Silicon carbide power device having step structure and fabrication method of silicon carbide power device

Abstract

The invention discloses a silicon carbide power device having a step structure and a fabrication method of the silicon carbide power device. The silicon carbide power device comprises an ohmic contactelectrode, an N<+>SiC substrate layer, an N<->SiC epitaxial layer and a Schottky contact electrode from bottom to top and also comprises a plurality of P-type junction terminals, wherein the Schottkycontact electrode is arranged in the center of the N<->SiC epitaxial layer, the P-type junction terminals are of closed-loop structures and are sequentially arranged around the Schottky contact electrode in an encircling way, an edge of an upper surface of the N<->SiC epitaxial layer is lower than an annular step formed in the center, the P-type junction terminals are arranged on a high step surface and a lower step surface of the annular step of the N<->SiC epitaxial layer, and the P-type junction terminals and the N<->SiC epitaxial layer form a PN heterojunction. By the silicon carbide power device, the concentration phenomenon of an edge electric field of a SiC power device junction can be improved, and the SiC power device with a high breakdown voltage is obtained.

Description

technical field [0001] The invention relates to a semiconductor device, in particular to a silicon carbide power device with a stepped structure and a preparation method thereof. Background technique [0002] Power devices based on wide-bandgap semiconductor materials (such as silicon carbide (SiC), gallium nitride (GaN)) can provide greater breakdown voltage and power density, and are expected to be widely used in next-generation power conversion. In SiC power devices, due to the discontinuity of the junction, the electric force lines tend to concentrate at the edge of the junction, resulting in the existence of a high electric field at the junction edge. The presence of a high field will lead to premature breakdown at the junction edge, which greatly limits the reverse breakdown voltage of the device. Therefore, in the design and manufacture of SiC power devices, various junction termination technologies are often used to alleviate the edge electric field concentration ef...

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Problems solved by technology

Among them, epitaxial growth is to directly grow P-type SiC on the entire surface of N-type SiC layer. Since the growth temperature of P-type SiC is often high (>1500°C), some P-type impurities (such as Al) will inevitably diffuse during the growth process. In weak N-type SiC, self-doping is formed on the surface of N-type SiC, and even the area is converted into P-type, which leads to changes in the doping characteristics of the N-type SiC surface, which in turn affects the acquisition of low device turn-on voltage; P for SiC Type ion implantation often requires advanced equipment such as high-temperature ion implanters and ultra-high temperature annealing furnaces to complete, and has complex manufacturing processes and high costs, which restricts its industrial development

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