Ultra-Fine Nanowire Fabrication via Mask Blocking Oxidation
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Solution Overview
Problem
The electronic beam photolithography process for fabricating nanowires is limited by low efficiency and high cost, making it unsuitable for mass industry production, especially for nanowires less than 20 nm, due to issues like electron scattering and the proximity effect.
Innovation Solution
A method combining a mask blocking oxidation process and a stepwise oxidation process, involving the deposition of a silicon nitride film, photolithography, dry etching, and controlled oxidation steps to precisely control the size of silicon nanowires, allowing for the fabrication of ultra-fine nanowires with diameters as small as 20 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electronic beam photolithography is used to fabricate nanowires, then manufacturing precision is improved, but productivity deteriorates and manufacturing cost increases
Solution Approach 1:
The patent replaces electronic beam photolithography (a complex, low-throughput mechanical/electronic system) with a chemical oxidation-based self-aligned patterning process. This substitution enables parallel processing of multiple nanowires simultaneously, dramatically improving productivity while maintaining precise size control through the self-aligned nature of the oxidation process and the use of standard photolithography tools.
Solution Approach 2:
The patent changes the fundamental processing parameters from electron beam exposure to chemical oxidation conditions (temperature, time, oxidant concentration). By controlling oxidation parameters rather than electron beam parameters, the process achieves both high precision in nanowire dimension control and high productivity through faster, parallel processing compatible with standard semiconductor manufacturing equipment.
2Manufacturing precision
If electronic beam photolithography is used to fabricate nanowires, then manufacturing precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent substitutes expensive electronic beam photolithography equipment and processes with standard photolithography equipment combined with chemical oxidation. This replacement dramatically reduces manufacturing cost by using widely available, lower-cost equipment while achieving comparable or superior precision through the self-aligned oxidation mechanism that naturally defines nanowire dimensions.
Solution Approach 2:
The patent employs consumable photoresist layers and sacrificial oxidation steps that are inexpensive compared to electronic beam processing costs. The photoresist is a low-cost material that can be easily applied and removed, and the oxidation process uses inexpensive chemical reagents, collectively reducing the cost per nanowire fabricated.
3Manufacturing precision
If electronic beam photolithography is used for nanowire fabrication, then manufacturing precision is improved for certain sizes, but difficulty increases for nanowires less than 20 nm due to electron scattering and proximity effect
Solution Approach 1:
The patent replaces electronic beam photolithography with a chemical oxidation-based self-aligned patterning approach. This substitution eliminates electron scattering and proximity effects entirely, as the process uses chemical reactions rather than electron beams to define patterns. The self-aligned nature of the oxidation process naturally produces precise sub-20 nm features without the fundamental limitations that plague electron beam methods at these dimensions.
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 method enables the cost-effective production of ultra-fine nanowires with precise size control, overcoming the limitations of electronic beam photolithography by rapidly slimming nanowires and simultaneously oxidizing top and side portions, enhancing applicability and reducing production costs.
Implementation Method 1
since there remains the silicon nitride film on the top of the nanowire, an oxidation of the top of the silicon nanowire is blocked
Implementation Method 2
performing a wet oxidation process to form a fine nanowire... a side surface of the silicon nanowire is oxidized
Implementation Method 3
performing a dry oxidation process on the nanowire obtained after the wet etching process... the top and the side portions of the nanowire are simultaneously oxidized
Implementation Method 4
the deposition of the silicon nitride film is performed by a low pressure chemical vapor deposition method
Data Source
AI summary
Disclosed herein is a method for fabricating an ultra fine nanowire, which relates to a manufacturing technology of a microelectronic semiconductor transistor. This method obtains a suspended ultra fine nanowire base on a combination of a mask blocking oxidation process and a stepwise oxidation process. A diameter of the suspended ultra fine nanowire fabricated by this method is precisely controlled to 20 nm by controlling a thickness of a deposited silicon nitride film and a time and temperature of the two oxidation process. Since a speed of a dry oxidation process is slower, the size of the final nanowire may be precisely controlled. This method can be used to fabricate an ultra fine nanowire with a lower cost and a higher applicability.