Backside Power Rail Switching Through FTVs for IC Signal Routing
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Solution Overview
Problem
Existing integrated circuit (IC) devices face challenges in minimizing power consumption, particularly when functional circuits are in non-active states, as current power control circuits are inefficient in managing power supply.
Innovation Solution
Incorporating feed through vias (FTVs) that extend through the substrate to connect front and back side power rails, allowing power control circuits to switch power supply on and off efficiently, enabling power to be provided from the back side while freeing up the front side for signal routing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If header switch and footer switch are used to control power supply to functional circuits, then power consumption is reduced when circuits are non-active, but the front side of the substrate is occupied by power control circuitry reducing signal routing capability
Solution Approach 1:
The patent moves the power control circuitry from the front side to the back side of the substrate, utilizing the third dimension (depth/thickness) to resolve the spatial conflict. Feed-through vias are used to extend power rails from the back side through the substrate to the front side, allowing power switches to control functional circuits without occupying front side real estate needed for signal routing.
2Productivity
If power control circuits are placed on the front side to enable efficient power switching, then power management is optimized, but signal routing capabilities are reduced due to occupied space
Solution Approach 1:
The invention relocates power control circuits to the back side of the substrate, using vertical feed-through vias to maintain electrical connectivity. This dimensional relocation allows power management circuits to operate efficiently while preserving front side space for optimal signal routing, thus resolving the productivity-adaptability contradiction.
3Adaptability or versatility
If feed through vias are used to extend power rails through the substrate, then power can be provided from the back side freeing up the front side, but the manufacturing process becomes more complex
Solution Approach 1:
The manufacturing process is divided into distinct stages: forming power rails on the back side, creating feed-through vias through the substrate, and completing connections to the front side. This segmentation of the manufacturing process makes the complex task of creating through-substrate connections more manageable and systematic.
4Adaptability or versatility
If power rails are extended through the substrate using feed through vias, then front side space is freed for signal routing, but manufacturing precision requirements increase
Solution Approach 1:
The feed-through vias are formed and positioned during earlier manufacturing stages before final assembly and testing. This preliminary action allows for precise alignment to be established early in the process when adjustment is more feasible, and subsequent layers can be built upon this established alignment framework.
Data Source
AI summary
A method includes fabricating at least one circuit over a substrate having opposite front and back sides, fabricating a front side redistribution structure on the front side of the substrate, fabricating feed through vias (FTVs) extending through the substrate, and fabricating a back side redistribution structure on the back side of the substrate. A front side metal layer in the front side redistribution structure has a first front side power rail coupled to a first source/drain of a transistor of the at least one circuit, and a second front side power rail coupled to a second source/drain of the transistor. The FTVs include first and second FTVs correspondingly coupled to the first and second front side power rails. A back side metal layer in the back side redistribution structure includes first and second back side power rails correspondingly coupled to the first and second FTVs.