CN210837767U

CN210837767U - GaN-based HEMT device

Info

Publication number: CN210837767U
Application number: CN201920477520.XU
Authority: CN
Inventors: 尹以安; 曾妮; 李锴
Original assignee: South China Normal University
Current assignee: Jiangsu Third Generation Semiconductor Research Institute Co Ltd
Priority date: 2019-04-09
Filing date: 2019-04-09
Publication date: 2020-06-23
Anticipated expiration: 2029-04-09

Abstract

The utility model discloses a gaN base HEMT device, supreme in proper order is mixed with gaN neutralization layer, intrinsic Al in drain electrode, substrate, current barrier layer, conduction through-hole, Mg and Si from down followed to the structure_xGa_1‑xThe N-GaN-based light-emitting diode comprises an N gradual change layer, an N-GaN cap layer, a source electrode, a passivation layer and a grid electrode. The intrinsic Al_xGa_1‑xTwo-dimensional electron gas channels are distributed in the N gradient layer, the source electrode is electrically connected with the N-GaN cap layer, the grid electrode is located on the passivation layer, and the drain electrode is located on the back of the substrate. The current blockThe layer is an insulating layer, the corresponding area under the grid of the insulating layer is an N-type current conduction through hole with high electron concentration, the cross section of the conduction through hole is in an inverted trapezoid shape, the structure is favorable for healing, and the problems of electric leakage of a gap area and the like can be effectively relieved. The utility model provides a pair of gaN base HEMT device has high withstand voltage, low electric leakage and advantages such as simple process.

Description

GaN-based HEMT device

Technical Field

The utility model relates to a semiconductor manufacturing technology field, concretely relates to gaN base HEMT device.

Background

The GaN-based HEMT is a hot point for development at home and abroad, has made a breakthrough in various fields, and particularly has wide application prospects in the aspects of high temperature, high power, high frequency and the like. At present, in the power electronics industry, silicon and sapphire substrates occupy the mainstream position, but the sapphire material is a heat-insulating material and cannot meet the heat dissipation requirement required by the GaN-based HEMT, and the two substrates have the problems of lattice mismatch and the like in epitaxial growth, so that a high-quality heterojunction is difficult to obtain. Therefore, the search for a suitable substrate is imminent. In addition, the conventional horizontal structure GaN-based HEMT has problems of current collapse, low high voltage resistance, poor reliability, and the like, so the vertical structure GaN-based HEMT is a major focus of the current research.

The GaN-based HEMT realizes work by controlling two-dimensional electron gas in a channel through Schottky gate voltage, and Al is used for replacing the conventional GaN buffer layer when the low-component AlGaN is used as the buffer layer_xGa_1-xMultiple heterojunctions can be formed in the N gradual change layer, the concentration of two-dimensional electron gas in a channel is increased, and the enhancement device is favorably realized. In addition, the current blocking layer and the via hole have been difficulties in the development of the vertical structure GaN-based HEMT. On one hand, the current blocking layer can form P-GaN by Mg injection or Mg doping, the P-GaN has higher potential barrier and can inhibit electric leakage so as to play a role of the current blocking layer, but Mg has lower activation efficiency and memory effect and is prevented from secondary epitaxial growth; on the other hand, a material with better insulation property, such as SiO, can be selected₂Etc., but there is a need to solve the problems of voids and the like generated during the healing process due to lateral epitaxial growth, which is also one of the research hotspots today.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a gaN base HEMT device and preparation method to overcome not enough among the prior art, obtain high withstand voltage, low electric leakage and simple process's HEMT device.

In order to achieve the above object, the present invention is achieved by the following technical solutions.

The utility model provides a GaN-based HEMT device, the device includes substrate, electric current resistanceBarrier layer, through via, Mg-Si co-doped GaN neutralizing layer, intrinsic Al_xGa_1-xN gradient layer, N-GaN cap layer, passivation layer, source electrode, grid electrode and drain electrode, and the intrinsic Al_xGa_1-xThe N-graded layer comprises intrinsic Al with Al components x increasing from 0.01 to 0.28_xGa_1-xA two-dimensional electron gas channel in the N graded layer and the heterojunction; the drain electrode is positioned on the back surface of the substrate; a current barrier layer, a Mg-Si co-doped GaN neutralizing layer and intrinsic Al are sequentially arranged on the front surface of the substrate from bottom to top_xGa_1-xThe N-GaN-based light-emitting diode comprises an N gradual change layer, an N-GaN cap layer and a passivation layer; the intrinsic Al_xGa_1-xThe N gradual change layers are sequentially arranged on the Mg-Si co-doped GaN neutralization layer from bottom to top, and the intrinsic Al_xGa_1-xTwo-dimensional electron gas channels are distributed in the N gradual change layer; the source electrode comprises a first source electrode and a second source electrode which are arranged on two sides of the passivation layer, and the first source electrode and the second source electrode penetrate through the passivation layer and are electrically connected with the N-GaN cap layer; the grid electrode is positioned between the first source electrode and the second source electrode and is in contact with the passivation layer; the conducting through hole is located in a corresponding area below a grid of the current blocking layer, the cross section of the conducting through hole is in an inverted trapezoid shape, the height of the conducting through hole is the same as the thickness of the current blocking layer, a lower surface hole of the conducting through hole is in contact with the front face of the substrate, and an upper surface hole of the conducting through hole is in contact with the second semiconductor layer.

