Reverse terminal structure of bidirectional withstand voltage power device based on step etching in drift region

Abstract

The invention belongs to the field of power semiconductor devices, and proposes a reverse terminal structure of a bidirectional withstand voltage power device based on stepwise etching of a drift region, including a semiconductor drift region of a first conductivity type and a semiconductor region of a second conductivity type below it, There is a ladder structure at the edge of the drift area, and the number of steps is ≥ 2; the ratio of the depth and width of each step can be a fixed value or a variable value. The sum of the step depths of each level is greater than the thickness of the drift region of the first conductivity type. The multi-level steps in the structure of the present invention form an equivalent positive grinding angle structure, which can effectively reduce the charge flux of the bottom PN junction in the reverse blocking state, so that the electric field in the multi-level step area of ​​the reverse terminal is significantly reduced, and this area is avoided. Avalanche breakdown occurs in the blocking state, which is also beneficial to suppress the leakage on the surface of the step, thereby improving the reverse blocking withstand voltage of the device.

Description

technical field [0001] The invention relates to a reverse terminal structure of a bidirectional withstand voltage power device based on step etching in a drift region, and belongs to the field of power semiconductor devices. Background technique [0002] Conventional power devices currently used in mainstream power electronics applications such as DC-DC and DC-AC often only have forward blocking capabilities. In AC-AC power conversion applications, the use of high-voltage power devices with bidirectional withstand voltage capabilities can save The series diode in the bidirectional switch can effectively reduce conduction loss and switching loss, and improve AC-AC power conversion efficiency. In the pulse power system, a high-voltage switching device with bidirectional withstand voltage capability is used, which can withstand the bidirectional high voltage of the positive and negative half cycles of the energy storage capacitor, so that the series diode and the anti-parallel ...

AI Technical Summary

Problems solved by technology

However, although the above reverse termination structures have been well applied in Si-based power devices, these termination structures are still difficult to realize in the fabrication of SiC high-voltage devices.

The main difficulty is that the diffusion process and deep etching process commonly used in the production of Si-based power devices are still difficult to apply to the processing of SiC materials.

The current common method for SiC power devices to achieve bidirectional withstand voltage is to use series diodes to withstand reverse blocking high voltage. Negative impact

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