阅读说明：本技术 一种制作增强型氮化镓功率器件的方法 (Method for manufacturing enhanced gallium nitride power device ) 是由 梁玉玉 蔡文必 刘成 叶念慈 赵杰 于 2020-03-13 设计创作，主要内容包括：本发明公开了一种制作增强型氮化镓功率器件的方法,是在半导体基底的势垒层上形成一层层状纳米材料层,蚀刻层状纳米材料层于预设栅极位置形成第一窗口,沉积p型氮化物层,然后剥离所述层状纳米材料层,余下所述第一窗口之内的p型氮化物层形成p型栅极层。所述层状纳米材料层是六方氮化硼薄膜或类石墨烯二维纳米材料。本发明采用层状纳米材料层制作一种增强型氮化镓功率器件,避免因p型氮化物层蚀刻造成的势垒层界面损伤,提升器件电性特性。(The invention discloses a method for manufacturing an enhanced gallium nitride power device, which is to form a layered nanometer material layer on a barrier layer of a semiconductor substrate, etch the layered nanometer material layer at a preset grid position to form a first window, deposit a p-type nitride layer, strip the layered nanometer material layer, and form a p-type grid layer by the remaining p-type nitride layer in the first window. The layered nano material layer is a hexagonal boron nitride film or a graphene-like two-dimensional nano material. The invention adopts the layered nanometer material layer to manufacture the enhanced gallium nitride power device, avoids the interface damage of the barrier layer caused by the etching of the p-type nitride layer and improves the electrical property of the device.)

1. A method for manufacturing an enhanced gallium nitride power device is characterized by comprising the following steps:

1) providing a semiconductor substrate, wherein the semiconductor substrate comprises a channel layer and a barrier layer;

2) forming a layered nanometer material layer on the barrier layer, wherein the layered nanometer material layer is a hexagonal boron nitride film or a graphene-like two-dimensional nanometer material;

3) etching the layered nanometer material layer, and forming a first window at the position of a preset grid;

4) depositing a p-type nitride layer;

5) and stripping the layered nanometer material layer, and forming a p-type gate layer by the p-type nitride layer in the first window.

2. The method of claim 1, wherein: the thickness of the layered nano material layer is 1-20 nm.

3. The method of claim 1, wherein: in the step 2), the semiconductor substrate is placed in a growth area in a cavity of plasma chemical vapor deposition equipment, inert gas is introduced after vacuum pumping, and the pressure of the inert gas is controlled to be 0.5-1.5 Torr; heating the semiconductor substrate to 300-700 ℃, introducing a boron-nitrogen reaction source, setting the power at 20-100W, and reacting for 10-60 minutes to form the hexagonal boron nitride film.

4. The method of claim 1, wherein: in the step 3), forming a photoresist with a second window at the position of a preset grid electrode on the hexagonal boron nitride film, etching the hexagonal boron nitride film by adopting plasma with the power of 6-10kW, the bias voltage of 0-500V and the time of 10-100s, and then removing the photoresist to form the first window.

5. The method of claim 1, wherein: the p-type nitride layer is made of p-GaN, p-AlGaN, p-InGaN or p-InAlGaN.

6. The method of claim 1, wherein: the thickness of the p-type nitride layer is 50-100 nm.

7. The method as set forth in claim 5, wherein the p-GaN is prepared by MOCVD at 900-¹⁹-8×10¹⁹cm^-3Reaction time is 5-10min, then in N₂The furnace temperature is reduced to 500-700 ℃ under the atmosphere, the temperature is kept for 10-30min, and the furnace temperature is reduced to 130-180 ℃ within 20-40 min.

8. The method according to claim 1 or 5, characterized in that: the semiconductor substrate further includes a substrate, a nucleation layer, and a buffer layer, and the substrate, the nucleation layer, the buffer layer, a channel layer, and a barrier layer are arranged in sequence, wherein the channel layer is GaN and the barrier layer is AlGaN.

