Stacked Single-Crystal TMD Channels Using Seeded Wafer Growth
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Solution Overview
Problem
Legacy transistor manufacturing methods using chemical vapor deposition result in non-single crystal TMD growth with grain boundaries, leading to detrimental performance variations in devices due to scattering effects at thin body thicknesses, which are difficult to overcome with silicon.
Innovation Solution
The use of seeded growth techniques to produce single crystal TMD layers on a wafer, allowing for the precise stacking of these layers without grain boundaries, utilizing a same seed material and growth promoter to create high-performance channels for transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemical vapor deposition is used to grow TMD layers, then the manufacturing process is simple and scalable, but the resulting TMD layers are non-single crystal with grain boundaries that degrade device performance
Solution Approach 1:
The patent applies preliminary action by pre-forming seed structures on the substrate before initiating TMD layer growth. These seeds serve as nucleation sites that guide the formation of single-crystal TMD layers, eliminating grain boundaries before they can form during the growth process. This preliminary structuring enables subsequent simple CVD growth to produce high-quality single crystal material.
Solution Approach 2:
The patent uses seed structures as intermediary elements between the substrate and the TMD layer. These seeds act as mediators that template the crystal structure of the growing TMD layer, ensuring single-crystal formation. The seed material serves as a temporary scaffold that directs atomic arrangement during growth, then can be removed or retained depending on the application.
2Reliability
If silicon-based transistors are used, then manufacturing isๆ็ and scalable, but scattering effects at thin body thicknesses limit further performance improvement
Solution Approach 1:
The patent changes the fundamental material parameter from silicon to transition metal dichalcogenides (TMDs), which have different physical properties including higher carrier mobility and better performance at thin body thicknesses. This material parameter change enables continued performance improvement and gate length reduction that is not achievable with silicon due to scattering effects.
Solution Approach 2:
The patent transitions from bulk silicon to two-dimensional TMD materials, representing a dimensional change from three-dimensional bulk material to two-dimensional layered material. This dimensional transition enables thinner effective channel thicknesses while maintaining structural integrity, overcoming the scattering limitations that plague thin-body silicon devices.
3Productivity
If multiple TMD layers are stacked to increase density, then transistor density improves, but maintaining single crystal quality across stacked layers becomes difficult
Solution Approach 1:
The patent uses preliminary seed structures that extend through multiple layer positions, enabling sequential growth of multiple TMD layers from the same seed. This preliminary seeding approach ensures that each stacked layer inherits the single-crystal quality from the seed, maintaining consistency across multiple layers without requiring separate seeding processes for each layer.
Solution Approach 2:
The patent maintains continuous single-crystal growth across stacked layers by using seeds that facilitate uninterrupted growth. The growth process continues from the seed through multiple layer formations without interruption or re-nucleation, preserving the single-crystal structure throughout the entire stacked architecture and ensuring uniform quality across all layers.
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 creation of high-density, high-performance transistors with uniform performance by eliminating grain boundaries and enabling thinner gate lengths, addressing the limitations of silicon-based transistors.
Implementation Method 1
a layer of single crystal material grown on a surface of the wafer from the formed seed
Data Source
AI summary
Embodiments described herein may be related to apparatuses, processes, systems, and/or techniques for a transistor structure that includes stacked nanoribbons as a single crystal or monolayer, such as a transition metal dichalcogenide (TMD) layer, grown on a silicon wafer using a seeding material. Other embodiments may be described and/or claimed.