Trench Gate Semiconductor Layout for Electric Field Relief
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Solution Overview
Problem
The high concentration of electric fields at the bottom and corners of trench gate structures in vertical transistor structures can damage the gate dielectric layer, compromising the reliability of the semiconductor device.
Innovation Solution
The semiconductor device incorporates a body region with a third part positioned below the trench gate structure's bottom surface, separated by a drift region, to adjust electric field distribution and reduce damage to the gate dielectric layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a trench gate structure is used in vertical transistor, then blocking voltage and on-resistance are balanced over the same area, but electric field concentration at bottom and near corner of trench causes high electric field strength that may damage the gate dielectric layer
Solution Approach 1:
The body region is segmented into three parts (first part, second part, third part) along the width direction of the trench gate structure. The third part is positioned below the bottom surface of the trench gate structure and separated from at least part of the bottom surface by the drift region. This segmentation allows different parts of the body region to serve different functions: the first part adjoins the source region and drift region, the second part is located between the first and third parts, and the third part specifically addresses electric field concentration at the trench bottom by being separated from it.
Solution Approach 2:
The body region extends into a third dimension by having the third part located below the bottom surface of the trench gate structure. This vertical extension into the depth dimension allows the body region to interact with and modulate the electric field distribution at the trench bottom, effectively reducing electric field concentration that would otherwise damage the gate dielectric layer.
2Reliability
If the third part of the body region is separated from the bottom surface of the trench gate structure by the drift region, then electric field distribution is adjusted and gate dielectric layer is protected, but device structure becomes more complex
Solution Approach 1:
The drift region serves multiple functions simultaneously: it acts as a separation layer between the third part of the body region and the bottom surface of the trench gate structure to reduce electric field concentration, while also serving as an active region for charge transport and field modulation. This multi-functionality reduces the need for additional dedicated structures, thereby limiting the increase in device complexity.
Solution Approach 2:
The invention merges the body region and drift region into a closely integrated structure where the drift region is positioned between the third part of the body region and the trench bottom. This merging allows the two regions to work together as a unified system for electric field management, rather than requiring separate independent structures, thus reducing overall device complexity.
Data Source
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AI summary
The present disclosure provides a semiconductor device including a semiconductor layer and a trench gate structure (151, 152). The semiconductor layer includes: a source region (130), a drift region (101), and a body region (110). The first part of the body region is located between the source region and the drift region, the first part of the body region and the source region both adjoin a first sidewall of the trench gate structure. The third part of the body region is located between a bottom surface of the trench gate structure and the second surface, at least part of the bottom surface of the trench gate structure is separated from the third part of the body region by the drift region. By separating the third part of the body region form the bottom surface of the trench gate structure along a vertical direction, electric field distribution at bottom of a trench and near corner is adjusted.