Backside Power Grid for Analog Cell Boundary Noise
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Solution Overview
Problem
In integrated circuit (IC) manufacturing, the increasing density of transistors and reduced component sizes lead to challenges in managing noise interference between digital and analog circuits, particularly due to the formation of parasitic bipolar junction transistors, which cause latchup and affect the operation of adjacent analog circuits.
Innovation Solution
The introduction of a backside power grid in the analog-cell-boundary regions, which repurposes otherwise empty space to accommodate power grid segments, reducing frontside routing congestion and facilitating the routing of conductive segments, thereby mitigating noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transistor density is increased and component sizes are reduced, then productivity and integration level are improved, but noise interference between digital and analog circuits increases
Solution Approach 1:
The patent introduces a backside power grid that extends from the frontside through via structures into the substrate, utilizing the vertical dimension and backside surface to route power connections. This three-dimensional power distribution approach allows power grid segments to be positioned in multiple layers and locations, reducing frontside routing congestion and minimizing noise coupling between digital and analog circuits while maintaining high transistor density
2Object-affected harmful factors
If guard ring structures are added to reduce noise interference, then noise protection is improved, but device complexity and manufacturing steps increase
Solution Approach 1:
The backside power grid serves multiple functions simultaneously: it provides power distribution to high-density transistors, acts as an electrostatic discharge (ESD) protection structure, and functions as a noise shielding mechanism. By integrating these protective functions into the existing power grid infrastructure rather than adding separate guard ring structures, the patent reduces overall device complexity while maintaining noise protection capabilities
Solution Approach 2:
The power grid segments themselves provide noise protection and ESD protection functions without requiring separate dedicated protective structures. The via structures and substrate connections that are necessary for power distribution also serve as noise shielding pathways and ESD protection mechanisms, allowing the power grid to protect itself and adjacent circuits
3Use of energy by moving object
If power grid segments are routed on the frontside, then power distribution is achieved, but routing congestion increases and analog circuit operation is affected
Solution Approach 1:
The patent routes power grid segments through the substrate from the frontside to the backside, utilizing the vertical dimension and backside surface for power distribution. This allows power connections to be made without occupying frontside routing space, reducing congestion and minimizing interference with analog circuit signals while ensuring stable power delivery to high-density transistor regions
Data Source
AI summary
A semiconductor device includes: first and second active regions (ARs) included correspondingly in abutting first and second analog cell regions, a region where the first and second analog cell regions abut (analog-cell-boundary (ACB) region) extending from about a top boundary of the first AR to about a bottom boundary of the second AR; via-to-PGBM_1st-segment contact structures (VBs) correspondingly being under the first or second ARs, a long axis of each VB and a short axis of each of the first and second ARs having about a same length; and a PG segment in a first buried metallization layer (PGBM_1st segment) under the VBs, the PGBM_1st segment underlapping a majority of each of the VBs, and a Y-midline of the PGBM_1st segment being at or proximal to where the first and second analog cell regions abut and thus being at or proximal to a middle of the ACB region.