AVS 49th International Symposium
    Nanometer Structures Friday Sessions
       Session NS-FrM

Paper NS-FrM6
Microwave Evanescent Microscope with Coupled Shear-field Topography Measurement

Friday, November 8, 2002, 10:00 am, Room C-207

Session: Novel Surface Nanoprobes
Presenter: S.W. Robey, National Institute of Standards and Technology
Authors: S.W. Robey, National Institute of Standards and Technology
S.J. Stranick, National Institute of Standards and Technology
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Near-field probes are being developed to combat the diffraction limit in a wide spectral range from the visible through the IR and into the microwave regime. We are developing evanescent capabilities at GHz frequencies for a variety of applications. Two design criteria are broadband capability and the ability to independently measure sample topography. A system based on a coaxial transmission line resonant structure evanescently coupled to the sample via a scanning tunneling microscope tip will be described. Standing wave resonances in the structure provide high sensitivity with quasi-broadband coverage from ~ 1 GHz to 20 GHz. While previous designs have used soft contact or employed the capacitive feedback to provide height control, we have successfully implemented shear-force measurement to provide the necessary independent topographic information on either conducting and insulating materials. A variable single stub mechanism allows tuning to critical coupling at a selected resonance once near-contact is achieved. The design and implementation of the microscope will be discussed, with comparison to other microwave evanescent systems. Measurements on compositionally graded thin films of Ba@subx@Sr@sub1-x@TiO@sub3@, buried metallic lines on IC's, and investigation of correlations in topographic and dielectric contrast will illustrate capabilities.