We report the direct etching of Al2O3 and SiO2 using 900-keV Au+ ions. 2000-mesh Cu grids were employed as masks using two different configurations: (1) the Cu mesh was placed on top of each insulator separately and independent irradiations were performed, and (2) the Al2O3 and SiO2 substrates were positioned in an edge-to-edge configuration with a single Cu grid providing a common mask to both insulators. Scanning electron microscopy (SEM) analysis revealed quite different patterns resulting from the two irradiation configurations. While the irradiation using individual masks resulted in mirror-image patterns of the Cu mask in the substrates, the use of a common mask led to single line structures approximately normal to the edges of the substrates. The role of charge buildup and sputtering in relation to relative dielectric properties of the substrates and close proximity of the samples during irradiation is discussed.
High Energy Focused Ion Beam (HEFIB) direct writing is proving to be an attractive and powerful maskless lithography technique for production of high aspect ratio 3-D microstructures in polymer resists and semiconductors. HEFIB with Proton beam (P-beam writing) offers several unique advantages for microfabrication applications: (a) the focused beam is scanned directly across the sample (no mask), (b) the range of the beam in the sample is well defined with minimal lateral straggling than any other techniques, (c) use of different energies allows different exposure depths, (d) complex shapes are possible and (e) patterns can be made within short exposure time. These characteristics allow P-beam writing to be applied in several areas of microfabrication including (a) rapid (and cheaper) prototyping of 3-D microstructures, (b) custom built structures for basic research, (c) mask production and (d) stamp and mold manufacturing. Recently we have implemented high energy P-beam direct writing with a nuclear microprobe at the Louisiana Accelerator Center (LAC). We are presenting some of the modular structures illustrating the capabilities of this maskless micromachining technique and possible application into Micro-Electro-Mechanical Systems (MEMS) devices.
In processes of obtaining a new NLO materials, modifying and enhancing the existing materials, various aromatic compounds were synthesized with the intent of comparing their nonlinear optical properties. Different techniques were used to characterize the proton-irradiated N-isobutyl-4-methyl-6- nitro-2-quinolinamine sample. From the electron paramagnetic resonance measurements; the spin concentration seemed to increase significantly when the proton beam increased from 0 to 2.2 Mev and then the spin concentration starts decreasing up to 3 Mev. The EPR signal for N-isobutyl was singlet up to 1.8 Mev then split into duplet around 2 Mev. Then EPR signal for N-isobutyl was singlet up to 1.8 Mev-irradiated-sample. FTIR analysis also shows a dramatic increase in transmission in different bands of the spectra. Due to higher energy proton irradiation, a high significant improvement in the nonlinear characteristics of the sample was observed. A theoretical interpretation for the effect of the proton irradiation enhancement of the nonlinearity of these will be presented as well.