Scanning Probe Microscope Z-Displacement Correction
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Solution Overview
Problem
Scanning probe microscopes (SPMs) face challenges in achieving high-accuracy, high-resolution measurements over broad ranges due to unintentional displacement in the Z-direction during XY-direction scanning, which affects planarity and measurement throughput in semiconductor and hard disk manufacturing processes.
Innovation Solution
A scanning probe microscope system that measures Z-direction displacement independently of the XY-stage and corrects measurement values to ensure high-accuracy profile measurement, using a probe drive mechanism with piezoelectric devices and optical interference displacement sensors to maintain planarity and improve throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the XY-stage is used for broad-range scanning, then the measurement coverage is improved, but unintentional Z-direction displacement occurs reducing measurement accuracy
Solution Approach 1:
A displacement sensor is introduced as an intermediary device to detect the unintentional Z-direction displacement of the XY-stage. The sensor measures the stage's vertical movement independently, and this measurement is used to correct the profile data, thereby eliminating the harmful effect of stage displacement on measurement accuracy.
Solution Approach 2:
The system implements feedback by continuously monitoring the XY-stage's Z-direction displacement using a displacement sensor. The measured displacement values are fed back to the measurement system to correct the profile data, compensating for the stage's unintentional movement and maintaining measurement precision during broad-range scanning.
2Measurement precision
If the probe is positioned and measured at each point sequentially, then high resolution measurement is achieved, but measurement throughput is reduced
Solution Approach 1:
The system enables continuous measurement by eliminating the need for repeated probe positioning and approach operations. Once the probe is positioned, measurements are taken continuously as the XY-stage scans across the sample surface, maintaining constant probe-sample contact and thereby improving throughput while preserving resolution.
Solution Approach 2:
The probe is positioned and brought into contact with the sample surface in advance before the broad-range scanning begins. This preliminary positioning action is performed only once, and then the measurement proceeds continuously during the stage scan, avoiding repeated positioning operations and thereby increasing measurement throughput.
3Measurement precision
If piezoelectric devices are used for probe positioning, then positioning accuracy is improved, but the system becomes sensitive to stage displacement fluctuations
Solution Approach 1:
A displacement sensor is introduced as an intermediary measurement device that independently monitors the XY-stage's Z-direction displacement. This sensor provides accurate stage position information that is used to correct the profile measurements, compensating for stage fluctuations and thereby maintaining measurement reliability despite the sensitivity of the piezoelectric positioning system.
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
The system enables high-accuracy profile measurement without influence from XY-stage fluctuations, optimizing manufacturing processes and improving device yield by enhancing measurement throughput and precision.
Implementation Method 1
optical interference displacement sensors to maintain planarity and improve throughput
Implementation Method 2
probe drive mechanism with piezoelectric devices
Data Source
AI summary
It has been difficult to highly accurately measure the profiles of samples using scanning probe microscopes at the time when scanning is performed due to scanning mechanism fluctuations in the non drive direction, i.e., vertical direction. The present invention is provided with, on the rear side of a sample stage, a high-accuracy displacement gauge for measuring fluctuation in the non drive direction, i.e., vertical direction, at the time when the sample stage is being scanned in the horizontal directions, and as a result, highly accurate planarity evaluation with accuracy of sample nm-order or less is made possible by correcting sample surface shape measurement results obtained using a probe.