阅读说明：本技术 基于ScAlMgO4衬底的氮化镓单晶及其制备方法 (Based on ScAlMgO4Gallium nitride single crystal of substrate and method for producing same ) 是由 张海涛 许彬 庞博 刘良宏 于 2020-06-02 设计创作，主要内容包括：本发明提供基于ScAlMgO<Sub>4</Sub>衬底的氮化镓单晶制备方法,包括如下步骤：(1)提供ScAlMgO<Sub>4</Sub>衬底；(2)在所述ScAlMgO<Sub>4</Sub>衬底表面进行缓冲层生长；(3)所述缓冲层进行退火处理；(4)于所述缓冲层上生长GaN晶体；(5)降温,GaN晶体自所述ScAlMgO<Sub>4</Sub>衬底自动剥离。本发明不需要使用复杂的MOCVD沉积GaN并预处理以制作掩模或分离层的工艺,有效降低了生产成本；相比于传统衬底如蓝宝石,具有更高的质量与更大的曲率半径,对于生长4英寸以上的GaN来说,不会造成OFFCUT不均匀的问题；最后,本发明可以实现连续生长成厚度高达5毫米以上的晶棒,进一步降低了成本。(The invention provides a method for preparing a semiconductor device based on ScAlMgO 4 The preparation method of the gallium nitride single crystal of the substrate comprises the following steps: (1) providing ScAlMgO 4 A substrate; (2) in the ScAlMgO 4 Carrying out buffer layer growth on the surface of the substrate; (3) annealing the buffer layer; (4) growing a GaN crystal on the buffer layer; (5) cooling, GaN crystal from the ScAlMgO 4 The substrate is automatically peeled off. The invention does not need a complex process of depositing GaN by MOCVD and preprocessing the GaN to manufacture the mask or the separation layer, thereby effectively reducing the production cost; compared with a traditional substrate such as sapphire, the GaN-based substrate has higher quality and larger curvature radius, and does not cause the problem of nonuniform OFFCUT for growing GaN of more than 4 inches; finally, the invention can realize continuous growth of crystal bars with the thickness of more than 5 mm, thereby further reducing the cost.)

1. A kind ofBased on ScAlMgO₄The method for preparing the gallium nitride single crystal of the substrate is characterized by comprising the following steps of:

(1) providing ScAlMgO₄A substrate;

(2) in the ScAlMgO₄Carrying out buffer layer growth on the surface of the substrate;

(3) annealing the buffer layer;

(4) growing a GaN crystal on the buffer layer;

(5) cooling, GaN crystal from the ScAlMgO₄The substrate is automatically peeled off.

2. ScAlMgO-based coating according to claim 1₄The preparation method of the gallium nitride single crystal of the substrate is characterized in that the ScAlMgO₄The substrate is circular or regular hexagonal.

3. ScalMgO-based optical device according to claim 2₄The preparation method of the gallium nitride single crystal of the substrate is characterized in that the ScAlMgO₄The surface of the substrate is polished to form an atomic layer surface, the surface roughness is not more than 0.5nm, and the c-plane OFFCUT is 0-1.5 degrees.

4. ScAlMgO-based coating according to claim 1₄The preparation method of the gallium nitride single crystal of the substrate is characterized in that a low-temperature AlN sputtering method is adopted for the growth of the buffer layer in the step (2), the temperature is set to be 300-800 ℃, the AlN thickness is 10-300 nm, and the buffer layer is subjected to high-temperature annealing treatment in the H2/N2 environment in the step (3).

5. ScAlMgO-based coating according to claim 1₄The preparation method of the gallium nitride single crystal of the substrate is characterized in that the buffer layer in the step (2) grows into an AlN thin film template which grows by adopting an MOCVD method, and the thickness of the AlN thin film template is 1-10 mu m.

6. ScAlMgO-based coating according to claim 1₄The preparation method of the gallium nitride single crystal of the substrate is characterized in that the growth of the buffer layer in the step (2) adopts high temperatureAnd (3) setting the AlN HVPE method at 1000-1600 ℃ and 50-3000 nm in thickness, and carrying out high-temperature 1600-1700 ℃ reduction or annealing treatment in an inert environment in the step (3).