Preferably, the substrate is an N-type GaN free-standing substrate.

Preferably, the current blocking layer is SiO₂Layer, the thickness of the current blocking layer is d₁，100nm＜d₁＜700nm。

Preferably, the through via is an N-type current through via with high electron concentration, and the carrier concentration is greater than 10¹⁸cm^-3And doping with Si ions.

Preferably, the aperture of the upper surface hole of the via hole is R, 1 μm < R <20 μm, and the aperture of the lower surface hole is R, 50nm < R <500 nm.

Preferably, the thickness of the Mg and Si co-doped GaN neutralizing layer is 1-10 nm.

Preferably, the intrinsic Al_xGa_1-xThe total thickness of the N gradual change layers is 1 to3μm。

Preferably, the carrier concentration of the N-type GaN cap layer is more than 10¹⁸cm^-3The thickness of the N-type GaN cap layer is 1-10 nm; the passivation layer is Si₃N₄The thickness of the passivation layer is 30-100 nm.

Preferably, the intrinsic Al_xGa_1-xThe value of the Al component x in the N gradual change layer from bottom to top is gradually increased from 0.01 to 0.28, and the corresponding Al_xGa_1-xThe thickness of the N layer is gradually reduced.

Preferably, a two-dimensional electron gas is formed in the two-dimensional electron gas channel.

The utility model provides a pair of among gaN base HEMT device, switch on through-hole aperture R, r, the thickness of electric current barrier layer, Mg and Si mix the thickness on gaN neutralization layer altogether, intrinsic Al_xGa_1-xThe total thickness of the N gradual change layer, the thickness of the N-GaN cap layer, the thickness of the passivation layer, the distance between the grid electrode and the source electrode, the width of the grid electrode, the length of the grid electrode and the like are all variable.

Compared with the prior art, the utility model discloses following beneficial effect has:

firstly, the device adopts an N-GaN self-supporting substrate, the problems of low heterojunction quality and the like caused by lattice mismatch and thermal mismatch in epitaxial growth can be effectively solved, and ohmic contact with a drain electrode on the back surface of the substrate is facilitated;

secondly, the device is of a vertical conduction structure, so that the problems of current collapse, low high voltage resistance, poor reliability and the like of the conventional horizontal structure HEMT can be effectively solved;

thirdly, the current barrier layer adopts SiO₂The corresponding area under the grid is an N-type current conduction through hole with high electron concentration, and the cross section of the conduction through hole is in an inverted trapezoid shape, so that the structure is favorable for healing, and the problems of electric leakage and the like in a gap area can be effectively relieved;

fourthly, the AlGaN layer with low Al component is adopted to replace a GaN buffer layer in the traditional structure, and the structure can form a plurality of heterojunctions, increase the concentration of two-dimensional electron gas in a channel and further improve the current density.

Drawings

In order to more clearly illustrate the technical solutions of the present invention or the prior art, the drawings required for the description of the present invention or the prior art will be briefly described below, and for those skilled in the art, other drawings can be obtained without creative efforts.

Fig. 1 is a schematic diagram of an overall structure of a GaN-based HEMT device provided in the present invention;

FIG. 2 shows the intrinsic Al provided by the present invention_xGa_1-xThe specific structure of the N gradient layer is shown schematically.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the following detailed description of the embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments of the invention shown in the drawings and described in accordance with the same are merely exemplary and the invention is not limited to these embodiments. All other embodiments obtained by a person skilled in the art without making any inventive step are within the scope of protection of the present invention.

FIG. 1 shows a GaN-based HEMT device, which is composed of a drain electrode 1, an N-type GaN self-supporting substrate 2, a current blocking layer 3, a through hole 4, a Mg and Si co-doped GaN neutralizing layer 5, and intrinsic Al sequentially from bottom to top_xGa_1-xAn N-graded layer 6, an N-GaN cap layer 7, a passivation layer 8, a source electrode 9, and a gate electrode 10, the gate electrode 10 being located between the first source electrode 901 and the second source electrode 902. The thickness of the current blocking layer 3 is 400nm, the aperture R of the upper surface of the N-type current conducting through hole 4 with high electron concentration is 1 mu m, the aperture R of the lower surface is 400nm, the thickness of the Mg and Si co-doped GaN neutralizing layer 5 is 6nm, the thickness of the N-GaN cap layer 7 is 3nm, and the thickness of the passivation layer 8 is 60 nm.