9. The method of claim 1, wherein: in the step 5), the layered nano material and the p-type nitride layer positioned on the layered nano material are stripped by adopting a mechanical stripping method or a chemical stripping method; the mechanical stripping method comprises a tape stripping method, a plasma etching method, a ball milling method and a fluid stripping method, and the chemical stripping method comprises a liquid phase ultrasonic method, a chemical functionalization method and an ion insertion stripping method.

10. The method of claim 1, further comprising the steps of:

6) manufacturing a source electrode metal and a drain electrode metal;

7) depositing a dielectric layer, and forming isolation through ion implantation or mesa etching;

8) etching an opening on the dielectric layer above the p-type gate layer to manufacture gate metal;

9) and etching the dielectric layer to form an opening above the source metal and the drain metal.

Technical Field

The invention relates to the technical field of semiconductors, in particular to a method for manufacturing an enhanced gallium nitride power device.

Background

The gallium nitride material has the characteristics of large forbidden band width, high critical breakdown electric field, high thermal conductivity and the like, and has wide application prospect in the fields of broadband communication, power electronics and the like. In particular, gallium nitride based high electron mobility field effect transistors (HEMTs) are a new type of electronic device based on nitride heterostructures. The device has the excellent characteristics of high frequency and high power, and is widely applied to the fields of information receiving and transmitting, energy conversion and the like of wireless communication base stations, power electronic devices and the like.

The most common processing method of the current enhancement type GaN device is mainly a p-type nitride gate structure, namely, a p-type nitride layer is formed on a barrier layer in an epitaxial mode, then the p-type nitride outside a gate region is removed in a dry etching mode, and the p-type nitride is used for raising an energy band and exhausting two-dimensional electron gas under a gate to realize enhancement. The difficulties with this approach are: the etchant used for dry etching of the p-type nitride layer generally has a corrosion effect on barrier layer materials (usually AlGaN), so that the requirement on etching accuracy is extremely high, the completeness and the uniformity of etching of the p-type nitride layer are kept, the completeness of the next layer is ensured, and the surface of the barrier layer is not damaged; both under-etching and over-etching can lead to poor device characteristics, such as large on-resistance or negative threshold.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a method for manufacturing an enhanced gallium nitride power device.

In order to achieve the above purpose, the technical scheme of the invention is as follows:

a method for manufacturing an enhanced gallium nitride power device comprises the following steps:

1) providing a semiconductor substrate, wherein the semiconductor substrate comprises a channel layer and a barrier layer;

2) forming a layered nanometer material layer on the barrier layer, wherein the layered nanometer material layer is a hexagonal boron nitride film or a graphene-like two-dimensional nanometer material;

3) etching the layered nanometer material layer, and forming a first window at the position of a preset grid;

4) depositing a p-type nitride layer;

5) and stripping the layered nanometer material layer, and forming a p-type gate layer by the p-type nitride layer in the first window.

Optionally, the thickness of the layered nano material layer is 1-20 nm.

Optionally, in step 2), the semiconductor substrate is placed in a growth area in a cavity of a plasma chemical vapor deposition device, and inert gas is introduced after vacuum pumping, wherein the pressure of the inert gas is controlled to be 0.5 to 1.5 Torr; heating the semiconductor substrate to 300-700 ℃, introducing a boron-nitrogen reaction source, setting the power at 20-100W, and reacting for 10-60 minutes to form the hexagonal boron nitride film.

Optionally, in step 3), a photoresist having a second window at a preset gate position is formed on the hexagonal boron nitride film, the hexagonal boron nitride film is etched by using plasma, the power is 6 to 10kW, the bias voltage is 0 to 500V, and the time is 10 to 100s, and then the photoresist is removed to form the first window.

Optionally, the p-type nitride layer is made of p-GaN, p-AlGaN, p-InGaN or p-InAlGaN.

Optionally, the thickness of the p-type nitride layer is 50-100 nm.

