Cross-Coupled Clock Signal Distribution in Multi-Height Sequential Cells
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Solution Overview
Problem
Semiconductor device manufacturers face challenges in integrating larger devices on a single chip due to area constraints and layout design restrictions in modern processing technologies, leading to inefficiencies in semiconductor layout designs, particularly in MOS devices.
Innovation Solution
The implementation of a cross-coupled clock signal distribution layout in multi-height sequential cells, where interconnects in different metal layers are configured to propagate signals in a specific direction, allowing for efficient use of space by reducing the area required for MOS device layouts while maintaining functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If traditional clock signal distribution layout is used in multi-height sequential cells, then signal propagation functionality is maintained, but area consumption increases
Solution Approach 1:
The patent applies dimensionality change by transitioning from a conventional two-dimensional planar layout to a three-dimensional stacked layout utilizing multiple metal layers (M1, M2, M3). Clock signals are distributed across different vertical layers with interconnects extending in both horizontal and vertical directions, enabling compact area utilization while maintaining signal propagation integrity through cross-layer routing.
Solution Approach 2:
The patent implements nesting by placing interconnects from different metal layers in a hierarchical structure where M1 interconnects are nested within the same plane as sequential cells, M2 interconnects are positioned above in the vertical stack, and M3 interconnects are positioned at the highest level. This nested multi-layer configuration allows dense packing of interconnects without mutual interference, reducing overall area consumption.
2Quantity of substance
If device integration density is increased to overcome area constraints, then more devices can be placed on chip, but layout design restrictions and complexity increase
Solution Approach 1:
The patent applies segmentation by dividing the clock signal distribution network into distinct segments assigned to different metal layers. Each metal layer (M1, M2, M3) carries specific clock signals to different groups of sequential cells, allowing independent routing optimization for each segment. This segmentation reduces layout complexity by organizing the dense interconnect network into manageable, layer-specific segments rather than a monolithic complex structure.
Solution Approach 2:
The patent resolves layout complexity by adding the vertical dimension through multi-layer interconnect structure. Instead of congesting all interconnects in a single planar layer, the design distributes them across multiple vertical layers, effectively transforming a two-dimensional layout problem into a three-dimensional solution space, thereby reducing routing complexity and improving designability.
3Area of stationary object
If interconnects are configured to extend in multiple directions across metal layers, then area efficiency improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies asymmetry in the interconnect configuration where interconnects in different metal layers are intentionally positioned with asymmetric offsets relative to each other. For example, M2 interconnects may be offset from M1 interconnects, and M3 interconnects may be offset from M2 interconnects, creating a staggered asymmetric pattern. This asymmetric arrangement reduces the need for precise perfect alignment while maintaining electrical connectivity, thereby reducing manufacturing precision requirements.
Data Source
AI summary
A MOS device includes first, second, third, and fourth interconnects. The first interconnect (402) extends on a first track in a first direction. The first interconnect is configured in a metal layer. The second interconnect (404) extends on the first track in the first direction. The second interconnect is configured in the metal layer. The third interconnect (408) extends on a second track in the first direction. The third interconnect is configured in the metal layer. The second track is parallel to the first track. The third interconnect is coupled to the second interconnect. The second and third interconnects (404. 408) are configured to provide a first signal (Clk). The fourth interconnect (410) extends on the second track in the first direction. The fourth interconnect is configured in the metal layer. The fourth interconnect is coupled to the first interconnect. The first and fourth interconnects (402, 410) are configured to provide a second signal (Clk) different than the first signal.