7. ScAlMgO-based coating according to claim 1₄The preparation method of the gallium nitride single crystal of the substrate is characterized in that the buffer layer in the step (2) grows by adopting a low-temperature GaN HVPE method, the temperature is set to be 300-800 ℃, the thickness is about 20-500 nm, and annealing treatment at 950-1100 ℃ is carried out in the step (3).

8. ScAlMgO-based coating according to claim 1₄The preparation method of the gallium nitride single crystal of the substrate is characterized by also comprising the step of carrying out treatment on the ScAlMgO between the step (3) and the step (4)₄And carrying out low-temperature AlN sputtering deposition treatment on the bottom surface and the side surface of the substrate, wherein the temperature is set to be 300-800 ℃, and the thickness is not more than 50 nm.

9. ScAlMgO-based coating according to claim 1₄The preparation method of the gallium nitride single crystal of the substrate is characterized in that the HVPE method is adopted in the step (4), and further the method for maintaining the continuous growth and the appearance of the GaN single crystal thick film comprises the following steps:

continuously increasing the temperature by 1-10 ℃ every time the GaN monocrystal thick film grows for 1 mm;

continuously adding NH 3; the increase amplitude is 5 to 50 percent of the increase of NH3 (or corresponding V/III) when the GaN single crystal thick film grows by 1 mm.

10. Based on ScAlMgO₄Gallium nitride single crystal on a substrate, characterized in that it is based on ScAlMgO₄The gallium nitride single crystal of the substrate is produced by the production method according to any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of semiconductors, in particular to a semiconductor device based on ScAlMgO₄Gallium nitride single crystal of a substrate and a method for producing the same.

Background

GaN is a typical representative of third-generation wide bandgap semiconductors, has been widely used in semiconductor illumination, microwave power devices, power electronic devices, and the like, and shows great application prospects. The most ideal substrate for gallium nitride growth is naturally gallium nitride single crystal material, and such homoepitaxy (i.e. the epitaxial layer and the substrate are the same material) can greatly improve the crystal quality of the epitaxial film, reduce the dislocation density, prolong the service life of the device, improve the luminous efficiency and improve the working current density of the device. However, the gallium nitride single crystal growth is difficult and expensive, and large-scale homoepitaxial growth is not possible at present. Therefore, at present, heteroepitaxy is still adopted in the preparation of gallium nitride single crystals, such as silicon substrates, sapphire substrates, silicon carbide substrates and the like.

Currently, substantially all commercial GaN substrates (wafers, substrates) are fabricated by HVPE. But their size is still typically limited to 2 inches, with larger sizes such as 4 inches being limited by the radius of curvature. In HVPE, however, due to heteroepitaxy, the stress caused by the lattice constant and the thermal expansion coefficient causes gallium nitride to crack when grown thick or when cooled.

The existing solution is to grow several microns of GaN thin film on the sapphire surface by using MOCVD and carry out interface treatment to form various masks, on one hand, the initial defect during growth is reduced and a stress yielding type substrate is formed, so that the critical thickness of GaN growth is as large as possible, such as several hundred microns or even several millimeters; another aspect is to create a weak interface that can cause self-peeling of GaN and sapphire or other substrates due to shear stress induced by the difference in the number of thermal expansions at the cool down. The essence of the method is that the transition layer is inserted into the interface of the foreign substrate, so as to achieve the purpose of reducing dislocation and stress during growth, and the grown gallium nitride is easy to be stripped from the substrate such as sapphire during cooling.

However, such methods have disadvantages: the HVPE based on sapphire adopts a heterogeneous material with a lattice mismatch constant of-13.9%, so that the dislocation of the grown gallium nitride crystal is high, the expansion to 4 inches is limited due to the stress curvature radius of below 10 meters, the stripping and dislocation reduction process is complex, the yield is low, and finally, the production cost is too high only by adopting a single-chip method.

