CN116053306A - Gallium nitride-based high electron mobility transistor device and preparation method thereof - Google Patents

Abstract

The invention provides a gallium nitride-based high electron mobility transistor device and a preparation method thereof, wherein the gallium nitride-based high electron mobility transistor device comprises: epitaxial substrate, source electrode, drain electrode and grid electrode; the epitaxial substrate comprises a substrate layer, an m-GaN layer and epsilon-Ga ₂ O ₃ A layer, wherein the m-GaN layer is disposed on the substrate, epsilon-Ga ₂ O ₃ The layer is arranged on one side of the m-GaN layer, which is away from the substrate layer; the grid is arranged on epsilon-Ga ₂ O ₃ The layer is away from the side of the m-GaN layer, and the source electrode and the drain electrode are both arranged on the side of the m-GaN layer away from the substrate layer and are positioned on epsilon-Ga ₂ O ₃ Both ends of the layer. The high electron mobility transistor device passesDisposing an m-GaN layer and epsilon-Ga on a substrate ₂ O ₃ Layer formation of epsilon-Ga ₂ O ₃ m-GaN heterojunction in which ε -Ga ₂ O ₃ Compared with the prior art, the device has the advantages of large saturation current, low leakage current, and high stability and reliability.

Description

GaN-based high electron mobility transistor device and its preparation method

technical field

The invention relates to the technical field of semiconductors, in particular to a gallium nitride-based high electron mobility transistor device and a preparation method thereof.

Background technique

GaN (gallium nitride) materials have the characteristics of large band gap, high breakdown field strength, high power density, and high mobility. has great advantages. GaN-based HEMTs generally use heterojunctions to induce 2DEG (two-dimensional electron gas). By bending the energy band on one side of gallium nitride, electrons are confined in the potential well, and an electric field is applied between the source and drain electrodes to enable electrons to obtain lateral direction. High migration speed. At present, the heterojunction barrier materials used in GaN-based HEMTs are generally AlGaN (aluminum gallium nitride), AlN (aluminum nitride) and InAlN (indium aluminum nitride), which have certain defects, such as:

First, AlGaN is used as a barrier layer, and the induced 2DEG concentration is not high enough to meet the application requirements of higher power. If the 2DEG concentration is increased by increasing the Al composition, the interface between AlGaN and GaN will be deteriorated, and the probability of electron scattering will be increased. reduce mobility;

Second, AlN is used as a barrier layer, although it can increase the polarization intensity to obtain a larger 2DEG concentration, but the lattice mismatch between AlN and GaN is large, and the stress problem caused by the mismatch will affect the reliability of the device;

Third, InAlN, as a barrier layer, can obtain a higher 2DEG concentration than AlGaN, and a greater electron mobility than AlN, but the breakdown characteristics of InAlN are relatively poor, and In has precipitation migration during the annealing process, resulting in potential Barrier degradation.

Therefore, the existing high electron mobility transistor devices have certain shortcomings, and it is necessary to design a new gallium nitride-based high electron mobility transistor device as an ideal material.

Contents of the invention

Based on the above statement, the present invention provides a GaN-based high electron mobility transistor device and its preparation method to solve the poor performance of the high electron mobility transistor device caused by heterojunction barrier defects in the prior art technical issues.

The technical scheme that the present invention solves the problems of the technologies described above is as follows:

In a first aspect, the present invention provides a gallium nitride-based high electron mobility transistor device, comprising: an epitaxial substrate, a source, a drain, and a gate;

The epitaxial substrate includes a substrate layer, an m-GaN layer and an ε-Ga ₂ O ₃ layer, wherein the m-GaN layer is disposed on the substrate layer, and the ε-Ga ₂ O ₃ layer is disposed on the The side of the m-GaN layer away from the substrate layer;

The gate is set on the side of the ε- _Ga2O3 layer away from the m- _GaN layer, the source and the drain are both set on the side of the m-GaN layer away from the substrate layer One side and two ends of the ε-Ga ₂ O ₃ layer.

On the basis of the above technical solutions, the present invention can also be improved as follows.

Further, the thickness of the ε-Ga ₂ O ₃ layer is 2-30 nm.

Further, the epitaxial substrate also includes a first passivation layer;

The first passivation layer is disposed on a side of the ε-Ga ₂ O ₃ layer away from the m-GaN layer.

Further, the gate is disposed on a side of the first passivation layer away from the ε-Ga ₂ O ₃ layer.

