Novel silicon carbide (SiC) small-angle tilting table terminal structure and preparation method thereof

Abstract

The invention provides a novel silicon carbide (SiC) small-angle tilting table terminal structure applicable to SiC large-sized high-voltage device terminal structures and a preparation method thereof. Such high-voltage devices include SiC GTO, SiC PiN and other SiC devices that adopt the small-angle tilting table terminal structure; and an etching technology of the invention uses an AZ4620 thickphotoresist as a mask mode and achieves uniform reflux of the large-area photoresist, and based on different reflux conditions of the photoresist, a base angle of an etched SiC small-angle tilting table can be between 0 degree and 20 degrees. As different types of devices have different etching depths on the tilting table, the etching technology can be used to prepare a single tilting table etching terminal structure, or can be used for multiple times to form a multi-stage tilting table etching terminal structure. Compared with other multi-table terminal etching scheme processes, the scheme ofthe invention can be significantly simplified, and as the scheme is an ideal slope, the suppression effect of the scheme on the edge field intensity aggregation of the devices is theoretically superior to other approximation schemes.

Description

technical field [0001] The invention relates to a novel silicon carbide small-angle inclined mesa terminal structure applicable to silicon carbide large-scale high-voltage devices and a preparation method thereof, belonging to the technical field of semiconductor power electronic devices. Background technique [0002] Wide bandgap semiconductor materials represented by silicon carbide (SiC) materials are new third-generation semiconductor materials that have been widely valued and developed at home and abroad in recent years. They have large bandgap width, high electron saturation drift speed, critical With strong breakdown field, radiation resistance and high working temperature, the current epitaxial growth technology of SiC material is relatively mature among wide bandgap semiconductor materials, and it is very suitable for preparing various power electronic devices with excellent performance. . [0003] Compared with traditional silicon materials, SiC material as a wide...

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Problems solved by technology

[0007] Although there have been no related reports on SiC GTO devices using a truly ideal negative-tilt terminal structure at home and abroad, there are some reports on the inclined mesa etching of SiC materials in the technical scheme of SiC avalanche photodetectors (APDs). Photoresist reflow method

However, it is a huge challenge to successfully apply some experience in the field of detectors to the terminal design of GTO power devices.

The first is the problem of whether the photoresist can be uniformly reflowed due to the huge difference in device size. At present, the typical device size of SiC APD is hundreds of microns, while the typical size of GTO devices is millimeter or even centimeter. The size of a single GTO device is APD The second is the significant difference in etching depth. Due to the limited mask blocking ability of photoresist, it is relatively easy to achieve a mesa etching depth of about 1 μm for APD devices, and at least 4 μm for typical GTO devices. It is more difficult to realize the etching depth

The core of photoresist reflow technology is to use photoresist instead of metal or oxide as a blocking mask. The two problems of device area and etching depth lead to the development of small-angle inclined mesa terminations that can be applied to SiC GTO devices. structure is very difficult

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