FIB Beam Drift Correction via Reference Image Feedback
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Solution Overview
Problem
Automated focused ion beam (FIB) processing faces challenges in maintaining positional accuracy due to sample stage drift during prolonged beam irradiation, leading to inaccurate micromachining and image distortion from adhered powder and scattered beams, which complicates precise image reading and processing.
Innovation Solution
A method involving setting a reference image region, obtaining pre- and post-ion beam irradiation images, calculating image deviation, and adjusting the beam system to correct for drift, with brightness and contrast adjustments to ensure accurate image detection and processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If beam irradiation time is prolonged to perform micromachining, then processing depth and quality are improved, but sample stage and electronics drift with time causing positional accuracy to deteriorate
Solution Approach 1:
The patent implements a feedback mechanism by continuously monitoring the position of a reference mark on the sample stage using imaging means. The detected position information is fed back to a control system that calculates positional deviation and generates correction signals to adjust the beam irradiation position, thereby compensating for drift that occurs during prolonged irradiation
Solution Approach 2:
The patent places a reference mark on the sample stage before micromachining begins. This reference mark serves as a preliminary positioning reference that enables continuous drift monitoring and correction throughout the prolonged beam irradiation process, allowing the system to maintain positional accuracy despite extended processing time
2Area of stationary object
If automated micromachining is performed with multiple beam irradiation positions, then processing coverage is improved, but mechanical accuracy of stage movement causes position reproduction to deteriorate
Solution Approach 1:
The patent uses imaging means to detect the position of a reference mark at multiple different positions on the sample stage during automated micromachining. The detected position information is fed back to correct for mechanical inaccuracies in stage movement, enabling accurate position reproduction across the entire processing area despite limitations in mechanical stage accuracy
Solution Approach 2:
The patent replaces reliance on mechanical stage accuracy with an optical/image-based positioning system. By using imaging means to detect reference mark positions and calculating actual coordinates based on these images, the system substitutes mechanical position measurement with optical measurement, thereby achieving higher position reproduction accuracy across multiple beam irradiation positions
3Measurement precision
If method using reflected signal reading is used to correct sample position, then position correction capability is improved, but powder adherence and beam scattering cause image reading to become impossible
Solution Approach 1:
The patent extracts the reference mark positioning function from the processed region. By placing a dedicated reference mark separate from the powder-prone processed areas, the system isolates the positioning reference from harmful effects such as powder adherence and beam scattering that occur during micromachining, thereby maintaining continuous image readability for position correction
Data Source
AI summary
A method and apparatus for correcting drift of the beam irradiation position during automated FIB (focused ion beam) processing with a reference image-setting unit, an image read-in unit for reading in images of the reference image region during the FIB processing, an arithmetic-and-control unit for finding the direction and amount of image deviation between the subsequent images, and a beam deflection system-adjusting unit for correcting the beam deflection system by correcting the image deviation based on the deviation in response to the output from the arithmetic-and-control unit. The arithmetic-and-control unit optimizes the brightness or contrast of the reference image.