Scanning probe microscopy with inherent disturbance suppression using micromechanical systems

All scanning probe microscopes (SPMs) are affected by disturbances, or mechanical noise, in their environments which can limit their imaging resolution. This thesis introduces a general approach for suppressing out-of-plane disturbances that is applicable to non-contact and intermittent contact SPM imaging modes. In this approach, two distinct sensors simultaneously measure the probe-sample separation: one sensor measures a spatial average over a large sample area while the other responds locally to topography underneath the nanometer-scale probe. When the localized sensor is used to control the probe-sample separation in feedback, the spatially distributed sensor signal reveals only topography. This technique was implemented on a scanning tunneling microscope (STM) and required a custom micromachined scanning probe with an integrated interferometer for the spatially averaged measurement. The interferometer design is unique to SPM because it measures the probe-sample separation instead of the probe deflection. A robust microfabrication process with a novel breakout scheme was developed and resulted in 100 % device yield. For imaging, an STM setup with optical readout was built and characterized. The suppression improvement over conventional SPM imaging was measured to be 50 dB at 1 Hz, in agreement with predictions from classical feedback theory. Images are presented as acquired with each sensor signal in several environments, and the interferometer images show remarkable clarity when compared with the conventional tunneling images.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Materials Science and Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2005

Author dc:creator

• Sparks, Andrew William, 1977-

Advisor dc:contributor.advisor

• Scott R. Manalis and Anne M. Mayes.

• Materials Science and 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/1721.1/30249
• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Identifier URI

http://dspace.mit.edu/handle/1721.1/30249

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/30249