L-Shaped Source/Drain Contact Layout for Single Diffusion Breaks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The close proximity between gate and source/drain contacts in vertically stacked transistors makes it difficult to connect metal lines on the same metal track, especially in densely packed semiconductor devices like nanosheet transistors.
Innovation Solution
The formation of L-shaped source/drain contacts with a vertical portion on top of a horizontal portion, extending into a sidewall spacer or diffusion break, allows for separate connections to a metal track, mitigating the risk of shorts by maintaining a gap equal to or larger than two-thirds of the source/drain region length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If vertically stacked transistors are used to increase device density, then device density is improved, but the close proximity between gate and source/drain contacts makes it difficult to connect metal lines on the same metal track
Solution Approach 1:
The source/drain contact is formed with an L-shape configuration, extending in both horizontal and vertical dimensions. The horizontal portion extends into the sidewall spacer region, while the vertical portion rises to connect to the metal track, utilizing three-dimensional space to resolve the connectivity issue in densely packed vertical transistor structures
Solution Approach 2:
The source/drain contact is divided into distinct horizontal and vertical portions, each serving a specific function. The horizontal portion provides lateral connection to the source/drain region through the sidewall spacer, while the vertical portion provides vertical connection to the metal track, allowing independent optimization of each segment
2Reliability
If gate contact is placed directly above the active channel region, then proper gate control is achieved, but the close proximity to source/drain contact creates short circuit risk
Solution Approach 1:
The sidewall spacer acts as an intermediary structure that the horizontal portion of the source/drain contact extends into. This intermediary region provides electrical connection to the source/drain region while maintaining physical separation from the gate contact, thus mediating between the need for proper source/drain connection and the need to prevent short circuits with the gate
Solution Approach 2:
The L-shaped source/drain contact creates an asymmetric configuration where the horizontal and vertical portions are positioned at different locations relative to the gate contact. This asymmetric positioning allows the contact to connect to the source/drain region without directly opposing or approaching the gate contact, reducing short circuit risk while maintaining proper gate control
Data Source
AI summary
Embodiments of present invention provide a semiconductor structure. The semiconductor structure includes a first and a second transistor separated by a single diffusion break; and a source/drain contact to a source/drain region of the first transistor, the source/drain region being next to the single diffusion break, where the source/drain contact has an L-shape having a vertical portion on top of a horizontal portion, the horizontal portion extending at least partially into a sidewall spacer at a sidewall of the single diffusion break. A method of forming the same is also provided.