Guard Ring Breakdown Voltage Structure for Chip Size Reduction
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Solution Overview
Problem
Conventional semiconductor devices with breakdown voltage maintaining structures, such as guard rings and RESURF structures, face challenges in minimizing chip area and susceptibility to external charge, leading to increased manufacturing costs and complexity.
Innovation Solution
A semiconductor device with a breakdown voltage maintaining structure featuring loop-shaped p-type guard rings and conductor layers with high impurity concentration, where the conductor layers extend to the inner side of adjacent guard rings, reducing chip area and susceptibility to external charge, and allowing for thinner insulating films and shorter guard ring lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional guard ring structures are used to maintain breakdown voltage, then breakdown voltage is maintained, but chip area increases and manufacturing cost increases
Solution Approach 1:
The patent changes the impurity concentration parameter of the guard ring from conventional levels to a specific range (1×10^15 to 1×10^17 atoms/cm³), which optimizes the electric field distribution and allows for a more compact structure while maintaining breakdown voltage. This parameter optimization enables the guard ring to achieve the same voltage maintenance function with reduced dimensions.
Solution Approach 2:
The patent introduces a vertical dimension consideration by specifying diffusion depth parameters (0.5 to 5.0 μm) in addition to the planar dimensions. This three-dimensional approach to guard ring design allows for more efficient space utilization and reduced chip area while maintaining the required electrical performance.
2Reliability
If guard ring structure is used to maintain breakdown voltage, then breakdown voltage is maintained, but manufacturing complexity and cost increase
Solution Approach 1:
The patent simplifies the manufacturing process by optimizing the impurity concentration to a specific range that achieves both breakdown voltage maintenance and reduced susceptibility to external charge. This parameter optimization eliminates the need for additional complex structures or processes, thereby reducing manufacturing complexity while maintaining reliability.
Solution Approach 2:
The patent applies local quality optimization by concentrating the guard ring impurity concentration within a specific range (1×10^15 to 1×10^17 atoms/cm³) rather than using uniform high concentration throughout. This localized optimization maintains breakdown voltage where needed while reducing overall complexity and susceptibility to external charge.
3Reliability
If conventional guard rings are used, then breakdown voltage is maintained, but susceptibility to external charge increases
Solution Approach 1:
The patent directly addresses susceptibility to external charge by optimizing the guard ring impurity concentration to a specific range (1×10^15 to 1×10^17 atoms/cm³). This parameter change reduces the guard ring's susceptibility to external charge while maintaining its breakdown voltage function, effectively resolving the contradiction between reliability and susceptibility.
Data Source
AI summary
A semiconductor device has an active portion having at least one well region in a semiconductor layer, and a breakdown voltage maintaining structure surrounding the active portion. The maintaining structure includes a conductor layer over each of a plurality of guard rings with an insulating film interposed in between and connected to the respective guard ring. An inner side end portion of each conductor layer projects over the immediate adjacent inner side guard ring. The impurity concentration of the guard rings is set between the impurity concentrations of the semiconductor layer and the well regions. A field plate can extend over the innermost conductor layer with the insulating film interposed in between. The field plate is in contact with the outermost well region and is in contact with the first conductor layer. The outer side end of the field plate extends outwardly beyond an outer side end of the innermost conductor layer. With these arrangements, the guard rings can be shortened and the chip size can be reduced. Furthermore, the device can be made less susceptible to external charge.