Segmented Gate Power Device Optimizing Breakdown Voltage and On-Resistance
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Solution Overview
Problem
Power devices with VDMOS transistors face a trade-off between improving breakdown voltage, specific on resistance, and parasitic capacitance characteristics, which affects driving currents and power consumption.
Innovation Solution
The power device design includes a semiconductor layer of a first conductivity type, a buried layer of a second conductivity type, a drift layer, source regions, and multiple gate electrodes with a floating or grounded third gate electrode, optimizing the structure to enhance breakdown voltage, reduce specific on resistance, and minimize parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the breakdown voltage is increased, then the driving current capability is improved, but the specific on resistance increases
Solution Approach 1:
The gate electrode is divided into multiple segments (first gate electrode, second gate electrode, and third gate electrode) arranged in sequence. This segmentation allows different regions of the drift layer to be controlled independently, enabling optimization of both breakdown voltage and on-resistance characteristics through selective gating.
Solution Approach 2:
Different gate electrodes are applied to different regions of the drift layer to create local electric field variations. The first and second gate electrodes control regions near source regions for low on-resistance, while the third gate electrode controls the central region for high breakdown voltage, achieving local optimization of electrical characteristics.
2Speed
If the parasitic capacitance is reduced, then the switching speed is improved, but the breakdown voltage decreases
Solution Approach 1:
The gate electrode is segmented into multiple independent gates, which reduces the total parasitic capacitance by distributing the capacitive load across multiple smaller gate-drain and gate-source capacitances rather than one large capacitance, thereby improving switching speed.
Solution Approach 2:
The third gate electrode positioned in the central region acts as an intermediary structure that provides electrical isolation and reduces direct capacitive coupling between the drain and the main gate electrodes, thereby reducing parasitic capacitance while maintaining breakdown voltage through controlled electric field distribution.
3Object-generated harmful factors
If the specific on resistance is reduced, then the driving current is improved, but the breakdown voltage decreases
Solution Approach 1:
The drift layer is divided into multiple regions controlled by different gate electrodes, allowing low on-resistance in source-proximal regions while maintaining high breakdown voltage in the central region controlled by the third gate electrode.
Solution Approach 2:
Different regions of the drift layer are optimized for different functions: regions near source regions have lower resistance for current conduction, while the central region has higher breakdown voltage for safety margin, achieving local quality differentiation through selective doping and gating.
Data Source
AI summary
A power device includes a drift layer of a second conductivity type located on a semiconductor layer of a first conductivity type, a first source region of the second conductivity type and a second source region of the second conductivity type, located on the drift layer to be apart from each other, and a gate electrode on the drift layer between the first and second source regions with a gate insulating layer between the gate electrode and the drift layer, wherein the gate electrode includes a first gate electrode and a second gate electrode adjacent to the first source region and the second source region, respectively, and a third gate electrode between the first and second gate electrodes, wherein the third gate electrode is floated or grounded.