of the epitaxial structure 2. The gate 5 is arranged in the gate preparation area and forms a Schottky contact with the upper surface of the epitaxial structure 2. The source 4 is arranged in the source preparation area and forms an ohmic contact with the upper surface of the epitaxial structure 2. The drain 6 is arranged in the drain preparation area and forms an ohmic contact with the upper surface of the epitaxial structure 2.

[0057] The side electrodes are arranged on opposite sides of the epitaxial structure 2, and the side electrodes are arranged with the epitaxial structure 2 separated by the passivation layer. The side electrodes include a gate side electrode 51 and a drain side electrode 61. The gate side electrode 51 is electrically connected to the gate 5 through a wire to form a large gate; the drain side electrode 61 is connected to the drain 6 through a wire to form a large drain. In this embodiment, the gate side electrode 51 is arranged close to the source 4, and the passivation layer is arranged between the gate side electrode 51 and the source 4 and between the gate side electrode 51 and the epitaxial structure 2 to prevent the gate side electrode 51 from directly contacting the source 4 and the epitaxial structure 2; the drain side electrode 61 is arranged close to the drain, and the passivation layer is also arranged between the drain side electrode 61 and the drain 6 and between the drain side electrode 61 and the epitaxial structure 2 to prevent the drain side electrode 61 from directly contacting the drain 6 and the epitaxial structure 2.

[0058] The HEMT device provided in the embodiment of the present application is provided with a gate side electrode 51 and a drain side electrode 61 on opposite sides of the outer wall of the epitaxial structure 2, respectively, so that part of the electric field is introduced into the epitaxial structure 2 through the gate side electrode 51 and the drain side electrode 61, thereby effectively avoiding the premature breakdown phenomenon caused by the high-point electric field concentration effect of the gate 5 on the drain 6 side under high off-state leakage voltage, and making the electric field distribution in the channel of the HEMT device uniform, thereby improving the breakdown voltage of the HEMT device and improving the brightness of the HEMT device; in addition, by providing the passivation layer covering the epitaxial structure 2, leakage caused by direct contact between the gate side electrode 51 and the drain side electrode 61 and the epitaxial structure 2 is avoided, thereby improving the stability and reliability of the HEMT device.

[0059] In some embodiments, the passivation layer 3 includes a top passivation layer 31 and a side passivation layer 32. In this embodiment, the passivation layer 3 is formed outside the epitaxial structure 2 by plasma enhanced chemical vapor deposition (PECVD).

[0060] The top passivation layer 31 is arranged on the upper surface of the epitaxial structure 2 and fills between the gate 5 and the source 4 and between the drain 6 and the gate 5; the side passivation layer 32 surrounds and covers the outer wall of the epitaxial structure 2 and fills between the side electrode and the epitaxial structure 2 and between the side electrode and the substrate 1. In the present embodiment, the side passivation layer 32 extends from the top passivation layer 31 toward the substrate 1 and covers the upper surface of the substrate 1 to ensure that the side passivation layer 32 can completely cover the outer wall of the epitaxial structure 2.

[0061] In this embodiment, the thickness of the top passivation layer 31 is 0.1-0.3 μm, for example, 0.1 μm, 0.2 μm, or 0.3 μm.

[0062] The thickness of the side passivation layer 32 is 2-3 μm, for example, 2 μm, 2.5 μm, or 3 μm.

[0063] The thickness of the side passivation layer 32 filled between the side electrode and the epitaxial structure 2 is 0.5-0.8 μm, for example, 0.5 μm, 0.6 μm, 0.7 μm, or 0.8 μm.

[0064] The passivation layer 3 provided in the embodiment of the present application is prepared by a PECVD method, which has little effect on the structure and physical properties of the epitaxial structure 2, and has good uniformity and high density of film formation. Since an excessively thick passivation layer 3 will cause the size of the HEMT device to be too large and affect the contact performance of the electrode, the thickness of the top surface passivation layer 31 of the present embodiment is reduced to 0.1-0.3 μm, which is conducive to the preparation of high-performance devices and can reduce the size of the HEMT device. The side passivation layer 32 of the present embodiment can also play a role in isolating two adjacent HEMT devices.

[0065] In some embodiments, the horizontal distance between the source electrode 4 and the gate-side electrode 51 is 0.5-0.8 μm; the horizontal distance between the drain electrode 6 and the drain-side electrode 61 is 0.5-0.8 μm.

