Backside Power Rail Isolation Using Dielectric Spacer Layers
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Solution Overview
Problem
Present semiconductor processing forms a backside power rail that is highly susceptible to shorting by being in contact with the silicon substrate.
Innovation Solution
The backside power rail is formed in a backside dielectric layer with dielectric spacer layers laterally extending inwardly from opposing sidewalls to avoid contact with the silicon substrate, and the dielectric spacer layers are disposed at the interface of the backside power rail and shallow trench isolation regions to minimize shorting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the backside power rail is formed in contact with the silicon substrate, then the manufacturing process is simpler, but the reliability deteriorates due to high susceptibility to shorting
Solution Approach 1:
The patent introduces dielectric spacer layers as intermediary structures between the backside power rail and the silicon substrate. These spacer layers physically separate the power rail from the substrate, preventing direct contact and eliminating the shorting pathway while maintaining the structural integrity and electrical isolation required for reliable operation
Solution Approach 2:
The patent transitions from a planar two-dimensional power rail configuration to a three-dimensional structure by adding vertical dielectric spacer layers. This dimensional change creates vertical separation between the power rail and substrate, providing electrical isolation without complicating the horizontal manufacturing process
2Power
If the backside power rail cross-section area is increased, then the power distribution capacity is improved, but the device complexity increases due to additional isolation structures
Solution Approach 1:
The dielectric spacer layers serve multiple functions simultaneously: they provide electrical isolation between the power rail and substrate, define the lateral boundaries of the power rail structure, and facilitate the manufacturing process by serving as etch stop layers. This multi-functionality increases power distribution capacity without proportionally increasing device complexity
Data Source
AI summary
A semiconductor structure includes a backside power rail disposed in a backside dielectric layer, and dielectric spacer layers laterally extending inwardly from opposing sidewalls of the backside dielectric layer and on a portion of a bottom surface of the backside power rail.