Suspended Ring-Shaped Nanowire via Selective Epitaxy
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Solution Overview
Problem
Existing methods for forming semiconductor nanowires require expensive semiconductor-on-insulator (SOI) substrates and are limited by the availability of materials, restricting the types of nanowires that can be formed.
Innovation Solution
A method involving the formation of a mandrel with vertical planar surfaces on a single crystalline semiconductor layer, followed by selective epitaxy to create a ring-shaped semiconductor nanowire suspended by support structures, eliminating the need for an SOI substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If semiconductor-on-insulator (SOI) substrates are used to form semiconductor nanowires, then nanowire formation is achieved, but production cost increases and material selection is limited
Solution Approach 1:
The invention extracts and removes the expensive SOI substrate requirement from the nanowire formation process. By using a bulk semiconductor substrate with a patterned mandrel structure instead of SOI, the method eliminates the need for pre-formed insulator layers, thereby reducing substrate cost while maintaining nanowire formation capability
Solution Approach 2:
The invention introduces a patterned mandrel structure as an intermediary element between the bulk substrate and the final nanowire. This mandrel serves as a temporary template that enables selective epitaxial growth of nanowires in specific regions, replacing the functional role previously played by the SOI substrate's insulator layer
2Adaptability or versatility
If SOI substrates are used, then nanowire formation is enabled, but the types of nanowires are limited by available materials in the top semiconductor layer
Solution Approach 1:
The invention applies local quality by creating spatially varying properties in the substrate system. The patterned mandrel structure provides localized regions for nanowire growth, while the bulk substrate maintains uniform material properties throughout. This allows different nanowire materials to be grown in different locations on the same substrate, increasing versatility without complicating the overall substrate structure
Solution Approach 2:
The invention changes the material parameter freedom by transitioning from SOI substrates with fixed top-layer materials to bulk substrates that allow selection of any semiconductor material. This parameter change enables formation of nanowires from diverse materials including silicon, germanium, III-V compounds, and II-VI compounds, significantly expanding the types of nanowires that can be manufactured
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
Enables the cost-effective formation of semiconductor nanowires without relying on SOI substrates, expanding the types of nanowires that can be manufactured and reducing production costs.
Implementation Method 1
An epitaxial semiconductor layer is formed on the single crystalline semiconductor layer by selective epitaxy
Data Source
AI summary
A mandrel having vertical planar surfaces is formed on a single crystalline semiconductor layer. An epitaxial semiconductor layer is formed on the single crystalline semiconductor layer by selective epitaxy. A first spacer is formed around an upper portion of the mandrel. The epitaxial semiconductor layer is vertically recessed employing the first spacers as an etch mask. A second spacer is formed on sidewalls of the first spacer and vertical portions of the epitaxial semiconductor layer. Horizontal bottom portions of the epitaxial semiconductor layer are etched from underneath the vertical portions of the epitaxial semiconductor layer to form a suspended ring-shaped semiconductor fin that is attached to the mandrel. A center portion of the mandrel is etched employing a patterned mask layer that covers two end portions of the mandrel. A suspended semiconductor fin is provided, which is suspended by a pair of support structures.