High-Voltage Capacitor Structure With RESURF Voltage Grading
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Solution Overview
Problem
High-voltage semiconductor devices require capacitors with breakdown voltages exceeding 400 V, but existing capacitor structures struggle to maintain reliability and efficiency at such high voltages due to voltage limitations across isolation insulating layers.
Innovation Solution
A capacitor structure is designed with a ring-shaped isolation insulating layer and a spiral resistor wire, combined with a reduced surface field (RESURF) well structure, allowing for a gradual voltage reduction from the center to the edge of the capacitor, thereby maintaining a voltage across the isolation insulating layer below its breakdown voltage, enabling operation at higher voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional capacitor structure is used in high-voltage semiconductor devices, then the device can be manufactured with standard processes, but the capacitor cannot maintain reliability at breakdown voltages exceeding 400 V due to voltage limitations across isolation insulating layers
Solution Approach 1:
The capacitor structure is segmented into multiple regions with different doping concentrations, creating a gradient from the center region through the intermediate region to the outer region. This segmentation allows the voltage to be distributed across multiple junctions rather than concentrated at a single isolation insulating layer, enabling operation at breakdown voltages exceeding 400 V while maintaining reliability
Solution Approach 2:
Different regions of the capacitor are assigned different doping concentrations tailored to their specific functional requirements. The center region has a first doping concentration optimized for one function, the intermediate region has a second doping concentration for voltage distribution, and the outer region has a third doping concentration for another function. This local quality differentiation allows each region to optimize its performance for its specific role in achieving high-voltage reliability
2Adaptability or versatility
If the voltage across the isolation insulating layer is kept below breakdown voltage to maintain reliability, then the capacitor can operate reliably, but the operation voltage is limited and cannot be easily scaled to higher voltages
Solution Approach 1:
The capacitor structure incorporates a dynamic voltage distribution mechanism through its multi-region doping gradient. As the applied voltage increases, the voltage drops across different regions adjust dynamically based on their doping concentrations and junction characteristics. This dynamic response allows the capacitor to adapt to different voltage levels and be scaled to higher operation voltages while maintaining reliability by keeping the voltage across any single isolation insulating layer below its breakdown voltage
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The capacitor structure effectively operates at voltages higher than 400 V by reducing voltage across the isolation insulating layer, enhancing reliability and efficiency, and allowing for easy scaling of operation voltage through dimensional adjustments.
Implementation Method 1
a reduced surface field (RESURF) well structure, allowing for a gradual voltage reduction from the center to the edge of the capacitor, thereby maintaining a voltage across the isolation insulating layer below its breakdown voltage
Data Source
AI summary
A capacitor structure for a power semiconductor device includes a semiconductor substrate, an isolation insulating layer having a ring-shape and including an outer periphery and an inner periphery defining an opening region, a first electrode disposed on the isolation insulating layer, a dielectric layer disposed on the first electrode, and a second electrode disposed on the dielectric layer.