Superjunction Semiconductor Device Reducing On Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current power MOSFETs face challenges in achieving low area-specific on resistance (Ron*A) while maintaining high breakdown voltage and high current conduction with low voltage drop, particularly in vertical semiconductor devices.
Innovation Solution
A semiconductor device with a superjunction structure is developed, featuring drift zone regions of monocrystalline semiconductor material of a second conductivity type, formed by etching trenches in the substrate and filled with semiconductor material, along with a gate electrode aligned self-alignedly with the drift zone regions, which reduces on resistance without compromising breakdown strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional power MOSFET structures are used, then breakdown voltage can be maintained, but area-specific on resistance (Ron*A) remains high
Solution Approach 1:
The drift zone is segmented into alternating superjunctions of first and second conductivity types, creating a periodic structure that simultaneously reduces on-resistance and maintains breakdown voltage. The segmentation allows independent optimization of each junction's properties while achieving overall device performance goals.
Solution Approach 2:
The device employs a composite structure combining semiconductor material of first conductivity type and semiconductor material of second conductivity type in alternating superjunctions. This composite arrangement enables the drift zone to exhibit both low resistance (through high-field regions) and high breakdown voltage (through low-field regions with appropriate doping).
2Loss of energy
If drift zone structure is optimized for low on resistance, then conduction loss decreases, but breakdown voltage may be compromised
Solution Approach 1:
Different regions within the drift zone are assigned different doping concentrations and conductivity types to create localized high-field and low-field regions. The high-field regions (superjunctions of opposite conductivity) provide low resistance for conduction, while the low-field regions maintain the electric field distribution necessary for high breakdown voltage.
Solution Approach 2:
The invention changes the doping concentration parameter across different superjunctions, with first superjunctions having a first doping concentration and second superjunctions having a second doping concentration. This parameter variation enables optimization of both conduction loss and breakdown voltage by controlling the electric field distribution throughout the drift zone.
Data Source
AI summary
A semiconductor device includes a semiconductor substrate having first regions of a first conductivity type and body regions of the first conductivity type, which are arranged in a manner adjoining the first region and overlap the latter in each case on a side of the first region which faces a first surface of the semiconductor substrate, and having a multiplicity of drift zone regions arranged between the first regions and composed of a semiconductor material of a second conductivity type, which is different than the first conductivity type. The first regions and the drift zone regions are arranged alternately and form a superjunction structure. The semiconductor device further includes a gate electrode formed in a trench in the semiconductor substrate.