Backside Power Rail Structure for Dense IC Cell Arrays
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Solution Overview
Problem
Integrated circuits (ICs) face challenges in achieving high integration density and performance due to increased parasitic elements from reduced wiring widths and power supply voltages, which affect their operation speed and reliability.
Innovation Solution
The integration of a backside power rail (BSPR) that provides power to a cell array through contacts extending from the transistor sources, reducing parasitic components and enabling efficient power delivery with a shorter path, thus enhancing operation speed and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If wiring width and spacing are reduced to increase integration density, then integration density is improved, but parasitic elements increase
Solution Approach 1:
The patent introduces a backside power rail structure that utilizes the vertical dimension (z-axis) by routing power supply lines through the substrate thickness direction. This dimensional transition allows power delivery without increasing planar wiring density, thereby maintaining high integration density while providing dedicated power paths that reduce parasitic effects in the horizontal plane.
Solution Approach 2:
The backside power rail acts as an intermediary structure between the power source and the cell array. By introducing this intermediate power distribution layer at the substrate backside, the patent creates a dedicated power delivery path that isolates power transmission from signal wiring, reducing mutual interference and parasitic coupling while maintaining high integration density.
2Use of energy by moving object
If power supply voltage is reduced to decrease power consumption, then power consumption is reduced, but the influence of parasitic elements increases
Solution Approach 1:
By routing power supply lines through the substrate thickness direction via backside power rails, the patent creates shorter and more direct power delivery paths. This dimensional change reduces the length of horizontal power wires, thereby reducing resistive losses and parasitic voltage drops that would be magnified at lower operating voltages, enabling efficient low-voltage operation.
Solution Approach 2:
The patent segments the power delivery function from signal transmission by creating separate backside power rails dedicated solely to power supply. This segmentation allows optimized power path design with minimal parasitic elements, enabling the use of lower power supply voltages without the detrimental effects of parasitic voltage drops that would occur in integrated signal-power routing.
3Device complexity
If conventional power routing is used to maintain simple structure, then device complexity is low, but operation speed is limited due to parasitic elements
Solution Approach 1:
The backside power rail structure utilizes the substrate thickness direction to create vertical power delivery paths through contact holes and via structures. This dimensional transition shortens the effective power delivery length compared to horizontal routing, reducing RC delays and parasitic effects, thereby improving operation speed while adding only moderate structural complexity through standard vertical interconnect techniques.
Data Source
AI summary
An integrated circuit includes a cell array comprising cells, each including a transistor, a power rail in a power rail layer under the cell array, the power rail providing power to the cell array, and contacts between the cell array and the power rail. Each contact extends downward from a source of a transistor of a corresponding one of the cells to the power rail.