Charged Particle Beam Magnification Error Correction

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Solution Overview

Problem

Conventional charged particle beam equipment struggles to accurately measure and correct magnification errors in both the X and Y directions simultaneously due to errors in image rotation circuits and the difficulty of mechanically rotating samples in vacuum environments, especially when dealing with small, visually indistinguishable periodic structure patterns.

Innovation Solution

The implementation of charged particle beam equipment that uses FFT transformation and coordinate transformation to measure and correct magnification errors in both X and Y directions simultaneously, without requiring alignment or elimination of rotation direction displacement, by storing magnification error values and applying correction data through data-processing means.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If image rotation is performed to align the periodic structure pattern with the X or Y direction for magnification error measurement, then the measurement can be performed, but errors in the image rotation circuit reduce measurement accuracy

Engineering Contradiction:

Improvemagnification error measurement accuracyVSAvoidimage rotation circuit error

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The invention extracts and eliminates the problematic image rotation step from the measurement process. By using FFT transformation on the electron image, the periodic structure pattern can be analyzed in its original orientation without requiring alignment with X or Y directions, thus removing the source of rotation errors while maintaining measurement capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the mechanical/image rotation approach with a computational FFT-based approach. Instead of physically or digitally rotating the image to align patterns, the FFT transformation analyzes the periodic structure in the frequency domain, substituting a computational method for the problematic mechanical rotation system

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If image rotation is performed to measure magnification error in one direction before measuring the other direction, then sequential measurement can be performed, but the need to rotate the image again prevents simultaneous measurement of both directions

Engineering Contradiction:

Improvemeasurement efficiencyVSAvoidtime for repeated rotation operations

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The invention merges the measurement of magnification errors in both X and Y directions into a single simultaneous operation. The FFT transformation processes the entire electron image at once, extracting periodic structure information in all directions concurrently, thereby combining what were previously separate sequential measurement steps into one unified process

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The FFT transformation is performed as a preliminary action on the complete electron image before any directional analysis. This preliminary frequency domain transformation contains all directional information simultaneously, allowing subsequent extraction of magnification errors in both X and Y directions without requiring intermediate rotation operations

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If the sample is mechanically rotated to change the orientation of the periodic structure pattern, then alignment can be achieved, but the sample cannot be easily taken out, re-inserted, and rotated in vacuum environment

Engineering Contradiction:

Improvesample reorientation capabilityVSAvoidsample manipulation complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The invention replaces the mechanical sample rotation system with a computational image processing approach. Instead of physically rotating the sample in the vacuum chamber, the FFT transformation mathematically analyzes the periodic structure in the electron image regardless of its orientation, substituting computational analysis for mechanical manipulation

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The FFT transformation acts as an intermediary that bridges the gap between the fixed sample orientation and the required measurement capability. Rather than changing the sample's physical orientation, the FFT mediator processes the image data to extract periodic structure information in any orientation, eliminating the need for mechanical sample rotation

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS7649172B2Charged particle beam equipment with magnification correction

Publication Date: 2010.01.19 HITACHI HIGH TECH CORP

AI summary

Charged particle beam equipment enables the simultaneous measurement and correction of magnification errors in both X and Y directions in one measurement without requiring the elimination of displacement, if any, in rotation direction between the direction of a periodic structure pattern of a sample having a known periodic structure and the X or Y direction on an electron image of the sample. The charged particle beam equipment of the invention enables the simultaneous measurement of magnification errors in the X and Y directions by FFT transformation and coordinate transformation of an electron image, even when there is a displacement in rotation direction between the direction of the periodic structural pattern and the X or Y direction on the electron image of the sample.