[0066] In this embodiment, the source 4 and the drain 6 are respectively arranged on opposite sides of the top surface of the epitaxial structure 2, and the horizontal spacing between the gate side electrode 51 and the source 4 and the epitaxial structure 2 is 0.5 to 0.8 μm, for example: 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, and the horizontal spacing between the drain side electrode 61 and the drain 6 and the epitaxial structure 2 is 0.5 to 0.8 μm, for example: 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm.

[0067] Therefore, the thickness of the side passivation layer 32 filled between the side electrode and the epitaxial structure 2 is 0.5-0.8 μm, for example, 0.5 μm, 0.6 μm, 0.7 μm, or 0.8 μm.

[0068] In the embodiment of the present application, the horizontal spacing between the side electrode and the epitaxial structure 2 and the electrode is set to 0.5-0.8 μm, so as to improve the regulating effect of the side electrode on the channel electric field in the HEMT device, thereby improving the breakdown performance of the HEMT device; if the horizontal spacing between the side electrode and the epitaxial structure 2 and the electrode is too large, the electric field introduced by the side electrode will be reduced, and the regulating effect on the channel electric field in the HEMT device will be weak; if the horizontal spacing between the side electrode and the epitaxial structure 2 and the electrode is too small, the side passivation layer 32 cannot form an insulating effect, and the side electrode contacts the two-dimensional electron gas (2DEG) heterojunction channel in the epitaxial structure 2, thereby causing leakage, affecting the stability and reliability of the HEMT device.

[0069] Please review Figure 1As shown, in this embodiment, the epitaxial structure 2 includes a stacked buffer layer 21, a GaN channel layer 22 and an AlGaN barrier layer 23, the side electrode extends downward in a vertical direction from the upper surface of the passivation layer 3 to the horizontal position of the buffer layer 21, and the bottom of the side electrode is spaced from the substrate 1 by the passivation layer 3.

[0070] In this embodiment, a channel heterojunction is formed between the GaN channel layer 22 and the AlGaN barrier layer 23 .

[0071] In the embodiment of the present application, the side electrode is set to penetrate into the horizontal position of the buffer layer 21 in the vertical direction, so that the side electrode is indirectly connected to the buffer layer 21 in the horizontal direction through the side passivation layer 32. Since the gate side electrode 51 and the gate 5 are electrically connected to form an equipotential body, and the drain side electrode 61 and the drain 6 are electrically connected to form an equipotential body, when a high off-state bias is applied, the gate side electrode 51 and the drain side electrode 61 respectively obtain the electric potential of the gate 5 and the drain 6 to form a lateral electric field in the buffer layer 21. The lateral electric field regulates the carrier distribution in the channel heterojunction formed by the GaN channel layer 22 and the AlGaN barrier layer 23, thereby alleviating the premature breakdown caused by the high electric field concentration effect on the drain 6 side of the gate 5.

[0072] In this embodiment, the material of the substrate 1 is selected from one of Si, SiC and GaN.

[0073] The material of the buffer layer 21 is selected from one or more of C-doped GaN and AlGaN. The thickness of the buffer layer 21 is 2.0-3.0 μm, for example, 2.0 μm, 2.5 μm, or 3.0 μm.

[0074] The doping method of the GaN channel layer 22 is unintentional doping, and the thickness of the GaN channel layer 22 is 0.05-0.10 μm, for example: 0.05 μm, 0.06 μm, 0.07 μm, 0.08 μm, 0.09 μm, 0.10 μm.

[0075] The doping method of the AlGaN barrier layer 23 is unintentional doping, and the thickness of the AlGaN barrier layer 23 is 0.04-0.15 μm, for example: 0.04 μm, 0.05 μm, 0.10 μm, 0.15 μm.

[0076] In this embodiment, a thick buffer layer 21 is formed by C-doped GaN and AlGaN, which can reduce the mismatch stress between the epitaxial structure 2 and the heterogeneous substrate 1 on the one hand, and can also reduce the leakage problem of the HEMT device caused by the internal defects of the buffer layer 21 on the other hand; the doping method of the GaN channel layer 22 and the AlGaN barrier layer 23 in this embodiment is unintentional doping, which can reduce the scattering effect of carriers in the channel heterojunction formed between the GaN channel layer 22 and the AlGaN barrier layer 23, thereby improving the 2DEG mobility in the channel heterojunction, which is suitable for the preparation of power radio frequency devices.

