Bridged Gate Structure for Middle of Line Scaling
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Solution Overview
Problem
As semiconductor processes scale down, fabricating middle of line (MOL) metallization features becomes challenging due to critical dimension scaling and limited process capabilities, particularly in finFET technologies where gate contacts require minimal size and precise inline process control to prevent shorting between gate contacts and source and drain metallization features.
Innovation Solution
The formation of a bridged gate structure by connecting adjacent gate structures, which reduces gate contact size, allows for a single gate contact in MOL multi-finger devices, and provides flexibility in source and drain metallization feature sizes, shapes, and placement, thereby increasing the process margin and reducing the risk of shorting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If gate contacts are made smaller to accommodate scaling, then device density increases, but process control difficulty increases and shorting risk increases
Solution Approach 1:
Multiple adjacent gate structures are merged into a single bridged gate structure, allowing a single gate contact to serve multiple gates. This merging reduces the number and size of gate contacts while maintaining proper electrical connection, thereby reducing shorting risk and process control difficulty despite smaller feature sizes
Solution Approach 2:
A bridge structure is introduced as an intermediary element that connects multiple gate structures. This bridge acts as a mediator that distributes the gate contact connection across multiple gates, reducing the burden on individual contacts and improving process margin
2Productivity
If gate contact size is reduced for scaling, then MOL structure density improves, but the risk of shorting between gate contacts and source/drain metallization increases
Solution Approach 1:
By merging multiple gate structures into a bridged gate structure, the effective gate contact area is reduced while the connection is distributed across multiple gates through the bridge, lowering the probability of shorting to source/drain metallization
Solution Approach 2:
The bridge structure extracts and isolates the gate connection function from individual gate contacts, creating a separate intermediary structure that reduces direct interaction between gate contacts and source/drain metallization, thereby reducing shorting risk
3Ease of operation
If multiple separate gate contacts are used for each gate, then individual gate control is maintained, but process steps and materials increase
Solution Approach 1:
Multiple gate structures are merged into a single bridged gate structure that can be contacted through a single gate contact, reducing the number of process steps and materials required while maintaining electrical connection to all gates
Solution Approach 2:
The bridge structure serves multiple functions: it connects multiple gate structures, distributes electrical connection, and reduces the number of required gate contacts. This multi-functionality reduces overall device complexity and process steps
Data Source
AI summary
The present disclosure generally relates to semiconductor structures and, more particularly, to middle of line gate structures and methods of manufacture. The structure includes: a plurality of adjacent gate structures; a bridged gate structure composed of a plurality of the adjacent gate structures; source and drain regions adjacent to the bridged gate structure and comprising source and drain metallization features; and contacts to the bridged gate structure and the source and drain metallization features.