Further, the first passivation layer is provided with an etching region, and the gate is connected to the Ga ₂ O ₃ layer through the etching region.

Further, the gate is a T-shaped gate.

Further, the gallium nitride-based high electron mobility transistor device also includes a second passivation layer;

The second passivation layer covers the outer surfaces of the epitaxial substrate, the source, the drain and the gate.

In the second aspect, the present invention also provides a method for preparing the gallium nitride-based high electron mobility transistor device according to any one of the first aspect, comprising:

Deposit m-GaN and ε-Ga ₂ O ₃ sequentially on the substrate layer to obtain an epitaxial substrate;

depositing metal on the m-GaN layer of the epitaxial substrate to make source and drain;

Metal is deposited on the ε-Ga ₂ O ₃ layer of the epitaxial substrate to make a gate.

On the basis of the above technical solutions, the present invention can also be improved as follows.

Further, after making the grid, it also includes:

Passivation treatment is performed on the outer surfaces of the epitaxial substrate, the source, the drain and the gate.

Compared with the prior art, the technical solution of the present application has the following beneficial technical effects:

The gallium nitride-based high electron mobility transistor device provided by the present invention forms an ε-Ga ₂ O ₃ /m-GaN heterojunction by setting an m-GaN layer and an ε-Ga ₂ O ₃ layer on a substrate, wherein, ε -The Ga ₂ O ₃ layer is a potential barrier layer. Compared with the prior art, the high electron mobility transistor device has the following advantages:

First, the device saturation current is large: due to the high spontaneous strength of the barrier layer ε-Ga ₂ O ₃ , the 2DEG concentration at the interface of ε-Ga ₂ O ₃ /m-GaN heterojunction can reach 10 ¹⁴ cm ^-2 On the order of magnitude, the device exhibits a large saturation current and can exhibit better power characteristics.

Second, the leakage current of the device is low: ε-Ga ₂ O ₃ has a large forbidden band width of 4.9eV, so the probability of tunneling leakage of the gate through the barrier layer is reduced, and the device exhibits a low level of leakage current.

Third, the stability and reliability of the device are high: the lattice constants of ε-Ga ₂ O ₃ and m-GaN are very close, so that the heterogeneous crystal lattice mismatch of the device is small, and the heterojunction strain of the device is smaller, so , the device has higher reliability and stability.

Description of drawings

Fig. 1 is one of the structural schematic diagrams of the gallium nitride-based high electron mobility transistor device provided by the present invention;

Fig. 2 is the second structural schematic diagram of the gallium nitride-based high electron mobility transistor device provided by the present invention;

Fig. 3 is one of the structural schematic diagrams of the epitaxial substrate provided by the present invention;

Fig. 4 is the second structural schematic diagram of the epitaxial substrate provided by the present invention;

Fig. 5 is one of the partial structural schematic diagrams of the gallium nitride-based high electron mobility transistor device provided by the present invention;

FIG. 6 is the second partial structural schematic diagram of the GaN-based high electron mobility transistor device provided by the present invention;

FIG. 7 is a schematic diagram of a preparation method of a gallium nitride-based high electron mobility transistor device provided by an embodiment of the present invention;

Fig. 8 is one of the simulation data renderings of the gallium nitride-based high electron mobility transistor device provided by the present invention;

Fig. 9 is the second rendering of the simulation data of the gallium nitride-based high electron mobility transistor device provided by the present invention;

Reference signs:

1. Substrate layer; 2. m-GaN layer; 3. ε-Ga ₂ O ₃ layer; 4. First passivation layer; 5. Source; 6. Drain; 7. Gate; 8. Second passivation layers.

Detailed ways

In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the application are given in the drawings. However, the present application can be embodied in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of this application more thorough and comprehensive.

The preparation of the front-end chip of the radio frequency circuit mainly uses CMOS (complementary metal oxide semiconductor transistor device) and SOI (silicon on insulator technology). Therefore, the coverage of the same distance requires radiation from a larger front, which leads to an increase in the area occupied by the system and the cost of circuit development; at the same time, a larger front corresponds to a narrower antenna beam. User coverage requirements require more frequent and complex beam scheduling algorithms, which increases a large amount of digital overhead and affects the effective spectrum utilization of the system.

