Defect-Free Fin Formation via Lateral Epitaxial Overgrowth
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods face challenges in co-integrating lattice mismatched materials like III-V and Germanium on a Silicon substrate, leading to defects in fin-based circuit devices due to large lattice mismatches, which affect device performance and yield.
Innovation Solution
The process involves epitaxially growing a first layer on the substrate surface at the bottom of trenches and a second layer over the trench and STI regions, with selective growth to avoid crystaline defects, followed by patterning and etching to form defect-free fin devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lattice mismatched materials (III-V, Germanium) are grown on Silicon substrate, then device performance and carrier mobility are improved, but crystalline defects are generated due to large lattice mismatch
Solution Approach 1:
A buffer layer is introduced as an intermediary between the Silicon substrate and the III-V or Germanium device layers. This buffer layer acts as a mediator that accommodates the lattice mismatch, preventing defect propagation to the device layers while enabling the growth of high-performance materials on Silicon.
Solution Approach 2:
The structure is segmented into distinct functional layers: a Silicon substrate, a buffer layer for defect management, and device layers for performance. This segmentation isolates the defect-generating interface from the performance-critical regions, allowing each layer to optimize its specific function.
2Area of stationary object
If conventional epitaxial growth is used on trench sidewalls, then material coverage is achieved, but defects propagate from trench sidewalls to fin structures
Solution Approach 1:
The problematic trench sidewall regions are selectively removed or excluded from the epitaxial growth process. By taking out the defect-prone sidewall areas, the growth is confined to defect-free regions, ensuring high-quality fin structures without sidewall-induced defects.
Solution Approach 2:
Different regions of the substrate are treated differently: trench sidewalls are excluded from growth to prevent defects, while the bottom and top surfaces are optimized for defect-free fin formation. This local quality approach ensures each region contributes positively to the final device quality.
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 minimizes crystaline defects in the fins, enhancing the quality and reliability of fin-based devices by avoiding defect propagation from the trench sidewalls, thereby improving device performance and reducing yield variations.
Implementation Method 1
a first layer of epitaxial material is epitaxially grown on a substrate surface at a bottom of a trench formed by a plurality of shallow trench isolation (STI) regions; a second layer of epitaxial material is epitaxially grown on the first layer in the trench and over top surfaces of the STI regions
Data Source
AI summary
Electronic device fins may be formed by epitaxially growing a first layer of material on a substrate surface at a bottom of a trench formed between sidewalls of shallow trench isolation (STI) regions. The trench height may be at least 1.5 times its width, and the first layer may fill less than the trench height. Then a second layer of material may be epitaxially grown on the first layer in the trench and over top surfaces of the STI regions. The second layer may have a second width extending over the trench and over portions of top surfaces of the STI regions. The second layer may then be patterned and etched to form a pair of electronic device fins over portions of the top surfaces of the STI regions, proximate to the trench. This process may avoid crystaline defects in the fins due to lattice mismatch in the layer interfaces.