Semiconductor Electrode Trench Isolation for Short-Circuit Robustness
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Solution Overview
Problem
Semiconductor devices, such as IGBTs, face challenges in achieving high short-circuit robustness while maintaining optimal charge carrier plasma in the drift zone, as reducing the source region area affects switching characteristics.
Innovation Solution
Incorporating electrode trench structures with dielectrics and electrodes, and isolation trench structures filled with insulating materials that extend through the semiconductor mesa and electrode trench structures, which helps in charge carrier confinement and reduces capacitance, thereby improving switching characteristics and reducing switch-on losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the source region area is reduced to achieve high short-circuit robustness, then the maximum short-circuit current is limited, but the charge carrier plasma in the drift zone is adversely affected
Solution Approach 1:
The source region is divided into multiple separated source regions arranged along the longitudinal direction of the semiconductor mesa, rather than a single continuous source region. This segmentation allows the total source area to be reduced for short-circuit robustness while maintaining adequate charge carrier injection through multiple distributed sources
Solution Approach 2:
An isolation trench structure filled with insulating material is introduced as an intermediary element between adjacent semiconductor mesas. This isolation structure prevents charge carrier plasma from short-circuiting laterally while maintaining the beneficial plasma effect in the drift zone, thus resolving the contradiction between limiting short-circuit current and maintaining switching characteristics
2Reliability
If source regions are separated along the longitudinal direction, then short-circuit current is limited, but charge carrier plasma formation in the drift zone is compromised
Solution Approach 1:
The isolation trench structure is positioned specifically between adjacent semiconductor mesas rather than within the drift zone itself. This localized isolation maintains the charge carrier plasma quantity in the drift zone while preventing lateral plasma spread that would increase short-circuit current
Solution Approach 2:
Multiple separated source regions are distributed along the longitudinal direction, each capable of generating charge carriers. The combined effect of multiple source copies maintains adequate total charge carrier plasma formation while each individual source contributes less to the maximum short-circuit current
Data Source
AI summary
An embodiment of a semiconductor device includes a semiconductor mesa in an active device area. The semiconductor mesa includes source regions arranged along a longitudinal direction of the semiconductor mesa and separated from one another along the longitudinal direction. The semiconductor device further includes an electrode trench structure including a dielectric and an electrode. The electrode trench structure adjoins a side of the semiconductor mesa. The semiconductor device further includes an isolation trench structure filled with one or more insulating materials. The isolation trench structure extends through the semiconductor mesa and into or through the electrode trench structure along a first lateral direction.