High electron mobility transistor devices based on gallium nitride can solve this problem, but as mentioned above, the existing high electron mobility transistor devices made of gallium nitride have certain defects and are not ideal materials. Therefore, The embodiment of the present invention provides a new high electron mobility transistor device based on gallium nitride. The heterojunction in this structure has the advantages of small lattice mismatch and high 2DEG concentration. The specific examples are as follows.

The embodiments of the present invention will be described in further detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

In the first aspect, as shown in FIG. 1 , the gallium nitride-based high electron mobility transistor device provided by the embodiment of the present invention includes: an epitaxial substrate, a source 5 , a drain 6 and a gate 7 .

The epitaxial _substrate includes a substrate layer 1, an m-GaN layer 2 and an ε- _Ga2O3 layer 3, wherein the m-GaN layer 2 is set on the substrate layer 1, and the ε- _Ga2O3 layer ₃ is set on the m-GaN Layer 2 is the side facing away from substrate layer 1 .

The gate 7 is set on the side of the ε- _Ga2O3 layer ₃ away from the GaN layer 2, the source 5 and the drain 6 are both set on the side of the m-GaN layer 2 away from the substrate layer 1, and are located on the ε- _Ga2 The distance between the source electrode 5 and the drain electrode 6 at both ends of the O ₃ layer 3 is 0.5-2um.

Specifically, m-GaN here refers to GaN with an m-plane, which is a GaN material with a non-polar plane. Studies have shown that this material can eliminate the decrease in the radiative recombination efficiency of nitride devices caused by piezoelectric polarization and Issues such as blue shift of luminescence wavelength.

ε-Ga ₂ O ₃ refers to Ga ₂ O ₃ with ε crystal phase. Ga ₂ O ₃ has many crystal systems, here the hexagonal system ε-Ga ₂ O ₃ is preferred, and the band gap of ε-Ga ₂ O ₃ Large (4.9eV), the tunneling probability of the device gate 7 electrons is small, the overall leakage level of the device is smaller, and it has better stability. Therefore, as a barrier layer, it will be able to avoid the problem of barrier layer degradation , to ensure the stability of device performance.

以蓝宝石为例，蓝宝石衬底层晶向包括

和(0001)；以碳化硅为例，碳化硅衬底层的晶向包括

和

碳化硅衬底层1的晶向包括(110)和(102)等。The substrate layer 1 is made of any one of sapphire, GaN, silicon and silicon carbide. Among them, taking silicon as an example, the crystal orientation of the Si substrate layer includes (100), (111) and

Taking sapphire as an example, the crystal orientation of the sapphire substrate layer includes

and (0001); taking silicon carbide as an example, the crystal orientation of the silicon carbide substrate layer includes

and

The crystal orientation of the silicon carbide substrate layer 1 includes (110) and (102) and the like.

In addition, the substrate layer 1 can be a flat substrate as shown in FIG. 3, and the substrate layer 1 can also be designed as a patterned substrate as shown in FIG. 4. There is no specific limitation on its pattern, and it can be set according to actual needs. .

The gallium nitride-based high electron mobility transistor device provided by the embodiment of the present invention forms an ε-Ga 2 O ₃ /m-GaN heterogeneous structure by setting an m-GaN layer 2 and an ε- _{Ga 2} O ₃ layer 3 on a substrate layer 1 In which, the ε-Ga ₂ O ₃ layer 3 is a barrier layer. Compared with the prior art, the high electron mobility transistor device has the following advantages: the device saturation current is large: due to the barrier layer ε-Ga ₂ O ₃ The spontaneous intensity is large, so that the 2DEG concentration at the interface of the ε-Ga ₂ O ₃ /m-GaN heterojunction can reach the order of 10 ¹⁴ cm ^-2 , the device presents a large saturation current, and can show more excellent Power characteristics; device leakage current is low: ε-Ga ₂ O ₃ has a large forbidden band width of 4.9eV, so the probability of gate 7 tunneling leakage through the barrier layer decreases, and the device exhibits a low leakage current level; device stability and high reliability: the lattice constants of ε-Ga ₂ O ₃ and m-GaN are very close, so that the heterogeneous crystal lattice mismatch of the device is small, and the heterojunction strain of the device is smaller. Therefore, the device has a higher reliability and stability.

Further, on the basis of the above embodiments, the thickness of the ε-Ga ₂ O ₃ layer 3 is 2-30 nm.

Specifically, due to the large spontaneous intensity of ε-Ga ₂ O ₃ , the 2DEG concentration at the interface using ε-Ga ₂ O ₃ /m-GaN heterojunction can reach the order of 10 ¹⁴ cm ^-2 , and the device exhibits a large saturation current, showing excellent power characteristics.

