FinFET Bottom Portion Epitaxial Transformation for Carrier Mobility
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Solution Overview
Problem
Current finFET fabrication methods face challenges in improving carrier mobility and overall device performance due to the architecture of fin-shaped structures, which affect the channel region and overall performance of semiconductor devices.
Innovation Solution
The method involves forming fin-shaped structures with different material compositions for the top and bottom portions, specifically using epitaxial growth to transform the bottom portions of fin-shaped structures into silicon germanium, while maintaining the top portions as pure silicon, to enhance carrier mobility and device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fin-shaped structure is used to increase gate control and reduce short channel effects, then device performance is improved, but carrier mobility in the channel region deteriorates due to structural constraints
Solution Approach 1:
The patent applies local quality by creating different material compositions at different locations within the fin-shaped structure. Specifically, the top portion is made of pure silicon while the bottom portion is made of silicon germanium alloy, allowing each region to have optimized properties for its specific function - high mobility at the top and strain control at the bottom
Solution Approach 2:
The patent uses composite materials by combining pure silicon and silicon germanium in a single fin-shaped structure. This composite approach allows the structure to simultaneously achieve high carrier mobility in the silicon region and effective strain control through the silicon germanium region, resolving the contradiction between performance improvement and mobility degradation
2Ease of manufacture
If uniform material composition is used in fin-shaped structure, then fabrication process is simplified, but carrier mobility and device performance are limited
Solution Approach 1:
The patent implements local quality by varying the material composition within the fin-shaped structure - pure silicon at the top for high mobility and silicon germanium at the bottom for strain control. This localized differentiation enhances device performance while using established semiconductor fabrication techniques
Solution Approach 2:
The patent applies preliminary action by forming the different material portions during the epitaxial growth process itself, rather than requiring post-fabrication modification. The selective epitaxial growth creates the stratified structure in advance, simplifying the overall manufacturing process while achieving superior device performance
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 improves carrier mobility and boosts the overall performance of semiconductor devices by optimizing the material composition of fin-shaped structures, reducing drain-induced barrier lowering and short channel effects.
Implementation Method 1
forming an epitaxial layer on the substrate to surround the bottom portion of the fin-shaped structure; transforming the bottom portion of the fin-shaped structure into the epitaxial layer
Data Source
AI summary
A method for fabricating semiconductor device includes the steps of: providing a substrate having at least one fin-shaped structure thereon, wherein the fin-shaped structure comprises a top portion and a bottom portion; removing part of the bottom portion of the fin-shaped structure; forming an epitaxial layer on the substrate to surround the bottom portion of the fin-shaped structure; transforming the bottom portion of the fin-shaped structure into the epitaxial layer; and removing part of the epitaxial layer.