Charged Particle Microscope Gain Adjustment for Dark Region Imaging
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Solution Overview
Problem
Charged particle microscopes face challenges in capturing high-quality images of dark parts in semiconductor patterns due to low signal amounts, which are exacerbated by noise and increased imaging time, and existing methods to enhance image quality, such as varying exposure amounts, can damage samples and increase imaging time.
Innovation Solution
The method involves setting different gain values for detectors to capture images, combining them to reduce thermal and quantization noise, and adjusting gain values based on dark part lightness to enhance image quality in dark regions without saturating other areas, while optimizing probe current, beam irradiation time, and sample charging levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the probe current is increased to increase the signal amount from dark parts, then the signal amount increases, but the image blurs because the intensity distribution of the charged particle beam spreads
Solution Approach 1:
The patent applies periodic action by performing multiple scans of the charged particle beam over the same region. Instead of using a single high-current scan that causes blurring, the system performs multiple lower-current scans and accumulates the signals, achieving high signal amount without beam spreading effects.
2Quantity of substance
If the beam irradiation time is increased to increase the signal amount from dark parts, then the signal amount increases, but the imaging time increases in proportion to the beam irradiation time
Solution Approach 1:
The patent divides the total imaging time into multiple periodic scan cycles. By performing multiple scans and accumulating signals, the system achieves high signal amount from dark parts without requiring proportionally long imaging time, as the scans are performed efficiently in repeated cycles.
Solution Approach 2:
The patent merges multiple scan results by accumulating signals from multiple scans. This combining of multiple lower-dose scans achieves the same signal amount as a single high-dose scan but with reduced beam damage and more efficient time utilization.
3Quantity of substance
If the dose amount is increased to increase the signal amount from dark parts, then the signal amount increases, but the sample is damaged and/or charged
Solution Approach 1:
The patent uses periodic scanning to distribute the total dose over multiple scan cycles rather than delivering it all at once. This allows the sample to recover between scans and prevents cumulative damage and charging effects that would occur with a single high-dose exposure.
Solution Approach 2:
The patent combines multiple low-dose scans to achieve the equivalent of a high-dose scan. By merging the signals from multiple gentle scans, the system obtains sufficient signal amount from dark parts without causing sample damage or charging that would result from a single intense exposure.
4Manufacturing precision
If image processing is performed on a captured image to improve image quality, then the image quality improves to some extent, but if the signal amount from dark parts is extremely small, a significant effect cannot be expected
Solution Approach 1:
The patent performs preliminary action by accumulating sufficient signal from dark parts during the multiple scan cycles before image processing is applied. By ensuring adequate signal amount is captured during scanning, the subsequent image processing can effectively enhance image quality rather than trying to recover from insufficient signal data.
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 high-quality image capture in dark regions with reduced noise and imaging time, minimizing sample damage and improving overall image clarity across all regions.
Implementation Method 1
a particle (a charged particle of the same type as or a different type from the emitted charged particle applied to the target sample, or electromagnetic wave, a photon) that is emitted from the target sample or transmits through the target sample are detected by a detector
Data Source
AI summary
A specimen image capture method using a charged particle microscope device includes: a first image acquisition step in which the gain of a detector in a charged particle microscope is set to a first gain value, charged particle beam scanning is carried out on a specimen, and a first image is obtained; a second image acquisition step in which the gain of the detector is set to a second gain value, which is different to the first gain value, charged particle beam scanning is carried out on the specimen, and a second image is obtained; and an image combination step in which the first gain value and the second gain value are used and the first image and the second image are combined.