Groove Gate MOSFET Grid Shielding for Oxide Breakdown Control
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Solution Overview
Problem
The groove gate MOSFETs suffer from electric field concentration at the bottom or corners of the gate oxide layer, leading to breakdown at voltages lower than rated, which affects the blocking feature and reliability of the semiconductor device.
Innovation Solution
A semiconductor device with a p-type shielding structure disposed in a grid shape around the gate oxide layer, comprising first and second shielding structures that extend in intersecting directions, providing protection and reducing electric field concentration, thereby increasing the breakdown voltage and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a groove gate MOSFET is used to reduce unit cell size and increase channel density, then the on-resistance is reduced and current capability is improved, but electric field concentration occurs at the bottom or corner of the gate oxide layer, causing breakdown at voltage lower than rated
Solution Approach 1:
A shielding structure comprising a first shielding layer and a second shielding layer is introduced as an intermediary element between the gate electrode and the gate oxide layer. The first shielding layer is disposed between the gate electrode and the gate oxide layer, while the second shielding layer is disposed between the first shielding layer and the gate oxide layer, creating a protective intermediary structure that mitigates electric field concentration at critical regions
Solution Approach 2:
The shielding structure is specifically positioned to provide localized protection where electric field concentration occurs most severely. The first shielding layer covers the bottom region of the gate oxide layer, while the second shielding layer extends to cover corner regions, providing non-uniform, location-specific shielding that targets the exact areas experiencing harmful electric field concentration
2Reliability
If the gate oxide layer is protected to prevent breakdown, then the blocking feature is improved, but the device complexity increases due to additional shielding structures
Solution Approach 1:
The first shielding layer and second shielding layer are merged into a single integrated shielding structure that performs multiple protective functions simultaneously. This combined structure reduces the number of separate components needed while maintaining comprehensive protection of the gate oxide layer against electric field concentration
Data Source
AI summary
Example semiconductor devices, integrated circuits, and electronic devices are provided. One example semiconductor device includes an n-type semiconductor substrate, a drift layer, a semiconductor layer, a groove, a shielding structure, a source, and a drain. A p-type shielding structure is disposed at the drift layer. The p-type shielding structure includes a plurality of first shielding structures and a plurality of second shielding structures. Each first shielding structure extends in a first direction. Each second shielding structure extends in a second direction. The first direction intersects with the second direction. The plurality of first shielding structures and the plurality of second shielding structures are disposed in a grid shape.