Semiconductor trench device with enhanced gate oxide integrity structure

Abstract

A method for making a trench DMOS (1) is provided that improves the breakdown voltage of the oxide layer in a device having at least a first trench (11) disposed in the active region (12) of the device and a second trench (11') disposed in the termination region (12') of the device. In accordance with the method, mask techniques are used to thicken the oxide layer (13') in the vicinity of the top corner of the second trench, to at least about 1.2 times the thickness of the oxide layer (13) in the first trench, thereby compensating for the thinning of this region (and the accompanying reduction in breakdown voltage) that occurs due to the two-dimensional oxidation during the manufacturing process.

Description

technical field [0001] The present invention relates generally to MOSFET transistors, and more particularly to DMOS transistors having a trench structure. Background technique [0002] A DMOS (Double Diffused MOS) transistor is a type of MOSFET (Metal Oxide Semiconductor Field Effect Transistor) that uses diffusion to form the transistor region. DMOS transistors are commonly used in power transistors to provide high voltage circuits for integrated circuits. DMOS transistors can deliver high current per unit area when low forward voltage drop is required. [0003] A typical DMOS circuit consists of two or more single DMOS transistor cells configured in parallel. Individual DMOS transistor cells share a common drain contact (substrate), their sources are shorted together by metal, and their gates are shorted together by polysilicon. Therefore, even though the discrete DMOS circuit is built from a matrix of small transistors, it behaves like a single large transistor. For a...

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Problems solved by technology

However, the method presented here is not suitable for power MOSFETs because the moving arsenic region can cause early avalanche breakdown

And, in the following processes such as sacrificial oxidation treatment and gate oxidation treatment, the part repeatedly doped with arsenic contains silicon defects

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