CN107516673A - GaN semiconductor device and its preparation method and application - Google Patents

Abstract

The invention discloses a GaN semiconductor device, comprising: a substrate; a seed layer arranged on the substrate; a buffer layer arranged on the seed layer; and the gallium nitride arranged on the buffer layer layer; an AlxGaN1-xN layer disposed on the gallium nitride layer; the AlxGaN1-xN layer includes a first aluminum gallium nitride layer, an aluminum nitride layer and a second layer stacked on the gallium nitride layer in sequence AlGaN layer. The structure of the above-mentioned GaN semiconductor device, when growing a two-dimensional electron gas (2DEG) aluminum gallium nitride thin film, effectively utilizes the aluminum gallium nitride/aluminum nitride/aluminum gallium nitride composite film as an inserted thin film structure; it can be effectively controlled at The remaining thickness of AlGaN in the subsequent etching process for the gate contact improves the dispersion problem in the characteristics of the transistor (MISFET Transistor).

Description

GaN semiconductor device and its preparation method and application

technical field

The invention relates to the technical field of semiconductors, in particular to a GaN semiconductor device and its preparation method and application.

Background technique

The power semiconductor market occupies a huge market of 10% of the entire semiconductor market, but the previous power semiconductor market was dominated by power devices using silicon. In the past 20 years, every 10 years, the power density of silicon power devices has increased by 5 to 6 times, and it is difficult to expect further improvements in performance.

Compared with silicon and gallium arsenide, gallium nitride has the characteristics of wide band gap (Eg=3.4eV) and stability at high temperature (700°C). Compared with silicon power semiconductors, gallium nitride power semiconductors have low-temperature resistance characteristics, which can not only reduce the loss of gates caused by power semiconductors, but also minimize system power consumption. Relying on the miniaturization of GaN semiconductor devices, high voltage, and high-speed gates, low-loss, high-efficiency next-generation power devices can be realized, which can meet the needs of industries, power grids, and information and communication departments.

However, because gallium nitride power semiconductors have a constant shutdown problem, gallium nitride power semiconductors cannot be used alone during the period, and must be used together with silicon power devices. In this way, use a positive electrode structure that has the same function as the normally open operation.

Normally-on gallium nitride semiconductors are under development, and the activity of gallium nitride high electron mobility transistors contained in the gallium nitride epitaxial layer structure is also gradually increasing.

In order to reflect the breakdown voltage in GaN power devices and to grow high-quality GaN layers; after growing seed layers such as aluminum nitride on silicon substrates, improving the quality of the buffer layer plays an important role. important role. That is, the quality and Management is important.

Contents of the invention

Based on this, the object of the present invention is to provide a structure of a GaN semiconductor device.

The specific technical scheme is as follows:

A GaN semiconductor device, comprising:

Substrate;

a seed layer disposed on the substrate;

a buffer layer disposed on the seed layer;

the gallium nitride layer disposed on the buffer layer;

an AlxGaN1-xN layer disposed on the gallium nitride layer;

The AlxGaN1-xN layer includes a first aluminum gallium nitride layer, an aluminum nitride layer and a second aluminum gallium nitride layer stacked on the gallium nitride layer in sequence.

In some embodiments, the aluminum content in the second AlGaN layer is less than or equal to the aluminum content in the first AlGaN layer.

In some of these embodiments, where 0<x<1.

In some of the embodiments, the thickness of the AlxGa1-xN layer is 3nm-50nm.

In some of these embodiments, the material of the seed layer is aluminum nitride, gallium nitride or aluminum gallium nitride.

In some of the embodiments, the material of the buffer layer is aluminum nitride, gallium nitride or aluminum gallium nitride.

In some of these embodiments, the gallium nitride layer is a carbon-deposited gallium nitride layer, a non-doped gallium nitride layer or a composite layer, and the composite layer is a multi-layered carbon-deposited gallium nitride layer and a non-doped gallium nitride layer. Doped gallium nitride layer.

In some of the embodiments, the thickness of the seed crystal layer is 100nm-200nm; the thickness of the buffer layer is 0.5um-10um; the thickness of the gallium nitride layer is 0.1um-1um.

Another object of the present invention is to provide a method for fabricating the above-mentioned GaN semiconductor device.

