Cell Pre-coloring Library Selection for Semiconductor Layout
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Solution Overview
Problem
In advanced semiconductor manufacturing, multiple-patterning lithography techniques face challenges in maintaining decomposability of layouts during engineering changes and suffer from large displacement and timing variations due to color misalignments, especially in single-library implementations, and timing differences across multiple libraries.
Innovation Solution
A design optimization methodology using multiple libraries that concurrently minimizes legalization displacement and timing variation impacts, employing Integer Linear Programming (ILP) and Linear Programming (LP) relaxation to determine the optimal use of single or multiple libraries for cell pin coloring, followed by color-aware cell swapping and legalization to align cells with correct track colors, thereby reducing displacement and timing variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If single-library implementation is used for cell placement, then library characterization time is reduced, but large displacement and timing variations occur due to color misalignments
Solution Approach 1:
The patent segments the cell library into multiple libraries, where each library corresponds to a specific pre-coloring arrangement. This segmentation allows the placement tool to select the most appropriate library for each cell based on track color requirements, thereby maintaining color alignment precision while managing library characterization time through selective usage.
Solution Approach 2:
The patent performs preliminary pre-coloring of cells before placement, creating multiple libraries with different color assignments. This preliminary action enables the placement tool to quickly select pre-colored cells that match track colors, avoiding the need for time-consuming color adjustments during placement and reducing both displacement and timing variations.
2Manufacturing precision
If multiple libraries with different pre-coloring are used, then color alignment precision is improved, but timing variations occur across different libraries
Solution Approach 1:
The patent applies local quality by assigning different pre-coloring arrangements to different cells based on their specific placement context and track color requirements. Rather than using a uniform approach across all cells, the system selects from multiple libraries the one that provides the best color match for each local placement scenario, thereby maintaining timing consistency while achieving color alignment precision.
Solution Approach 2:
The patent changes the pre-coloring parameter of cells by maintaining multiple libraries with different color assignments. The placement tool dynamically selects which library to use for each cell based on track color matching, effectively changing the color parameter locally without affecting timing consistency, as the selection is made to optimize both color alignment and timing performance.
3Reliability
If full-set multiple-library implementation is used, then timing variation is minimized, but library characterization time and device complexity increase
Solution Approach 1:
The patent applies partial action by using multiple libraries selectively rather than mandatorily for all cells. The placement tool determines on a per-cell basis whether multiple libraries are needed, using them only when track color matching requires it. This partial usage minimizes timing variation where needed while avoiding the excessive complexity of full-set multiple-library implementation across the entire design.
Solution Approach 2:
The patent introduces dynamics by making the library selection process adaptive and context-dependent. Rather than statically assigning all cells to multiple libraries, the system dynamically selects the appropriate library for each cell based on real-time track color requirements and placement constraints, thereby reducing timing variation only where necessary and minimizing overall library management complexity.
Data Source
AI summary
The present disclosure is directed to systems and methods for using multiple libraries with different cell pre-coloring. In embodiments, the present disclosure determines a first set of cells to be placed using a single library methodology for pre-coloring and a second set of cells to be placed using a multiple library methodology for pre-coloring. In further embodiments, color-aware cell swapping can be performed based on the first set of cells and the second set of cells to align cells to swap the pre-coloring arrangements of cells to align with a track color of a closest legalization site candidate.