MRS Bulletin

Technical Feature

Technical Feature

Nanometer-Scale Laser Direct-Write Using Near-Field Optics

Costas P. Grigoropoulos, David J. Hwang and Anant Chimmalgi

Abstract

This article summarizes research on laser-based processing and structuring of materials at the nanoscale using optical near-field schemes. Both apertureless and tapered fiber near-field scanning optical microscope probes can deliver highly confined irradiation at sufficiently high intensities to cause morphological and structural changes in materials at the nanometer level. The energy emitted by the probes and the absorption within the target material are predicted by carrying out calculations of the near-field electromagnetic distribution. The effects of shrinking laser beam dimensions compete with the energy diffusion into the target material. Experimental results have shown well-controlled subtractive material modification with minimum feature size in the neighborhood of 10 nm. Precise patterning can be achieved via laser-assisted chemical etching. Control of the nucleation of nanostructures via rapid melting and crystallization is demonstrated. The article concludes with an outlook to applications.

Costas P. Grigoropoulos is a professor in the Department of Mechanical Engineering at the University of California, Berkeley, and on the materials science/engineering faculty of the Environmental Energy Technologies Division at Lawrence Berkeley National Laboratory.

Grigoropoulos received Diploma degrees in naval architecture and marine engineering and in mechanical engineering from the National Technical University of Athens, Greece. He holds MSc and PhD degrees in mechanical engineering from Columbia University.

His current research interests are in micro/ nanoengineering, laser materials processing and micro/nanomachining, microscale and nanoscale diagnostics for chemical analysis, phase transformations in semiconductors and electronic materials, laser-driven thin-film crystal growth for applications in microelectronic devices, nanofluidics, microscale fuel cells, catalytic microreactors, hydrogen storage, thermal management in microdevices, and transport diagnostics in MEMS. Grigoropoulos is a fellow of ASME.

Grigoropoulos can be reached at the University of California, Berkeley, Department of Mechanical Engineering, 6177 Etcheverry Hall, Berkeley, CA 94720-1740 USA; tel. 510-642-2525, fax 510-642-6163, and e-mail cgrigoro@me.berkeley.edu.

David J. Hwang is a postdoctoral research associate in the Mechanical Engineering Department at the University of California, Berkeley. He received his BSE and MSE degrees in mechanical engineering from Seoul National University in 1995 and 1997, respectively, and his PhD degree in mechanical engineering from UC–Berkeley in 2005.

Hwang worked for the Samsung Advanced Institute of Technology (SAIT) in South Korea from 1997 to 2000, where he was involved in automotive engine control, superconductorrelated cryogenics, and microjetting devices. His major research interest is in micro/nanoscale processing of electronic materials based on pulsed lasers coupled through high-magnification objective lenses and/or optical nearfield probes.

Hwang can be reached at 5144 Etcheverry Hall, University of California, Berkeley, CA 94720-1740 USA; tel. 510-642-1006 and e-mail djhmech@me.berkeley.edu.

Anant Chimmalgi is a system design engineer at KLA Tencor Corp. He received his BE degree from the National Institute of Technology in Surathkal, India, and his MS and PhD degrees from the Department of Mechanical Engineering at the University of California, Berkeley (2003 and 2005, respectively). Chimmalgi's current research interests include bright-field wafer inspection technologies, semiconductor yield management, nanofabrication technologies, nanoscale heat transfer, nanoparticle manipulation, scanning probe microscopy, and ultrashort laser phenomena.

Chimmalgi can be reached at 5144 Etcheverry Hall, University of California, Berkeley, CA 94720-1740 USA; tel. 510-642-1006 and e-mail anchip@ocf.berkeley.edu.

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