Via Coloring Methods for IC Layout Color Loop Violations
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Solution Overview
Problem
Current photolithographic processes face limitations in feature size and spacing due to optical constraints, leading to color loop violations in IC design layouts, particularly when multi-patterning is used to enhance feature density, making it challenging to predict and optimize via spacing effectively.
Innovation Solution
A method and system for identifying prospective zones for via placement and assigning colors to poly pitches, shifting color sequences based on zone interactions and same-mask distances to resolve color loop violations, ensuring compatible and efficient via coloring within and across cell boundaries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multi-patterning is used to enhance feature density, then feature density is improved, but color loop violations occur
Solution Approach 1:
The patent applies preliminary action by performing via coloring assignment during the placement phase before routing occurs. The system proactively assigns colors to vias based on prospective zones and poly pitch interactions, preventing color loop violations before they can affect routing decisions. This advance coloring ensures that when routing happens later, the color constraints are already resolved, eliminating the reliability issue while maintaining high feature density through multi-patterning.
2Area of stationary object
If via spacing is reduced to optimize layout, then space usage is improved, but predictability of via placement deteriorates
Solution Approach 1:
The patent applies parameter changes by systematically varying the coloring parameters (color assignments) based on the spatial relationships between prospective zones and poly pitches. The system changes coloring parameters dynamically according to zone interactions and same-mask distances, enabling predictable via placement even at reduced spacings. This parameter-based approach transforms the unpredictable placement problem into a controlled optimization where spacing can be minimized while maintaining predictability through systematic color assignment rules.
Data Source
AI summary
In a particular implementation, a method includes: identifying prospective zones for placement of one or more vertical interconnect access pads (via) in a cell, where each of the prospective zones comprises one or more poly pitches; and assigning a first color for a particular poly pitch of a first identified zone of the identified prospective zones or assigning a first color sequence for one or more sections of the first identified zone.