Standard Cell Interconnect Layout for Power-Signal Tradeoffs
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Solution Overview
Problem
As IC technologies progress towards smaller technology nodes, challenges arise in configuring transistors and interconnect structures to optimize performance, power consumption, area, and cost, while managing increased resistance and capacitance in multilayer interconnect features.
Innovation Solution
The interconnect-driven optimization of IC design layouts involves adjusting dimensions of interconnect structures and layers relative to one another to optimize power or signal performance without changing the footprint of the IC design layout, including width adjustments of M1 level lines and corresponding interconnects to reduce resistance and improve performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multilayer interconnect features are scaled down to increase functional density, then production efficiency increases and costs decrease, but resistance and capacitance increase which degrades performance
Solution Approach 1:
The patent applies local quality by differentiating the treatment of interconnect features based on their function. Power lines are given larger widths and optimized dimensions compared to signal lines, creating non-uniform interconnect structures that locally optimize for their specific electrical requirements. This resolves the contradiction by allowing functional density to increase through scaling while maintaining performance through localized dimensional adjustments.
Solution Approach 2:
The patent changes physical parameters of interconnect features, specifically line widths, via dimensions, and spacing, to optimize the balance between functional density and electrical performance. By adjusting these parameters locally for power versus signal lines, the patent achieves both improved productivity through scaling and maintained reliability through optimized electrical characteristics.
2Area of moving object
If interconnect dimensions are reduced to increase functional density, then area utilization improves, but resistance increases which degrades performance
Solution Approach 1:
The patent implements local quality by creating different interconnect dimensions for different functional requirements within the same cell. Power lines maintain larger dimensions to minimize resistance, while signal lines are optimized for area efficiency. This local differentiation resolves the contradiction between area utilization and performance by allowing each interconnect type to have optimal dimensions for its specific function.
Solution Approach 2:
The patent addresses the area-performance contradiction by utilizing multiple metal layers and varying interconnect dimensions across different layers. By distributing interconnects across multiple dimensions (different metal layers with different thicknesses and widths), the patent achieves high area utilization while maintaining low resistance through strategic dimensional choices in the vertical and lateral dimensions.
3Ease of manufacture
If interconnect features are made compact to increase functional density, then manufacturing cost decreases, but capacitance increases which degrades performance
Solution Approach 1:
The patent applies local quality by optimizing interconnect dimensions locally rather than uniformly across the entire chip. Power lines use larger dimensions to minimize resistance and capacitance effects, while signal lines use smaller dimensions to maximize functional density. This localized optimization resolves the contradiction between manufacturing cost and performance by achieving cost efficiency through compact design where appropriate while maintaining performance where critical.
Data Source
AI summary
An exemplary method includes receiving a device layout for a standard cell that includes a transistor and a multilayer interconnect. The multilayer interconnect includes a power line, signal lines, a source contact connected to the power line and a source of the transistor, and a drain contact connected to one of the signal lines and a drain of the transistor. The method includes modifying the device layout for the standard cell. For example, if performance of the standard cell is sensitive to power-related features, the method includes enlarging the power line and the source contact and shrinking the signal lines and the drain contact. If performance of the standard cell is sensitive to signal-related features, the method includes shrinking the power line and the source contact and enlarging the signal lines and the drain contact. A cell height of the standard cell is the same after modifying the device layout.