FinFET Epitaxy Curvature Reduces Parasitic Capacitance
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Solution Overview
Problem
The development of three-dimensional FinFET transistors faces challenges due to parasitic capacitance issues caused by sharp corners in the epitaxy structure, which limit the alternating current (AC) performance and overall device performance.
Innovation Solution
The formation of a semiconductor device involves shaping the epitaxy structure to remove sharp corners, creating a smooth top surface with a curved portion and flat portions, which reduces parasitic capacitance by preventing the formation of fringe electric fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sharp corners are present in the epitaxy structure, then device density can be increased, but parasitic capacitance increases and AC performance deteriorates
Solution Approach 1:
The patent applies curvature by rounding the sharp corners of the epitaxy structure to create a smooth curved surface. This spheroidality principle eliminates the geometric discontinuities that cause fringe electric fields, thereby reducing parasitic capacitance while maintaining the compact three-dimensional FinFET structure needed for high device density.
2Reliability
If sharp corners are removed to reduce parasitic capacitance, then AC performance improves, but manufacturing complexity increases
Solution Approach 1:
The patent changes the geometric parameters of the epitaxy structure by introducing a curvature radius parameter. Instead of removing corners through complex multi-step processes, the solution modifies the shape parameter directly by specifying a curvature radius (e.g., R1, R2) that defines the rounded corners, simplifying the manufacturing while achieving the desired AC performance.
3Ease of manufacture
If sharp corners are present in the epitaxy structure, then fabrication is simpler, but fringe electric fields form causing parasitic capacitance
Solution Approach 1:
The patent eliminates fringe electric fields by replacing sharp corners with smooth curved surfaces defined by specific radius parameters. This curvature modification prevents the formation of electric field concentrations at corner regions, thereby eliminating parasitic capacitance while maintaining a relatively simple fabrication process.
Data Source
AI summary
A transistor includes a semiconductive fin having a channel portion, a gate stack over the channel portion of the semiconductive fin, source and drain structures on opposite sides of the gate stack and adjoining the semiconductive fin, and a sidewall structure extending along sidewalls of a body portion of the source structure. The source structure has a curved top, and the source structure has a top portion protruding over a top of the sidewall structure.