CN211062722U - Semiconductor epitaxial device with modified substrate - Google Patents

Abstract

A semiconductor epitaxial device with a modified substrate comprises a substrate, an oxide layer, a carbide layer and a gallium nitride epitaxial layer, wherein the oxide layer is arranged on the substrate, the carbide layer is arranged on the oxide layer, and the gallium nitride epitaxial layer is arranged on the carbide layer. According to this, the semiconductor epitaxial device with a modified substrate can improve the lattice matching of the gallium nitride epitaxial layer by modifying the substrate at a low cost, and significantly improve the defects on the surface of the epitaxial lattice, so as to grow a gallium nitride epitaxial layer with high epitaxial lattice quality and a flat surface.

Description

Semiconductor epitaxial device with modified substrate

technical field

The utility model relates to the technical field of semiconductor epitaxy, in particular to a semiconductor epitaxy device with a modified substrate.

Background technique

Gallium Nitride (GaN) materials have become more and more widely used in the semiconductor field, and have now developed into one of the trends of future radio frequency and high-power devices. Therefore, the epitaxial quality requirements of gallium nitride are becoming more and more strict, and the defect in the epitaxial technology of gallium nitride is that for the epitaxial materials, the three-fifth group elements will bring higher epitaxial crystals under the condition of high five-to-three ratio. However, the surface of the formed epitaxial lattice of gallium nitride is very rough; on the contrary, under the condition of low five-to-three ratio, although the quality of the epitaxial lattice of gallium nitride is poor, a flat nitride can be obtained. Epitaxial lattice surface of gallium.

In order to achieve the performance of low defects and high electron mobility on the surface of the epitaxial lattice, the current technology will choose silicon carbide (SiC) as the substrate, but the price of the silicon carbide substrate is high, so the product market is still based on cost Inexpensive silicon substrates are the mainstream, but the lattice compatibility between silicon substrates and Group III and V elements is poor, and defects are likely to occur on the surface of the lattice during the epitaxy process, making it difficult to grow high-quality GaN epitaxy device.

Utility model content

According to the problems disclosed in the prior art, the present invention mainly utilizes a low-cost silicon substrate, carbonizes the surface of the silicon substrate to form a semiconductor epitaxial device with a modified substrate, and grows nitrogen on the modified substrate The gallium nitride epitaxial layer can achieve the advantages of high epitaxial lattice quality and flat surface of the epitaxial lattice.

According to the above purpose, the present invention provides a semiconductor epitaxial device with a modified substrate, comprising a substrate, an oxide layer, a carbide layer and a gallium nitride epitaxial layer, wherein the substrate is silicon and the oxide layer is silicon oxide. On the substrate, a silicon carbide layer is provided on the oxide layer, and a gallium nitride epitaxial layer is provided on the carbide layer. Accordingly, the semiconductor epitaxial device with modified substrate can improve the lattice matching of the gallium nitride epitaxial layer by modifying the low-cost substrate, and significantly improve the defects on the surface of the epitaxial lattice, so as to grow the epitaxial crystal. GaN epitaxial layers with high lattice quality and flat surfaces.

Description of drawings

1-3 are schematic diagrams showing the steps of forming a semiconductor epitaxial device with a modified substrate according to the technology of the present invention.

4 is a flow chart showing the steps of forming a semiconductor epitaxial device with a modified substrate according to the technology of the present invention.

Detailed ways

In order to make the purpose, technical features and advantages of the present utility model more understandable to those in the relevant technical field and to implement the present utility model, the technical features and implementations of the present utility model are explained in detail here in conjunction with the accompanying drawings. , and further illustrate the preferred embodiments. The drawings contrasted in the following text are schematic representations related to the features of the present invention, and do not and do not need to be completely drawn according to the actual situation. The description about the embodiments of the present application involves technical contents well known to those skilled in the art, and will not be described again.

First, please refer to Figure 1 to Figure 3 . 1 to 3 are schematic views showing steps of forming a semiconductor epitaxial device with a modified substrate. In FIG. 1 , the substrate 10 is provided first. In the present invention, in order to save the manufacturing cost, the substrate 10 is preferably a silicon (Si) substrate. Next, an oxide layer 20 is grown on the substrate 10 , and the oxide layer 20 is silicon oxide (SiO _x ), preferably silicon dioxide (SiO ₂ ). In the present invention, the thickness of the oxide layer 20 is 100nm-2000nm.

