SiGe Fin Channel Structure for Reduced Deformation and Higher Mobility
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Solution Overview
Problem
As semiconductor devices undergo miniaturization, the reduction in minimum feature size leads to increased deformation of fins during etching, which can decrease carrier mobility and yield, and existing methods fail to effectively manage this deformation while maintaining sufficient germanium concentration for improved performance.
Innovation Solution
A method involving the formation of a semiconductor layer with a low germanium concentration, followed by an oxidation process that condenses germanium along the sidewalls of the fins, increasing the germanium concentration in the channel regions and reducing deformation, thereby enhancing carrier mobility without causing excessive strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the minimum feature size is reduced to increase integration density, then more components can be integrated into a given area, but fin deformation during etching increases and carrier mobility decreases
Solution Approach 1:
The patent applies local quality by creating a non-uniform germanium concentration distribution within the semiconductor layer. The germanium concentration is increased specifically at the sidewalls of the fins through selective oxidation, while maintaining lower concentration in the channel region. This localized modification of material properties addresses the fin deformation problem without compromising the overall device performance and integration density.
Solution Approach 2:
The patent utilizes parameter changes by modifying the germanium concentration parameter through oxidation processing. The oxidation process transforms the silicon germanium alloy by selectively removing silicon, thereby increasing the germanium concentration at the fin sidewalls. This parameter change enhances the mechanical properties of the fins to reduce deformation during etching while maintaining compatibility with miniaturized feature sizes.
2Manufacturing precision
If the germanium concentration is increased to reduce fin deformation, then manufacturing precision improves, but strain-related issues may arise that affect device performance
Solution Approach 1:
The patent resolves this contradiction by applying local quality - the germanium concentration is selectively increased only at the sidewalls of the fins where mechanical support is needed, while the channel region maintains lower germanium concentration to avoid excessive strain. This spatially differentiated approach allows simultaneous achievement of fin deformation control and device performance.
Solution Approach 2:
The patent applies segmentation by dividing the semiconductor layer into distinct regions with different germanium concentrations - the sidewall regions with higher germanium content for mechanical stability and the channel region with lower germanium content for optimal electrical performance. This segmentation allows independent optimization of mechanical and electrical properties.
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
This approach reduces fin deformation and increases carrier mobility by increasing the germanium concentration in the channel regions, improving the performance of semiconductor devices while maintaining low initial germanium levels to prevent strain-related issues.
Implementation Method 1
An oxidation process is performed to form an oxide layer on sidewalls of the fins. During oxidation, the germanium of the second semiconductor material is condensed along the sidewalls of the fins.
Data Source
AI summary
In an embodiment, a device includes: a substrate; a first semiconductor region extending from the substrate, the first semiconductor region including silicon; a second semiconductor region on the first semiconductor region, the second semiconductor region including silicon germanium, edge portions of the second semiconductor region having a first germanium concentration, a center portion of the second semiconductor region having a second germanium concentration less than the first germanium concentration; a gate stack on the second semiconductor region; and source and drain regions in the second semiconductor region, the source and drain regions being adjacent the gate stack.