Split-Gate Trench Layout to Prevent Voids and Preserve Breakdown Voltage
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Solution Overview
Problem
Existing semiconductor devices with split-gate structures face challenges in maintaining high breakdown voltage due to void formation and inadequate insulation layer growth at the terminal end of the gate trench, which can lower the device's performance.
Innovation Solution
The semiconductor device incorporates a field plate electrode with a widened portion in the second region of the gate trench, ensuring that even when the insulation layer grows from three directions, it does not form an enclosure, thereby preventing void formation and maintaining adequate breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the insulation layer is grown in the gate trench to separate the gate electrode and field plate electrode, then electrical insulation is achieved, but void formation occurs at the terminal end due to three-directional growth enclosure
Solution Approach 1:
The gate trench structure employs asymmetric width design where the trench width varies along its length. Specifically, the trench is wider at the terminal end region where the field plate electrode is located, and narrower at the gate electrode region. This asymmetric geometry prevents the insulation layer from being enclosed by three-directional growth at the terminal end, eliminating void formation while maintaining effective electrical insulation between the gate electrode and field plate electrode.
2Productivity
If the gate trench width is reduced to increase device density, then productivity is improved, but breakdown voltage decreases due to inadequate insulation layer thickness
Solution Approach 1:
The gate trench structure implements local quality variation through width modulation along the trench length. The trench width is locally increased at the terminal end region housing the field plate electrode, ensuring sufficient insulation layer thickness for high breakdown voltage. Meanwhile, the trench width is reduced at the gate electrode region to increase device density and productivity. This spatially varying geometry optimizes both breakdown voltage and device density simultaneously.
Data Source
AI summary
A semiconductor device includes: a semiconductor layer; a gate trench formed in the semiconductor layer, the gate trench extending in a first direction in plan view; an insulation layer formed on the semiconductor layer; a field plate electrode arranged in the gate trench and having a width in the second direction; and a gate electrode arranged in the gate trench and separated from the field plate electrode by the insulation layer. The gate trench includes a first region in which the gate electrode is located above the field plate electrode in a depth-wise direction of the gate trench, and a second region including an end of the gate trench in the first direction. The field plate electrode in the second region includes a widened portion having a width that is greater than a width of the field plate electrode in the first region.