Multi-Beam Detector Thin Film Passage Hole Design
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Solution Overview
Problem
As the number of beams increases in multi-beam electron beam writing techniques, it becomes challenging to individually detect each beam due to the small beam diameter and narrow pitch, leading to difficulties in maintaining accurate irradiation positions and high throughput, especially as minute holes used in detectors tend to close quickly due to adhering impurities.
Innovation Solution
A thin film with a passage hole smaller than the beam pitch but larger than the beam diameter, supported by a base with an opening that maintains a temperature higher than the evaporation temperature of impurities, allows individual beam detection by a sensor positioned to discern the contrast from beams passing through without being blocked by the support base.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of beams is increased to improve writing throughput, then productivity increases, but it becomes difficult to individually detect each beam due to small beam diameter and narrow pitch
Solution Approach 1:
A thin film with a passage hole is introduced as an intermediary component between the multiple beams and the sensor. The passage hole acts as a spatial filter that allows only the target beam to pass through while blocking other beams, enabling individual beam detection even when many beams are present with narrow pitch
Solution Approach 2:
A thin film structure is used instead of a bulk material. The thin film minimizes heat dissipation to the substrate, allowing the passage hole periphery to be heated to high temperatures that prevent impurity adhesion and hole closure, thereby maintaining detection capability over time
2Measurement precision
If a minute hole is used in the detector to block other beams and acquire contrast, then measurement precision improves, but the minute hole closes quickly due to adhering impurities
Solution Approach 1:
The temperature parameter of the passage hole periphery is changed and maintained above the evaporation temperature of impurities. This parameter change prevents impurities from adhering to and closing the passage hole, thereby extending the operational duration while maintaining the small hole size needed for beam detection contrast
Solution Approach 2:
The system utilizes the phase transition concept by maintaining temperature above the evaporation point of impurities. This ensures impurities remain in vapor phase and cannot condense or adhere to the passage hole walls, preventing hole closure and maintaining detection reliability
3Productivity
If the pitch between beams is narrowed to increase the number of beams, then productivity improves, but the ability to individually detect each beam deteriorates
Solution Approach 1:
The thin film with passage hole serves as a mediator that decouples the detection precision from the beam pitch. By using the passage hole as a spatial selector, the system can detect individual beams accurately even when beams are closely spaced, as the passage hole physically filters out adjacent beams
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 configuration effectively prevents the minute holes from closing with impurities, enabling accurate and prolonged detection of individual beams, thereby maintaining high precision and throughput in multi-beam writing processes.
Implementation Method 1
a thin film in which a passage hole smaller than a pitch between beams of multiple beams each being an electron beam and larger than a diameter of a beam of the multiple beams is formed, and through which the multiple beams can penetrate
Implementation Method 2
a support base to support the thin film, in which an opening is formed under a region including the passage hole in the thin film, and a width size of the opening is formed to have a temperature of a periphery of the passage hole in the thin film higher than an evaporation temperature of impurities adhering to the periphery
Implementation Method 3
a sensor arranged, in a case where a surface of the thin film is scanned with the multiple beams, at a position away from the thin film by a distance based on which a detection target beam having passed through the passage hole of the thin film can be detected by the sensor as a detection value with contrast discernible from beams which have penetrated the thin film and are passing the opening without being blocked by the support base
Data Source
AI summary
An individual beam detector for multiple beams includes a thin film in which a passage hole smaller than a pitch between beams of multiple beams and larger than the diameter of a beam is formed and through which the multiple beams can penetrate, a support base to support the thin film in which an opening is formed under the region including the passage hole, and the width size of the opening is formed to have a temperature of the periphery of the passage hole higher than an evaporation temperature of impurities adhering to the periphery in the case that the thin film is irradiated with the multiple beams, and a sensor arranged, at the position away from the thin film by a distance based on which a detection target beam having passed the passage hole can be detected by the sensor as a detection value with contrast discernible.