Superjunction Semiconductor Edge Pillar Charge Balancing
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Solution Overview
Problem
Superjunction semiconductor devices face deteriorated breakdown characteristics due to unbalanced quantities of p and n charges in specific regions, particularly in the corners and edges of the edge p pillar, which increases ON resistance and reduces switching speed.
Innovation Solution
The introduction of subsidiary p pillars with bar, island, or bent belt shapes in the active n region to compensate for charge imbalances, ensuring balanced p and n charge quantities across the device, particularly in the corners and edges, by adjusting the width and arrangement of active p pillars and adding supplementary p pillars to match n charge levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of the drift layer is increased to provide high breakdown voltage, then the breakdown voltage is improved, but the ON resistance is increased
Solution Approach 1:
The drift layer is segmented into alternating n-type and p-type columns, creating a superjunction structure. This segmentation allows the device to achieve high breakdown voltage through the alternating polarity columns while maintaining low ON resistance via the parallel conduction paths formed by the segmented structure.
Solution Approach 2:
The drift layer uses a composite structure combining n-type and p-type semiconductor materials in an alternating columnar arrangement. This composite structure enables simultaneous achievement of high breakdown voltage and low ON resistance by leveraging the complementary properties of the alternating conductivity types.
2Ease of manufacture
If the quantity of n charges and p charges is unbalanced in the edge p pillar, then the manufacturing is simplified, but the breakdown characteristic is deteriorated
Solution Approach 1:
The patent applies different charge balancing strategies to different regions: the edge p pillar uses a simplified structure for ease of manufacture, while subsidiary p pillars are strategically placed in specific local regions (corners and edges of the active region) to balance charge quantities and improve breakdown characteristics without complicating the overall manufacturing process.
Solution Approach 2:
Subsidiary p pillars are introduced as intermediary structures between the edge p pillar and the active n pillars. These intermediary pillars serve to balance the charge quantities in critical regions, mediating between the simplified edge p pillar structure and the requirement for balanced charges for good breakdown characteristics.
3Reliability
If subsidiary p pillars are added to balance charge quantities, then the breakdown characteristic is improved, but the device complexity is increased
Solution Approach 1:
Subsidiary p pillars are not added throughout the entire device but are strategically placed only in specific regions (corners and edges of the active region) where charge imbalance occurs. This localized approach improves breakdown characteristics while minimizing the increase in device complexity.
Solution Approach 2:
Instead of adding subsidiary p pillars uniformly across the entire device, the patent applies partial action by placing them only where needed (in corners and edges). This partial approach provides sufficient charge balancing to improve breakdown characteristics without unnecessarily increasing device complexity in regions where it is not needed.
Data Source
AI summary
A superjunction semiconductor device includes an edge p pillar, an active region, and a termination region. The edge p pillar has a rectangular ring shape with rounded corners surrounding the active region. The active region includes an active n region and active p pillars having vertical stripe shapes disposed at regular intervals in the active n region. The top and bottom ends of the active p pillars are separated from the edge p pillar. The termination region includes termination n pillars and termination p pillars alternately arranged around the edge p pillar. Surplus p charges that are not used to balance the quantity of p charges and the quantity of n charges among p charges included in the upper and lower parts of the edge p pillar are eliminated or n charges are supplemented to balance the quantity of p charges and the quantity of n charges.