CN111900148A - A kind of radiation-resistant GaN-based high electron mobility transistor and preparation method thereof - Google Patents

Abstract

The invention discloses a radiation-resistant GaN-based high electron mobility transistor and a preparation method thereof. The transistor structure comprises a substrate, a buffer layer, a channel layer, a potential barrier layer, a source electrode, a drain electrode, a gate electrode, a first passivation passivation layer and second passivation layer. Aiming at the problem that the device performance of conventional GaN HEMT is obviously degraded after being irradiated by high-energy particles, the invention can effectively shield the barrier layer and the channel by introducing barium titanate with high displacement threshold energy as the second passivation layer. Most of the radiation effects of the layer are improved, and the working reliability of GaN HEMT devices under extreme environmental conditions in aerospace, communication satellites, space exploration and other fields is improved.

Description

A kind of radiation-resistant GaN-based high electron mobility transistor and preparation method thereof

technical field

The invention belongs to the technical field of semiconductor devices, in particular to a radiation-resistant GaN-based high electron mobility transistor and a preparation method thereof.

Background technique

In recent years, the third-generation semiconductor GaN has important application prospects in wireless communication, power system, photoelectric detection and other fields due to its excellent physical properties such as wide band gap, high breakdown field strength, and high saturation electron drift velocity. As a wide-bandgap semiconductor, the theoretical displacement threshold energies of Ga atoms and N atoms in GaN are 20.5 eV and 10.8 eV, respectively, which are much higher than the theoretical values of GaAs, and have excellent radiation resistance characteristics.

However, due to the influence of current material epitaxy quality and device technology level, the device output characteristics of GaN HEMTs under irradiation of high-energy particles such as γ-rays, electrons, protons, and neutrons are significantly degraded, and the radiation resistance performance is far from reaching the theoretical level. , which greatly limits the application of GaN HEMT devices under extreme environmental conditions in aerospace, communication satellites, space exploration and other fields.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a radiation-resistant GaN-based high electron mobility transistor and a preparation method thereof, which adopts a double passivation layer structure and uses barium titanate with high displacement valve energy as the radiation-resistant reinforcement layer, which can effectively The radiation effect of high-energy particles on the barrier layer and the channel layer is shielded, and the radiation resistance of GaN HEMT devices is improved.

The technical solution to achieve the purpose of the present invention is: a radiation-resistant GaN-based high electron mobility transistor, the transistor structure includes a substrate, a buffer layer, a channel layer and a barrier layer in sequence from bottom to top, and the barrier layer The source electrode, the gate electrode and the drain electrode are arranged in parallel on the top of the gate, the first passivation layer and the second passivation layer are sequentially covered on the barrier layer, the source electrode, the drain electrode and the gate electrode, and the source electrode and the drain electrode , The position corresponding to the grid is provided with a window for electrical contact with the outside world.

Further, the substrate is any one of Si, sapphire, SiC, diamond and GaN self-supporting substrates.

Further, the buffer layer is a single-layer or multi-layer structure composed of one or more of GaN, AlN, and AlGaN.

Further, the channel layer is one of GaN, AlGaN, and AlN.

Further, the barrier layer is one of AlGaN, AlInN, AlN, and AlInGaN.

Further, the metals of the source electrode and the drain electrode are Ti-Al alloy, Ti-Al-Ti-TiN alloy, Ti-Al-Ti-Au alloy, Ti-Al-Ni-Au alloy, Ti-Al- One of the Mo-Au alloys, which can be the same or different.

Further, the gate is one of W, Ni, Pt, TiN, Ni-Au alloy, and Pt-Al alloy.

Further, the first passivation layer is one or more of SiO ₂ , Si ₃ N ₄ , Al ₂ O ₃ , Ga ₂ O ₃ , HfO ₂ , and diamond.

Further, the second passivation layer is one or more of BaTiO ₃ , SrTiO ₃ , PZT, HfZrO _x , and BiFeO ₃ .