The preparation method of the above-mentioned GaN semiconductor device includes the following steps:

Get the substrate;

forming a seed layer on the substrate;

forming a buffer layer on the seed layer;

forming a gallium nitride layer on the buffer layer;

forming an AlxGaN1-xN layer on the gallium nitride layer;

The AlxGaN1-xN layer includes a first aluminum gallium nitride layer, an aluminum nitride layer and a second aluminum gallium nitride layer stacked on the gallium nitride layer in sequence.

Another object of the present invention is to provide a semiconductor device including the above-mentioned GaN semiconductor device.

In order to reflect the breakdown voltage in GaN power devices and to grow high-quality GaN layers. In order to form a two-dimensional electron gas (2DEG) structure, use undoped gallium nitride/aluminum gallium nitride (u-GaN/AlGaN layer); in order to form a transistor (MISFET Transistor) structure, in the subsequent process, especially for the gate In the etching process of electrode contacts, the etching degree of AlGaN will cause the thickness difference of AlGaN after etching. This causes a problem of poor distribution of transistors (MISFET Transistors).

The structure of the above-mentioned GaN semiconductor device, when growing a two-dimensional electron gas (2DEG) aluminum gallium nitride thin film, the aluminum nitride thin film structure, that is, the composite of the first aluminum gallium nitride/aluminum nitride/second aluminum gallium nitride membrane. In the subsequent gate contact etching process, due to the poor etching amount of the aluminum gallium nitride film combined with the aluminum nitride film, when the second aluminum gallium nitride film is removed, the aluminum nitride film can perform the etching termination function, which can be controlled to a certain extent. The thickness of the first AlGaN layer improves the spread of MISFET transistor characteristics.

Description of drawings

Fig. 1 is the structure of existing GaN semiconductor device;

Fig. 2 is the situation that the aluminum gallium nitride layer is all etched in the existing GaN semiconductor device;

Fig. 3 is the situation that the AlGaN layer is partially etched in the existing GaN semiconductor device;

4 is a schematic structural view of a GaN semiconductor device according to an embodiment (101, substrate; 102, seed layer; 103, buffer layer; 104, gallium nitride layer; 105, first aluminum gallium nitride layer; 106, aluminum nitride layer; 107, the second aluminum gallium nitride layer);

Fig. 5 is the situation after the structure etching of GaN semiconductor device of an embodiment;

Figure 6 shows the etch rate curves of GaN, AlGaN, and AlN.

detailed description

In order to facilitate the understanding of the present invention, the following will describe the present invention more fully. However, the present invention can be embodied in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present invention more thorough and comprehensive.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field of the invention. The terms used herein in the description of the present invention are for the purpose of describing specific embodiments only, and are not intended to limit the present invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

A GaN semiconductor device, comprising:

Substrate 101;

a seed layer 102 disposed on the substrate;

It can be understood that the material of the seed layer 102 can be aluminum nitride, gallium nitride or aluminum gallium nitride;

a buffer layer 103 disposed on the seed layer 102;

It can be understood that the material of the buffer layer 103 can be aluminum nitride, gallium nitride or aluminum gallium nitride;

the gallium nitride layer 104 disposed on the buffer layer 103;

It can be understood that the gallium nitride layer 104 is a carbon-deposited gallium nitride layer, a non-doped gallium nitride layer or a composite layer, and the composite layer is a multi-layered carbon-deposited gallium nitride layer and a non-doped gallium nitride layer. gallium nitride layer;

an AlxGaN1-xN layer disposed on the gallium nitride layer; wherein 0<x<1;

The AlxGaN1-xN layer includes a first aluminum gallium nitride layer 105 , an aluminum nitride layer 106 and a second aluminum gallium nitride layer 107 sequentially stacked on the gallium nitride layer (as shown in FIG. 4 ).

The first AlGaN layer in contact with GaN is to form the 2DEG, and the second AlGaN layer in contact with the source/drain is to improve the source to AlGaN, drain to AlN Gallium contact capability.

The aluminum content in the second aluminum gallium nitride layer is less than or equal to the aluminum content in the first aluminum gallium nitride layer.

The preparation method of the above-mentioned GaN semiconductor device includes the following steps:

Get the substrate;

forming a seed layer on the substrate; the material of the seed layer can be selected from aluminum nitride AlN, gallium nitride GaN or aluminum gallium nitride AlGaN;

Process parameters are controlled at: temperature at 1000-1150°C, thickness at 100nm-200nm.

