Enlarged STI Layout for Backside Power Rail Isolation
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Solution Overview
Problem
The removal of the semiconductor substrate during backside power distribution network formation can damage neighboring structures such as gate dielectric and source/drain contact vias, leading to electrical shorting and other issues.
Innovation Solution
The formation of enlarged shallow trench isolation (STI) structures in multiple stages between semiconductor device regions, which extends partially underneath the devices, helps protect these structures by creating a dielectric isolation and allowing for the formation of buried power rails and conductive vias that connect the devices without damaging them during substrate removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the semiconductor substrate is removed during backside power distribution network formation, then power distribution capability is improved, but neighboring structures such as gate dielectric and source/drain contact vias are damaged
Solution Approach 1:
The patent applies preliminary action by forming enlarged shallow trench isolation structures before substrate removal. These isolation structures are created in advance to extend laterally underneath the semiconductor devices, providing protective coverage before the substrate is removed. This preliminary protective measure prevents damage to gate dielectric and source/drain contact vias during the subsequent substrate removal process, while still enabling backside power distribution network formation.
2Reliability
If shallow trench isolation structures are formed to protect neighboring structures, then structural integrity is improved, but the ability to form buried power rails and conductive vias is restricted
Solution Approach 1:
The patent applies segmentation by dividing the isolation structure into different regions with different functions. The enlarged shallow trench isolation structures provide protective isolation in device regions, while separate regions are designated for buried power rails and conductive vias. This segmentation allows the isolation structures to protect neighboring structures from damage during substrate removal, while simultaneously enabling the formation of buried power rails and conductive vias in dedicated regions for backside power distribution.
Data Source
AI summary
Semiconductor devices and methods of forming the same include a first semiconductor device in a first device region and a second semiconductor device in a second device region. A dielectric structure between the first device region and the second device region laterally extends part way underneath the first semiconductor device and the second semiconductor device. A buried power rail is under the dielectric structure. A conductive via penetrates the dielectric structure to connect the first semiconductor device to the buried power rail.