Staggered Via Layout Across Unit Cells to Cut Parasitic Effects
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Solution Overview
Problem
Designing integrated circuit structures with smaller unit cells is challenging due to the proximity of signal tracks and vias, leading to parasitic effects that degrade device performance and result in wasted area and reduced Power, Performance, and Area (PPA) efficiency.
Innovation Solution
Implementing a staggered via arrangement between adjacent cells, where vias are intentionally positioned to avoid overlap along the cell height direction, reducing dead space and allowing for a more compact cell design by increasing the effective size utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If unit cells are made smaller to increase density, then area efficiency is improved, but parasitic effects increase and performance degrades
Solution Approach 1:
The patent applies staggered via arrangement across multiple interconnect layers, transitioning from a single-plane via layout to a three-dimensional staggered configuration. This dimensional change allows vias in adjacent cells to be offset vertically across layers, reducing parasitic coupling while maintaining compact cell area.
Solution Approach 2:
The via connections are segmented across multiple interconnect layers rather than concentrated in a single layer. By distributing vias across different vertical levels (layer 1, layer 2, etc.), the patent reduces parasitic effects between adjacent cells while maintaining electrical connectivity.
2Ease of manufacture
If vias are aligned in adjacent cells for manufacturing simplicity, then manufacturing precision is improved, but dead space increases and area efficiency decreases
Solution Approach 1:
The patent moves from two-dimensional aligned via placement to three-dimensional staggered placement across multiple layers. Vias in adjacent cells are offset in the vertical dimension across interconnect layers, eliminating dead space while maintaining manufacturing feasibility through standardized via formation processes.
Solution Approach 2:
The staggered via arrangement is pre-planned in the design stage with specific offset patterns between adjacent cells. This preliminary positioning optimizes space utilization before manufacturing, allowing compact cell layout while accounting for the multi-layer via structure.
3Area of stationary object
If signal tracks are routed closely to maintain compact cell layout, then area efficiency is improved, but parasitic effects increase and performance degrades
Solution Approach 1:
The patent utilizes the vertical dimension across multiple interconnect layers to separate signal tracks and vias. By routing signals through different vertical levels and staggering via positions, the patent reduces parasitic coupling while maintaining horizontal compactness of the cell layout.
Solution Approach 2:
Signal tracks and vias are segmented across multiple interconnect layers, distributing the routing paths vertically. This segmentation reduces parasitic interactions by separating closely spaced conductors into different vertical levels while maintaining compact horizontal cell dimensions.
Data Source
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AI summary
Techniques are described for designing and forming cells having transistor devices. In an example, an integrated circuit structure includes a plurality of cells where adjacent cells have a decreased distance between them along their height and a staggered via arrangement. Accordingly, a first cell may be adjacent to a second cell along a shared cell boundary. A first via is provided between a first gate structure of the first cell adjacent to the cell boundary and a first metal layer above the first gate structure, and a second via is provided between a second gate structure of the second cell adjacent to the cell boundary and a second metal layer above the second gate structure. No part of the first via is aligned with any part of the second via along the first direction.