A preparation method of a radiation-resistant GaN-based high electron mobility transistor, comprising the following steps:

Step 1, using an epitaxial growth method to sequentially grow a buffer layer, a channel layer, and a barrier layer on the substrate;

Step 2, defining a mask for the source electrode and the drain electrode above the barrier layer, depositing an ohmic metal by evaporation or sputtering, forming a source electrode and a drain electrode by a lift-off process, and forming an ohmic contact by an annealing process, the The mask is made by optical lithography or electron beam direct writing;

Step 3, defining a gate mask above the barrier layer, depositing gate metal by evaporation or sputtering, and forming a gate by a lift-off process;

Step 4, making an active region mask above the barrier layer, and then isolating by etching or ion implantation to form an active region;

Step 5, depositing a first passivation layer over the barrier layer, the source electrode, the drain electrode and the gate electrode, the growth method of the first passivation layer includes low pressure chemical vapor deposition, plasma enhanced chemical vapor deposition and Atomic layer deposition;

Step 6, depositing a second passivation layer above the first passivation layer, and the growth method of the second passivation layer includes magnetron sputtering and atomic layer deposition;

Step 7, defining an interconnection opening region mask above the source electrode, the drain electrode and the gate electrode, and etching the first passivation layer and the second passivation layer by an etching method to form interconnection openings.

Compared with the prior art, the present invention has the following significant advantages:

(1) Through investigation, it is found that the average theoretical displacement threshold energy of BaTiO ₃ , SrTiO ₃ and other materials is about 80eV, and the resistance to total dose irradiation can reach 10 ⁸ rad, which is much higher than that of GaN; therefore, BaTiO ₃ is introduced , SrTiO ₃ , etc., as the anti-irradiation reinforcement layer of the device, can effectively reduce the radiation damage of high-energy particles such as gamma rays, electrons, protons and neutrons to GaN HEMTs, and greatly improve the working reliability of the device under extreme environmental conditions;

(2) The first passivation layer in the double passivation layer structure is the preferred passivation medium in the GaN HEMT device process, which can form an excellent interface structure with the barrier layer and reduce the impact of the second passivation layer preparation process on the barrier layer. The influence of the interface improves the working stability of the device.

Description of drawings

FIG. 1 is a schematic structural diagram of a radiation-resistant GaN-based high electron mobility transistor proposed by the present invention.

FIG. 2( a ) is a schematic diagram of the epitaxial growth steps of the radiation-resistant GaN-based high electron mobility transistor proposed by the present invention.

FIG. 2( b ) is a schematic diagram of the preparation steps of the source and drain electrodes of the radiation-resistant GaN-based high electron mobility transistor proposed by the present invention.

FIG. 2( c ) is a schematic diagram of the fabrication steps of the gate electrode of the radiation-resistant GaN-based high electron mobility transistor proposed by the present invention.

FIG. 2(d) is a schematic diagram of the preparation steps of the first passivation layer of the radiation-resistant GaN-based high electron mobility transistor proposed by the present invention.

FIG. 2(e) is a schematic diagram of the preparation steps of the second passivation layer of the radiation-resistant GaN-based high electron mobility transistor proposed by the present invention.

FIG. 2( f ) is a schematic diagram of the preparation steps of the dielectric opening of the radiation-resistant GaN-based high electron mobility transistor proposed by the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be further described below with reference to the accompanying drawings and embodiments.

1 is a schematic structural diagram of a radiation-resistant GaN-based high electron mobility transistor according to the present invention. The structure of the transistor includes, from bottom to top, a substrate 1, a buffer layer 2, a channel layer 3 and a The barrier layer 4; the upper part of the barrier layer 4 is provided with a source electrode 5, a gate electrode 7 and a drain electrode 6 in parallel from left to right, and the first passivation layer 8 and the second passivation layer 9 are sequentially covered on the potential barrier layer 4. A window is opened above the barrier layer 4 , the source electrode 5 , the drain electrode 6 and the gate electrode 7 and at the positions corresponding to the source electrode 5 , the drain electrode 6 and the gate electrode 7 for making electrical contact with the outside world.

Referring to FIG. 2(a) to FIG. 2(f), a preparation method of a radiation-resistant GaN-based high electron mobility transistor proposed by the present invention includes the following specific steps:

1) The buffer layer 2, the channel layer 3 and the barrier layer 4 are sequentially grown on the top of the substrate 1 by an epitaxial growth method, as shown in FIG. 2(a);

Wherein, the substrate 1 is any one of Si, sapphire, SiC, diamond and GaN self-supporting substrates; the buffer layer 2 is a single layer or a single layer composed of one or more of GaN, AlN, AlGaN Multilayer structure; the channel layer 3 is one of GaN, AlGaN, and AlN; the barrier layer 4 is one of AlGaN, AlInN, AlN, and AlInGaN. Epitaxial growth methods include MOCVD (Metal Organic Chemical Vapor Deposition), MBE (Molecular Beam Epitaxy) and HVPE (Hydride Vapor Phase Epitaxy).