Optionally, the preparation method of the p-GaN adopts an MOCVD process, the temperature is raised to 900-¹⁹-8×10¹⁹cm^-3Reaction time is 5-10min, then in N₂The furnace temperature is reduced to 500-700 ℃ under the atmosphere, the temperature is kept for 10-30min, and the furnace temperature is reduced to 130-180 ℃ within 20-40 min.

Optionally, the semiconductor substrate further includes a substrate, a nucleation layer and a buffer layer, and the substrate, the nucleation layer, the buffer layer, the channel layer and the barrier layer are arranged in sequence, wherein the channel layer is GaN and the barrier layer is AlGaN.

Optionally, in step 5), the layered nanomaterial and the p-type nitride layer located on the layered nanomaterial are stripped by a mechanical stripping method or a chemical stripping method; the mechanical stripping method comprises a tape stripping method, a plasma etching method, a ball milling method and a fluid stripping method, and the chemical stripping method comprises a liquid phase ultrasonic method, a chemical functionalization method and an ion insertion stripping method.

Optionally, the method further comprises the following steps:

6) manufacturing a source electrode metal and a drain electrode metal;

7) depositing a dielectric layer, and forming isolation through ion implantation or mesa etching;

8) etching an opening on the dielectric layer above the p-type gate layer to manufacture gate metal;

9) and etching the dielectric layer to form an opening above the source metal and the drain metal.

The invention has the beneficial effects that:

1) the invention adopts the layered nanometer material layer to manufacture the enhanced gallium nitride power device, avoids the barrier layer interface damage caused by the etching of the p-type nitride layer and improves the electrical property of the device;

2) the etching precision of the p-type nitride layer is not required to be controlled, the manufacturing process difficulty is reduced, and the manufacturing process efficiency and the yield are improved;

3) the adopted layered nano material layer has excellent chemical stability and thermal stability and can resist the high temperature of the subsequent deposition of the p-type nitride layer;

4) the layered nanometer material layer is stripped by various methods, particularly, Van der Waals force is mainly applied between molecular layers, the molecular force is weak in combination and easy to break and separate, the layered nanometer material layer is separated by horizontal sliding along the atomic layers under the action of external force, the layered nanometer material layer can be cleanly stripped by adopting simple and easy-to-implement methods such as adhesive tape stripping, and the like, so that the subsequent process is not influenced by residues.

Drawings

Fig. 1 is a process flow diagram of a method for fabricating an enhanced gan power device according to an embodiment of the invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. The drawings are only schematic and can be easily understood, and the specific proportion can be adjusted according to design requirements. The relative positions of elements in the figures described herein are understood by those skilled in the art to refer to relative positions of elements, and thus all elements may be reversed to represent the same, all falling within the scope of the disclosure. In addition, the number of the elements and the structure shown in the drawings is only an example, and the number is not limited thereto, and can be adjusted according to the design requirement.

Referring to fig. 1A, a semiconductor substrate is provided, and the semiconductor substrate includes a Si substrate 1, a nucleation layer 2, a GaN buffer layer 3, a GaN channel layer 4, and an AlGaN barrier layer 5, which are arranged in sequence, and the specific materials and epitaxial processes thereof refer to the prior art, and in addition, other known functional layers may be added according to actual requirements.

Referring to FIG. 1B, the cleaned semiconductor substrate is placed in a growth area in a chamber of a plasma CVD apparatus, and vacuum is applied to 10 deg.C^-3Torr, introducing inert gas, heating the substrate to 300 ℃ and 700 ℃, and controlling the pressure of the inert gas to be 0.5-1.5 Torr. When the temperature is raised to the growth temperature, introducing a boron-nitrogen reaction source, starting a plasma power supply, enabling the power to be between 20 and 100W, ionizing and cracking the boron-nitrogen reaction source, reacting the active groups under the action of the plasma, connecting the active groups at the edge, generating a hexagonal boron nitride film 6 on the surface of the AlGaN barrier layer 5 on the surface of the substrate according to a nucleation-growth mode, and controlling the reaction time to be between 10 and 60 minutes. And after the reaction is finished, closing the plasma power, cooling, and taking out the sample when the temperature is reduced to the room temperature. The thickness of the hexagonal boron nitride film 6 is 1-20 nm. Hexagonal boron nitride (h-BN) is a layered hexagonal lattice nano material, in each atomic layer, N atoms and B atoms alternately form an infinitely extended hexagonal grid, and the B atoms and the N atoms are connected by sp2 hybridized covalent bonds; the layers are arranged along the C-axis direction according to an ABAB … mode, mainly under the action of van der Waals force, the molecular force is weak in combination and easy to break and separate. The hexagonal boron nitride can resist the high temperature of 2000 ℃.

