Columnar Super Junction Regions in Semiconductor Drift Layers
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Solution Overview
Problem
Super junction semiconductor devices face challenges in achieving low on-state resistance while maintaining high reverse breakdown voltage, particularly in high-voltage applications, due to the high impurity concentration in n-doped columns which affects the drift layer resistance.
Innovation Solution
The implementation of a super junction semiconductor device structure with columnar first and second super junction regions of opposite conductivity types, formed perpendicular to the surface, and a doped layer of a first conductivity type, where the distance between the super junction regions and the second surface does not exceed 30 μm, allowing for a low on-state resistance and high reverse breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If high impurity concentration is used in n-doped columns, then on-state resistance is reduced, but reverse breakdown voltage decreases
Solution Approach 1:
The drift layer is segmented into alternating p-doped and n-doped columns, creating a super junction structure. This segmentation allows the n-doped columns to provide low on-state resistance while the p-doped columns enable high reverse breakdown voltage through lateral depletion zone formation between adjacent columns.
Solution Approach 2:
Different regions of the semiconductor device have different doping characteristics: n-doped columns have high impurity concentration for low on-state resistance, while p-doped columns have doping optimized for reverse breakdown voltage. The local quality varies spatially to optimize both conflicting performance parameters simultaneously.
2Reliability
If columnar super junction regions extend deep into the drift layer, then reverse breakdown voltage increases, but on-state resistance increases
Solution Approach 1:
The super junction structure utilizes lateral depletion zones extending between adjacent columns in the horizontal dimension, rather than relying solely on vertical depletion depth. This dimensional approach allows high reverse breakdown voltage to be achieved without proportionally increasing the vertical extension of doped regions, thereby maintaining lower on-state resistance.
Data Source
AI summary
A super junction semiconductor device includes a semiconductor portion with first and second surfaces parallel to one another and including a doped layer of a first conductivity type formed at least in a cell area. Columnar first super junction regions of a second conductivity type extend in a direction perpendicular to the first surface and are separated by columnar second super junction regions of the first conductivity type. The first and second super junction regions form a super junction structure between the first surface and the doped layer. A first electrode structure directly adjoins the first surface and a second electrode structure directly adjoins the second surface. The first electrode structure has a first thickness and the second electrode structure has a second thickness. A sum of the first and second thicknesses is at least 20% of the thickness of the semiconductor portion between the first and second surfaces.