2) A mask for the source electrode 5 and the drain electrode 6 is defined above the barrier layer 4, ohmic metal is deposited by evaporation or sputtering, the source electrode 5 and the drain electrode 6 are formed by a lift-off process, and an ohmic electrode is formed by an annealing process contact, as shown in Figure 2(b); wherein, the mask is made by optical lithography or electron beam direct writing, and the metals of the source electrode 5 and the drain electrode 6 are Ti-Al alloy, Ti-Al alloy, respectively. -One of Ti-TiN alloy, Ti-Al-Ti-Au alloy, Ti-Al-Ni-Au alloy, Ti-Al-Mo-Au alloy, which can be the same or different.

3) A mask for gate 7 is defined above the barrier layer 4, gate metal is deposited by evaporation or sputtering, and a lift-off process is used to form gate 7, as shown in FIG. 2(c); wherein, the gate The metal of 7 is one of W, Ni, Pt, TiN, Ni-Au alloy, and Pt-Al alloy.

4) An active region mask is formed above the barrier layer 4, and then an active region is formed by etching or ion implantation for isolation.

5) A first passivation layer 8 is deposited over the barrier layer 4, the source electrode 5, the drain electrode 6 and the gate electrode 7, as shown in FIG. 2(d); wherein, the first passivation layer 8 is SiO _2. One or more of Si ₃ N ₄ , Al ₂ O ₃ , Ga ₂ O ₃ , HfO ₂ , and diamond; the growth method of the first passivation layer 8 includes LPCVD (low pressure chemical vapor deposition), PECVD (Plasma Enhanced Chemical Vapor Deposition) and ALD (Atomic Layer Epitaxy).

6) A first passivation layer 9 is deposited on the top of the first passivation layer 8, as shown in FIG. 2(e); wherein, the second passivation layer 9 is BaTiO ₃ , SrTiO ₃ , PZT (PbZr _{1- x} Ti _x O ₃ ), HfZrO _x , BiFeO ₃ and other high-displacement threshold energy materials; the growth method of the second passivation layer 9 includes magnetron sputtering, ALD (atomic layer epitaxy), etc. .

7) Define an interconnection opening region mask above the source, drain and gate, and etch the first passivation layer 8 and the second passivation layer 9 by an etching method to form interconnection openings, as shown in Figure 2 (f); wherein, the etching method includes dry etching and wet etching.

Aiming at the problem that the device performance of conventional GaN HEMTs is obviously degraded after being irradiated by high-energy particles, the invention can effectively shield the high-energy particles against the potential barrier by introducing barium titanate (BaTiO ₃ ) with high displacement threshold energy as the second passivation layer. Most of the radiation effects of the layer and the channel layer improve the reliability and stability of GaN HEMT devices under extreme environmental conditions in aerospace, communication satellites, space exploration and other fields.

It should be noted that, in the accompanying drawings or the text of the description, the implementations that are not shown or described are in the form known to those of ordinary skill in the technical field, and are not described in detail. In addition, the above definitions of each element and method are not limited to various specific structures, shapes or manners mentioned in the embodiments, and those of ordinary skill in the art can simply modify or replace them, for example:

(1) According to specific requirements, groove etching, F ion implantation or introduction of p-GaN or p-AlGaN layer can be performed on the barrier layer to prepare enhancement mode devices;

(2) Field plate structures can be prepared at the source, drain and gate according to specific requirements to optimize the electric field distribution of the device;

(3) According to specific requirements, a dielectric layer can be deposited under the gate to prepare a metal-insulator-semiconductor (MIS) structure, etc., to optimize the gate leakage and breakdown characteristics of the device.

