Two-Height Source-Drain Contact for Short-Free Via Routing
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Solution Overview
Problem
As integrated circuits shrink in size, forming interconnects between densely packed transistors becomes challenging due to limited spacing and the number of tracks in interconnect layers, making direct connections difficult without causing shorts.
Innovation Solution
The formation of an elongated conductive contact with varying thickness sections over source or drain regions, allowing it to extend laterally and make contact with a via without directly contacting adjacent regions, thereby alleviating patterning challenges and enabling easier lithography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transistors are packed more densely to reduce integrated circuit size, then productivity and integration density improve, but manufacturing precision and reliability of interconnect formation deteriorate due to limited spacing and track availability
Solution Approach 1:
The conductive contact is segmented into multiple sections with different thicknesses along its length. The first section has a first thickness that makes contact with the source or drain region, while the second section has a second thickness that extends over the adjacent source or drain region without making contact. This segmentation allows the single conductive contact structure to simultaneously achieve reliable electrical connection and physical isolation, resolving the contradiction between dense packing and manufacturing precision.
2Adaptability or versatility
If direct connections are made between densely packed source or drain regions, then interconnect capability improves, but reliability deteriorates due to risk of shorts between adjacent regions
Solution Approach 1:
The conductive contact exhibits local quality variations along its length through different thickness sections. The first section is locally optimized for electrical connection with appropriate thickness to ensure reliable contact with the source or drain region, while the second section is locally optimized for isolation with reduced thickness to prevent contact with adjacent regions. This local differentiation enables the structure to simultaneously provide interconnect capability and short prevention.
3Ease of manufacture
If conventional uniform thickness contacts are used, then manufacturing simplicity improves, but adaptability deteriorates due to inability to both contact and avoid adjacent regions
Solution Approach 1:
The conductive contact transitions from a static uniform thickness structure to a dynamic structure with varying thickness along its length. This dynamic variation in thickness allows the contact to adapt its electrical connection properties at different locations - making contact where needed and avoiding contact where isolation is required - thereby providing routing flexibility while maintaining manufacturability through a single continuous structure.
Data Source
Figure 1A~1B
Figure 1C
Figure 2A~2B
AI summary
Techniques are provided herein to form semiconductor devices that include an elongated contact having two different heights on a source or drain region. A semiconductor device includes a gate structure around or otherwise on a semiconductor region (or channel region) that extends from a source or drain region. An elongated conductive contact is formed over the source or drain region that stretches or otherwise extends laterally across the source/drain trench above an adjacent source or drain region without contacting the adjacent source or drain region. A conductive via may contact the portion of the conductive contact over the adjacent source or drain region. Accordingly, the conductive contact may have a first thickness above the source or drain region and a second thickness above the adjacent source or drain region with the first thickness being greater than the second thickness.