III-V Fin Structures via Silicon Mandrel Segmentation
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Solution Overview
Problem
The challenge lies in fabricating high-quality III-V fin structures, particularly due to difficulties in growing III-V compound semiconductor films on dissimilar substrates with different lattice constants and thermal expansion coefficients, which hinders the integration of III-V materials into advanced transistor designs.
Innovation Solution
A method involving the use of fins as mandrels, where a group III-V material layer is conformally deposited, planarized, and then segmented into U-shaped structures, ultimately forming III-V fin structures with smaller pitch, utilizing STIs and isolating structures to achieve precise alignment and isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If III-V compound semiconductor films are grown on dissimilar substrates, then high electron mobility is achieved, but lattice mismatch and thermal expansion differences cause poor film quality and high manufacturing difficulty
Solution Approach 1:
The patent uses silicon fins as intermediary mandrels to grow III-V materials. The fins serve as a bridge between the silicon substrate and the III-V compound semiconductor, allowing epitaxial growth while managing lattice mismatch through the controlled fin structure and buffer layers.
Solution Approach 2:
The patent segments the III-V material layer into discrete fin structures by using self-aligned etching processes. The mandrel fins are selectively removed to create isolated III-V fins, enabling precise control over material placement and reducing the impact of lattice mismatch across the entire substrate.
2Manufacturing precision
If fins are used as mandrels for III-V material deposition, then precise alignment and smaller pitch are achieved, but process complexity increases
Solution Approach 1:
The patent employs self-aligned processes where the fin structures automatically define the positions of subsequent layers. The mandrel fins serve as self-aligned masks for etching, and the III-V material deposition is automatically positioned relative to the fins, eliminating the need for additional alignment steps.
Solution Approach 2:
The patent performs preliminary formation of silicon fins and STI structures before III-V material deposition. These pre-formed structures serve as templates and mandrels that guide subsequent processing steps, ensuring precise final alignment without requiring complex real-time alignment procedures.
3Productivity
If integration density is increased through smaller pitch fins, then transistor drive current is improved, but manufacturing cost and process difficulty increase
Solution Approach 1:
The patent makes the silicon fin structures serve multiple functions: as mechanical support, as alignment masks, as etch stop layers, and as templates for III-V material growth. This multi-functionality reduces the number of separate process steps and components needed, lowering overall manufacturing complexity despite high integration density.
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 enables the formation of high-quality III-V fin structures with improved integration density and reduced manufacturing costs, enhancing transistor performance by leveraging the high electron mobility of III-V materials.
Implementation Method 1
a deposition process is performed to conformally form a group III-V material layer encapsulating an upper portion of each of the fins and covering the STIs
Data Source
AI summary
A method of fabricating III-V fin structures includes providing numerous fins. Then, a group III-V material layer is formed to encapsulate an upper portion of each of the fins. Later, part of the group III-V material layer is removed to expose an end of each of the fins, and divides the group III-V material layer into numerous U-shaped structures. Next, a first part of each of the fins and the entire silicon oxide layer are removed. Finally, part of each of the U-shaped structures is removed to segment each of the U-shaped structures into two III-V fin structures.