Focused ion beam techniques for fabricating geometrically-complex components and devices.

Abstract

We have researched several new focused ion beam (FIB) micro-fabrication techniques that offer control of feature shape and the ability to accurately define features onto nonplanar substrates. These FIB-based processes are considered useful for prototyping, reverse engineering, and small-lot manufacturing.Ion beam-based techniques have been developed for defining features in miniature, nonplanar substrates. We demonstrate helices in cylindrical substrates having diameters from 100 µm to 3 mm. Ion beam lathe processes sputter-define 10-µm wide features in cylindrical substrates and tubes. For larger substrates, we combine focused ion beam milling with ultra-precision lathe turning techniques to accurately define 25-100 µm features over many meters of path length. In several cases, we combine the feature defining capability of focused ion beam bombardment with additive techniques such as evaporation, sputter deposition and electroplating in order to build geometrically-complex, functionally-simple devices. Damascene methods that fabricate bound, metal microcoils have been developed for cylindrical substrates.Effects of focused ion milling on surface morphology are also highlighted in a study of ion-milled diamond.

Fundamentals of Focused Ion Beam Nanostructural Processing: Below, At, and Above the Surface

“…1,2 Experimentally, surface topographies spontaneously develop when targets are eroded by either broad static ion beams or a uniformly rastered FIB. [28][29][30][31][32][33][34][35][36][37][38][39][40] Although roughness is a bane during erosion of sputter targets used in physical vapor deposition, nanometer-scale structures such as ripples (Figure 3a), steps ( Figure 3b and 3c), and dots (Figure 3d) inspire efforts to understand and manipulate surface instabilities. Judicious FIB control has the potential to fabricate functional arrays of quantum dots.…”

“…Diamonds also provide beautiful ripples, 36,40,50,53,58,59 with the optimization of FIB processing of micromachining toolbits 53 providing an ideal study of the interaction of angle, yields, chemistry, and ripples. By increasing the angle of ion incidence, Adams 53 and Datta 36 observe three classic regimes: smooth, 1D ripples, and steps ( Figure 3b).…”

“…Most often amplitudes saturate at a small fraction of wavelength. 33,43,40,57 However, modulations with high aspect ratio 39,49,50 offer intriguing possibilities, such as for high-surface-area catalysts. Many models and experiments indicate the wavelength saturates as a function of fluence, which is of practical utility to reliable future FIB processes.…”