Electron-Beam Overlay Measurement for Pattern Dispersion Correction
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Solution Overview
Problem
The precision of overlay measurement between upper and lower patterns in semiconductor manufacturing is compromised by double and quadruple patterning technologies and dispersion within cells, limiting the accuracy of existing measurement methods.
Innovation Solution
An overlay measuring method that involves setting an offset on a substrate, obtaining cell images using electron beams, merging these images to measure overlay, and correcting measurement parameters based on failure values to improve consistency and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If overlay measurement is performed using conventional methods on substrates with double or quadruple patterning, then measurement coverage is achieved, but measurement precision deteriorates due to pattern dispersion and process complexity
Solution Approach 1:
The patent segments the overlay measurement process into distinct phases: obtaining separate first and second images of upper and lower patterns, merging them through image processing, and then performing measurement. This segmentation allows each step to be optimized independently, improving overall measurement precision despite process complexity
Solution Approach 2:
The patent introduces an intermediary merging process that combines first and second images into a composite overlay image. This intermediary step serves as a mediator between the complex patterning processes and the final measurement, enabling accurate overlay assessment by integrating multiple pattern layers into a unified measurement target
2Reliability
If measurement parameters are not corrected, then measurement process is simple, but measurement reliability deteriorates due to inconsistent results between overlay offset and measured values
Solution Approach 1:
The patent implements a feedback mechanism where measurement results are analyzed to identify failure values, and measurement parameters are corrected based on this feedback. The system uses the discrepancy between overlay offset and measured values to drive parameter adjustments, ensuring improved consistency and reliability of subsequent measurements
Solution Approach 2:
The patent performs preliminary classification of measurement results into normal and failure values before final measurement completion. This preliminary action allows problematic measurements to be identified and corrected in advance, preventing unreliable data from affecting overall measurement reliability
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
Enhances the precision of overlay measurement by reducing measurement failures and improving the correlation coefficient between the offset and result values, ensuring higher accuracy in overlay assessment.
Implementation Method 1
obtaining a cell image by irradiating an electron beam
Data Source
AI summary
Provided is an overlay measuring method including setting an overlay offset on a substrate, obtaining a cell image by irradiating an electron beam, and obtaining a first image of an upper pattern and a second image of a lower pattern, based on the cell image, merging the first image with the second image, and measuring an overlay of the merged image, and correcting a measuring parameter used in measuring the overlay to improve consistency between the overlay offset and a measured result value of the overlay, wherein the measuring parameter is corrected based on a number of measuring failure values classified as a measurement failure in result values of the overlay.