SEM Electron Beam Quality Verification via PSD Curve Comparison
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for detecting the quality of electron beams in scanning electron microscopes (SEM) are inadequate for ensuring high accuracy in measuring fine patterns, as they are affected by environmental factors and component wear, leading to inaccurate measurements due to unsatisfactory electron beam quality.
Innovation Solution
A method involving a detection sample with multiple line patterns, where a power spectral density (PSD) curve is obtained and compared to a standardized model to determine the electron beam's quality, ensuring high-quality electron beams are used for accurate measurements by eliminating noise effects and roughness distributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional electron beam quality examination methods are used, then the examination process is simple, but the measurement precision of fine patterns deteriorates due to environmental factors and component wear
Solution Approach 1:
The patent performs preliminary quality examination of the electron beam before actual measurement by scanning a reference sample and comparing the obtained image with a stored reference image. This preliminary action ensures that the electron beam quality meets requirements before fine pattern measurement, preventing measurement errors caused by beam quality degradation from environmental factors or component wear.
Solution Approach 2:
The patent creates a digital copy (reference image) of the reference sample scanned under known good conditions and stores it for comparison. This copying approach allows continuous quality verification by comparing current scans against the stored reference, enabling detection of electron beam quality changes without requiring physical reference standards and ensuring consistent measurement precision.
2Reliability
If reference samples are scanned and compared with calibration patterns, then the electron beam quality can be examined, but the complexity of the detection process increases
Solution Approach 1:
The system uses an automatically stored reference image of the reference sample to perform self-verification of electron beam quality. The examination process automatically compares current scan results with the stored reference without requiring manual intervention or complex external calibration equipment, reducing detection process complexity while maintaining reliability.
3Productivity
If the electron beam quality is not properly examined, then the detection process is faster, but the accuracy of detected dimensions of fine patterns deteriorates
Solution Approach 1:
The patent implements a quick preliminary quality check by scanning the reference sample and comparing with the stored reference image before actual fine pattern measurement. This preliminary action is designed to be rapid while ensuring measurement accuracy, allowing the system to quickly verify electron beam quality and proceed with measurement when conditions are acceptable.
Solution Approach 2:
By using a digital copy of the reference sample image for comparison, the system enables rapid automated quality verification without requiring physical reference standards or complex measurement procedures. This copying approach accelerates the quality check process while maintaining measurement accuracy through automated image comparison.
Data Source
AI summary
Methods for detecting an electron beam of a SEM and for detecting fine patterns are provided. Line patterns having a length in a first direction can be formed on a detection sample. A power spectral density (PSD) curve of a standardized model, formed under a same exposure process of the detection sample, can be obtained. An edge contour of each line pattern of the detection sample can be obtained by the SEM and can be sampled at a sampling frequency to obtain a variation range at a sampling point on the edge contour in a second direction that is perpendicular to the first direction. A PSD curve of the detection sample can be obtained according to the variation range and can be compared with the PSD curve of the standardized model to determine whether an electron beam of the SEM has a high quality in the second direction.