Variable Width Channel FET for High Voltage Breakdown

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Solution Overview

Problem

Conventional high voltage-control MOS transistors face issues with reduced breakdown voltage due to electric field convergence at the edges of heavily doped regions, leading to potential short circuits and defects, particularly when the channel region's first width is larger than the second width.

Innovation Solution

The design incorporates a channel region with a first portion having a smaller width than the second portion, where the first width is interposed between the second substrate region and the field insulation layer, reducing electric field convergence and preventing short circuits by maintaining a larger second width to increase breakdown voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the first width of the first region is made larger than the second width of the second region to prevent short circuits, then the reliability is improved, but the turn-on breakdown voltage decreases due to electric field convergence

Engineering Contradiction:

Improveshort circuit preventionVSAvoidturn-on breakdown voltage

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The channel width is varied locally along the channel length, with a first channel width in the first region and a second channel width in the second region. This local variation allows different sections to serve different functions: the first region prevents short circuits while the second region maintains high breakdown voltage

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The channel region is divided into multiple sections (first region and second region) with different width characteristics. This segmentation allows each section to be optimized independently for its specific function, resolving the contradiction between short circuit prevention and breakdown voltage maintenance

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS8188542B2Field effect transistors including variable width channels and methods of forming the same

Publication Date: 2012.05.29 SAMSUNG ELECTRONICS CO LTD

AI summary

A field effect transistor includes a first substrate region having a channel region and a second substrate region where a heavily doped region is formed. The channel region includes a first portion having a first width and a second portion having a second width larger than the first width. Related fabrication methods are also described.