Semiconductor Device Gate Electrode Overlap Segmentation
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Solution Overview
Problem
In semiconductor devices using wide-gap semiconductors, the concentration of electric fields can lead to dielectric breakdown, particularly at the overlap regions of the gate and drain electrodes, which reduces the withstand voltage and on-state current.
Innovation Solution
The semiconductor device incorporates a wide-gap semiconductor film with a first and second region, where the gate electrode overlaps with part of one electrode and the first region but not the other, and the second region has lower electric resistance than the first, reducing electric field concentration and maintaining on-state current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gate electrode and drain electrode are positioned to overlap in conventional semiconductor devices, then the device structure is compact and manufacturing is simplified, but electric field concentration occurs at the overlap region leading to dielectric breakdown and reduced withstand voltage
Solution Approach 1:
The semiconductor device structure is segmented into distinct regions: a first region where the gate electrode overlaps with the source electrode, a second region where the gate electrode overlaps with the drain electrode, and a third region where the gate electrode does not overlap with either electrode. This segmentation allows the electric field distribution to be controlled, preventing concentration at any single location and thereby improving withstand voltage.
Solution Approach 2:
Different regions of the semiconductor device are given different structural characteristics. The first and second regions have overlapping electrode configurations for compactness, while the third region has a non-overlapping configuration to reduce electric field concentration. This local variation in structure optimizes both compactness and reliability.
2Reliability
If the gate electrode overlaps with both source and drain electrodes to maximize active area, then on-state current is improved, but electric field concentration increases causing dielectric breakdown
Solution Approach 1:
The gate electrode overlap is segmented into three distinct regions along the channel length. The first region allows overlap with the source electrode for good contact, the second region allows overlap with the drain electrode for active area, and the third region eliminates overlap to reduce electric field concentration. This segmentation prevents dielectric breakdown while maintaining adequate on-state current.
Solution Approach 2:
Instead of having the gate electrode overlap with both source and drain electrodes throughout the entire channel length, the invention applies partial overlap only in specific regions (first and second regions), while eliminating overlap in the third region. This partial application of the overlap principle maintains sufficient active area for on-state current while preventing excessive electric field concentration.
Data Source
AI summary
It is an object to reduce concentration of an electric field on an end of a drain electrode of a semiconductor device. A semiconductor device includes an oxide semiconductor film including a first region and a second region; a pair of electrodes which is partly in contact with the oxide semiconductor film; a gate insulating film over the oxide semiconductor film; and a gate electrode that overlaps with part of one of the pair of electrodes and the first region with the gate insulating film provided therebetween. At least part of the first region and part of the second region are between the pair of electrodes. The gate electrode does not overlap with the other of the pair of electrodes.