FIG. 2 shows the intrinsic Al_xGa_1-xThe specific structure of the N graded layer is 10 layers from bottom to top, which are respectively marked as 601, 602, 603, 604, 605, 606, 607, 608, 609 and 610, the dotted line part indicates a two-dimensional electron gas channel 611, and the two-dimensional electron gas channel 611 contains two-dimensional electron gas. 601. The value of x in

layers

602, 603, 604, 605, 606, 607, 608, 609 and 610 (xRespective thickness of each layer) are: 0.01(500nm), 0.04(300nm), 0.07(250nm), 0.10(230nm), 0.13(200nm), 0.16(160nm), 0.19(80nm), 0.22(40nm), 0.25(20nm), 0.28(10nm), i.e. the intrinsic Al_xGa_1-xThe total thickness of the N gradient layer is 1790 nm.

The utility model provides a manufacturing method of GaN-based HEMT device, including following step:

s1, depositing and growing a layer of SiO with the thickness of 400nm on the front surface of the N-type GaN self-supporting substrate 2 by utilizing PECVD equipment₂As a current blocking layer 3;

s2, forming a conduction through hole area table top with an inverted trapezoid cross section through pretreatment, spin coating of an adhesive, coating of glue, development and wet etching to obtain a patterned substrate epitaxial wafer;

s3, firstly preprocessing the formed patterned substrate epitaxial wafer, placing the patterned substrate epitaxial wafer into a 200 ℃ oven for baking for 2 hours before MOCVD epitaxial growth, removing surface moisture and impurities, preparing for MOCVD epitaxial growth, then placing the patterned substrate epitaxial wafer into a reaction chamber of an MOCVD system, epitaxially growing a Si heavily doped GaN layer, and filling a through hole 4 with an inverted trapezoid cross section;

s4, pretreating the epitaxial wafer obtained after S3 treatment, drying in an oven at 200 ℃ for 2 hours, removing surface moisture and impurities, putting the epitaxial wafer into a reaction chamber, taking trimethyl gallium (TMGa) and trimethyl aluminum (TMAl) as III group sources, ammonia as V group sources, and magnesium dipentantexide Cp₂Mg and high purity silane SiH₄Respectively serving as P-type and N-type dopants, and taking high-purity hydrogen as carrier gas to grow a Mg and Si co-doped GaN neutralizing layer 5;

s5, introducing ammonia gas, trimethylaluminum and trimethylgallium, and carrying out MOCVD epitaxial growth on intrinsic Al_xGa_1-xAn N graded layer 6;

s6, intrinsic Al_xGa_1-xAn N-GaN cap layer 7 is epitaxially grown on the N gradual change layer 6, so that ohmic contact between the later N gradual change layer and the source electrode 9 is conveniently formed;

s7, firstly, cleaning the epitaxial wafer after the epitaxial growth after the treatment of S6 with organic solution, washing with deionized water, purging with high-purity nitrogen, and then depositing passivation layers 8 such as silicon nitride and the like by utilizing PECVD equipment;

s8, source ohmic contact: photoetching and etching the epitaxial wafer on which the silicon nitride passivation layer 8 is deposited to form a source electrode 9, putting the source electrode into an electron beam deposition table to deposit ohmic contact metal Ti/Al/Ni/Au (20nm/110nm/40nm/130nm), and stripping and cleaning;

s9, drain ohmic contact: after ohmic contact of a source electrode, ohmic contact of a drain electrode is carried out on the back surface of the substrate 2, Ti/Al/Ni/Au (20nm/110nm/40nm/130nm) is deposited by electron beams and stripped and cleaned, and then alloying treatment is carried out on the metal after the ohmic contact is finished so as to obtain ohmic contact, wherein the alloying temperature is 750 ℃, and the alloying time is 40 seconds;

s10, after alloying treatment of the sample, photoetching and developing are carried out, a photoresist mask is used for protecting the active area, and fluorine ions are injected to form device isolation;

s11, gate schottky contact: after the mesa isolation is completed, cleaning and photoetching are carried out to form a grid electrode 10, Ni/Au (30nm/130nm) is deposited by electron beams and stripped and cleaned, and the Schottky contact is formed by annealing under the conditions of 400 ℃ of annealing temperature and 10min of annealing time in the nitrogen atmosphere, so that the whole device is manufactured.

