ECO Base Cell Layout for Flexible IC Routing and Voltage Support
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Solution Overview
Problem
The challenge in integrated circuit (IC) design is to efficiently manage and route standard functional cells and engineering change order (ECO) cells within strict design and manufacturing specifications, while ensuring flexibility and minimizing additional design activities.
Innovation Solution
The solution involves using ECO base cells, which are spare cells that can be programmed to provide common logic functions, and placing them in dedicated n-well regions. These ECO base cells can be transformed into functional cells by altering connections, allowing for flexible routing and avoiding the need for additional design iterations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If ECO base cells are integrated into standard functional cell layouts, then routing flexibility is improved, but design complexity increases
Solution Approach 1:
The patent segments the cell library into two distinct types: standard functional cells with fixed layouts and ECO base cells with configurable layouts. This segmentation allows routing flexibility to be introduced through ECO base cells without complicating the design process for standard functional cells, as they remain simple and well-defined.
Solution Approach 2:
ECO base cells are designed with dynamic configurability, allowing their internal connections and transistor configurations to be modified after initial placement. This dynamic nature provides routing flexibility while maintaining a standardized base structure, thus adding adaptability without proportionally increasing overall design complexity.
2Adaptability or versatility
If ECO cells are added to support design changes, then adaptability is improved, but manufacturing precision requirements increase
Solution Approach 1:
ECO base cells are pre-configured with standardized transistor patterns, well regions, and connection points that meet all manufacturing specifications in advance. This preliminary preparation ensures that when ECO cells are used for design changes, the manufacturing precision requirements are already satisfied, eliminating the need for additional verification steps.
Solution Approach 2:
The patent allows ECO cells to be configured with different parameters (such as transistor connections, well regions, and contact points) while maintaining a consistent base structure. This parameter-based configurability enables design changes without violating manufacturing precision requirements, as all parameter variations are pre-validated against specification constraints.
3Adaptability or versatility
If multiple n-well regions are used for different voltage levels, then functional versatility is improved, but layout area increases
Solution Approach 1:
ECO base cells are designed as universal structures that can operate at multiple voltage levels through configurable connections to different n-well regions. A single ECO base cell type can be adapted to support various voltage requirements by modifying its internal connections, eliminating the need for separate specialized cells for each voltage level and reducing overall layout area.
Solution Approach 2:
The patent merges multiple voltage level support capabilities into a single ECO base cell structure by incorporating configurable connections to multiple n-well regions. This consolidation allows one cell type to replace what would traditionally require multiple specialized cell types, thereby reducing the total layout area while maintaining functional versatility.
Data Source
AI summary
An IC structure includes first through third n-wells aligned along a first direction in a semiconductor substrate, wherein the first n-well is separated from each of the second and third n-wells by corresponding spaces, a first plurality of active areas, gate structures, and metal-like defined (MD) segments overlying and electrically connected to the active areas positioned in the first n-well, a first tap structure overlying and electrically connected to the second n-well, a second tap structure overlying and electrically connected to the third n-well, and a first metal segment extending in the first direction, overlying the first plurality of transistors, and electrically connected to each of the first and second tap structures.