Jogged Via Rail Layout for Lower Contact Resistance
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Solution Overview
Problem
As semiconductor IC dimensions shrink, conductive features experience increased resistance due to reduced contact areas, necessitating a method to reduce contact resistance without increasing the via rail's footprint.
Innovation Solution
The introduction of jog portions protruding from the via rail's sidewalls to increase contact area with source features, specifically designed to match the shape of the source features, thereby reducing contact resistance without inducing via-metal leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If via rail dimensions are scaled down to reduce device size, then device footprint is reduced, but contact resistance increases due to reduced contact areas
Solution Approach 1:
The via rail structure transitions from a simple linear configuration to a three-dimensional structure with jog portions extending in multiple directions. The jog portions protrude from the main via rail body in directions perpendicular to the main current flow, creating additional contact interfaces with source features without increasing the device footprint in the planar direction.
Solution Approach 2:
The via rail is segmented into a main body portion and multiple jog portions that extend in different directions. Each jog portion can independently contact different source features, effectively dividing the contact function across multiple spatial locations while maintaining a compact overall structure.
2Reliability
If via rail contact area is increased to reduce contact resistance, then contact resistance decreases, but via rail footprint increases
Solution Approach 1:
Instead of expanding the via rail footprint in the planar direction, the jog portions extend vertically and laterally in three-dimensional space from the main via rail body. This allows increased contact area with source features while maintaining a compact footprint when viewed from above.
Solution Approach 2:
The jog portions are integrated into the overall via rail structure, with the jog portions effectively nested within or extending from the main via rail body. This nested configuration allows multiple contact points to be achieved within the bounds of a single via rail footprint.
3Adaptability or versatility
If pattern density is increased to accommodate more features, then device functionality increases, but current leakage increases
Solution Approach 1:
The jog portions are strategically positioned to contact specific source features at optimized locations, creating localized high-quality contact interfaces. This selective contact approach ensures reliable electrical connection while maintaining adequate spacing from drain features to prevent current leakage paths.
Data Source
AI summary
A device includes a semiconductor substrate, an active region over the semiconductor substrate extending lengthwise in a first direction, a gate structure over the active region extending lengthwise in a second direction perpendicular to the first direction, a source feature and a drain feature on the active region and interposed by the gate structure, a source contact on the source feature, a drain contact on the drain feature, and a via rail over the substrate spaced from the active region. The via rail includes a main portion extending lengthwise in the first direction having a sidewall surface facing opposite the end surface of the drain contact, and a jog via extending from the main portion along the second direction and having a sidewall surface facing the second direction, each of the main portion and the jog via contacting the source contact.