Next, please refer to FIG. 2 . A carbide layer 30 is grown on the structure formed in FIG. 1 to form a modified substrate. In the present invention, the carbide layer 30 is preferably silicon carbide in order to achieve the performance of low defects and high electronic mobility on the surface of the epitaxial lattice. In the present invention, the thickness of the carbide layer 30 ranges from 50 nm to 2000 nm.

Please refer to Figure 3 next. Using general epitaxial technology, a gallium nitride epitaxial layer 40 is grown on the modified substrate formed in FIG. 2 , wherein the gallium nitride epitaxial layer 40 is made of gallium nitride, aluminum gallium nitride, indium gallium nitride or aluminum nitride Indium gallium is used as the main material, and the gallium nitride epitaxial layer 40 can be a single-layer structure or a multi-layer structure. The five-to-three ratio of gallium nitride refers to a multi-layer structure in which the gallium nitride epitaxial layer 40 gradually changes from a large five-to-three ratio to a small five-to-three ratio from the bottom layer to the upper layer. In the present invention, the thickness of the carbide layer 30 ranges from 500 nm to 6000 nm.

In addition, according to the above-mentioned FIGS. 1 to 3 , the present invention also provides a flowchart of the steps of forming a semiconductor epitaxial device with a modified substrate in FIG. 4 . In step 50, a substrate 10 is provided, wherein the substrate 10 is silicon. Step 52 , growing the oxide layer 20 on the substrate 10 to form the oxide layer 20 of silicon dioxide through thermal oxidation reaction. The process includes chemical vapor deposition method or physical vapor deposition method, but is not limited thereto. In step 54, a carbide layer 30 is grown on the oxide layer 20, and a silicon carbide carbide layer 30 is formed by carbonizing silicon dioxide. The method of carbonizing the silicon dioxide includes introducing a carbon-containing precursor gas such as methane and ethane at a high temperature of 1000° C., and growing a carbonized carbonized layer 30 on the oxide layer 20 by a low pressure chemical vapor deposition method, but not limited to this. The modification of the substrate 10 is completed through steps 50 , 52 and 54 . The modified substrate includes the substrate 10 , the oxide layer 20 , and the carbide layer 30 from bottom to top. After step 56, an epitaxial process is performed to form the gallium nitride epitaxial layer 40 on the carbide layer 30; the epitaxial process includes chemical vapor deposition or physical vapor deposition, but is not limited thereto. The structures and functions of the above-mentioned layers have been disclosed in FIG. 1 to FIG. 3 and will not be further described.

Therefore, according to the above, the present invention utilizes a low-cost silicon substrate to carbonize the surface of the silicon substrate to form a modified substrate. The surface of the modified substrate is silicon carbide, which can improve the performance of the gallium nitride epitaxial layer. Lattice compatibility, significantly improve the defects on the surface of the epitaxial lattice, and grow high-quality gallium nitride epitaxial layers. Moreover, silicon carbide has better electron mobility than silicon, and the electron mobility can be increased to 1.2 to 1.5 times that of the silicon substrate.

Claims (9)

1. a semiconductor epitaxial device with modified substrate, is characterized in that, comprises: substrate; an oxide layer, the oxide layer is disposed on the substrate; a carbonized layer disposed on the oxide layer; and A gallium nitride epitaxial layer, the gallium nitride epitaxial layer is disposed on the carbide layer. 2 . The semiconductor epitaxial device with a modified substrate according to claim 1 , wherein the substrate is silicon. 3 . 3 . The semiconductor epitaxial device with a modified substrate according to claim 1 , wherein the oxide layer is an oxide of silicon. 4 . 4. The semiconductor epitaxial device with a modified substrate according to claim 1, wherein the carbide layer is silicon carbide. 5 . The semiconductor epitaxial device with a modified substrate according to claim 1 , wherein the gallium nitride epitaxial layer has a single-layer structure. 6 . 6 . The semiconductor epitaxial device with a modified substrate according to claim 1 , wherein the gallium nitride epitaxial layer is a multi-layer structure, and the multi-layer structure has different five-to-three ratios. 7 . 7 . The semiconductor epitaxial device with a modified substrate according to claim 1 , wherein the thickness of the oxide layer is 100 nm-2000 nm. 8 . 8 . The semiconductor epitaxial device with a modified substrate according to claim 1 , wherein the thickness of the carbide layer is 50 nm-2000 nm. 9 . 9 . The semiconductor epitaxial device with a modified substrate according to claim 1 , wherein the thickness of the gallium nitride epitaxial layer is 500 nm-6000 nm. 10 .

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