High precision stereo profilometry

Metrological data from sample surfaces can be obtained by using a variety of profilome try methods. Atomic Force Microscopy (AFM), which relies on contact inter-atomic forces to extract topographical images of a sample, is one such method that can be used on a wide range of surface types, with possible nanometer resolution (both vertical andlateral). However, AFM images are commonly distorted by convolution, which reduces metrological accuracy. This type of distortion is more significant when the sample surface containshigh aspect ratio features such as lines, steps or sharp edges or when probe and sample share similar characteristic dimensions. Therefore, as the size of engineered features arepushed into the micrometer and sub-micrometer range by the development of new high precision fabrication techniques, convolution distortions embedded in the images becomeincreasingly more significant. Aiming at mitigating these distortions and recovering metrology sound ness, we introduce a novel image deconvolution scheme based on the principle of stereo imaging. Multiple images of a sample, taken at different angles, allow for separation ofcon volution artifacts from true topographic data. As a result, accurate samplereconstruction and probe shape estimation can be achieved simultaneously. Additionally, shadow zones, which are areas of the sample that cannot be reached by the AFM probe, are greatly re duced. Most importantly, this technique does not require a priori probe characterizationor any sort of shape assumption. It also reduces the need for slender or sharper probes,which, on one hand, induce less convolution distortion but, on the other hand, are more prone to wear and damage, thus decreasing the overall inspection system reliability.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Mechanical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2001

Author dc:creator

• Aumond, Bernardo Dantas, 1972-

Advisor dc:contributor.advisor

• Kamal Youcef-Toumi.

• Mechanical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/88892

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/88892