Standard Cell Height Layout Using Virtual Grids for Smaller ICs
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Solution Overview
Problem
In integrated circuit design, standard cells with cell heights that are integral multiples of the nominal minimum pitch T limit flexibility and increase die size, as designers must enlarge cell size to meet integral multiple requirements, which can be inefficient and wasteful.
Innovation Solution
Designing standard cells with non-integral multiples of the nominal minimum pitch T cell heights, such as 7.5T, allows for more flexibility and reduces overall die size by enabling the use of virtual grid lines for routing metal lines, thereby optimizing the placement and routing of standard cells within the integrated circuit layout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If standard cells are designed with cell heights that are integral multiples of the nominal minimum pitch T, then manufacturing compatibility is improved, but design flexibility deteriorates and die size increases
Solution Approach 1:
The patent divides the standard cell structure into modular components that can be independently designed and then assembled. By segmenting the cell into functional blocks with standardized interfaces, the design achieves both manufacturing compatibility through modular assembly and design flexibility through varied internal configurations of the segments.
Solution Approach 2:
The patent changes the critical parameter from fixed integral multiples of pitch T to a range of acceptable heights including non-integral multiples. This parameter change enables continuous optimization of cell height for specific functional requirements while maintaining compatibility with manufacturing processes through established pitch guidelines.
2Ease of manufacture
If standard cells are enlarged to meet integral multiple pitch requirements, then manufacturing compatibility is improved, but die size increases
Solution Approach 1:
The patent applies partial adherence to pitch multiples rather than requiring full integral multiples. By using pitch T as a guideline rather than a strict constraint, the design achieves sufficient manufacturing compatibility without the excessive cell enlargement that would be required to force non-optimal dimensions, thereby reducing overall die size.
3Adaptability or versatility
If standard cells are designed with non-integral multiple pitch heights, then design flexibility and die size optimization are improved, but manufacturing complexity increases
Solution Approach 1:
The patent performs preliminary planning and coordination during the design phase to anticipate manufacturing requirements. By pre-coordinating cell placements and routing strategies to work with non-integral heights, the design achieves flexibility without transferring excessive complexity to the manufacturing process.
Solution Approach 2:
The patent introduces virtual grid lines as an intermediary concept that bridges design flexibility and manufacturing requirements. These virtual grids provide a reference framework for routing and placement that accommodates non-integral cell heights while maintaining systematic organization that simplifies manufacturing processes.
Data Source
AI summary
An integrated circuit includes a plurality of metal lines extending along a first direction, the plurality of metal lines being separated, in a second direction perpendicular to the first direction, by integral multiples of a nominal minimum pitch. The integrated circuit further includes a plurality of standard cells, at least one of the plurality of standard cells having a cell height along the second direction being a non-integral multiple of the nominal minimum pitch.