Daisy-Chained Delay Cell Layout Without Interior Dummy Groups
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Solution Overview
Problem
Current semiconductor device designs require unnecessary dummy groups to protect delay cells from layout-dependent effects, leading to increased footprint and inefficiency, as they provide excessive protection in scenarios where no layout-dependent inducing cells are present between delay cells.
Innovation Solution
A semiconductor device design that arranges delay cells without additional dummy groups between them, optimizing the layout to maintain protection while reducing footprint, by using a sequence of dummy groups and delay cells where Σ(DG) < Σ(DC), and incorporating float-resistant inverters to manage signal delays effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dummy groups are added between delay cells to protect from layout-dependent effects, then reliability is improved, but device area increases
Solution Approach 1:
The patent applies local quality by making the protection structure non-uniform: dummy groups are placed only at the beginning and end of the delay cell chain, while the interior regions between delay cells are left empty. This localized approach provides protection where it is most needed (at boundaries) while avoiding unnecessary area consumption in the interior regions where layout-dependent effects are less critical.
Solution Approach 2:
The patent extracts and removes the unnecessary dummy groups from the interior regions between delay cells. By taking out these redundant protection elements, the design achieves significant area reduction while maintaining adequate protection through the boundary dummy groups at the chain ends.
2Reliability
If dummy groups are placed between all delay cells, then protection from layout-dependent effects is maximized, but manufacturing efficiency decreases
Solution Approach 1:
The patent implements local quality by concentrating dummy groups at specific locations (beginning and end of the chain) rather than uniformly distributing them. This localized protection strategy reduces the total number of dummy groups, thereby simplifying the manufacturing process and improving efficiency while maintaining effective protection against layout-dependent effects.
3Reliability
If excessive dummy groups are used to protect delay cells, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates excessive dummy groups from the interior regions between delay cells. By removing these redundant protection elements, the design significantly reduces layout complexity and simplifies the overall device structure while maintaining adequate protection through the essential boundary dummy groups.
Solution Approach 2:
Instead of the conventional approach of uniformly distributing dummy groups between all delay cells, the patent inverts the strategy by placing dummy groups only at the boundaries and leaving the interior regions empty. This inverted approach reduces complexity while maintaining protection effectiveness.
Data Source
AI summary
A semiconductor device includes a first dummy group having a first set of dummy transistors; a first delay cell having a first set of active transistors; a second delay cell having a second set of active transistors; a second dummy group having a second set of dummy transistors; and relative to a first direction the first and second dummy groups and the first and second delay cells being arranged in a first sequence arranged as the first dummy group, the first delay cell, the second delay cell, and the second dummy group; and the first and second delay cells being free from having another dummy group therebetween.