Deep Trench Via Connection for Misaligned Frontside-Backside Metal Wires
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Solution Overview
Problem
The challenge in semiconductor manufacturing is forming effective connections between misaligned metal tracks on the frontside and backside of a semiconductor chip, as vertical vias are ineffective when these levels are not perfectly aligned.
Innovation Solution
A deep trench via is introduced in a single diffusion break region, with a frontside metal wire connected to its top surface and a backside metal wire connected to its bottom surface, both parallel and perpendicular to the trench, allowing communication between misaligned metal levels through a semiconductor structure that includes inner spacers and a gate cut dielectric.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a deep vertical via is formed to connect frontside and backside metal levels, then communication between metal levels is enabled, but the solution fails when metal levels are misaligned horizontally
Solution Approach 1:
The patent transitions from a purely vertical via structure to a L-shaped connection that incorporates both vertical and horizontal segments. The via structure extends vertically from the frontside metal level, then turns horizontally to reach the backside metal level, enabling connection despite horizontal misalignment. This dimensional expansion allows the connection to accommodate misalignment while maintaining reliability.
Solution Approach 2:
The patent introduces an intermediary horizontal conductive segment that bridges the gap between the vertical via and the backside metal level. This intermediate structure acts as a mediator that connects the frontside and backside metal levels when they are misaligned, enabling communication that would otherwise be impossible with a purely vertical via.
2Manufacturing precision
If metal levels at frontside and backside are vertically aligned, then deep vertical via can connect them effectively, but misalignment occurs due to manufacturing variations
Solution Approach 1:
The patent adds a horizontal dimension to the via structure to compensate for vertical alignment imprecision. By extending the via horizontally after the vertical segment, the structure can reach misaligned metal levels even when vertical alignment precision is insufficient, thereby maintaining connection effectiveness despite manufacturing variations.
Solution Approach 2:
The L-shaped via structure provides a built-in compensation mechanism that cushions against alignment errors before they cause connection failure. The horizontal segment acts as a buffer zone that absorbs misalignment variations, ensuring that connection effectiveness is maintained even when vertical alignment precision is compromised by manufacturing tolerances.
3Adaptability or versatility
If a horizontal connection is created to accommodate misaligned metal tracks, then alignment tolerance is improved, but the device structure becomes more complex
Solution Approach 1:
The patent implements a simple L-shaped via structure that adds only one horizontal segment to the conventional vertical via. This minimal dimensional addition provides alignment tolerance without significantly increasing device complexity, as the structure follows a straightforward geometric path with just two segments (vertical and horizontal) rather than requiring complex multi-layer routing.
Data Source
AI summary
Embodiments of present invention provide a semiconductor structure. The semiconductor structure includes a deep trench via in a single diffusion break region; a frontside metal wire conductively connected to a top surface of the deep trench via; and a backside metal wire conductively connected to a bottom surface of the deep trench via, where the frontside metal wire and the backside metal wire are parallel to each other and perpendicular to the deep trench via. A method of forming the same is also provided.