Further, on the basis of the above embodiments, as shown in FIG. 3 , the epitaxial substrate further includes a first passivation layer 4 .

The first passivation layer 4 is disposed on the side of the ε-Ga ₂ O ₃ layer 3 away from the m-GaN layer 2 .

As shown in FIG. 1 , the gate 7 is disposed on the side of the first passivation layer 4 away from the ε-Ga ₂ O ₃ layer 3 .

Further, on the basis of the above embodiments, as shown in FIG. 1 , the first passivation layer 4 is provided with an etching region, and the gate 7 is connected to the ε-Ga ₂ O ₃ layer 3 through the etching region.

In actual operation, the gate 7 is connected to the epitaxial substrate in the following three ways:

In the first type, the epitaxial substrate has no first passivation layer 4, and the gate 7 _is directly connected to the upper surface of the ε- _Ga2O3 layer 3;

In the second type, the epitaxial substrate is provided with a first passivation layer 4, and the gate 7 is connected to the upper surface of the first passivation layer 4;

The third type is that the epitaxial substrate is provided with a first passivation layer 4, and an etching _area is provided on the first passivation layer 4, and the gate 7 is provided on the etching area and the ε- _Ga2O3 layer 3 surface connection.

It should be noted that the material of the first passivation layer 4 is GaN or SiN, and its function is to protect ε-Ga ₂ O ₃ .

In an optional embodiment, as shown in FIG. 1 , the gate 7 is a T-shaped gate with a gate length of 20-100 nm, and the specific length can be set according to actual needs.

Further, on the basis of the above embodiments, in order to protect the entire device, as shown in FIG. 2 , the gallium nitride-based high electron mobility transistor device further includes a second passivation layer 8 .

The second passivation layer 8 covers the outer surfaces of the epitaxial substrate, the source 5 , the drain 6 and the gate 7 .

In the second aspect, as shown in FIG. 7 , an embodiment of the present invention also provides a method for preparing a gallium nitride-based high electron mobility transistor device according to any one of the first aspect, including:

Step S1: sequentially depositing m-GaN and ε-Ga ₂ O ₃ on the substrate layer 1 to obtain an epitaxial substrate;

Step S2: Depositing metal on the m-GaN layer 2 of the epitaxial substrate to form the source 5 and the drain 6;

Step S3: Deposit metal on the ε-Ga ₂ O ₃ layer 3 of the epitaxial substrate to make the gate 7 .

Further, after making the gate 7, it also includes:

The outer surfaces of the epitaxial substrate, the source 5 , the drain 6 and the gate 7 are passivated.

Specifically, in step S1, first, a substrate layer 1 is prepared, and the substrate layer 1 can be one of a silicon substrate, a sapphire substrate, and a silicon carbide substrate, and a sapphire substrate can be selected as an example for introduction here; then The m-GaN is grown on the upper surface of the sapphire substrate, and ε-Ga ₂ O ₃ is further grown on the m-plane of the m-GaN as a barrier layer to obtain a heterostructure of ε-Ga ₂ O ₃ /m-GaN.

A passivation layer can be selectively deposited on the surface of ε-Ga ₂ O ₃ according to actual needs to protect the barrier layer.

In step S2, the preparation of the electrode has the following two implementation methods:

Method 1. Source-drain regrowth method: use a dry method to etch the source-drain regrowth region on the ε-Ga ₂ O ₃ layer 3 and the m-GaN layer 2. The etching gas is BCl ₃ and Cl ₂ , and the etching depth is 30-100nm; After the etching is completed, use organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE) to re-grow highly doped GaN in the source and drain etching regions, the doping concentration is greater than 10 ¹⁹ cm ^-3 , and the growth The thickness is 30-100nm. Use photolithography to uncover a lift-off (lift-off) process to form a GaN electrode, use an electron beam to evaporate the source and drain metal Ti/Pt/Au on the electrode, and deposit it to form a source and drain electrode with a total thickness of 0.1-0.5um , the resulting structure is shown in Figure 5.

Method 2. Alloy annealing method: use photolithography to define the source and drain ohmic metal regions on the m-GaN layer 2, and deposit metal Ti/Al/Ni/Au in this region, and the corresponding thicknesses can be 10/160/55 /45nm, annealing treatment was performed, the annealing temperature was 830°C, the annealing atmosphere was nitrogen, and the annealing time was 50S. The obtained structure is shown in Figure 6.

