SEM Image Alignment for Charging-Induced Distortion Correction
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Solution Overview
Problem
Scanning electron microscope (SEM) images in lithographic processes are distorted due to charging-induced deflections of the electron beam, leading to inaccuracies in feature measurement and positioning, which are critical for semiconductor manufacturing but difficult to correct with existing methods.
Innovation Solution
A method and system for determining and correcting charging-induced distortion in SEM images by modeling the deflection of the electron beam caused by charge build-up on the substrate, allowing for precise isolation and reduction of this distortion in the imaging process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If SEM imaging is performed on a substrate, then the substrate surface can be visualized and measured, but charging-induced beam deflection causes distortion in the image
Solution Approach 1:
The system measures the actual beam deflection caused by charging effects during SEM imaging and uses this feedback information to calculate and apply correction factors to the image data, thereby compensating for the charging-induced distortion and improving measurement accuracy
Solution Approach 2:
The patent introduces an intermediary correction model that acts between the charged substrate and the imaging system. This model calculates the deflection field caused by charge accumulation and uses it to transform the distorted image coordinates back to their true positions, effectively mediating the harmful charging effect
2Manufacturing precision
If conventional distortion correction methods are applied, then general image quality can be improved, but charging-induced distortion cannot be isolated and corrected
Solution Approach 1:
The patent segments the total image distortion into distinct components, specifically isolating the charging-induced deflection component from other sources of distortion. By calculating the deflection field separately based on charge distribution models, the system can apply targeted correction to charging effects without being confounded by other distortion mechanisms
Solution Approach 2:
The system changes the approach from direct image correction to parameter-based correction. Instead of manipulating pixel values directly, the patent models the physical parameters (charge density, deflection field) causing the distortion and uses these parameters to compute correction transformations, providing a more fundamental and isolatable correction method
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 enables more accurate SEM image correction by isolating and reducing charging-induced distortions, improving measurement precision and reducing errors in semiconductor manufacturing, thereby enhancing the yield and quality of integrated circuits.
Implementation Method 1
determining, at each of a plurality of locations in a SEM image of at least part of a sample, a deflection of an illuminating charged particle beam caused by a charging of the sample at the location
Data Source
AI summary
Disclosed herein is a non-transitory computer readable medium that has stored therein a computer program, wherein the computer program comprises code that, when executed by a computer system, instructs the computer system to perform a method of determining the charging induced distortion of a SEM image, the method comprising: determining, at each of a plurality of locations in a SEM image of at least part of a sample, a deflection of an illuminating charged particle beam caused by a charging of the sample at the location; and determining the charging induced distortion of the SEM image in dependence on the determined deflections at each of the plurality of locations in the SEM image.