Referring to fig. 1C, the hexagonal boron nitride film 6 is etched to form a first window a at a predetermined gate position. Specifically, a photoresist (not shown) having a second window is formed on the hexagonal boron nitride film 6; the patterned photoresist defines the position of a grid electrode, the photoresist is used as a mask, the hexagonal boron nitride film 6 is etched by utilizing plasma, the plasma forming power of Ar or He is 6-10kW, the bias voltage is 0-500V, and the plasma etching time is 10-100 s. And removing the photoresist after the etching is finished, and forming the hexagonal boron nitride film 6 in a patterning mode.

Referring to fig. 1D, a p-GaN layer 7 is deposited. The growth of the p-GaN layer 7 adopts an MOCVD mode, the temperature is raised to 900-₃And TGM gas, and Mg element with concentration of 5 × 10¹⁹cm^-3Controlling the time to be 5-10 min; in N₂And reducing the furnace temperature to 600 ℃ in the atmosphere, heating for 20min, activating the conductivity of Mg, reducing the furnace temperature to 150 ℃ for 30min, and finishing the cooling operation. The thickness of the obtained p-GaN layer 7 is 50-100 nm. p-GaN material is deposited on the surface of the AlGaN barrier layer 5 and the surface of the hexagonal boron nitride film 6 of the first window a.

Referring to fig. 1E and 1F, a layer of adhesive tape 8 is adhered to the surface of the above structure, and the adhesion of the adhesive tape is utilized to resist the van der waals force between the hexagonal boron nitride layers, so that the layer structure of the hexagonal boron nitride is easily separated by horizontal slip between the atomic layers under the action of mechanical external force when the adhesive tape 8 is torn, the hexagonal boron nitride film 6 and the p-GaN layer 7 thereon are peeled off, and the p-GaN layer 7 in the first window a is remained to form the p-type gate layer 71.

Referring to fig. 1G, a photolithography process is used to define the source and drain metal regions, metal deposition is performed to form an ohmic electrode, and annealing is performed to fabricate a source metal 9 and a drain metal 10 on the surface of the AlGaN barrier layer 5.

Referring to fig. 1H, a dielectric layer 11 having a passivation effect is deposited, and isolation is formed by ion implantation or mesa etching.

Referring to fig. 1I, a gate region is defined by a photolithography process, a dielectric layer 11 is etched to form an opening above the p-type gate layer 71, and a gate metal 12 in contact with the p-type gate layer 71 is formed in the opening.

Referring to 1J, a source and drain electrode area is defined by adopting a photoetching process, and the medium layer 11 is etched to open holes in the source and drain electrode metal area, so that a basic device structure is completed.

The p-GaN layer may be a p-type nitride layer made of other materials such as p-AlGaN, p-InGaN, or p-InAlGaN. The hexagonal boron nitride film can also be a layered nanometer material layer formed by other layered nanometer materials such as a graphene-like two-dimensional nanometer material. The method for stripping the layered nano material layer can also be a mechanical stripping method such as a plasma etching method, a ball milling method, a fluid stripping method and the like, and a chemical stripping method such as a liquid phase ultrasonic method, a chemical functionalization method, an ion insertion stripping method and the like.

The above embodiments are only used to further illustrate a method for fabricating an enhanced gan power device of the present invention, but the present invention is not limited to the embodiments, and any simple modification, equivalent change and modification made to the above embodiments according to the technical spirit of the present invention fall within the protection scope of the technical solution of the present invention.