Gregory A. Magel

In situ laser processing in a scanning electron microscope

Laser delivery probes using multimode fiber optic delivery and bulk focusing optics have been constructed and used for performing materials processing experiments within scanning electron microscope/focused ion beam instruments. Controlling the current driving a 915-nm semiconductor diode laser module enables continuous or pulsed operation down to sub-microsecond durations, and with spot sizes on the order of 50 μm diameter, achieving irradiances at a sample surface exceeding 1 MW/cm2. Localized laser heating has been used to demonstrate laser chemical vapor deposition of Pt, surface melting of silicon, enhanced purity, and resistivity via laser annealing of Au deposits formed by electron beam induced deposition, and in situ secondary electron imaging of laser induced dewetting of Au metal films on SiOx.

Laser-assisted focused He+ ion beam induced etching with and without XeF2 gas assist

Focused helium ion (He+) milling has been demonstrated as a high-resolution nanopatterning technique; however, it can be limited by its low sputter yield as well as the introduction of undesired subsurface damage. Here, we introduce pulsed laser- and gas-assisted processes to enhance the material removal rate and patterning fidelity. A pulsed laser-assisted He+ milling process is shown to enable high-resolution milling of titanium while reducing subsurface damage in situ. Gas-assisted focused ion beam induced etching (FIBIE) of Ti is also demonstrated in which the XeF2 precursor provides a chemical assist for enhanced material removal rate. Finally, a pulsed laser-assisted and gas-assisted FIBIE process is shown to increase the etch yield by ∼9× relative to the pure He+ sputtering process. These He+ induced nanopatterning techniques improve material removal rate, in comparison to standard He+ sputtering, while simultaneously decreasing subsurface damage, thus extending the applicability of the He+ probe as a nanopattering tool.

Laser-assisted nanofabrication in the scanning electron microscope

A prototype apparatus was developed to deliver up to ~300 kW/cm2 of cw or pulsed near IR light to a sample inside a scanning electron microscope (SEM) or focused ion beam (FIB) instrument. Transient heating of localized areas around the electron or ion beam can be performed with fine control of power and pulse parameters, down to sub-microsecond durations. In conjunction with a gas injection system, electron beam induced deposition (EBID) of enhanced purity Pt and Au structures was demonstrated. Dynamics of pulsed laser induced solid-state dewetting of Ni and Au were also observed in real time in a SEM/FIB, which may lead to improved understanding and manipulation of self-assembled nanostructures.