Profiled Semiconductor Contact for High Voltage Breakdown
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Solution Overview
Problem
High voltage semiconductor devices often experience premature breakdown due to non-uniform electric fields at electrode edges, particularly in materials like GaN, leading to failures before reaching the bulk semiconductor's breakdown voltage, as the high annealing temperature used for ohmic contacts results in rough edges and increased electric field spikes.
Innovation Solution
The profiling of contact corners and edges in a direction parallel and perpendicular to the semiconductor surface limits peak electric fields to match the average field, reducing electric field spikes and preventing premature breakdown, thereby increasing the operating voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If electrode spacing is reduced to increase device integration, then device density is improved, but electric field between electrodes increases causing breakdown in air or encapsulating material
Solution Approach 1:
By rounding or beveling contact edges, the patent eliminates sharp corners that concentrate electric field lines. This curvature reduces peak electric field strength in the air/encapsulating material above the contacts, enabling smaller electrode spacing without premature breakdown, thus increasing device density.
Solution Approach 2:
The patent changes the geometric parameters of contact edges (introducing curvature radius or bevel angles) to modify the electric field distribution. This parameter change reduces peak field strength, allowing reduced electrode spacing while maintaining breakdown resistance.
2Area of stationary object
If sharp contact edges are used to minimize contact area, then device area is reduced, but electric field spikes at edges cause premature breakdown
Solution Approach 1:
The patent replaces sharp edges with curved or beveled edges. This geometric modification maintains small contact area while eliminating electric field concentration at corners, thereby preventing premature breakdown without sacrificing area efficiency.
Data Source
AI summary
A profiled contact for a device, such as a high power semiconductor device is provided. The contact is profiled in both a direction substantially parallel to a surface of a semiconductor structure of the device and a direction substantially perpendicular to the surface of the semiconductor structure. The profiling can limit the peak electric field between two electrodes to approximately the same as the average electrical field between the electrodes, as well as limit the electric field perpendicular to the semiconductor structure both within and outside the semiconductor structure.