Nanowire Shadow-Wall Deposition Without Etch Surface Damage
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Solution Overview
Problem
Existing semiconductor device fabrication methods face limitations due to surface damage from etching processes, which can degrade the interface between nanowires and additional materials, and are not scalable for complex devices, especially for semiconductor-superconductor hybrid devices that require precise control over material deposition.
Innovation Solution
The method involves forming a shadow wall on a substrate with a bridge portion that overhangs the substrate to control directional deposition of further materials, allowing for the growth of vertically oriented nanowires and deposition of materials without etching, thereby maintaining a high-quality interface and enabling scalable fabrication of semiconductor-superconductor hybrid devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If etching processes are used to pattern materials, then desired shapes can be formed, but surface damage occurs that degrades the interface between nanowires and additional materials
Solution Approach 1:
The patent removes the etching step from the fabrication process entirely. Instead of depositing material and then etching away excess, the method uses shadow evaporation to deposit material only in desired locations from the start, eliminating the harmful etching process that causes surface damage to nanowires.
Solution Approach 2:
The patent inverts the conventional approach by using shadow evaporation to create patterns through selective deposition rather than through etching. Instead of depositing material everywhere and removing unwanted portions, the method deposits material only where needed by controlling the evaporation direction relative to shadow walls, thereby avoiding surface damage.
2Ease of manufacture
If conventional fabrication methods are used, then simple devices can be manufactured, but scalability to complex devices is limited
Solution Approach 1:
The patent introduces shadow walls with overhangs that extend in the vertical dimension, creating three-dimensional shadow regions that control material deposition. This vertical dimension allows for complex patterning and multi-layer structures to be formed in a single deposition process, enabling scalability to complex devices while maintaining fabrication simplicity.
Solution Approach 2:
The patent divides the deposition process into controlled segments using shadow walls that create distinct shadowed and non-shadowed regions. This segmentation allows different areas of the substrate to receive different materials or thicknesses independently, enabling complex device architectures to be built through sequential depositions without increasing process complexity.
3Manufacturing precision
If shadow walls without overhangs are used, then material deposition can be controlled, but nanowire growth is interfered with and adatom diffusion is blocked
Solution Approach 1:
The shadow wall is segmented into a base portion that contacts the substrate and a bridge portion that overhangs. This segmentation allows the base portion to support nanowire growth while the bridge portion provides shadowing for deposition control, resolving the conflict between growth quality and deposition precision.
Solution Approach 2:
The bridge portion extends in the vertical dimension above the substrate, creating shadow regions without physically blocking the substrate surface. This vertical extension allows adatoms to diffuse freely on the substrate while still enabling precise deposition control in specific areas through the shadow effect.
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 prevents surface damage and allows for the fabrication of high-quality semiconductor-superconductor hybrid devices with improved interfaces, enabling operation at reduced voltages and lower magnetic fields, and facilitates scalable integration for quantum computing applications.
Implementation Method 1
directionally depositing a layer of a further material on the nanowire from a direction selected such that the shadow wall casts a shadow on the nanowire, the shadow being a region in which the further material is not deposited
Implementation Method 2
the bridge portion overhangs the substrate and the base portion supports the bridge portion
Implementation Method 3
subsequently growing a nanowire of semiconductor material on the substrate; and directionally depositing a layer of a further material on the nanowire wherein the nanowire is vertically orientated with respect to the substrate
Data Source
AI summary
A semiconductor device is fabricated by: forming a shadow wall on a substrate; subsequently growing a nanowire of semiconductor material on the substrate; and directionally depositing a layer of a further material on the nanowire from a direction selected such that the shadow wall casts a shadow on the nanowire, the shadow being a region in which the further material is not deposited. The nanowire is vertically orientated relative to the substrate. The shadow wall comprises a base portion and a bridge portion. The bridge portion overhangs the substrate and is supported by the base portion. Patterning of the further material may be achieved without the use of etching, thereby avoiding damage to the semiconductor. Also provided is a semiconductor-superconductor hybrid device; a quantum computing device comprising the semiconductor-superconductor hybrid device; and a shadow wall for controlling directional deposition of a material.