Backside Via Contact Structure for Lower-Resistance IC Interconnects
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Solution Overview
Problem
As feature sizes in semiconductor integrated circuits (ICs) continue to decrease, the complexity of fabrication processes increases, making it challenging to form reliable semiconductor devices at smaller scales.
Innovation Solution
The proposed solution involves a method of manufacturing an integrated circuit that includes forming semiconductor strips over a substrate, creating a backside via in an isolation structure, and forming source/drain contacts that extend into the isolation structure to contact the backside via, thereby establishing an electrical connection between the front and back sides of the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feature sizes continue to decrease to increase functional density, then production efficiency improves and costs decrease, but fabrication process complexity increases and manufacturing reliability deteriorates
Solution Approach 1:
The patent introduces backside vias that extend through the substrate thickness dimension, creating electrical connections from the front surface through to the back surface. This vertical dimension approach allows routing signals and power through the substrate depth rather than only laterally, reducing congestion and complexity in planar fabrication processes while maintaining scaling benefits.
Solution Approach 2:
The patent segments the electrical connection path into multiple components: frontside contacts, via structures extending through the substrate, and backside contacts. This segmentation allows each component to be formed using optimized processes appropriate to its specific requirements, simplifying the overall fabrication by breaking down the complex task of creating through-substrate connections into manageable stages.
2Productivity
If feature sizes continue to decrease to increase functional density, then production efficiency improves and costs decrease, but manufacturing reliability deteriorates
Solution Approach 1:
By utilizing the vertical dimension through backside vias, the patent reduces lateral feature size requirements while maintaining connection integrity. The via structures provide robust electrical pathways that are less sensitive to lateral dimensional variations, improving manufacturing reliability even as lateral features scale down.
Solution Approach 2:
The via structures act as intermediary elements that bridge the frontside and backside of the substrate. These intermediaries provide reliable electrical connection points that can be independently formed and tested, adding process control and reliability checkpoints in the fabrication sequence.
3Adaptability or versatility
If source/drain contacts extend into the isolation structure to contact the backside via, then routing flexibility improves, but device complexity increases
Solution Approach 1:
The patent utilizes the vertical dimension by extending contacts through the substrate thickness to reach backside vias. This three-dimensional routing approach provides additional path options for electrical connections, allowing signals to route through the substrate depth rather than being constrained to lateral paths only, thereby enhancing routing flexibility.
Solution Approach 2:
The contact structure is segmented into frontside contact portions and backside contact portions separated by via regions. This segmentation allows independent optimization of each segment for its specific function while maintaining overall connectivity, managing complexity through modular design.
Data Source
AI summary
An integrated circuit includes a strip structure having a front side and a back side. The integrated circuit includes a gate structure on the front side of the strip structure. The integrated circuit includes an isolation structure surrounding the strip structure. The integrated circuit includes a backside via in the isolation structure. The integrated circuit includes a contact over the strip structure, wherein a first portion of the contact extends into the isolation structure and contacts the backside via. The integrated circuit includes a backside power rail on the back side of the strip structure and in contact with the backside via.