Calibrating CD-SEM Data with Cross-Section Measurements
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current measuring tools, such as CD-SEM, STEM, TEM, and AFM, face challenges in accurately calibrating cross-section dimensions due to limited sampling capabilities and high measurement costs, making it difficult to correlate measurement results between different tools.
Innovation Solution
A method that involves measuring the CD average and dispersion using CD-SEM, calculating the required number of cross-section measurement points, and statistically processing roughness to achieve accurate calibration by determining the calibration correction value, enabling high-accuracy calibration between different measuring tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cross-section measurement is performed using STEM, TEM, or cross-section observation SEM tools, then measurement precision of cross section dimension is improved, but measuring cost increases due to required sample preparation such as FIB process
Solution Approach 1:
The patent introduces CD-SEM measurement data as an intermediary to bridge the gap between top-down CD measurements and cross-section measurements. By using CD-SEM to measure CD at multiple positions and calculate dispersion, the method enables indirect calibration without requiring expensive FIB sample preparation for each measurement point, thus reducing measuring cost while maintaining calibration accuracy.
2Measurement precision
If cross-section measurement is performed using AFM tool, then measurement precision of cross section dimension is improved, but measuring time increases
Solution Approach 1:
The patent applies partial action by determining the required number of cross-section measurement points based on statistically calculated CD dispersion from CD-SEM data. Instead of measuring all possible points or using excessive sampling, the method calculates the minimum necessary sample size to achieve calibration accuracy, thereby reducing measuring time while maintaining precision.
3Productivity
If limited sampling is performed with cross-section observation tools, then measuring cost and time are reduced, but calibration accuracy deteriorates due to inability to correlate with multiple CD-SEM measurement points
Solution Approach 1:
The patent changes the parameter of sampling strategy by using statistically calculated sample size based on CD dispersion. Instead of arbitrary or uniform sampling, the method determines the optimal number of cross-section measurement points required to achieve calibration accuracy, balancing productivity and measurement precision through parameter optimization.
4Productivity
If multiple CD positions are measured using CD-SEM tool, then productivity is improved with high throughput, but measurement precision of specific cross section height deteriorates due to top-down view limitation
Solution Approach 1:
The patent uses CD dispersion calculated from multiple CD-SEM measurements as an intermediary parameter to bridge the limitation of top-down viewing. By statistically analyzing CD variations at multiple positions and using this dispersion data to determine required cross-section sample size, the method enables indirect access to cross-section height specific information while maintaining high throughput CD-SEM measurement capability.
Data Source
AI summary
A method, and a corresponding system, are provided for calibrating data of an object measured by different measuring tools, including measuring a Critical-Dimension (CD) and roughness of an object by using a CD-SEM tool, calculating a number of cross section measurement points required for calibration, by statistically processing the roughness of the object, measuring the cross section of the object by using a cross section measuring tool to obtain cross section data at the calculated number of cross section measurement points, calculating the average measurement of the cross section measurement height, and calculating a calibration correction value that is a function of a difference between the average CD measurement of the object and the average measurement of the cross section measurement height of the object.