Electron Beam Image Correction for Cross-Tool Measurement Consistency
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Solution Overview
Problem
Existing electron beam observation devices face challenges in accurately reducing machine differences due to variations in electron beam shapes, especially with aging or environmental influences, which affect measurement accuracy and image quality across multiple devices.
Innovation Solution
A method involving multiple electron beam observation devices that calculate a correction factor based on frequency characteristics of images from reference patterns, allowing for image correction to ensure consistent frequency characteristics across devices, thereby reducing machine differences and maintaining accurate measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hardware or software adjustment is used to reduce machine differences, then measurement accuracy is improved, but the method approaches its limits with further miniaturization of patterns
Solution Approach 1:
The invention changes the parameter of electron beam intensity distribution by introducing a correction factor derived from frequency characteristics. Instead of relying on hardware adjustments that fail at miniaturized scales, the system mathematically adjusts the intensity distribution parameters through image correction processes, enabling accurate measurement even of highly miniaturized patterns.
2Measurement precision
If image correction using estimated electron beam profiles is performed, then machine difference reduction is attempted, but accurate recognition of electron beam shapes is extremely hard
Solution Approach 1:
The invention replaces the mechanical/optical approach of directly measuring electron beam shapes with a mathematical frequency domain analysis. Instead of attempting to directly detect and measure the physical electron beam profile (which is extremely difficult), the system uses frequency characteristics of images to derive correction factors, substituting direct physical measurement with mathematical transformation and analysis.
Solution Approach 2:
The invention introduces frequency characteristics as an intermediary between the electron beam and the correction process. Rather than directly using electron beam shape data (which is hard to obtain), the system uses frequency characteristics of images as a mediator to derive correction factors, enabling indirect but accurate correction of machine differences.
3Productivity
If electron beam observation devices are used over time, then productivity is improved, but the electron beam shape varies with aging and environmental influences
Solution Approach 1:
The invention implements a feedback mechanism where frequency characteristics of images are continuously analyzed to derive correction factors. As devices are used over time and electron beam shapes vary due to aging or environmental influences, the system repeatedly performs frequency analysis and applies appropriate correction factors, creating a closed-loop feedback system that maintains measurement accuracy throughout the device lifecycle.
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 effectively reduces machine differences and maintains measurement accuracy by correcting images using calculated correction factors, ensuring consistent performance across multiple electron beam observation devices.
Implementation Method 1
An electron beam observation device such as a scanning electron microscope (SEM) uses an electron beam to observe, inspect, or measure specimens. The electron beam observation device accelerates electrons emitted from an electron source
Implementation Method 2
converges them on the specimen surface through the use of an electrostatic lens or an electromagnetic lens
Implementation Method 3
converges them on the specimen surface through the use of an electrostatic lens or an electromagnetic lens
Implementation Method 4
The injection of the primary electron causes the specimen to emit a secondary electron
Implementation Method 5
Depending on conditions, low-energy electrons are called secondary electrons, and high-energy electrons are called backscattered electrons
Implementation Method 6
It is possible to acquire scanned images of a fine pattern or composition distribution on the specimen by detecting the secondary electrons while deflecting and scanning the electron beam
Data Source
AI summary
The objective of the present invention is to reduce differences between individual electron beam observation devices accurately by means of image correction. This method for calculating a correction factor for correcting images between a plurality of electron beam observation devices, in electron beam observation devices which generate images by scanning an electron beam across a specimen, is characterized by including: a step in which a first electron beam observation device generates a first image by scanning a first electron beam across first and second patterns, on either a specimen including the first pattern and the second pattern, having a different shape or size to the first pattern, or a first specimen including the first pattern and a second specimen including the second pattern; a step in which a second electron beam observation device generates a second image by scanning a second electron beam across the first and second patterns; and a step in which the first or second electron beam observation device calculates a correction factor at a peak frequency extracted selectively from first and second frequency characteristics calculated on the basis of the first and second images.