III-V on Silicon via Aligned Recesses and Epitaxy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in manufacturing III-V compound semiconductor thin films is the high defect density due to lattice constant and thermal expansion coefficient mismatches between existing substrates and III-V semiconductors, leading to poor performance in MOS transistors.
Innovation Solution
A method involving the formation of shallow trench isolation regions with aligned recesses on a silicon substrate, where III-V compound semiconductors are epitaxially grown, with specific growth conditions controlling facet orientations to minimize defects, such as adjusting substrate temperature and V-to-III flow ratio during nucleation to direct high-defect facets towards the sidewalls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If III-V compound semiconductors are grown on silicon or SiC substrates using conventional epitaxial methods, then the manufacturing process is simple and substrates are readily available, but high defect densities result due to lattice constant and thermal expansion coefficient mismatches
Solution Approach 1:
The invention divides the substrate surface into discrete recess regions separated by shallow trench isolation. Each recess acts as an independent growth zone for III-V compound semiconductor material, isolating defect propagation between regions. This segmentation allows the use of silicon substrates while confining misfit dislocations within individual recesses, thereby reducing overall defect density in the grown layers.
Solution Approach 2:
The invention creates localized regions with different geometric and material properties by forming recesses with specific dimensions, orientations, and depths in the silicon substrate. These locally modified regions provide optimized growth conditions for III-V compound semiconductors, with the recess geometry tailored to reduce misfit dislocation densities while maintaining compatibility with the silicon substrate's lattice structure.
2Reliability
If shallow trench isolation regions are formed with recesses to reduce defect densities, then defect densities are reduced compared to blanket silicon wafers, but defect densities remain high and the process complexity increases
Solution Approach 1:
The invention performs preliminary structuring of the silicon substrate by forming shallow trench isolation regions and recesses before epitaxial growth. This pre-prepared substrate topology with aligned recesses guides the subsequent III-V compound semiconductor growth, ensuring that material nucleates and grows in the desired locations with optimized orientations, thereby reducing defect densities while streamlining the overall manufacturing process.
Solution Approach 2:
The invention introduces asymmetric features into the substrate structure by forming recesses with specific directional orientations and non-uniform geometries. This asymmetry in the recess configuration influences the growth morphology and crystal orientation of the III-V compound semiconductor, promoting preferential growth directions that minimize misfit dislocation formation and reduce defect densities.
3Manufacturing precision
If aligned recesses with specific orientations are formed and III-V compound semiconductors are epitaxially grown with controlled facet orientations, then defect densities are reduced and film quality is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The invention optimizes growth parameters including substrate temperature, V-to-III flow ratio, and pressure conditions during epitaxial growth to control facet orientations of the III-V compound semiconductor. By carefully adjusting these parameters, the growth process produces films with desired crystallographic orientations that minimize defect formation, achieving high manufacturing precision while maintaining process feasibility.
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 defect densities and improves the quality of III-V compound semiconductor films, enhancing the performance of MOS transistors by aligning long sides of recesses and adjusting growth conditions to suppress defects.
Implementation Method 1
A III-V compound semiconductor material is then epitaxially grown in the recesses
Implementation Method 2
adjusting substrate temperature and V-to-III flow ratio during nucleation to direct high-defect facets towards the sidewalls
Data Source
AI summary
A method of forming an integrated circuit structure includes providing a wafer having a silicon substrate; forming a plurality of shallow trench isolation (STI) regions in the silicon substrate; and forming recesses by removing top portions of the silicon substrate between opposite sidewalls of the plurality of STI regions. Substantially all long sides of all recesses in the silicon substrate extend in a same direction. A III-V compound semiconductor material is then epitaxially grown in the recesses.