[0077] Embodiment of the method for preparing the HEMT device of the present application

[0078] See also Figure 2 As shown, the embodiment of the present application provides a method for preparing a HEMT device, which is used to prepare the HEMT device as described above, and specifically includes the following steps:

[0079] Step S100, providing a substrate, and preparing an epitaxial structure on the substrate.

[0080] In this embodiment, the material of the substrate 1 is selected from one of Si, SiC and GaN.

[0081] A buffer layer 21, a GaN channel layer 22, and an AlGaN barrier layer 23 are sequentially epitaxially grown on a substrate 1 by metal organic chemical vapor deposition to form an epitaxial structure 2, such as Figure 3a shown.

[0082] The material component of the buffer layer 21 is a combination of C-doped GaN and AlGaN, and the thickness of the buffer layer 21 is 2.0-3.0 μm.

[0083] The doping method of the GaN channel layer 22 is unintentional doping, and the thickness of the GaN channel layer 22 is 0.05-0.10 μm.

[0084] The doping method of the AlGaN barrier layer 23 is unintentional doping, and the thickness of the AlGaN barrier layer 23 is 0.04-0.15 μm.

[0085] Step S200, preparing a passivation layer on the periphery of the epitaxial structure.

[0086] In this embodiment, before preparing the passivation layer 3 on the periphery of the epitaxial structure 2, a dry etching process is used to etch the opposite sides of the epitaxial structure 2 so that the opposite sides of the epitaxial structure 2 are both reduced inward by 2.0 to 3.0 μm to expose the upper surface of the substrate 1.

[0087] After etching the opposite sides of the epitaxial structure 2, a passivation layer 3 is formed on the epitaxial structure 2 and the substrate 1 by a plasma enhanced chemical vapor deposition method, wherein the top passivation layer 31 completely covers the upper surface of the epitaxial structure 2, and the side passivation layer 32 surrounds and covers the outer wall of the epitaxial structure 2 and the upper surface of the substrate 1, wherein the thickness of the top passivation layer 31 and the side passivation layer 32 prepared by the plasma enhanced chemical vapor deposition method are both 2 to 3 μm. Figure 3b shown.

[0088] In this embodiment, after the passivation layer 3 is prepared on the periphery of the epitaxial structure 2 and before the source electrode preparation region and the drain electrode preparation region are etched on the passivation layer 3, the step S200 further includes the following steps:

[0089] The passivation layer 3 located on the upper surface of the epitaxial structure 2 is thinned. In this embodiment, the top passivation layer 31 located on the upper surface of the epitaxial structure 2 is thinned by ion thinning technology, wherein the thickness of the top passivation layer 31 after the thinning process is 0.1-0.3 μm.

[0090] Step S300, etching a source electrode preparation region and a drain electrode preparation region on the passivation layer to prepare a source electrode and a drain electrode.

[0091] In this embodiment, the source electrode preparation region and the drain electrode preparation region are respectively etched on opposite sides of the top passivation layer 31 by a dry etching process.

[0092] Source metals of Ti / Al / Ni / Au are respectively deposited in the source preparation area by electron beam evaporation deposition method to prepare the source 4, and are rapidly annealed at high temperature to form an ohmic contact electrode, and the lower surface of the source 4 forms an ohmic contact with the upper surface of the AlGaN barrier layer 23, wherein the thickness of the Ti / Al / Ni / Au is 25 / 150 / 50 / 100 μm.

[0093] Drain metals of Ti / Al / Ni / Au are respectively deposited in the drain preparation area by electron beam evaporation deposition method to prepare the drain 6, and are rapidly annealed at high temperature to form an ohmic contact electrode, and the lower surface of the drain 6 forms an ohmic contact with the upper surface of the AlGaN barrier layer 23, wherein the thickness of the Ti / Al / Ni / Au is 25 / 150 / 50 / 100 μm.

[0094] In this embodiment, the source electrode 4 and the drain electrode 6 are made of the same type of electrode metal material.

[0095] Step S400, etching the side wall of the passivation layer close to the drain electrode to form a drain side electrode preparation area to prepare a drain side electrode.

