In Plane Drift Compensation in Microscopy
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Solution Overview
Problem
Integrated circuit metrology systems face drift errors due to undesired motion between the observing component and the sample, which current solutions attempt to mitigate through precise mechanical design or image-based software adjustments, but these methods are inefficient and prone to increased drift over time.
Innovation Solution
A microscope system that uses a sensor to independently generate position data from the sample, which is then applied by a controller to correct image data and compensate for drift, allowing for real-time or delayed error correction, thereby reducing positional drift and improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high precision mechanical components are used in the mechanical loop, then drift error is reduced, but device complexity and cost increase
Solution Approach 1:
The patent replaces reliance on high-precision mechanical components with an optical measurement system. A separate observing component (such as a laser interferometer or optical sensor) independently measures the position of the sample or stage, providing position data that is not subject to mechanical drift. This optical substitution eliminates the need for overly precise mechanical components while maintaining measurement accuracy.
Solution Approach 2:
The patent introduces an intermediary optical measurement system that acts as a mediator between the mechanical scanning system and the final measurement result. The observing component independently tracks position, serving as an intermediary reference that corrects for mechanical drift in the scanning system, thereby resolving the contradiction between mechanical simplicity and measurement precision.
2Measurement precision
If multiple scans with software correction are performed, then measurement accuracy is improved, but productivity decreases
Solution Approach 1:
The patent implements continuous drift compensation during a single scan by independently measuring position with an observing component throughout the scanning process. This continuous measurement allows for real-time correction of drift errors without requiring multiple scans or interruptions, thereby maintaining both high measurement accuracy and productivity.
Solution Approach 2:
The patent employs a feedback mechanism where the observing component continuously provides position data that is used to correct drift errors during the scanning process. This real-time feedback allows for dynamic compensation of mechanical drift, eliminating the need for multiple scans while maintaining measurement accuracy, thus resolving the contradiction between precision and productivity.
3Measurement precision
If mechanical components are designed for high precision, then drift is minimized initially, but reliability decreases over time due to wear
Solution Approach 1:
The patent substitutes mechanical precision requirements with an independent optical observation system. By using an observing component to independently measure position rather than relying on mechanical component precision, the system eliminates wear-related degradation of positional stability. The optical measurement system does not suffer from mechanical wear, thereby maintaining reliability over time.
Solution Approach 2:
The observing component serves itself as a reference standard, independent of the mechanical scanning system's precision. It autonomously provides accurate position data without being affected by mechanical wear, effectively making the measurement system self-correcting and maintaining reliability over the long term without requiring mechanical component replacement or recalibration.
Data Source
AI summary
A microscope that produces magnified images of a sample. An observing component generates image data from the sample, and a moving component generates relative movement between the sample and the observing component. A sensor independently generates position data directly from the sample. A controller receives the image data from the observing component and the position data from the sensor, and applies the position data to correct special relations between the image data.