Multi-Layer Single Diffusion Break Isolation for FinFET Parasitic Capacitance
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Solution Overview
Problem
In modern integrated circuits, the formation of single diffusion break (SDB) isolation structures is challenging due to the adverse effects of parasitic capacitors, which degrade device performance as device dimensions decrease, especially in FinFET transistor devices where packing densities and device sizes are increased, leading to difficulties in forming insulating material isolation regions.
Innovation Solution
A multi-layer single diffusion break (SDB) structure is created by forming a conformal liner layer engaging the fin portions, an insulating material positioned on the liner layer, and a cap structure above with an air gap between the cap and the insulating material, which defines the SDB isolation structure, reducing parasitic capacitor effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional trench isolation structures are formed to electrically isolate devices, then device isolation is achieved, but valuable plot space on the substrate is consumed
Solution Approach 1:
The patent transitions from planar trench isolation to a multi-layer vertical structure. The SDB isolation structure utilizes the vertical dimension with multiple layers (first insulating material layer, first SDB layer, second insulating material layer, second SDB layer) stacked above the substrate, thereby achieving effective isolation without consuming additional horizontal plot space.
2Productivity
If device sizes are decreased and packing densities are increased in FinFET devices, then integration density is improved, but it becomes difficult to form desired insulating material isolation regions
Solution Approach 1:
The isolation structure is segmented into multiple functional layers: first insulating material layer for base isolation, first SDB layer for diffusion barrier, second insulating material layer for additional isolation, and second SDB layer for enhanced diffusion barrier. This segmentation allows each layer to perform its specific function effectively, making the formation of isolation regions feasible even at reduced device dimensions.
Solution Approach 2:
The patent employs composite material structure combining different insulating materials and SDB layers with distinct properties. The first and second insulating material layers provide electrical isolation, while the first and second SDB layers provide diffusion barriers. This composite approach enables effective isolation and control at scaled dimensions where single-material structures fail.
3Reliability
If single break diffusion (SDB) isolation structures are formed by removing sacrificial gate structure and etching trenches, then device isolation is achieved, but parasitic capacitors are formed that degrade device performance
Solution Approach 1:
The SDB layers act as intermediary diffusion barrier structures between the insulating material layers and the active device regions. These intermediary SDB layers prevent direct parasitic capacitor formation by blocking diffusion paths, thereby reducing parasitic effects while maintaining effective device isolation.
Data Source
AI summary
One illustrative integrated circuit product disclosed herein includes a single diffusion break (SDB) isolation structure positioned between a first fin portion and a second fin portion, wherein the first fin portion comprises a first end surface and the second fin portion comprises a second end surface. In this example, the SDB structure includes a conformal liner layer that engages the first end surface of the first fin portion and the second end surface of the second fin portion, an insulating material positioned on the conformal liner layer, a cap structure positioned above an upper surface of the insulating material and an air gap positioned between a bottom surface of the cap structure and the upper surface of the insulating material.