Bi-Directional RDL Power Routing to Reduce Chip IR Drop
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Solution Overview
Problem
Current chip designs experience significant IR drops in power/ground distribution networks due to sparse via contacts and additional routing at lower metal layers, leading to reduced operating voltage and power efficiency, especially in high-performance circuits.
Innovation Solution
Implement bi-directional power and ground routing structures in the redistribution layer (RDL) with interleaved fingers to evenly distribute vias, reducing IR drops and optimizing power/ground distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional unidirectional power and ground routing structures are used in the redistribution layer, then the layout is simple, but the via contacts are sparse and additional routing at lower metal layers is required, leading to significant IR drops and reduced operating voltage
Solution Approach 1:
The power and ground routing structures are segmented into multiple fingers that extend in opposite directions from elongated members. This segmentation creates numerous via contact points distributed across the chip area, reducing the spacing between adjacent vias and minimizing IR drops in the power/ground distribution network
Solution Approach 2:
The routing structures transition from traditional unidirectional layouts to bi-directional configurations where fingers extend in two opposite directions from each elongated member. This dimensional change allows vias to be distributed more evenly across both directions, reducing the need for additional routing at lower metal layers and decreasing overall IR drops
Solution Approach 3:
Power and ground routing structures are merged into an interleaved configuration where power fingers and ground fingers alternate in the redistribution layer. This merging creates a tightly coupled power/ground network with reduced loop area and improved current distribution, minimizing IR drops without requiring additional lower layer routing
2Reliability
If traditional power and ground routing are implemented, then the structure is simpler, but the via contact distribution is sparse, requiring additional routing at lower metal layers and reducing power/ground network efficiency
Solution Approach 1:
The routing structures are divided into multiple segmented fingers with via contacts distributed at regular intervals along each finger. This segmentation ensures dense and uniform via contact distribution across the entire chip area, improving power/ground network reliability and eliminating the need for additional lower layer routing
Solution Approach 2:
The routing architecture evolves from planar unidirectional traces to three-dimensional bi-directional finger structures that extend in opposite directions. This dimensional transformation enables superior via contact distribution in multiple directions, enhancing power delivery reliability without increasing overall structure complexity
Solution Approach 3:
The power and ground routing structures form a composite interdigitated network where power fingers and ground fingers are tightly coupled and interleaved. This composite configuration creates low-inductance power/ground loops with distributed via contacts, improving network efficiency and reliability while maintaining manageable structural complexity
3Power
If unidirectional routing structures are used, then the layout is less complex, but the operating voltage is reduced due to IR drops, impacting high-performance circuit operation
Solution Approach 1:
The power delivery path is segmented into multiple parallel finger structures with distributed via contacts, creating multiple current paths that reduce resistance and minimize IR drops. This segmentation maintains higher operating voltage for high-performance circuits while keeping the routing structure manageable
Solution Approach 2:
The routing structure transitions to bi-directional finger extensions that utilize vertical and horizontal space more efficiently. This dimensional change creates shorter current paths and better voltage distribution across the chip, maintaining operating voltage levels required for high-performance operation without excessive structural complexity
Data Source
AI summary
A chip includes a bi-directional power routing structure in a redistribution layer. The bi-directional power routing structure includes a first elongated member extending in a first direction, a second elongated member extending from the first elongated member in a second direction perpendicular to the first direction, and first fingers extending from the second elongated member in the first direction. The chip also includes a bi-directional ground routing structure in the redistribution layer. The bi-directional ground routing structure includes a third elongated member extending in the first direction, a fourth elongated member extending from the third elongated member in the second direction, and second fingers extending from the fourth elongated member in the first direction, wherein the second fingers are interleaved with the first fingers.