Backside Skip-Level Via Layout for Lower-Resistance Signal Routing
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Solution Overview
Problem
The increased pitch of backside metal levels due to the addition of backside signal lines alongside power rails in semiconductor structures leads to higher resistance and a higher risk of open circuits, particularly in via-to-backside power rail connections, resulting in increased resistance in the first backside metal level.
Innovation Solution
A semiconductor structure incorporating a backside skip-level through via that connects the backside signal line to the gate structure, with a dielectric spacer on its sidewall, positioned between backside power rails in the first metal level, reducing the resistance of the first backside metal level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If backside signal lines are added to the first backside metal level alongside power rails, then signal line functionality is improved, but the pitch of the first backside metal level must be reduced, causing higher resistance and increased risk of open circuits
Solution Approach 1:
The patent introduces a skip-level through via that extends vertically from the first backside metal level through intermediate levels to reach the third backside metal level. This vertical dimensionality change allows the signal line to bypass the congested first metal level, avoiding the pitch reduction problem while maintaining signal line functionality.
Solution Approach 2:
The skip-level through via acts as an intermediary structure that connects the first backside metal level to the third backside metal level without requiring direct horizontal routing through the congested first level. This intermediary vertical pathway resolves the conflict between maintaining pitch and providing signal line access.
2Adaptability or versatility
If backside signal lines are added to the first backside metal level, then signal line functionality is improved, but the resistance of the first backside metal level increases
Solution Approach 1:
The signal path is moved from horizontal routing in the first metal level to vertical routing through the skip-level through via. This dimensional change creates a dedicated low-resistance vertical pathway that bypasses the high-resistance congested first metal level, reducing overall signal resistance.
3Adaptability or versatility
If the pitch of the first backside metal level is reduced to accommodate both power rails and signal lines, then signal line functionality is achieved, but manufacturing precision requirements increase
Solution Approach 1:
Instead of reducing horizontal pitch in the first metal level, the patent uses vertical extension through the skip-level through via to achieve signal line functionality. This maintains the original horizontal pitch dimensions, avoiding increased manufacturing precision requirements while still providing signal line access.
Data Source
AI summary
A semiconductor structure is provided that includes a gate structure that is wired to a backside signal line through a backside gate contact extension and a backside skip-level through via. The backside skip-level through via has a dielectric spacer located on a sidewall thereof and a portion of the backside skip-level through via is positioned between a pair of backside power rails that are located in a first backside metal level that is located beneath a second backside metal level that includes the backside signal line.