Power semiconductor device and manufacturing technology

Abstract

The invention provides a power semiconductor device and a manufacturing method. A RESURF oxide layer with the thickness gradually reduced in a step mode from bottom to top is manufactured on the side wall of a groove, the distance between gate oxides is enlarged, and therefore under the premise of the same cell pitch width and the same trench width, the epitaxy concentration is doubled, the conduction resistance is effectively reduced, and the epitaxy thickness is effectively exhausted during breakdown. The structure conforms to a reasonable design rule, and the optimization of the conduction resistance is achieved simply with the simple resurf structure.

Description

technical field [0001] The present invention relates to the field of semiconductors, specifically, to a trench-type power semiconductor device and a manufacturing process. Background technique [0002] In the field of power electronics, a power MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor, Metal-Oxide-Semiconductor Field Effect Transistor) is widely used in a switching device structure. In order to make the function of the switching device play well, the power MOSFET needs to meet two requirements: 1. When the device is in the on state, it can have a very low on-resistance to minimize the power loss of the device itself; 2. When the device is in the In the off state, it can have a sufficiently high reverse breakdown voltage. Super Junction is called a milestone invention of power devices, which greatly improves the epitaxial concentration of power devices under the same withstand voltage and reduces the specific on-resistance of devices. A new type of trench M...

AI Technical Summary

Problems solved by technology

[0003] The vertical electric field of the conventional Split-gate MOSFET structure is a bimodal distribution, although it is better than the triangular distribution of the ordinary Trench MOS, but no matter how to optimize the epitaxial concentration and Trench spacing, its vertical electric field distribution is difficult to achieve the trapezoidal distribution of the superjunction

The reason is that the potential at the bottom of the trench is the largest, and the curvature effect causes the electric field to be too large. In addition, the silicon potential at the middle of the trench is low, which leads to the low electric field of silicon and silicon dioxide there.

Images