Disclosure of Invention

Aiming at the problems and the defects of the prior art, the invention makes research and improvement and provides a method based on ScAlMgO₄The invention relates to a gallium nitride single crystal of a substrate and a preparation method thereof, wherein ScAlMgO with a lattice constant very close to that of GaN is adopted₄As a substrate for HVPE growth, ScAlMgO was used₄Depositing a buffer layer on the substrate, and obtaining the dislocation density at 1E6cm during growth^-2The following GaN crystal.

Specifically, the ScAlMgO-based material provided by the invention₄The preparation method of the gallium nitride single crystal of the substrate comprises the following steps:

(1) providing ScAlMgO₄A substrate;

(2) in the ScAlMgO₄Carrying out buffer layer growth on the surface of the substrate;

(3) annealing the buffer layer;

(4) growing a GaN crystal on the buffer layer;

(5) cooling, GaN crystal from the ScAlMgO₄The substrate is automatically peeled off.

In a preferred embodiment of the present invention, the ScAlMgO layer is formed of ScAlMgO₄The substrate is circular or regular hexagonal.

In a preferred embodiment of the present invention, the ScAlMgO layer is formed of ScAlMgO₄The surface of the substrate is polished to form an atomic layer surface, the surface roughness is not more than 0.5nm, and the c-plane OFFCUT is 0-1.5 degrees.

Preferably, in the step (2), a low-temperature AlN sputtering method is adopted for the growth of the buffer layer, the temperature is set to be 300-800 ℃, the AlN thickness is 10-300 nm, and in the step (3), the buffer layer is subjected to high-temperature annealing treatment in an H2/N2 environment.

As a preferable setting of the invention, the growth of the buffer layer in the step (2) is an AlN thin film template grown by an MOCVD method, and the thickness is 1-10 um.

As a preferable setting of the invention, the buffer layer in the step (2) grows by adopting a high-temperature AlNHVPE method, the temperature is set to be 1000-1600 ℃, the thickness is 50-3000 nm, and the buffer layer is subjected to high-temperature 1600-1700 ℃ reduction or annealing treatment in an inert environment in the step (3).

As a preferable setting of the invention, the buffer layer in the step (2) grows by adopting a low-temperature GaNHVP E method, the temperature is set to be 300-800 ℃, the thickness is about 20-500 nm, and the annealing treatment at 950-1100 ℃ is carried out in the step (3).

As a preferable arrangement of the invention, the ScAlMg O is added between the step (3) and the step (4)₄And carrying out low-temperature AlN sputtering deposition treatment on the bottom surface and the side surface of the substrate, wherein the temperature is set to be 300-800 ℃, and the thickness is not more than 50 nm.

As a preferred arrangement of the invention, step (4) adopts HVPE method, further includes maintaining the continuous growth and morphology of the GaN single crystal thick film:

continuously increasing the temperature by 1-10 ℃ every time the GaN monocrystal thick film grows for 1 mm;

continuously adding NH 3; the increase amplitude is 5 to 50 percent of the increase of each 1mmNH3 (or corresponding V/III) of the GaN single crystal thick film.

The invention also provides a method for preparing the ScAlMgO-based material₄Gallium nitride single crystal of substrate, said ScAlMgO-based₄The gallium nitride single crystal of the substrate is produced by the production method according to any one of claims 1 to 9.

The invention has the beneficial effects that: firstly, the dislocation of the crystal grown by the process provided by the invention is effectively reduced; secondly, the invention does not need a complex process of depositing GaN by MOCVD and preprocessing the GaN to manufacture a mask or a separation layer, thereby effectively reducing the production cost; thirdly, compared with the traditional substrate such as sapphire, the invention has higher quality and larger curvature radius, and the problem of nonuniform OFFCUT can not be caused for growing GaN of more than 4 inches; finally, the invention can realize continuous growth of crystal bars with the thickness of more than 5 mm, thereby further reducing the cost.

Drawings

FIG. 1 is a flow chart of the production process of the present invention.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

It should be noted that the drawings provided in the present embodiment are only schematic and illustrate the basic idea of the present invention, and although the drawings only show the components related to the present invention and are not drawn according to the number, shape and size of the components in actual implementation, the form, quantity and proportion of the components in actual implementation may be changed arbitrarily, and the layout of the components may be more complicated.