Interdigitated Electrode Design for Low-Resistance Semiconductor Devices
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Solution Overview
Problem
Semiconductor devices with low sheet resistance exhibit non-uniform current density along device fingers due to resistance comparable to metal electrodes, leading to suboptimal on-state resistance reduction with increasing finger width.
Innovation Solution
Designing semiconductor devices with interdigitated electrodes, where target attributes such as finger depth, effective width, and current feeding contact attributes are determined to minimize total resistance, achieving a low total device impedance by optimizing finger configuration and contact impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the finger width is increased to reduce device resistance, then the device resistance per unit finger width initially decreases, but it flattens and then increases as the width is further increased due to non-uniform current density
Solution Approach 1:
The patent applies local quality by varying the finger width along the length of the finger. Specifically, the finger width is smaller at the edges and larger in the middle region. This non-uniform width distribution compensates for the non-uniform current density, ensuring that current is more evenly distributed across the finger structure and minimizing total device resistance.
Solution Approach 2:
The patent changes the geometric parameter of finger width from a constant value to a variable value that changes along the finger length. By optimizing the width profile (smaller at edges, larger in middle), the design achieves better current distribution and lower resistance compared to uniform width fingers.
2Reliability
If semiconductor layers with very low sheet resistance are used, then the resistance of the semiconductor layer becomes comparable to that of the metal electrodes, but this leads to non-uniform current density along the device finger
Solution Approach 1:
The patent addresses the current density non-uniformity caused by low sheet resistance semiconductor layers by implementing non-uniform finger width. The varying width profile (narrower at edges, wider in middle) locally adjusts the current path to compensate for the resistance characteristics of the low-sheet-resistance semiconductor, achieving more uniform current distribution.
3Reliability
If multi-finger structures are used to increase total periphery, then on state resistance is reduced, but the resistance does not decrease inversely proportionally to finger width due to non-uniform current distribution
Solution Approach 1:
The patent improves resistance reduction efficiency by making the finger width vary locally along its length. The edge regions have smaller width while the middle region has larger width, creating optimal current distribution that allows the multi-finger structure to achieve better resistance reduction than uniform width designs.
Solution Approach 2:
The patent changes the finger width parameter from constant to variable along the finger length. This parameter optimization ensures that the multi-finger structure achieves resistance reduction closer to the ideal inverse proportionality to finger width, improving productivity in terms of resistance reduction efficiency.
Data Source
AI summary
A solution for designing a semiconductor device, in which two or more attributes of a pair of electrodes are determined to, for example, minimize resistance between the electrodes, is provided. Each electrode can include a current feeding contact from which multiple fingers extend, which are interdigitated with the fingers of the other electrode in an alternating pattern. The attributes can include a target depth of each finger, a target effective width of each pair of adjacent fingers, and one or more target attributes of the current feeding contacts. Subsequently, the device and/or a circuit including the device can be fabricated.