Imaging Embedded Structures using Microfabricated Scanning Near-Field
Microwave Probes Compatible with Atomic Force Microscopy
Massood Tabib-Azar
Department of Electrical Engineering and Computer Science
Case Western Reserve University, Cleveland, Ohio 44106
mxt7@case.edu, (216) 368-6431
Abstract
Design, fabrication and characterization of near-field microwave scanning probes
compatible with atomic force microscope (AFM) for imaging of embedded anostructures
will be discussed. The existing local probe microscopy tools operate either at very low
frequencies, such as scanning capacitance microscope (SCM) at MHz range, or at optical
frequencies, such as near field scanning optical microscope (NSOM). The microwave
probes discussed here enable local probe microscopy to bridge the frequency gap
between the existing tools and enable localized microwave spectroscopy and imaging of
molecules and nanostructures. The microwave/AFM probe consists of a co-axially
shielded, heavily-doped silicon tip and an aluminum co-planar waveguide. The co-axial
tip structure was formed by a thick photoresist process enabling the silicon apex to
protrude through a well-defined aperture in the aluminum shield layer. The aperture
confines the electromagnetic field in the exposed tip region to perform microwave
measurements with high spatial resolution. Co-axial tips ~ 10 µm high with apex radius ~
50 Å and an aperture radius of ~ 500 nm were fabricated. I will discuss mechanical and
electrical characterizations of the microwave probes and simultaneous AFM and
microwave imaging of breast cancerous cells and standard grid structures. Important
fabrication steps, and characterization/calibration procedures will also be reviewed.
Biosketch: Massood Tabib-Azar received M.S. and Ph.D. degrees in electrical
engineering from the Rensselaer Polytechnic Institute in 1984 and 1986, respectively. In
1986-87 academic year he was an instructor in the ECSE department at RPI and in 1987,
he joined the faculty of EECS department at Case Western Reserve University (CWRU).
He was a fellow at NASA during 1992-1992, he was on Sabbatical at Harvard University
during 93-94, and at Yale University during 2000-2001. Massood is currently a professor
at EECS with joint appointments in Macromolecular Engineering and Physics
Departments. His current research interests include nanometrology tools (microwaveatomic force microscopy), molecular electronics, novel devices based on solid
electrolytes, sensors and actuators (microfluidics), and quantum computing. His teaching
interests include development of courses in the area of electronic device physics and
electromagnetics with an emphasis on solving problems and the use of computer-aided
instruction tools. He is author of three books, two book chapters, more than 110 journal
publications, and numerous conference proceeding articles. He has introduced and chairs
many international symposia in his fields of interest.
Dr. Tabib-Azar is a recipient of the 1991 Lilly Foundation Fellowship and he is a
member of the New York Academy of Sciences, IEEE (Electron Devices), APS, AAPT,
and Sigma Xi research societies. He has also received more than 10 certificate of
appreciation and recognition for his professional activities and a best paper award from
Design Automation conference in 2001 for his work on electromagnetic properties of
interconnects and defects in ICs.