A buffer layer (buffer layer) is formed on the aluminum nitride seed layer; the material of the buffer layer can be selected from AlN, gallium nitride GaN or aluminum gallium nitride AlGaN, or a single film of gallium nitride or nitrogen AlGaN/GaN superlattice composition. Process parameters are controlled at a temperature of 1000-1150°C and a thickness of 0.5um-10um.

A gallium nitride layer (GaN layer) is formed on the buffer layer; the process parameters are controlled at a temperature of 1000-1150°C and a thickness of 0.1um-1um.

An AlxGaN1-xN layer is formed on the gallium nitride layer; the process parameters are controlled at a temperature of 1000-1150°C and a thickness of 3nm-50nm, and the Al content is 0<x<1.

The AlxGaN1-xN layer includes a first aluminum gallium nitride layer, an aluminum nitride layer and a second aluminum gallium nitride layer stacked on the gallium nitride layer in sequence, wherein the second aluminum gallium nitride layer The aluminum content is less than or equal to the aluminum content in the first aluminum gallium nitride layer.

The structure of the above-mentioned GaN semiconductor device, when growing a two-dimensional electron gas (2DEG) aluminum gallium nitride thin film, effectively utilizes the aluminum gallium nitride/aluminum nitride/aluminum gallium nitride composite film as an inserted thin film structure; it can be effectively controlled at The remaining AlGaN thickness (as shown in FIG. 5 and FIG. 6 ) in the subsequent etching process for the gate contact improves the dispersion problem in the characteristics of the transistor (MISFET Transistor).

The technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, should be considered as within the scope of this specification.

The above-mentioned embodiments only express several implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but should not be construed as limiting the patent scope of the invention. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (10)

1. A kind of 1. GaN semiconductor devices, it is characterised in that including：

   Substrate；

   The crystal seed layer being arranged on the substrate；

   The cushion being arranged on the crystal seed layer；

   The gallium nitride layer being arranged on the cushion；

   The AlxGaN1-xN layers being arranged on the gallium nitride layer；

   The AlxGa1-xN layers include stack gradually in the first aluminum gallium nitride layer on the gallium nitride layer, aln layer and Second aluminum gallium nitride layer.
2. 2. GaN semiconductor devices according to claim 1, it is characterised in that the aluminium in second aluminum gallium nitride layer contains The aluminium content that amount is less than or equal in first aluminum gallium nitride layer.
3. 3. GaN semiconductor devices according to claim 1 or 2, it is characterised in that wherein 0<x<1.
4. 4. GaN semiconductor devices according to claim 1 or 2, it is characterised in that the thickness of the AlxGa1-xN layers is 3nm~50nm.
5. 5. GaN semiconductor devices according to claim 1 or 2, it is characterised in that the material of the crystal seed layer is nitridation Aluminium, gallium nitride or aluminium gallium nitride alloy.
6. 6. GaN semiconductor devices according to claim 1 or 2, it is characterised in that the material of the cushion is nitridation Aluminium, gallium nitride or aluminium gallium nitride alloy.
7. 7. GaN semiconductor devices according to claim 1 or 2, it is characterised in that the gallium nitride layer nitrogenizes for Carbon deposition Gallium layer, undoped gallium nitride layer or composite bed, the composite bed are the Carbon deposition gallium nitride layer of multilayer interaction cascading and undoped Gallium nitride layer.
8. 8. GaN semiconductor devices according to claim 1 or 2, it is characterised in that the thickness of the crystal seed layer is 100nm ~200nm；The thickness of the cushion is 0.5um~10um；The thickness of the gallium nitride layer is 0.1um~1um.
9. 9. the preparation method of the GaN semiconductor devices described in claim any one of 1-8, it is characterised in that comprise the following steps：

   Obtain substrate；

   Crystal seed layer is formed on the substrate；

   Cushion is formed on the crystal seed layer；

   Gallium nitride layer is formed on the cushion；

   AlxGaN1-xN layers are formed on the gallium nitride layer；

   The AlxGaN1-xN layers include stack gradually in the first aluminum gallium nitride layer on the gallium nitride layer, aln layer and Second aluminum gallium nitride layer.
10. 10. a kind of semiconductor device, it is characterised in that including the GaN semiconductor devices described in claim any one of 1-8.