Backside Power Rail Decoupling Capacitors for IC Noise Stability
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Solution Overview
Problem
Integrated circuits face noise issues due to transient currents with high intensity, which can cause voltage fluctuations on power supply lines, necessitating effective decoupling capacitors to stabilize the power supply.
Innovation Solution
A decoupling capacitor design is implemented with transistors formed on one side of a semiconductor substrate and a power rail on the opposite side, utilizing interconnecting structures to enhance capacitance and stabilize the power supply, allowing for a reduced size and increased capacitance value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional decoupling capacitor designs are used, then power supply stability can be achieved, but the capacitor occupies large area and has limited capacitance value
Solution Approach 1:
The patent utilizes the back side of the semiconductor substrate to place the power rail, effectively using the third dimension (vertical stacking) to increase capacitance without increasing planar area. The capacitor structure extends from the front side through the substrate to the back side, where the power rail is located, thereby doubling the effective capacitance density.
Solution Approach 2:
The capacitor structure is nested within the semiconductor device architecture by integrating the capacitor electrodes with existing transistor source/drain regions and interconnect structures. The power rail on the back side serves as one electrode, while the front side interconnect structures serve as the other electrode, nesting the capacitor function within the existing device footprint.
2Reliability
If transient current handling capability is increased, then power supply stability improves, but noise on power supply lines increases
Solution Approach 1:
The decoupling capacitor is positioned strategically close to the transient current sources (logic circuits) and connected via low-inductance paths. By having the capacitor ready and positioned in advance, it can immediately respond to transient current demands before they cause significant voltage fluctuations or noise on the power supply lines.
Solution Approach 2:
The capacitor provides localized power supply stabilization directly at the point where transient currents are generated. By placing the capacitor in close proximity to the logic circuits and using localized interconnect structures, the solution addresses the noise problem at its source rather than attempting to manage it globally across the entire power distribution network.
3Reliability
If capacitance value is increased to handle transient currents, then power supply stability improves, but device size increases
Solution Approach 1:
The patent achieves increased capacitance by utilizing the vertical dimension through the substrate thickness. The capacitor structure extends from the front side interconnect structures, through the substrate, to the back side power rail, effectively using the third dimension to increase capacitance without increasing planar footprint or overall device volume.
Solution Approach 2:
The capacitor structure is merged with the existing semiconductor device architecture by integrating it with transistor source/drain regions and interconnect structures. The power rail on the back side and front side interconnect structures serve as capacitor electrodes, combining the capacitor function with existing device elements rather than adding separate discrete components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively stabilizes the power supply by increasing the total capacitance value and reducing the size of the decoupling capacitor, making it easier to deploy and improve power supply stability in integrated circuits.
Implementation Method 1
decoupling capacitors are typically used, acting as temporary charge reservoirs to prevent momentary fluctuations in supply voltage
Data Source
AI summary
A semiconductor device includes a substrate having a first side and a second side. The semiconductor device on the first side includes: an active region that extends along a first lateral direction and comprises a first sub-region and a second sub-region; a first gate structure that extends along a second lateral direction and is disposed over the active region, with the first and second sub-regions disposed on opposite sides of the first gate structure, wherein the second lateral direction is perpendicular to the first lateral direction; and a first interconnecting structure electrically coupled to the first gate structure. The semiconductor device on the second side includes a second interconnecting structure that is electrically coupled to the first and second sub-regions and configured to provide a power supply. The active region, the first gate structure, the first interconnecting structure, and the second interconnecting structure are collectively configured as a decoupling capacitor.