SEM Roughness Index Correction Using PSD Machine Calibration
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Solution Overview
Problem
Existing SEM type length measurement apparatuses face challenges in accurately measuring edge roughness due to machine differences caused by apparatus-specific noise components like vibration and power supply noise, which current noise removal methods fail to address effectively.
Innovation Solution
A charged particle beam apparatus and method that includes a charged particle beam optical system, detector, and image processing unit to calculate a roughness index by inputting power spectral density data, correcting for machine differences using a reference apparatus, and applying correction functions to scanning images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If noise frequency and amplitude are obtained from an SEM image and fed back to a deflector, then some noise can be removed, but trial and error are required to identify an optimum phase since phase is not known
Solution Approach 1:
The patent implements feedback by using the measured power spectral density data from the reference apparatus to correct the power spectral density of subsequent measurements. The correction function, derived from the reference measurement, is applied to remove apparatus-specific noise components automatically, eliminating trial-and-error procedures and reducing the time required to achieve optimal measurement conditions.
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
The method effectively corrects for machine differences in roughness measurements, ensuring accurate and consistent edge roughness evaluation across different apparatuses.
Implementation Method 1
a charged particle beam optical system configured to two-dimensionally scan a line pattern formed on a sample with a charged particle beam
Implementation Method 2
a detector configured to detect electrons emitted from the sample by being irradiated with the charged particle beam
Data Source
AI summary
Roughness measurement corrects a machine difference utilizing first PSD data indicating power spectral density of a line pattern measured for a line pattern formed on a wafer for machine difference management by a reference machine in roughness index calculation and second PSD data indicating power spectral density of a line pattern measured for the line pattern formed on the wafer for machine difference management by a correction target machine are used to obtain a correction method for correcting the power spectral density of the second PSD data to the power spectral density of the first PSD data, power spectral density of a line pattern is measured as third PSD data from a scanning image of the line pattern, and corrected power spectral density obtained by correcting the power spectral density of the third PSD data by the obtained correction method is calculated.