Silicon carbide MPS diode with buried layer structure and preparation method thereof

Abstract

The silicon carbide MPS diode comprises a cathode ohmic contact electrode, a silicon carbide N + substrate and a silicon carbide N-epitaxial layer which are laminated from bottom to top, two P + injection regions are formed at the top of the silicon carbide N-epitaxial layer, the two P + injection regions are respectively contacted with the tops of the two P + buried layers I through the two P + buried layers II, and the widths of the P + injection regions and the P + buried layers I are greater than those of the P + buried layers II; two ohmic contact electrodes are arranged at the tops of the two P + injection regions, and a Schottky contact electrode is arranged between the two ohmic contact electrodes. The P + injection region and the P + buried layer I are connected through the narrow P + buried layer II, the proportion of PN junctions is increased in the epitaxial layer, and the snapback phenomenon during forward conduction of the MPS diode is eliminated; and meanwhile, the breakover voltage of the MPS diode from a unipolar working state to a bipolar working state is reduced, so that the diode enters the bipolar working state under a relatively low forward current, the high-current working temperature of the diode is reduced, and higher surge current resistance is achieved.

Description

technical field [0001] The invention belongs to the technical field of semiconductors, and more specifically, the invention relates to a silicon carbide MPS diode with a buried layer structure and a preparation method thereof. Background technique [0002] The third-generation wide-bandgap semiconductor material silicon carbide relies on its excellent material physical and electrical properties. For example, compared with silicon (Si) materials, silicon carbide (4H-SiC) has a wide band gap (3 times that of Si) and high electron saturation. Significant advantages such as drift speed (2.5 times that of Si), high thermal conductivity (3.3 times that of Si), high critical breakdown electric field (10 times that of Si), can operate at high power density, high frequency and high temperature, and conduct The loss during switching and switching is also lower, especially suitable for the preparation of semiconductor power devices with high voltage resistance, high power, radiation re...

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Problems solved by technology

In order to ensure that the working current under normal operation meets the requirements, usually the PN junction area accounts for a small proportion of the total chip area. Due to the small proportion of the PN junction area to the total chip area, the PN junction conduction voltage is large, and the PN junction is under the impact of surge current. The junction is not conducting, causing the diode to fail prematurely

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