[0096] In this embodiment, the side passivation layer 32 close to the drain 6 is etched by a dry etching process to form a drain side electrode preparation area, wherein the drain side electrode preparation area is spaced apart from the upper surface of the substrate 1, and the side passivation layer 32 is filled between the drain side electrode preparation area and the upper surface of the substrate 1.

[0097] The drain side electrode 61 is prepared by depositing drain metals of Ti / Al / Ni / Au in the drain side electrode preparation area by electron beam evaporation deposition method, and then rapidly annealed at high temperature to form an ohmic contact electrode, wherein the drain side electrode 61 and the drain 6 are made of the same type of electrode metal material, and the horizontal distance between the drain 6 and the drain side electrode 61 is 0.5-0.8 μm, as shown in FIG. Figure 3c shown.

[0098] Step S500, etching a gate preparation region on the passivation layer to prepare a gate.

[0099] In this embodiment, a gate preparation region is etched on the top passivation layer 31 by a dry etching process, wherein the gate preparation region is located between the source preparation region and the drain preparation region, and the gate preparation region is arranged close to the source preparation region.

[0100] Ni / Au are respectively deposited in the gate preparation region by electron beam evaporation deposition method to prepare the gate 5, wherein the lower surface of the gate 5 forms a Schottky contact with the upper surface of the AlGaN barrier layer 23, and the thickness of the Ni / Au is 50 / 250 μm.

[0101] Step S600 , etching the side wall of the passivation layer close to the source electrode 4 to form a gate side electrode preparation area to prepare a gate side electrode.

[0102] In this embodiment, the side passivation layer 32 close to the source electrode 4 is etched by dry etching to form a gate side electrode preparation area, wherein the gate side electrode preparation area is spaced apart from the upper surface of the substrate 1, and the side passivation layer 32 is filled between the gate side electrode preparation area and the upper surface of the substrate 1.

[0103] Ni / Au are deposited in the gate side electrode preparation area by electron beam evaporation deposition method to prepare the gate side electrode 51, wherein the gate side electrode 51 and the gate 5 are made of the same type of electrode metal material, and the horizontal distance between the source 4 and the gate side electrode 51 is 0.5-0.8 μm. Figure 3d shown.

[0104] Step S700, the gate and the gate side electrode are electrically connected through a wire to form a large gate, and the drain and the drain side electrode are electrically connected through a wire to form a large drain, such as Figure 1 shown.

[0105] In this embodiment, a large gate is formed by electrically connecting the gate 5 and the gate side electrode 51 through a wire to form a gate equipotential body, and a large drain is formed by electrically connecting the drain 6 and the drain side electrode 61 through a wire to form a drain equipotential body, so that when a high off-state bias is applied to the HEMT device, the gate side electrode 51 can obtain the same potential as the gate 5, and the drain side electrode 61 can obtain the same potential as the drain 6, so as to reduce the gate electric field concentration effect of the HEMT structure.

[0106] The method for preparing a HEMT device provided in an embodiment of the present application adds a gate side electrode 51 and a drain side electrode 61 which extend into the horizontal position of the buffer layer 21 on opposite sides of the HEMT device, and electrically connects the gate side electrode 51 to the gate 5 to form an equipotential body, and connects the drain side electrode 61 to the drain 6 to form an equipotential body. When a high off-state bias is applied to the HEMT device, the gate side electrode 51 and the drain side electrode 61 are respectively connected to the buffer layer 21 at intervals, forming a lateral electric field in the buffer layer 21, thereby regulating the carrier distribution in the channel heterojunction formed between the GaN channel layer 22 and the AlGaN barrier layer 23, thereby alleviating the premature breakdown caused by the high electric field concentration effect on the drain side of the gate.

