SiC secondary epitaxial structure

Abstract

The invention discloses a silicon carbide secondary epitaxial material structure used for the preparation of silicon carbide devices, comprising: a silicon carbide single crystal substrate, a primary homoepitaxial layer located on the surface of the substrate, and a primary homoepitaxial layer located on the surface of the primary homoepitaxial layer The secondary epitaxial layer, wherein the primary homoepitaxial layer includes a p-type silicon carbide buffer layer, an n-type silicon carbide active layer and an unintentionally doped intrinsic silicon carbide layer. Compared with the MESFET (Metal Field Effect Transistor) with a general structure, the MESFET prepared by the secondary epitaxial method has the advantages of small source-drain resistance, large ohmic contact area, and uniform electric field distribution in the working area of ​​the tube, which can improve transconductance. Increase the working voltage and power of the device. At the same time, the process of device preparation is greatly simplified and the stability of the device is guaranteed.

Description

technical field [0001] The invention relates to a silicon carbide secondary epitaxy structure, in particular to a silicon carbide secondary epitaxy structure which can shorten the process flow and improve the performance of silicon carbide devices. Background technique [0002] Silicon carbide material is one of the representative materials of the third-generation semiconductor. Compared with the first-generation semiconductor element material represented by silicon and the second-generation compound semiconductor material represented by gallium arsenide, silicon carbide has a wide band gap and high critical mass. Breakdown electric field, high carrier saturation drift velocity, high thermal conductivity and other characteristics. Specifically, taking 4H-SiC as an example, at 300K (27°C), the forbidden band width of silicon carbide is 3.2eV, which is much wider than 1.12eV of silicon and 1.43eV of gallium arsenide. In this way, the operating temperature of silicon carbide m...

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Problems solved by technology

[0004] 1. The depth of ion implantation in silicon carbide is shallow, the activation rate of implanted ions is very low, and the implantation efficiency is low, which makes it difficult to apply this common and important process in semiconductor preparation

[0005] 2. There is no practical wet etching process in the device processing technology, only dry etching process can be used

[0007] 1. Dry etching will cause damage, resulting in a decrease in carrier mobility that is critical to device performance, a decrease in crystal quality, and degradation of material properties, ultimately affecting device performance

[0008] 2. The length of the process flow is increased, resulting in a decrease in the final yield

[0009] 3. Increased equipment cost and process cost

Since the influence of thermal stress is reduced, and silicon carbide materials have very high thermal conductivity and good oxidation resistance, the thermal stability of devices using silicon carbide structures will be greatly improved. However, if unintentional Doped intrinsic silicon carbide layer, the source and drain of conventional MESFET (Metal Field Effect Transistor) devices are difficult to lead out

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