Asymmetric Interdigitated Electrodes for Power Devices
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Solution Overview
Problem
Existing interdigitated electrode designs for semiconductor devices face challenges with non-uniform current flow and high device on-state resistance, leading to potential breakdown and low breakdown voltage due to corner effects and non-uniform field distribution.
Innovation Solution
The use of asymmetrically shaped interdigitated electrodes with varying base widths and smooth, angular corner-free finger tips, defined by circular, oval, or power function geometries, to enhance current distribution and field spreading, thereby reducing the likelihood of breakdown and improving power handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If rectangular interdigitated electrodes are used, then fabrication is simple and easy to implement, but current flow is non-uniform and corner effects cause high field concentration
Solution Approach 1:
The patent applies asymmetry by transitioning from symmetric rectangular electrodes to asymmetric interdigitated electrodes with varying finger widths. The fingers are designed with different widths to compensate for corner effects and achieve uniform current density distribution across the electrode surface, resolving the contradiction between fabrication simplicity and field distribution uniformity.
Solution Approach 2:
The patent applies curvature by replacing sharp rectangular corners with rounded or curved finger tips. This eliminates the high field concentration at sharp corners (corner effects) while maintaining ease of fabrication. The curved geometry naturally distributes the electric field more uniformly without requiring complex manufacturing processes.
2Reliability
If interdigitated electrodes with varying finger widths are used, then current distribution is improved, but device on-state resistance increases
Solution Approach 1:
The patent applies local quality by varying the finger widths at different locations to achieve uniform current density. Narrower fingers are placed in regions where current density would naturally be higher, and wider fingers where it would be lower. This local optimization compensates for geometric effects while minimizing overall resistance by ensuring uniform current distribution across the entire electrode surface.
3Reliability
If rounded finger tips are used, then corner effects are reduced and field distribution is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies curvature by designing finger tips with rounded or curved geometries instead of sharp corners. This eliminates field concentration at corners while the specific curvature profiles are designed to be compatible with standard semiconductor fabrication processes, balancing manufacturing precision requirements with field distribution improvement.
4Reliability
If asymmetric electrode geometries are used, then breakdown voltage is improved, but device complexity increases
Solution Approach 1:
The patent applies asymmetry by designing interdigitated electrodes with varying finger widths to improve breakdown voltage. The asymmetric geometry distributes the electric field more uniformly, preventing localized field concentration that would lead to premature breakdown. Despite the asymmetric appearance, the design follows systematic patterns that can be implemented using standard layout techniques, limiting the increase in device complexity.
Data Source
AI summary
This invention relates to interdigitated electrodes for power electronic and optoelectronic devices where field and current distribution determine the device performance. Described are geometries based on rounded asymmetrical fingers and electrode bases of varying width. Simulations demonstrate benefits for reducing self-heating and thermal power loss, which reduces overall on-state resistance and increases reverse break down voltages.