High-Voltage Termination Field Plates for Breakdown and Bonding
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Solution Overview
Problem
High voltage semiconductor devices face challenges in achieving area efficiency while maintaining high voltage breakdown capability, particularly in the design of field plate structures that separate different voltage domains.
Innovation Solution
The semiconductor device incorporates a field plate structure with laterally separated metal layers and interlayer dielectrics, allowing for independent adaptation of metal layer thickness and patterning to optimize both high voltage breakdown and area efficiency, with the uppermost metal layer serving as a wire bond base and further metal layers shaping the electric field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single metal layer is used for field plate structure, then manufacturing process is simplified, but area efficiency and voltage breakdown capability are compromised
Solution Approach 1:
The field plate structure is divided into multiple laterally separated metal layers (first metal layer with first field plate elements, second metal layer with second field plate elements) instead of using a single metal layer. This segmentation allows each layer to be independently optimized for different functions: the first layer provides voltage breakdown capability while the second layer serves as wire bond base, thereby resolving the contradiction between manufacturing simplicity and voltage breakdown performance.
Solution Approach 2:
The invention transitions from a planar single-layer field plate structure to a three-dimensional multi-layer structure with vertical stacking. The laterally separated metal layers are positioned at different heights, creating a vertical dimension that enables independent optimization of each layer's thickness and patterning, thus achieving both manufacturing feasibility and enhanced voltage breakdown capability.
2Reliability
If metal layer thickness is increased to provide stable wire bond pads, then wire bond reliability is improved, but wiring density across the device is reduced
Solution Approach 1:
The metal layering is segmented into functional zones: the first metal layer is optimized for electric field shaping with appropriate thickness for voltage breakdown, while the second (uppermost) metal layer is specifically designed with sufficient thickness to serve as stable wire bond base. This segmentation resolves the contradiction by assigning different thickness requirements to different layers based on their specific functions.
Solution Approach 2:
Different regions of the metal structure have different thickness characteristics tailored to local requirements. The uppermost metal layer has increased thickness specifically where wire bond pads are located to ensure mechanical stability, while other regions maintain optimized thickness for electric field control and wiring density, thus resolving the local contradiction between wire bond stability and overall wiring density.
3Ease of manufacture
If field plate elements are laterally separated to allow passivation layer deposition, then manufacturing feasibility is improved, but electric field control precision is reduced
Solution Approach 1:
The invention compensates for the lateral separation of field plate elements by introducing vertical positioning through multiple laterally separated metal layers. The electric field control precision is maintained through careful design of the vertical stacking arrangement and lateral positioning of each layer, allowing passivation layer deposition in the gaps while preserving field control through the multi-layer configuration.
Solution Approach 2:
The laterally separated first metal layer elements are nested within the vertical projection of the second metal layer elements, creating a nested configuration. This nesting arrangement allows the passivation layer to be deposited in the lateral gaps between elements while the vertical overlap maintains effective electric field control, thus resolving the contradiction between manufacturability and field control precision.
Data Source
AI summary
A high voltage semiconductor device includes a substrate having a background doping of a first conductivity type. The substrate includes doped shielding regions of a complementary second conductivity type formed along a first substrate surface. An insulator layer is formed on the first substrate surface. A semiconductor layer is formed on the insulator layer opposite the substrate. A first interlayer dielectric is formed on the semiconductor layer. A first metal layer including laterally separated first field plate elements is formed on first portions of the first interlayer dielectric in a high voltage termination region. A second interlayer dielectric is formed on the first metal layer and on second portions of the first interlayer dielectric between the first field plate elements.