Super Junction Pillar Layout for Reverse Recovery Current Dissipation
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Solution Overview
Problem
Super junction semiconductor devices face a challenge in suppressing the reduction of pillar length and effectively dissipating reverse recovery current, which can lead to increased voltage overshoot and damage in the peripheral region due to the reverse recovery phenomenon.
Innovation Solution
A super junction semiconductor device with a reverse recovery layer of a second conductive type is implemented, featuring different vertical formation heights on pillars and epitaxial layers in the transition region, allowing for effective dissipation of reverse recovery current and reducing resistance, thereby suppressing the burnt phenomenon and maintaining breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reverse recovery layer is formed in the transition region to dissipate reverse recovery current, then reverse recovery phenomenon is suppressed, but the effective length of the N-type pillar is reduced
Solution Approach 1:
The reverse recovery layer is formed with different vertical heights in different regions: a first reverse recovery layer pattern is formed on the N-type pillar with a certain height, while a second reverse recovery layer pattern is formed on the epitaxial layer with a different height. This local differentiation allows the reverse recovery layer to effectively dissipate reverse recovery current in the transition region while preserving the effective length of the N-type pillar in the active region, thus resolving the contradiction between reverse recovery suppression and pillar length maintenance.
2Ease of manufacture
If the reverse recovery layer has uniform height, then manufacturing is simplified, but breakdown voltage is reduced due to shortened pillar length
Solution Approach 1:
The reverse recovery layer is designed with spatially varying height characteristics: the first reverse recovery layer pattern on the N-type pillar has a height optimized for maintaining breakdown voltage, while the second reverse recovery layer pattern on the epitaxial layer has a height optimized for dissipating reverse recovery current. This local quality differentiation enables the structure to simultaneously achieve high breakdown voltage and effective reverse recovery current dissipation, overcoming the limitation of uniform-height designs.
3Length of moving object
If reverse recovery current is not dissipated, then pillar length is maintained, but voltage overshoot increases causing damage in peripheral region
Solution Approach 1:
The reverse recovery layer acts as an intermediary structure between the N-type pillar and the surrounding epitaxial layer. By forming the reverse recovery layer with different height patterns, it provides a controlled path for reverse recovery current dissipation in the transition region while maintaining the full length of the N-type pillar. This intermediary structure effectively mediates between the need to maintain pillar length and the need to dissipate reverse recovery current, preventing voltage overshoot and peripheral region damage.
Data Source
AI summary
A super junction semiconductor device includes a substrate of a first conductive type, the substrate including an active region, a peripheral region surrounding the active region and a transition region interposed between the active region and the peripheral region, an epitaxial layer disposed on the substrate, the epitaxial layer having a the first conductive type, a plurality of pillars extending in a vertical direction and arranged within the epitaxial layer, gate structures disposed on the epitaxial layer in both the active region and the transition region, and the each of the gate structures extending across the epitaxial layer and the pillars in a horizontal direction, and a reverse recovery layer of a second conductive type, the reverse recovery layer having a vertical formation heights different as between on the pillars and on the epitaxial layer, the reverse recovery layer configured to dissipate a reverse recovery current in the transition layer.