Heterogeneous Superjunction Structure for Higher Breakdown Voltage
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Solution Overview
Problem
One-dimensional unipolar power devices face limitations due to increasing specific on-resistance with the square of breakdown voltage, and vertical superjunction devices suffer from peak electric fields that limit breakdown voltage.
Innovation Solution
The design incorporates a substrate with a first semiconductor region and a second semiconductor region of different conductivity types, forming a superjunction structure with the second semiconductor region having a higher product of critical electric field and permittivity, which reduces peak electric fields by maintaining a charge balance between the two regions, thereby improving breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If one-dimensional unipolar power devices are used to achieve high breakdown voltage, then the breakdown voltage is improved, but the specific on-resistance increases with the square of the breakdown voltage
Solution Approach 1:
The drift region is segmented into alternating n-type and p-type semiconductor regions forming a superjunction structure. This segmentation allows charge balance between the regions to reduce peak electric fields while maintaining low on-resistance, resolving the contradiction between high breakdown voltage and low specific on-resistance
Solution Approach 2:
The patent changes the material parameters of the semiconductor regions by selecting materials with different products of critical electric field and permittivity. This parameter change enables optimization of the charge balance in the superjunction structure, allowing simultaneous achievement of high breakdown voltage and low specific on-resistance
2Reliability
If vertical superjunction devices are used to reduce specific on-resistance, then the specific on-resistance is improved, but peak electric fields limit the breakdown voltage
Solution Approach 1:
The patent changes the material parameters by selecting semiconductor materials with different products of critical electric field and permittivity for the alternating n-type and p-type regions. This enables optimization of the charge balance to reduce peak electric fields while maintaining low on-resistance
Solution Approach 2:
The superjunction structure uses composite semiconductor materials with different conductivity types and material properties. The alternating n-type and p-type regions with different critical electric field and permittivity products create a composite structure that balances charge distribution and reduces peak electric fields
Data Source
AI summary
A device may include a substrate of a first conductivity type, the first conductivity type being one of a n-type conductivity and a p-type conductivity, the substrate having a base surface. A device may include a first terminal coupled with the base surface of the substrate, a first semiconductor region disposed over the substrate, the substrate positioned between the first semiconductor region and the first terminal, the first semiconductor region including a top surface, which defines a plurality of trenches having sidewalls, the plurality of trenches separated by a plurality of pillars, the first semiconductor region formed of a first material with the first conductivity type, a second semiconductor region disposed over the sidewalls of the first semiconductor region to form a superjunction with the first semiconductor region, the second semiconductor region formed of a second material different from the first material and having a second conductivity type.