Nitride Semiconductor Drain Layout for Lower Output Capacitance
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Solution Overview
Problem
High-frequency power semiconductor devices face a significant challenge with large output capacitance, leading to substantial switching losses due to the charging and discharging of capacitance, which hinders the achievement of high breakdown electric field strength and electron mobility.
Innovation Solution
The semiconductor device design incorporates a drain electrode with separated first and second drain wirings and a specific arrangement of holes and side holes in the drain and source electrodes, reducing the area of contact with the nitride semiconductor layer and minimizing the concentration of two-dimensional electron gas, thereby decreasing output capacitance while maintaining relatively low on-resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the drain electrode contact area with the nitride semiconductor layer is increased, then the on-resistance decreases, but the output capacitance increases
Solution Approach 1:
The drain electrode is divided into multiple separate drain wirings (first drain wiring, second drain wiring, third drain wiring) instead of a single continuous contact. This segmentation reduces the total contact area with the nitride semiconductor layer, thereby decreasing output capacitance while maintaining adequate electrical connection through the distributed wiring structure
Solution Approach 2:
Different regions of the drain electrode structure are assigned different functions: the drain wirings provide electrical connection with controlled contact area, while the holes and side holes in specific regions further reduce capacitance. The element isolation region locally separates adjacent drain wirings to prevent capacitance coupling, creating non-uniform local properties optimized for both conduction and capacitance reduction
2Loss of energy
If the wiring area is reduced to decrease output capacitance, then the switching losses are reduced, but the on-resistance increases
Solution Approach 1:
The drain electrode structure utilizes three-dimensional configuration with holes and side holes penetrating through the wiring layers. This dimensional approach allows the wiring to maintain adequate cross-sectional area for conduction while reducing the planar contact area with the semiconductor layer, thereby reducing capacitance without proportionally increasing resistance
Solution Approach 2:
The element isolation region acts as an intermediary structure between adjacent drain wirings, providing electrical isolation while allowing the wirings to maintain their conductive function. This intermediary element enables the wiring area to be reduced for capacitance minimization while the isolation structure prevents excessive resistance by maintaining proper electrical pathways
3Object-affected harmful factors
If the holes are arranged with increasing spacing from the first wiring, then the two-dimensional electron gas concentration is minimized, but the manufacturing complexity increases
Solution Approach 1:
The spacing between holes is systematically varied as a parameter, with the distance from the first wiring increasing progressively. This parameter change optimizes the distribution of two-dimensional electron gas by creating specific spacing patterns that minimize carrier concentration in critical regions, while the variation follows a controlled gradient rather than random arrangement
Data Source
AI summary
A semiconductor device has a first wiring extending in a first direction on a nitride semiconductor layer. A source electrode is electrically connected to the first wiring and extends in a second direction. A drain electrode extends in the second direction and includes a first and second portion extending in the second direction, spaced from each other in the first direction. An element isolation region is in the second nitride semiconductor layer between the first and second portions. A third portion extends in the second direction on the first and second portions. A gate electrode extends in the second direction on the second nitride semiconductor layer between the source electrode and the drain electrode. The portion includes holes therein aligned with each other along the second direction with the spacing between adjacent holes in the second direction increasing with increasing distance in the second direction from the first wiring.