Multi-Charged Particle Beam Calibration Aperture Array
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Solution Overview
Problem
Current multi-beam writing techniques face challenges in accurately measuring and adjusting the shape of multi-beam images due to difficulties in measuring the position and shape of individual beams, leading to issues with signal-to-noise ratio and increased beam drift, especially when trying to increase the number of beams for improved throughput.
Innovation Solution
A multi-charged particle beam apparatus and method that uses a forming aperture array substrate with larger calibration beams to form calibration beams, allowing for precise detection of secondary electrons and calculation of the irradiation region shape, enabling adjustment of the multi-beam image shape through lens excitation control, while minimizing deflection distortion and field curvature aberration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of beams is increased to improve writing throughput, then productivity increases, but measurement precision of the multi-beam image shape deteriorates
Solution Approach 1:
The patent divides the measurement function into separate calibration beams positioned at the periphery of the multi-beam array. These calibration beams are spatially separated from the writing beams, allowing independent measurement of beam shape and position without interference from the writing process. This segmentation enables accurate measurement even as the number of writing beams increases.
Solution Approach 2:
The patent introduces calibration beams as intermediary elements that mediate between the multi-beam system and the measurement process. These calibration beams serve as reference markers that can be detected to determine the actual shape and position of the multi-beam image, providing an indirect but accurate measurement method that works regardless of the number of writing beams.
2Measurement precision
If mark scanning operations are performed multiple times to obtain sufficient S/N ratio, then measurement precision improves, but loss of time increases
Solution Approach 1:
The patent performs preliminary measurement using calibration beams positioned at the periphery before or during the writing process. By pre-establishing reference points and measuring beam shape characteristics in advance, the system eliminates the need for repeated mark scanning operations during writing, significantly reducing measurement time while maintaining precision.
Solution Approach 2:
The calibration beams operate continuously alongside the writing beams, providing ongoing measurement capability without interrupting the writing process. This continuous measurement approach replaces discrete, repeated mark scanning operations, maintaining measurement precision while eliminating idle time between measurements.
3Productivity
If the region size of the aperture array is increased to accommodate more beams, then productivity improves, but device complexity increases
Solution Approach 1:
The patent segments the aperture array into functional zones: a central region for writing beams and a peripheral region for calibration beams. This spatial segmentation allows the system to manage large aperture arrays by treating different regions with different functions, simplifying the control and measurement processes even as the overall array size increases to accommodate more beams.
4Device complexity
If calibration is performed using the same beams for writing, then device complexity is reduced, but measurement precision deteriorates due to beam drift and S/N ratio issues
Solution Approach 1:
The patent segments the beam system into writing beams and calibration beams that are spatially separated. The calibration beams are positioned at the periphery and are distinct from the writing beams, allowing independent calibration measurements without the interference of writing operations. This segmentation resolves the conflict between using the same beams for both functions versus using separate beams.
Solution Approach 2:
The calibration beams act as intermediary reference elements that enable accurate measurement without being affected by writing process variations. These intermediary beams provide stable reference points for calibration while the writing beams perform their primary function, eliminating the beam drift and S/N ratio problems that occur when the same beams are used for both writing and calibration.
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 allows for accurate measurement and adjustment of multi-beam image shapes, achieving a substantial signal-to-noise ratio without increasing the beam irradiation area, thus reducing distortion and aberration effects, and enabling reliable multi-beam writing and inspection processes.
Implementation Method 1
an emission source that emits a charged particle beam; a forming aperture array substrate configured to form multi-beams by making a region including a whole of the plurality of first openings irradiated by the charged particle beam
Implementation Method 2
a detector that detects a secondary electron including a reflected electron generated by scanning the mark by deflecting the selected calibration beam
Data Source
AI summary
A multi charged particle beam apparatus includes a forming aperture array substrate, where there are formed a plurality of first openings and a plurality of second openings on the periphery of the whole plurality of first openings, each being larger than each of the plurality of first openings, to form multi-beams by the plurality of first openings, and to be able to form a plurality of calibration beams by the plurality of second openings, a shutter to select, one by one, one of the plurality of calibration beams formed by passing through the plurality of second openings, in accordance with a slide position, and a detector to detect a secondary electron including a reflected electron generated by scanning a mark by deflecting the selected calibration beam, in the state of all the multi-beams controlled to be OFF.