Gate Contact Structure Above Active Region
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Solution Overview
Problem
In modern integrated circuits, forming gate contact structures entirely over the active region of transistor devices is complex and inefficient, leading to increased costs and reduced product yields, as existing methods require additional process steps and new materials, and often result in electrical shorts due to the placement of gate contacts above isolation regions rather than active areas.
Innovation Solution
A simplified method for forming gate contact structures above the active region of transistor devices, involving the use of notched insulating source/drain cap structures and sidewall spacers to position conductive gate contacts in notches, allowing for efficient contact with both the gate and source/drain structures without electrical shorts, while conserving valuable IC space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the CB gate contact is positioned above the isolation region to avoid electrical shorts, then electrical short prevention is improved, but IC area utilization deteriorates due to area penalty
Solution Approach 1:
The gate contact structure transitions from a planar configuration to a three-dimensional structure by extending vertically through multiple layers (M0 layer, M1 layer, and upper levels). This vertical dimensionality allows the contact to reach the gate electrode while positioning the upper portions over the isolation region, thus preventing electrical shorts while maintaining area efficiency.
Solution Approach 2:
The gate contact structure is nested within the metallization system, with the M0 layer contact portion embedded in the first insulating layer, and the M1 layer contact portion embedded in the second insulating layer. This nesting allows the contact to pass through multiple levels while maintaining electrical isolation from source/drain regions.
2Area of stationary object
If the CB gate contact is positioned entirely over the active region to improve area utilization, then IC area utilization is improved, but manufacturing complexity increases due to additional process steps
Solution Approach 1:
The gate contact structure serves multiple functions: it provides electrical connection to the gate electrode, acts as a via structure for inter-level connections, and its upper portions over the isolation region provide natural electrical isolation. This multi-functionality eliminates the need for separate isolation measures and complex process steps.
Solution Approach 2:
The gate contact structure merges the functions of vertical electrical connection and electrical isolation by extending through multiple metallization layers and positioning upper portions over the isolation region. This combination of functions into a single structure simplifies the overall device architecture and manufacturing process.
3Area of stationary object
If the CB gate contact is positioned entirely over the active region to conserve IC space, then area penalty is reduced, but reliability deteriorates due to increased risk of electrical shorts
Solution Approach 1:
The gate contact structure utilizes the vertical dimension by extending through multiple metallization layers (M0, M1, and upper levels). This allows the lower contact portions to be positioned over the active region for area efficiency, while upper portions extend over the isolation region to provide electrical isolation and prevent shorts.
Solution Approach 2:
The contact structure is nested within the metallization system with insulating material surrounding the conductive portions at different levels. This nesting provides inherent electrical isolation without requiring additional lateral spacing, thus conserving IC space while preventing electrical shorts.
Data Source
AI summary
One illustrative IC product disclosed herein includes a gate structure for a transistor, a conductive source/drain contact structure and an insulating source/drain cap structure positioned above the conductive source/drain contact structure, wherein the insulating source/drain cap structure has a first notch formed therein. In one illustrative example, the product also includes a sidewall spacer that has a second notch in an upper portion of the sidewall spacer, wherein a first portion of the insulating source/drain cap structure is positioned in the second notch, and a conductive gate contact structure comprising first and second portions, the first portion of the conductive gate contact structure being positioned in the first notch and the second portion of the conductive gate contact structure being in contact with the gate structure.