Pulsed Laser-Assisted Focused Electron-Beam-Induced Etching of Titanium with XeF₂: Enhanced Reaction Rate and Precursor Transport

Abstract

In order to enhance the etch rate of electron-beam-induced etching, we introduce a laser-assisted focused electron-beam-induced etching (LA-FEBIE) process which is a versatile, direct write nanofabrication method that allows nanoscale patterning and editing. The results demonstrate that the titanium electron stimulated etch rate via the XeF2 precursor can be enhanced up to a factor of 6 times with an intermittent pulsed laser assist. The evolution of the etching process is correlated to in situ stage current measurements and scanning electron micrographs as a function of time. The increased etch rate is attributed to photothermally enhanced Ti-F reaction and TiF4 desorption and in some regimes enhanced XeF2 surface diffusion to the reaction zone.

Laser-Assisted Focused He+ Ion Beam Induced Etching with and without XeF2 Gas Assist

“…Figure b is an Arrhenius plot of the natural log of the etch yield versus the inverse of the simulated temperature achieved by 100 ns laser pulses during the LA-FIBIE processes with varying laser irradiance (as shown in Figure a). From the slope of the Arrhenius plot, the effective activation energy of the etch process is ∼49 meV for a pulsed process with 0.5% duty cycle, which is in good agreement with laser-assisted electron beam induced etching enhancements . As the laser irradiance, and hence photothermal energy, increases, etch yield is enhanced.…”

“…Ti was chosen as the model material system in this work as it is a standard refractory metal. Furthermore, XeF 2 electron beam induced etching and laser-assisted electron beam induced etching have recently been explored . First, we demonstrate that, by synchronizing pulsed laser irradiation with a standard He + milling process, subsurface He + swelling is significantly reduced and milling quality/fidelity is enhanced.…”

In Situ Mitigation of Subsurface and Peripheral Focused Ion Beam Damage via Simultaneous Pulsed Laser Heating

“…It is believed that not only will the subsurface damage be mitigated, but deposited material purity will be enhanced as we have demonstrated in laser-assisted focused electron beam induced deposition. [26][27][28][29] Furthermore, it is expected that laserassisted and gas-assisted etching, in a similar fashion as laser-assisted focused electron beam induced etching [ 30 ] can realize higher etching rates.…”

Pulsed Laser-Assisted Helium Ion Nanomachining of Monolayer Graphene—Direct-Write Kirigami Patterns

“…Complementary STEM images of a pattern are shown in Figure 6. Although lattice imaging was attempted in order to reveal any peripheral graphene damage, as has been observed in other two-dimensional materials [26,30,31], the residual carbon around the deposits made it impossible to directly image the lattice at an atomic resolution. Images for a corner cut are shown in Figure 6a,b and images for a vertical cut are shown in Figure 6c,d.…”

“…We have explored laser-assisted focused ion and electron beam induced processing using a synchronized pulsed laser to enhance the purity of deposits [25,26,27,28], mitigate subsurface ion beam damage [29], and enhance chemically assisted etching [30,31]. In this study, a systematic study of laser-assisted He + milling of monolayer graphene is demonstrated.…”