SEM Pattern Inspection Distortion Correction
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Solution Overview
Problem
Existing pattern inspection methods using SEM images face challenges in ensuring accurate correspondence between design data and SEM images due to distortion, leading to incomplete or inaccurate dimensional measurements.
Innovation Solution
A pattern inspection apparatus and method that includes an electron scanning unit, signal processor, storage, and controller to detect and adjust for distortion in SEM images by matching design data with SEM images using distortion amount data, allowing for accurate alignment and measurement of pattern dimensions even with distorted images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If distortion correction is applied to SEM images, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing distortion amount data for various positions in the SEM image field of view. This distortion correction data is prepared in advance and stored in memory, allowing rapid correction during measurement without complex real-time processing, thus improving measurement precision while limiting device complexity
Solution Approach 2:
The patent introduces an intermediary element - a distortion amount data table that acts as a mediator between the raw distorted SEM image and the corrected measurement data. This intermediary contains pre-computed correction values that simplify the distortion correction process, enabling accurate measurements without requiring complex real-time distortion compensation algorithms
2Productivity
If automatic measurement region placement is implemented, then productivity is improved, but measurement precision may deteriorate due to distortion
Solution Approach 1:
The system performs preliminary action by automatically placing measurement regions based on design data coordinates before actual measurement occurs. This automated placement increases productivity while the subsequent distortion correction using pre-stored distortion amount data ensures measurement precision is maintained despite the automated process
Solution Approach 2:
The patent implements feedback by using distortion amount data that is determined based on the relationship between design data and actual SEM image positions. This feedback mechanism allows the system to automatically compensate for distortion effects in measurement region placement, maintaining precision while achieving high productivity through automation
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
Enables accurate pattern inspection and measurement by adjusting either the design data or SEM image based on distortion data, ensuring precise correspondence and reducing manual intervention in setting measurement regions, thus facilitating efficient dimensional measurement across multiple patterns.
Implementation Method 1
an electron scanning unit configured to scan a surface of a sample with an electron beam and to detect secondary electrons emitted from the surface of the sample
Data Source
AI summary
A pattern inspection apparatus configured to perform pattern inspection based on a SEM image previously measures distortion amount data representing a magnitude distribution of positional displacement caused by distortion of the SEM image in a scanning direction. When the pattern inspection is performed, the apparatus makes design data and the SEM image correspond to each other by adjusting at least one of the design data and the SEM image on the basis of the distortion amount data, and places a measurement region on the SEM image on the basis of a correspondence between the design data and the SEM image. The apparatus may further find a matching rate between a pattern of the design data and a pattern of the SEM image.