Embedded Source-Drain Contacts for Lower Contact Resistance
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Solution Overview
Problem
As integrated circuits scale to smaller feature dimensions and higher transistor densities, the reduced contact area between source or drain regions and their corresponding contacts increases contact resistance, negatively impacting transistor performance.
Innovation Solution
The integrated circuit structure includes source or drain contacts that extend within the corresponding source or drain regions, with the region wrapping around the lower section of the contact, reducing contact resistance by increasing the contact area and improving performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If integrated circuits are scaled to smaller feature dimensions and higher transistor densities, then transistor density increases, but contact area between source/drain regions and contacts decreases, leading to increased contact resistance
Solution Approach 1:
The contact structure transitions from a planar surface contact to a three-dimensional embedded configuration. The source and drain contacts extend vertically into the source/drain regions, utilizing the depth dimension to increase contact area. This dimensional transition allows the contact to interface with the source/drain region along its entire perimeter, effectively multiplying the contact area without increasing the lateral footprint, thus maintaining high transistor density while reducing contact resistance
Solution Approach 2:
The contact structure is nested within the source/drain region, with the contact extending into and being surrounded by the source/drain material. This nested configuration allows the source/drain region to wrap around the contact, creating a conformal interface that maximizes the contact area. The nesting approach enables the contact to be embedded within the active region, increasing the effective contact area while maintaining compact device dimensions and high transistor density
2Productivity
If pitch for source and drain contacts is reduced to increase transistor density, then more transistors can be packed, but contact area decreases, negatively impacting transistor performance
Solution Approach 1:
By extending the contact vertically into the source/drain region rather than relying solely on lateral contact area, the invention compensates for the reduced pitch. The vertical extension into the depth dimension provides additional contact area that offsets the reduction in lateral dimensions, allowing high transistor density to be achieved without sacrificing contact quality or transistor performance
Solution Approach 2:
The contact structure is segmented into multiple interface points along its perimeter where it contacts the source/drain region. Instead of a single planar contact interface, the embedded contact creates multiple contact points around its circumference, distributing the current flow path and reducing overall contact resistance even when the lateral pitch is reduced
Data Source
AI summary
An integrated circuit structure includes a source or drain region, and a contact for the source or drain region. The contact has (i) an upper portion outside the source or drain region and (ii) a lower portion extending within the source or drain region. For example, the source or drain region wraps around the lower portion of the contact, such that an entire perimeter of the lower portion of the contact is adjacent to the source or drain region.