[0107] The above scheme is further described below in conjunction with specific implementation examples. The preferred embodiments of the present invention are described in detail as follows:

[0108] Example 1

[0109] (1) Providing a substrate 1, wherein the material of the substrate 1 is SiC;

[0110] (2) adjusting the ambient temperature to 500-560° C., epitaxially growing a buffer layer 21 on the substrate 1 by metal organic chemical vapor deposition at normal pressure, wherein the buffer layer 21 has a thickness of 2.0 μm;

[0111] (3) adjusting the ambient temperature to 1000-1060° C., epitaxially growing a GaN channel layer 22 on the buffer layer 21 by metal organic chemical vapor deposition at normal pressure, wherein the thickness of the GaN channel layer 22 is 0.1 μm;

[0112] (4) adjusting the ambient temperature to 980-1090° C., epitaxially growing an AlGaN barrier layer 23 on the GaN channel layer 22 by metal organic chemical vapor deposition at normal pressure to form an epitaxial structure 2, wherein the thickness of the AlGaN barrier layer 23 is 0.04 μm;

[0113] (5) etching the opposite sides of the epitaxial structure 2 by a dry etching process, so that the opposite sides of the epitaxial structure 2 are both reduced inward by 2.5 μm, exposing the upper surface of the substrate 1;

[0114] (6) adjusting the ambient temperature to 290-360° C., and forming a passivation layer 3 on the epitaxial structure 2 and the substrate 1 by a plasma enhanced chemical vapor deposition method, wherein the passivation layer has a thickness of 2 μm;

[0115] (7) The top passivation layer 31 on the upper surface of the epitaxial structure 2 is thinned by ion thinning technology, wherein the thickness of the top passivation layer 31 after the thinning process is 0.2 μm, and the thickness of the side passivation layer 32 on the opposite sides of the epitaxial structure 2 is 2 μm;

[0116] (8) etching the source electrode preparation region and the drain electrode preparation region on opposite sides of the top passivation layer 31 by dry etching process;

[0117] (9) Depositing Ti / Al / Ni / Au source metals in the source preparation area by electron beam evaporation deposition to prepare the source 4, and rapidly annealing at high temperature to form an ohmic contact electrode;

[0118] ⑽ Ti / Al / Ni / Au drain metals are deposited in the drain preparation area by electron beam evaporation deposition to prepare the drain 6, and then rapidly annealed at high temperature to form an ohmic contact electrode;

[0119] ⑾ Etching the side passivation layer 32 close to the drain electrode 6 by dry etching process to form a drain side electrode preparation area;

[0120] ⑿ Ti / Al / Ni / Au drain metals are deposited in the drain side electrode preparation area by electron beam evaporation deposition method to prepare the drain side electrode 61, and then rapidly annealed at high temperature to form an ohmic contact electrode;

[0121] ⒀ Etching the gate preparation area on the top passivation layer 31 by dry etching process;

[0122] ⒁ Depositing Ni / Au gate metals in the gate preparation area respectively by electron beam evaporation deposition method to prepare gate 5;

[0123] ⒂ The side passivation layer 32 close to the source electrode 4 is etched by dry etching to form a gate side electrode preparation area;

[0124] ⒃ Ni / Au gate metals are deposited in the gate side electrode preparation area by electron beam evaporation deposition method to prepare gate side electrodes 51;

[0125] ⒄ A large gate is formed by electrically connecting the gate 5 and the gate side electrode 51 through a wire to form a gate equipotential body, and a large drain is formed by electrically connecting the drain 6 and the drain side electrode 61 through a wire to form a drain equipotential body.

[0126] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that after the drain electrode is prepared in step ⑼, steps ⒀ and ⒁ are directly performed to prepare the gate electrode. After the gate electrode is prepared, the preparation of the HEMT device of Comparative Example 1 is completed.

[0127] Test result analysis:

[0128] The performance of the HEMT devices prepared by the preparation methods of Example 1 and Comparative Example 1 was tested. The test results are as follows: Figure 4 As shown in FIG. 1 , under the premise of the same drain current, the drain voltage is gradually increased. When the drain voltage reaches 120V, the drain current of the HEMT device obtained in Comparative Example 1 is in a short-circuit state; when the drain voltage reaches 770V, the drain current of the HEMT device obtained in Example 1 is in a short-circuit state. Therefore, Figure 4 It can be seen that the breakdown voltage of the HEMT device obtained in Example 1 is increased by 642% compared with the conventional HEMT structure, and is suitable for high-power applications under high temperature and high pressure.

[0129] Obviously, the embodiments described above are only some embodiments of the present application, rather than all embodiments. The preferred embodiments of the present application are given in the accompanying drawings, but they do not limit the patent scope of the present application. The present application can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive. Although the present application is described in detail with reference to the aforementioned embodiments, for those skilled in the art, it is still possible to modify the technical solutions recorded in the aforementioned specific implementation methods, or to perform equivalent replacement of some of the technical features therein. Any equivalent structure made using the contents of the specification and drawings of this application, directly or indirectly used in other related technical fields, is similarly within the scope of patent protection of this application.