In step S3, anneal the alloy to obtain the structure, use photolithography and lift-off process to form GaN HEMT grid 7 electrode shapes on the upper surface of ε-Ga ₂ O ₃ , and then electron beam evaporate T-shaped grid metal Ni, Pt or Au , the total thickness is 0.4 ~ 0.8um, the gate foot length is 20 ~ 100nm, the resulting structure is shown in Figure 1.

Finally, in order to protect the entire device, the second passivation layer 8 is deposited on the outer surface of the prepared HEMT device, and the SiNx passivation protection layer is grown by plasma enhanced vapor deposition (PECVD), and its thickness is 1-3um. The obtained structure is as follows Figure 2 shows.

Through simulation, the performance of the HEMT device with the heterostructure of ε-Ga ₂ O ₃ /m-GaN provided by the embodiment of the present invention is compared with the performance of the HEMT device with the same structure of the device and the heterojunction is AlN/GaN, and the results are shown in the figure 8 and 9, it can be seen that the HEMT device provided by the embodiment of the present invention has a larger saturation current, which is more than double that of the HEMT device using an AlN barrier layer; and the HEMT device provided by the present invention exhibits A low level of leakage current is achieved, thanks to the large forbidden band width of ε-Ga ₂ O ₃ close to 5eV, and the probability of tunneling leakage of the gate 7 through the barrier layer is reduced. Therefore, compared with the prior art, the high electron mobility transistor device based on gallium nitride provided by the embodiment of the present invention has better electrical characteristics.

In the description of this specification, descriptions with reference to the terms "specific examples" or "some examples" mean that specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment of the embodiments of the present invention or example. In this specification, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples and features of different embodiments or examples described in this specification without conflicting with each other.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (9)

1. A gallium nitride-based high electron mobility transistor device, comprising: epitaxial substrate, source electrode, drain electrode and grid electrode;

the epitaxial substrate comprises a substrate layer, an m-GaN layer and epsilon-Ga ₂ O ₃ A layer, wherein the m-GaN layer is arranged on the substrate layer, and the epsilon-Ga ₂ O ₃ The layer is arranged on one side of the m-GaN layer, which is away from the substrate layer;

the grid electrode is arranged on the epsilon-Ga ₂ O ₃ The layer is away from one side of the m-GaN layer, the source electrode and the drain electrode are both arranged on one side of the m-GaN layer away from the substrate layer and are positioned on the epsilon-Ga ₂ O ₃ Both ends of the layer.

2. Gallium nitride-based high electron mobility transistor device according to claim 1, wherein the epsilon-Ga ₂ O ₃ The thickness of the layer is 2-30 nm.

3. The gallium nitride-based high electron mobility transistor device of claim 1, wherein the epitaxial substrate further comprises a first passivation layer;

the first passivation layer is arranged on the epsilon-Ga ₂ O ₃ The side of the layer facing away from the m-GaN layer.

4. A gallium nitride-based high electron mobility transistor device according to claim 3, wherein said gate is disposed on said first passivation layer facing away from said epsilon-Ga ₂ O ₃ One side of the layer.

5. A gallium nitride-based high electron mobility transistor device according to claim 3, wherein the first passivation layer is provided with an etched region through which the gate passes with the epsilon-Ga ₂ O ₃ The layers are connected.

6. The gallium nitride-based high electron mobility transistor device of claim 1, wherein the gate is a T-gate.

7. The gallium nitride based high electron mobility transistor device of claim 1, further comprising a second passivation layer;

the second passivation layer covers the outer surfaces of the epitaxial substrate, the source electrode, the drain electrode and the grid electrode.

8. A method for preparing the gallium nitride-based high electron mobility transistor device of any of claims 1 to 7, comprising:

sequentially depositing m-GaN and epsilon-Ga on a substrate layer ₂ O ₃ Obtaining an epitaxial substrate;

depositing metal on the m-GaN layer of the epitaxial substrate to manufacture a source electrode and a drain electrode;

epsilon-Ga on said epitaxial substrate ₂ O ₃ And depositing metal on the layer to manufacture the grid electrode.

9. The method of manufacturing of claim 8, further comprising, after the gate is manufactured:

and passivating the outer surfaces of the epitaxial substrate, the source electrode, the drain electrode and the grid electrode.

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