The embodiment of the utility model provides an adopt novel vertical construction, utilize the self-supporting GaN substrate, can effectively solve the current that conventional horizontal construction GaN base HEMT device exists and collapse, high pressure and reliability subalternation problem. By means of SiO₂As the current blocking layer, the problem of leakage of the vertical conduction HEMT through the current blocking layer under a high leakage voltage condition can be reduced, so that the breakdown voltage of the device is improved to 1.8 kV. And the cross section of the conducting through hole is in an inverted trapezoid shape, so that the structure is favorable for healing, and the problems of current leakage of the current blocking layer and the like can be effectively relieved. The AlGaN layer with low Al component is adopted to replace a GaN buffer layer in the traditional structure, and intrinsic Al_xGa_1-xMultiple heterojunctions can be formed in the N gradient layer, the concentration of two-dimensional electron gas in a channel is increased, and the current density is increased to 2kA/cm²。

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way. Any equivalent changes, modifications or evolutions made by those skilled in the art to the above embodiments by using the technical solutions of the present invention still belong to the scope of the technical solutions of the present invention.

Claims

1. The GaN-based HEMT device is characterized by comprising a substrate (2), a current blocking layer (3), a through via (4), a Mg-Si co-doped GaN neutralizing layer (5) and intrinsic Al_xGa_1-xAn N gradual change layer (6), an N-GaN cap layer (7), a passivation layer (8), a source electrode (9), a grid electrode (10) and a drain electrode (1), wherein the intrinsic Al is_xGa_1-xThe N-graded layer (6) comprises intrinsic Al with Al components x increasing from 0.01 to 0.28_xGa_1-xA two-dimensional electron gas channel (611) in the N-graded layer and the heterojunction; the drain electrode (1) is positioned on the back surface of the substrate (2); a current barrier layer (3), a Mg-Si co-doped GaN neutralizing layer (5) and intrinsic Al are sequentially arranged on the front surface of the substrate (2) from bottom to top_xGa_1-xAn N gradual change layer (6), an N-GaN cap layer (7) and a passivation layer (8); the intrinsic Al_xGa_1-xThe N gradual change layers are sequentially arranged on the Mg-Si co-doped GaN neutralization layer (5) from bottom to top, and intrinsic Al_xGa_1-xTwo-dimensional electron air channels (611) are distributed in the N gradual change layer; the source electrode (9) comprises a first source electrode (901) and a second source electrode (902) which are arranged on two sides of the upper surface of the passivation layer (8), and the first source electrode (901) and the second source electrode (902) are electrically connected with the N-GaN cap layer (7) through the passivation layer (8); the gate (10) is positioned between the first source electrode (901) and the second source electrode (902) and is in contact with the passivation layer (8); the conducting through hole (4) is located in a corresponding area below a grid of the current blocking layer (3), the cross section of the conducting through hole (4) is in an inverted trapezoid shape, the height of the conducting through hole (4) is the same as the thickness of the current blocking layer (3), a lower surface hole of the conducting through hole (4) is in contact with the front surface of the substrate (2), and an upper surface hole of the conducting through hole (4) is in contact with the Mg-Si co-doped GaN neutralizing layer (5).

2. A GaN-based HEMT device according to claim 1, wherein said substrate (2) is an N-type GaN free-standing substrate.

3. The GaN-based HEMT device according to claim 1, wherein the current blocking layer (3) is SiO₂The thickness of the insulating layer and the current blocking layer (3) is d₁，100 nm＜d₁＜700 nm。

4. The GaN-based HEMT device according to claim 1, wherein the via (4) is a high electron concentration N-type current via with a carrier concentration greater than 10¹⁸cm^-3And doping with Si ions.

5. A GaN-based HEMT device according to claim 1, wherein said through via (4) has an upper surface hole with a pore size R of 1 μm < R <20 μm and a lower surface hole with a pore size R of 50nm < R <500 nm.

6. The GaN-based HEMT device according to claim 1, wherein the thickness of the Mg-Si co-doped GaN neutralizing layer (5) is 1 to 10 nm.

7. The GaN-based HEMT device of claim 1, wherein the intrinsic Al is_xGa_1-xThe total thickness of the N-graded layer (6) is 1 to 3 μm.

8. The GaN-based HEMT device according to claim 1, characterized in that the N-type GaN cap layer (7) has a carrier concentration greater than 10¹⁸cm^-3The thickness of the N-type GaN cap layer (7) is 1-10 nm; the passivation layer (8) is Si₃N₄The thickness of the passivation layer (8) is 30-100 nm.

9. The GaN-based HEMT device of claim 1, wherein the intrinsic Al is_xGa_1-xThe value of the Al component x in the N gradual change layer (6) from bottom to top is gradually increased from 0.01Increased to 0.28, corresponding intrinsic Al_xGa_1-xThe thickness of the N gradual change layer (6) is gradually reduced.

10. The GaN-based HEMT device according to claim 1, wherein a two-dimensional electron gas is formed within the two-dimensional electron gas channel (611).