Backside IC Routing Layout for Electromigration and RC Performance
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Solution Overview
Problem
The miniaturization of integrated circuits poses challenges in design and manufacturing, including stricter specifications and reliability issues, particularly in optimizing standard cell layout designs to improve current resistance, electromigration, and resistance capacitance performance while reducing the complexity of metal routing.
Innovation Solution
The solution involves positioning power rails and signal lines on the back-side of the substrate, which reduces the need for upper metal layer tracks, increases gate density, and enhances routing flexibility by electrically coupling gates and contacts, thereby improving current resistance, electromigration, and resistance capacitance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power rails and signal lines are positioned on the front-side of the substrate using upper metal layer tracks, then routing is achieved, but current resistance increases and electromigration performance deteriorates
Solution Approach 1:
The patent moves power rails and signal lines from the front-side (upper metal layers) to the back-side of the substrate, utilizing the z-dimension (vertical stacking) to resolve the contradiction. This dimensional shift allows routing functions to be performed on the back-side, reducing current resistance and improving electromigration performance while maintaining routing flexibility through the vertical arrangement of gates, contacts, and back-side routing structures.
2Area of stationary object
If upper metal layer tracks are used for routing, then connectivity is achieved, but the physical height and area of the circuit increase
Solution Approach 1:
By utilizing the back-side of the substrate for routing, the patent effectively uses the vertical dimension to reduce the horizontal footprint of the circuit. The back-side routing structures, including modified gates and contacts, enable connectivity without increasing the planar area, while maintaining routing flexibility through the vertical integration of routing paths.
3Reliability
If standard front-side routing is used, then manufacturing is simplified, but reliability under miniaturization deteriorates
Solution Approach 1:
The patent addresses miniaturization reliability by moving critical power and signal routing to the back-side, where longer current paths and improved routing geometries can be implemented without further miniaturization. This dimensional separation allows the front-side to focus on compact transistor placement while the back-side handles robust routing, improving reliability under miniaturization constraints.
Solution Approach 2:
The patent segments the routing function from the transistor placement function by using separate layers and locations: front-side for gates and contacts, back-side for power rails and signal lines. This segmentation allows each to be optimized independently for their respective functions, improving overall reliability while managing manufacturing complexity through specialized processing steps.
Data Source
AI summary
An integrated circuit includes a first and second conductor, and a first and second pair of transistors. The first conductor is on a back-side of a substrate, extending in a first direction, and being configured to supply a first supply voltage. The second conductor is on the back-side of the substrate, and extending in the first direction. The first pair of transistors includes a first gate extending in a second direction, overlapping at least the second conductor, being located on a first level of a front-side of the substrate opposite from the back-side. The second pair of transistors includes a second gate extending in the second direction, overlapping at least the second conductor, being on the first level, and being separated from the first gate in the first direction. The second conductor electrically couples the first gate and the second gate together.