Nanopore Formation via Current-Threshold Voltage Control
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Solution Overview
Problem
Existing nanopore formation methods face challenges in achieving precise control over hole diameter and position, leading to variations in signal strength during optical and tunnel current measurements, resulting in low reproducibility and high costs.
Innovation Solution
A method involving repeated voltage applications across an insulating film with a near-field light generating element, where the current is monitored to determine when a pre-set threshold is reached, allowing for accurate hole formation at a specific position and size, thereby enhancing measurement reproducibility and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the hole opening method using TEM device is employed, then the hole can be formed with a diameter of not greater than 10 nm, but the hole diameter varies by 2 nm at 3σ and position varies by 5 nm at 3σ from the target position
Solution Approach 1:
The patent employs feedback control by monitoring current changes during voltage application. When the current reaches a predetermined threshold, the voltage application is stopped, indicating that the hole has formed at the target position with the desired diameter. This feedback mechanism eliminates the need for TEM device positioning adjustments and achieves both diameter and position control without the variations mentioned in the contradiction.
Solution Approach 2:
The patent replaces the mechanical positioning system of the TEM device with an electrical control system. Instead of mechanically adjusting the beam position to achieve precise hole formation, the system uses voltage application with current monitoring to control hole formation electrically, achieving both diameter and position precision without mechanical positioning errors.
2Manufacturing precision
If voltage is continuously applied to form a nanopore, then a nanopore with hole diameter of 5 nm can be formed, but the process takes 400-500 seconds and requires high voltage (5 V)
Solution Approach 1:
The patent uses periodic voltage application instead of continuous application. Voltage is applied in controlled pulses or cycles, and the application is stopped when the current reaches the threshold. This periodic action reduces the total time required compared to continuous application while maintaining precise control over hole formation, eliminating the need for prolonged high voltage application.
3Measurement precision
If the hole is formed at the center point position of the bow-tie gap, then optical measurement can be performed, but misalignment of 5 nm at 3σ occurs due to position adjustment operations
Solution Approach 1:
The patent replaces mechanical position adjustment operations with electrical control. Instead of mechanically positioning the hole formation site at the bow-tie gap center, the system applies voltage and monitors current to automatically form the hole at the correct position. This eliminates mechanical positioning errors and makes the manufacturing process easier by removing the need for complex position adjustment operations.
4Measurement precision
If repeated hole opening operations are performed to improve position accuracy, then the hole can be formed closer to the target position, but the process complexity and time increase
Solution Approach 1:
The patent uses feedback control to achieve accurate hole positioning in a single operation. By monitoring current changes during voltage application and stopping when the threshold is reached, the system automatically forms the hole at the correct position without requiring repeated trial-and-error operations. This feedback mechanism simplifies the process while maintaining high position accuracy.
Data Source
AI summary
While an insulating film having a near-field light generating element placed thereon is being irradiated with light in an electrolytic solution, or after the film that has been irradiated with light is disposed in the electrolytic solution, a first voltage is applied between the two electrodes installed in the electrolytic solution across the film, a second voltage is then applied between the two electrodes, and a value of a current that flows between the two electrodes due to the application of the second voltage is detected. This procedure is stopped when the current value reaches or exceeds a pre-set threshold value, whereby a hole is formed at a desired location in the thin-film.