FinFET Gate Isolation Plug Structure for Void-Free Dielectric Filling
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Solution Overview
Problem
Existing semiconductor manufacturing processes face challenges in achieving effective electrical isolation between metal gates in FinFET devices, leading to potential gaps or voids in dielectric layers that affect device performance.
Innovation Solution
A multi-layered insulating film stack is employed, comprising a non-conformal first dielectric layer lining the sidewalls and a conformal second dielectric layer filling the gap, ensuring complete filling and preventing voids, thereby enhancing electrical isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single dielectric layer is used to isolate metal gates, then the manufacturing process is simple, but gaps or voids form in the dielectric layer reducing electrical isolation
Solution Approach 1:
The dielectric layer is segmented into multiple layers: a first dielectric layer deposited conformally on the metal gate, and a second dielectric layer deposited over the first layer. This segmentation allows each layer to fulfill specific functions - the first layer provides initial isolation and surface coverage, while the second layer fills gaps and voids, collectively achieving complete electrical isolation without the gaps that occur in single-layer structures.
Solution Approach 2:
The patent employs a composite dielectric structure combining two different dielectric materials with distinct properties. The first dielectric layer and second dielectric layer have different deposition characteristics and physical properties that complement each other, enabling the composite structure to achieve superior gap-filling and void-prevention capabilities compared to either material alone.
2Reliability
If dielectric layers are deposited to fill gaps between metal gates, then electrical isolation is improved, but deposition process complexity increases
Solution Approach 1:
The first dielectric layer is deposited preliminarily over the metal gate structure before the second dielectric layer is applied. This preliminary action creates a foundation layer that modifies the surface topology and provides a controlled interface for subsequent deposition, enabling the second layer to fill gaps more effectively while maintaining process control and simplicity.
Solution Approach 2:
The first dielectric layer acts as an intermediary between the metal gate and the second dielectric layer. It mediates the deposition process by providing a conformal base layer that controls material flow and prevents direct contact between the second dielectric and metal gate, thereby simplifying the overall deposition process while achieving superior gap-filling results.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The multi-layered insulating film stack improves electrical isolation properties, reducing gaps and voids, thus enhancing the performance and reliability of FinFET devices.
Implementation Method 1
depositing a first dielectric layer in the opening
Implementation Method 2
depositing a second dielectric layer into the opening
Data Source
AI summary
A device includes first and second gate structures respectively extending across the first and second fins, and a gate isolation plug between a longitudinal end of the first gate structure and a longitudinal end of the second gate structure. The gate isolation plug comprises a first dielectric layer and a second dielectric layer over the first dielectric layer. The first dielectric layer has an upper portion and a lower portion below the upper portion. The upper portion has a thickness smaller than a thickness of the lower portion of the first dielectric layer.