Claims

1. A HEMT device, characterized in that: It includes a substrate, an epitaxial structure, a passivation layer, a source electrode, a gate electrode, a drain electrode, and a side electrode; The epitaxial structure is disposed on the substrate; The passivation layer is coated outside the epitaxial structure; The source electrode, the gate electrode and the drain electrode are all disposed on the passivation layer and in contact with the upper surface of the epitaxial structure, and the gate electrode is located between the source electrode and the drain electrode; The side electrodes are arranged on opposite sides of the epitaxial structure, and the side electrodes are arranged with the epitaxial structure separated by the passivation layer; The side electrodes include a gate side electrode and a drain side electrode; The gate side electrode is electrically connected to the gate through a wire to form a large gate; The drain-side electrode is electrically connected to the drain through a wire to form a large drain.

2. The HEMT device according to claim 1, characterized in that: The horizontal distance between the source electrode and the gate side electrode is 0.5-0.8 μm; The horizontal distance between the drain electrode and the drain-side electrode is 0.5-0.8 μm.

3. The HEMT device according to claim 1, characterized in that: The passivation layer includes a top passivation layer and a side passivation layer; The top passivation layer is disposed on the upper surface of the epitaxial structure and is filled between the gate and the source and between the drain and the gate; The side passivation layer surrounds and covers the outer wall of the epitaxial structure, and fills between the side electrode and the epitaxial structure and between the side electrode and the substrate.

4. The HEMT device according to claim 3, characterized in that: The thickness of the top passivation layer is 0.1 to 0.3 μm; and / or The side passivation layer has a thickness of 2 to 3 μm, wherein the side passivation layer filled between the side electrode and the epitaxial structure has a thickness of 0.5 to 0.8 μm.

5. The HEMT device according to any one of claims 1 to 4, characterized in that: The epitaxial structure includes a buffer layer, a GaN channel layer and an AlGaN barrier layer which are stacked; The side electrode extends downward from the upper surface of the passivation layer to the horizontal position where the buffer layer is located, and the bottom of the side electrode is spaced from the substrate by the passivation layer.

6. The HEMT device according to claim 5, characterized in that: The material of the substrate is selected from one of Si, SiC and GaN; and / or The material of the buffer layer is selected from one or more of C-doped GaN and AlGaN; and / or The doping method of the GaN channel layer is unintentional doping; and / or The doping method of the AlGaN barrier layer is unintentional doping.

7. The HEMT device according to claim 5, characterized in that: The thickness of the buffer layer is 2.0 to 3.0 μm; and / or The thickness of the GaN channel layer is 0.05-0.10 μm; and / or The thickness of the AlGaN barrier layer is 0.04-0.15 μm.

8. A method for preparing a HEMT device, for preparing the HEMT device as claimed in any one of claims 1 to 7, characterized in that: The following steps are involved: Providing a substrate, and preparing an epitaxial structure on the substrate; preparing a passivation layer on the periphery of the epitaxial structure; Etching a source electrode preparation region and a drain electrode preparation region on the passivation layer to prepare a source electrode and a drain electrode; Etching the side wall of the passivation layer close to the drain electrode to form a drain side electrode preparation area to prepare a drain side electrode; etching a gate preparation region on the passivation layer to prepare a gate; Etching the side wall of the passivation layer close to the source electrode to form a gate side electrode preparation area to prepare a gate side electrode; The gate electrode and the gate-side electrode are electrically connected through a wire to form a large gate, and the drain electrode and the drain-side electrode are electrically connected through a wire to form a large drain.

9. The method for preparing a HEMT device according to claim 8, characterized in that: After preparing a passivation layer on the periphery of the epitaxial structure and before etching a source electrode preparation region and a drain electrode preparation region on the passivation layer, the method further includes the following steps: The passivation layer on the upper surface of the epitaxial structure is thinned.

10. The method for preparing a HEMT device according to claim 8, characterized in that: The drain side electrode preparation region and the gate side electrode preparation region are both spaced apart from the upper surface of the substrate.

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