Thicker bottom oxide for reduced Miller capacitance in trench metal oxide semiconductor field effect transistor (MOSFET)

Abstract

Semiconductor device fabrication method and devices are disclosed. The semiconductor power device is formed on a semiconductor substrate having a plurality of trench transistor cells each having a trench gate. Each of the trench gates having a thicker bottom oxide (TBO) formed by a REOX process on a polysilicon layer deposited on a bottom surface of the trenches.

Description

technical field [0001] The present invention mainly relates to the method and structure of preparing trench semiconductor power devices (such as DMOS devices), more precisely, the present invention relates to the preparation of device structures and structures of trench semiconductor power devices with variable-thickness gate oxides. method. Background technique [0002] A DMOS (Double Diffused MOS) transistor is a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) that utilizes two successive diffusion steps aligned to a common edge, forming the channel region of the transistor. DMOS transistors are commonly used as high-voltage, high-current devices, as stand-alone transistors, or as components in power integrated circuits. The advantage of this application is that DMOS transistors can provide high current per unit area with very low forward voltage drop. [0003] A typical DMOS transistor is a trench DMOS transistor. In this type of DMOS transistor, the gate is...

AI Technical Summary

Problems solved by technology

The downside of this approach is that it is difficult to control the thickness of the IPO on the wafer

The thickness of the IPO depends on two independent, unrelated etch-back steps, resulting in under-etch-back of polysilicon or over-etch-back of polysilicon or both, resulting in non-uniform and localized thinning of the IPO

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