Transistor Trench Field Plate Structure for Breakdown Voltage
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Solution Overview
Problem
Transistors with trench structures face issues due to doping imbalances in termination regions, leading to lower breakdown voltage caused by geometric shape of the trench, which existing technologies fail to adequately compensate for.
Innovation Solution
A method involving the formation of separate conductive trench structures with a wider transverse cross-sectional width in the termination section compared to the device section, along with a field plate structure and gate structure located closer to one sidewall, and increased dielectric between the gate and field plate and drain sidewall to accommodate potential differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a trench structure is used in transistor fabrication, then device integration is improved, but doping imbalances occur in termination regions leading to lower breakdown voltage
Solution Approach 1:
The patent applies local quality by creating different trench widths at different locations: a first trench width in the device region and a second, wider trench width in the termination region. This local variation compensates for doping imbalances specifically in the termination region without affecting the device region, thereby maintaining high breakdown voltage while preserving device integration benefits.
Solution Approach 2:
The trench structure is segmented into different width sections along its length - a narrower section in the device region and a wider section in the termination region. This segmentation allows independent optimization of each region's electrical characteristics, addressing the doping imbalance problem in termination regions while maintaining proper device operation.
2Reliability
If the trench width is increased in termination regions, then breakdown voltage is improved by compensating doping imbalances, but device complexity increases
Solution Approach 1:
The patent implements local quality by varying the trench width only in the termination region where doping imbalances occur, while keeping the device region trench width standard. This targeted approach improves breakdown voltage without unnecessarily complicating the entire device structure.
Data Source
AI summary
A method includes forming separate conductive trench structures in a trench and then removing an upper portion of one of the conductive structures where the remaining portion serves as field gate for a transistor. Removing the upper portion includes forming a second trench. The second trench is filled with a gate material that is used as a gate for the transistor. The transistor includes a source region for the transistor on the side of the trench and a drain region for the transistors on the other side of the trench, wherein the drain region includes a portion located at an upper portion of a semiconductor material. The transistor includes a channel region having a portion located along a sidewall of a trench.