Backside Power Rail Air Spacers for Capacitive Coupling Isolation
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Solution Overview
Problem
As semiconductor devices continue to reduce minimum feature sizes for increased integration density, issues such as capacitive coupling between conductive lines in backside interconnect structures become significant, limiting device performance and speed.
Innovation Solution
The formation of air spacers adjacent conductive lines in the backside interconnect structure, achieved by etching a first dielectric layer, depositing a second dielectric layer, and anisotropically etching to form spacers, which are then sealed with an additional dielectric layer to reduce capacitive coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If minimum feature sizes are reduced to increase integration density, then more components can be integrated into a given area, but capacitive coupling between conductive lines increases
Solution Approach 1:
Air spacers are introduced as intermediary structures between adjacent conductive lines in the backside interconnect structure. These spacers create physical separation and reduce the electric field coupling between lines, thereby reducing capacitive coupling while allowing continued miniaturization of feature sizes for higher integration density.
Solution Approach 2:
The patent applies different materials and structures locally between conductive lines where capacitive coupling occurs. Air spacers are selectively placed in regions where coupling is problematic, providing localized isolation without affecting other areas of the device, thus enabling high integration density while managing coupling effects where they matter most.
2Productivity
If conductive lines are placed closer together to increase integration density, then more components can be integrated, but device speed decreases due to increased capacitive coupling
Solution Approach 1:
Air spacers serve as intermediary structures that enable closer spacing of conductive lines without the penalty of increased capacitive coupling. By introducing this intermediate element, the patent allows lines to be positioned closer for higher integration density while the spacers maintain electrical isolation to preserve signal speed and device performance.
3Object-generated harmful factors
If air spacers are formed by etching and depositing dielectric layers, then capacitive coupling is reduced, but manufacturing complexity increases
Solution Approach 1:
The air spacer formation process utilizes self-aligned fabrication techniques where previously formed structures serve as alignment references for subsequent steps. The etching and deposition processes are integrated into the existing manufacturing flow, allowing the structure to form itself with minimal additional complexity beyond standard semiconductor fabrication capabilities.
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
The air spacers provide improved isolation between conductive lines, reducing coupling capacitance and allowing for increased device speeds and performance.
Implementation Method 1
anisotropically etching to form spacers
Implementation Method 2
depositing a second dielectric layer over the first dielectric layer and the conductive lines
Data Source
AI summary
Semiconductor devices including air spacers formed in a backside interconnect structure and methods of forming the same are disclosed. In an embodiment, a device includes a first transistor structure; a front-side interconnect structure on a front-side of the first transistor structure; and a backside interconnect structure on a backside of the first transistor structure, the backside interconnect structure including a first dielectric layer on the backside of the first transistor structure; a first via extending through the first dielectric layer, the first via being electrically coupled to a first source/drain region of the first transistor structure; a first conductive line electrically coupled to the first via; and an air spacer adjacent the first conductive line, the first conductive line defining a first side boundary of the air spacer.