Bridge Structure Layout for Mixed Threshold-Voltage Devices
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Solution Overview
Problem
The challenge in chip layout is to efficiently place active devices with different threshold voltages in the same row without violating design rule check (DRC) requirements, which is difficult due to the need to avoid abutment of devices with different threshold voltages.
Innovation Solution
A bridge structure comprising a first and second single diffusion break (SDB) with a diffusion region in between is used to create a transition region between active devices with different threshold voltages, allowing them to be placed in the same row without violating DRC rules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional tap structures are used to separate devices with different threshold voltages, then DRC requirements are satisfied, but layout area is increased
Solution Approach 1:
The bridge structure is segmented into multiple diffusion regions (first diffusion region, second diffusion region, third diffusion region) separated by single diffusion breaks. This segmentation allows the transition between different threshold voltage devices to be achieved through a compact series of discrete diffusion regions rather than requiring a large tap structure, thereby reducing the overall layout area while maintaining DRC compliance.
Solution Approach 2:
The bridge structure acts as an intermediary element between devices with different threshold voltages. It provides a transition region with intermediate threshold voltage characteristics through its series of diffusion regions, enabling smooth voltage transitions and satisfying DRC requirements without requiring the large area of traditional tap structures.
2Productivity
If devices with different threshold voltages are placed in the same row, then layout efficiency is improved, but DRC violations occur
Solution Approach 1:
The bridge structure implements local quality by creating regions with different threshold voltage characteristics at specific locations. The first, second, and third diffusion regions have progressively different threshold voltages, allowing the structure to locally adapt to the requirements of adjacent devices with different threshold voltages while maintaining overall DRC compliance.
Solution Approach 2:
The bridge structure changes the threshold voltage parameter progressively through its series of diffusion regions. By transitioning from the first diffusion region with one threshold voltage to the second and third diffusion regions with different threshold voltages, it enables the placement of devices with different threshold voltages in the same row while avoiding DRC violations.
Data Source
AI summary
A chip includes a first active device having a first threshold voltage, and a second active device having a second threshold voltage, wherein the first threshold voltage is higher than the second threshold voltage. The chip also includes a bridge structure between the first active device and the second active device. The bridge structure includes a first single diffusion break (SDB), a second SDB, and a first diffusion region extending in a first direction between the first SDB and the second SDB.