It should also be noted that demonstrations of parameters including specific values may be provided herein, but these parameters need not be exactly equal to the corresponding values, but may be approximated within acceptable error tolerances or design constraints. The directional terms mentioned in the embodiments, such as "up", "down", "front", "rear", "left", "right", etc., are only for referring to the directions of the drawings, and are not intended to limit the present invention. protected range. Furthermore, unless specifically described or the steps must occur sequentially, the order of the above steps is not limited to those listed above, and may be varied or rearranged according to the desired design. In addition, the above embodiments can be mixed and matched with each other or with other embodiments based on the consideration of design and reliability, that is, the technical features in different embodiments can be freely combined to form more embodiments.

The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention, and are not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A radiation-resistant GaN-based high electron mobility transistor, characterized in that: the transistor structure sequentially comprises a substrate (1), a buffer layer (2), a channel layer (3) and a barrier layer from bottom to top (4), a source electrode (5), a gate electrode (7) and a drain electrode (6), a first passivation layer (8) and a second passivation layer are arranged in parallel on the top of the barrier layer (4). (9) sequentially covering the barrier layer (4), the source electrode (5), the drain electrode (6) and the gate electrode (7), and covering the source electrode (5), the drain electrode (6), the gate electrode (7) ) is provided with a window for electrical contact with the outside world. 2. The radiation-resistant GaN-based high electron mobility transistor according to claim 1, wherein the second passivation layer (9) is BaTiO ₃ , SrTiO ₃ , PZT (PbZr _1-x Ti _x O ₃ ), one or more of HfZrO _x and BiFeO ₃ . 3. The radiation-resistant GaN-based high electron mobility transistor according to claim 1, wherein the substrate (1) is any one of Si, sapphire, SiC, diamond and GaN self-supporting substrates . 4. The radiation-resistant GaN-based high electron mobility transistor according to claim 1, characterized in that: the buffer layer (2) is a single-layer or multi-layer composed of one or more of GaN, AlN, and AlGaN. layer structure. 5. The radiation-resistant GaN-based high electron mobility transistor according to claim 1, wherein the channel layer (3) is one of GaN, AlGaN, and AlN. 6. The radiation-resistant GaN-based high electron mobility transistor according to claim 1, wherein the barrier layer (4) is one of AlGaN, AlInN, AlN, and AlInGaN. 7. The radiation-resistant GaN-based high electron mobility transistor according to claim 1, wherein the metal of the source (5) and the drain (6) is Ti-Al alloy, Ti-Al- One of Ti-TiN alloy, Ti-Al-Ti-Au alloy, Ti-Al-Ni-Au alloy, Ti-Al-Mo-Au alloy, which can be the same or different. 8. The radiation-resistant GaN-based high electron mobility transistor according to claim 1, wherein the gate (7) is made of W, Ni, Pt, TiN, Ni-Au alloy, or Pt-Al alloy. a kind of. 9. The radiation-resistant GaN _- based high electron mobility transistor according to claim ₁ , wherein the first passivation layer ( ₈ ) is _SiO2 , Si3N4, _Al2O3 , _Ga2 One or more of O ₃ , HfO ₂ and diamond. 10. A method for preparing a radiation-resistant GaN-based high electron mobility transistor according to any one of claims 1-9, characterized in that, comprising the steps of: Step 1, using an epitaxial growth method to sequentially grow a buffer layer, a channel layer, and a barrier layer on the substrate; Step 2, defining a mask for the source electrode and the drain electrode above the barrier layer, depositing an ohmic metal by evaporation or sputtering, forming a source electrode and a drain electrode by a lift-off process, and forming an ohmic contact by an annealing process, the The mask is made by optical lithography or electron beam direct writing; Step 3, defining a gate mask above the barrier layer, depositing gate metal by evaporation or sputtering, and forming a gate by a lift-off process; Step 4, making an active region mask above the barrier layer, and then isolating by etching or ion implantation to form an active region; Step 5, depositing a first passivation layer above the barrier layer, the source electrode, the drain electrode and the gate electrode, the growth method of the first passivation layer includes low pressure chemical vapor deposition, plasma enhanced chemical vapor deposition and Atomic layer deposition; Step 6, depositing a second passivation layer above the first passivation layer, and the growth method of the second passivation layer includes magnetron sputtering and atomic layer deposition; Step 7, defining an interconnection opening region mask above the source electrode, the drain electrode and the gate electrode, and etching the first passivation layer and the second passivation layer by an etching method to form interconnection openings.

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