FinFET Gate Stack Structure for Short-Circuit Isolation
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Solution Overview
Problem
The challenge in semiconductor manufacturing lies in forming reliable three-dimensional FinFET devices as feature sizes decrease, making fabrication processes increasingly difficult due to the complexity of achieving reliable semiconductor devices with improved performance.
Innovation Solution
The process involves forming multiple fin structures over a semiconductor substrate, using isolation structures and gate stacks with a protection element to prevent short circuiting during gate replacement, allowing for the formation of reliable semiconductor devices with improved performance by controlling the growth of source/drain features and enhancing carrier mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feature sizes are decreased to increase functional density, then productivity and cost efficiency are improved, but fabrication difficulty and reliability increase
Solution Approach 1:
The patent transitions from planar device architecture to three-dimensional FinFET structures, utilizing vertical fins extending from the substrate to increase functional density without proportionally increasing planar footprint, thereby maintaining productivity while managing fabrication complexity through dimensional transformation
Solution Approach 2:
The device structure is segmented into multiple vertical fins rather than a single planar channel, allowing the fabrication process to be divided into manageable steps while achieving high functional density through the multiplicity of parallel fin structures
2Productivity
If planar MOSFET devices are scaled down, then functional density increases, but short channel effects and leakage increase
Solution Approach 1:
The invention employs vertical fin structures that extend upward from the substrate, creating a three-dimensional channel that provides better gate control over the channel region compared to planar devices, thereby reducing short channel effects while maintaining scaled dimensions
Solution Approach 2:
The FinFET structure combines multiple materials including semiconductor fins, dielectric layers, and metal gates in a composite architecture that enables effective electrostatic control of the channel while managing leakage currents through material property optimization
3Reliability
If gate replacement is performed to improve device performance, then carrier mobility is enhanced, but short circuiting risk increases
Solution Approach 1:
A dielectric layer is introduced as an intermediary between adjacent gate structures during gate replacement, serving as an isolation barrier that prevents short circuiting while allowing the gate to be replaced with higher performance materials for improved carrier mobility
Solution Approach 2:
The dielectric layer is formed in advance before gate replacement to preemptively prevent short circuiting, addressing the harmful effect before it can occur during the gate replacement process
Data Source
AI summary
A semiconductor device structure is provided. The semiconductor device structure includes a first semiconductor fin and a second semiconductor fin over a substrate. The semiconductor device structure also includes a metal gate stack over the first semiconductor fin. The semiconductor device structure further includes a gate stack extending across edges of the first semiconductor fin and the second semiconductor fin. The gate stack has a semiconductor element and a gate dielectric layer between the semiconductor element and the substrate. The semiconductor element has a footing portion with a curved surface facing upwards, and the footing portion is a continuous part of the semiconductor element. The gate dielectric layer has a curved sidewall surface extending upward from the first semiconductor fin and ending at the curved surface of the semiconductor element.