Offset Gate Cut Areas for Transistor Cross-Connections
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Solution Overview
Problem
The existing layout of flip-flop circuits in semiconductor devices requires complex cross-connections between transistors, which consume additional area and are difficult to implement without using higher metal layers, especially when connecting PMOS and NMOS transistors that are not aligned along the same gate structure.
Innovation Solution
The use of offset gate cut areas in non-active regions allows for cross-connections between PMOS and NMOS transistors by routing metal lines around these cut areas, reducing the need for higher metal layers and minimizing area usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional layout methods are used for cross-connections between PMOS and NMOS transistors, then the circuit functionality is achieved, but additional area is consumed and higher metal layers are required
Solution Approach 1:
The patent applies dimensionality change by utilizing the vertical dimension (different metal layers) to resolve horizontal routing conflicts. Specifically, metal lines are routed in different metal layers (e.g., M0 and M1) to connect gates of PMOS and NMOS transistors that are not aligned horizontally, thereby avoiding the need for complex via structures while reducing overall circuit area.
Solution Approach 2:
The gate connection structure is segmented into multiple parts: gate contacts, metal lines in different layers, and via connections. This segmentation allows independent optimization of each component, enabling efficient routing paths that minimize area consumption while maintaining electrical connectivity between cross-coupled transistors.
2Adaptability or versatility
If higher metal layers are used for cross-connections, then routing flexibility is improved, but the number of metal layers increases and area is consumed
Solution Approach 1:
The patent makes metal lines multi-functional by using them for both local gate connections and cross-connections between different transistor types. The same metal layer (e.g., M0) is used for both functions, eliminating the need for dedicated higher metal layers and reducing overall circuit area while maintaining routing flexibility.
3Reliability
If gate cut areas are placed in active regions, then transistor isolation is achieved, but cross-connection routing becomes difficult
Solution Approach 1:
The patent introduces non-active regions as intermediary zones between active transistor regions. These non-active regions serve as routing corridors that allow metal lines to pass through and connect gates of PMOS and NMOS transistors without interfering with the active transistor regions, thereby maintaining both isolation and routing ease.
Data Source
AI summary
Cell circuits formed in circuit cells employing offset gate cut areas in a non-active area for routing transistor gate cross-connections. In exemplary aspects disclosed herein, to allow cross-connections to be made across different gates between PMOS and NMOS transistors formed in the circuit cell, cut areas in the circuit cell are located in different horizontal routing tracks and offset from each other in the direction of longitudinal axes of gates. Gate cross-connections can be routed around offset gate cut areas and coupled to active gates to form gate cross-connections. In this manner, fewer metal layers may be required to provide such cross-connections in the circuit cell, thus reducing area. Further, gate contacts of cross-connected gates can be formed as gate contacts over active areas (GCOAs) in diffusion areas of the circuit cell, thus facilitating easier routing of interconnections in non-diffusion area of the circuit cell for further ease of routing.