Trench Gate Semiconductor Structure to Suppress Gate Oxide Breakdown
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Solution Overview
Problem
Conventional semiconductor devices with trench structures experience dielectric breakdown due to field concentration on the bottom portion of the gate insulating layer when a reverse bias is applied.
Innovation Solution
The semiconductor device incorporates a trench structure that penetrates through a second semiconductor layer with an extended portion closer to the second face, a channel region with lower impurity concentration, and additional semiconductor regions to mitigate field concentration, including a recessed portion and additional semiconductor regions formed around the trench.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a trench structure is used to improve device integration, then device density increases, but field concentration occurs at the bottom of the gate insulating layer causing dielectric breakdown
Solution Approach 1:
The patent applies local quality by creating a recessed portion at the bottom of the trench and forming an extended semiconductor layer in that recessed area. This local structural modification changes the electric field distribution specifically at the critical bottom region of the gate insulating layer, reducing field concentration and preventing dielectric breakdown while maintaining the overall trench structure for device integration.
2Reliability
If the trench penetrates deeply through semiconductor layers to reach the first semiconductor layer, then device performance improves, but the extended portion of the second semiconductor layer increases complexity
Solution Approach 1:
The patent applies preliminary action by forming the extended portion of the second semiconductor layer in the recessed area before the trench is fully formed. This preliminary structural preparation allows the trench to be etched through to the first semiconductor layer while the extended portion is already in place to provide the necessary field management, simplifying the overall manufacturing process.
Data Source
AI summary
A semiconductor device includes a semiconductor layer having a first face with a trench formed thereon and a second face opposite to the first face, a gate electrode, and a gate insulating layer. The semiconductor layer includes a first n-type semiconductor layer, a second n-type semiconductor layer, a p-type semiconductor layer, and an n-type semiconductor region. The trench is formed to penetrate through the p-type semiconductor layer and to reach the second n-type semiconductor layer. The p-type semiconductor layer includes an extended portion extending to a position closer to the second face of the semiconductor layer than the trench is. Such structure allows suppressing dielectric breakdown in the gate insulating layer.