Self-assembled pick and place methods for heterogeneous integration of micro and nano-scale structures

Heterogeneous integration is the process of bringing together two or more different kinds of materials to form novel structures and devices. A limiting factor in current heterogeneous integration schemes is the pick and place process, by which devices and structures are picked up from their mother substrates and placed on host substrates. In this dissertation, two novel pick and place schemes that rely on self assembly are suggested as a means to overcome limitations in existing pick and place procedures.; The first pick and place scheme utilizes the hydrophobic force as a means of self-assembling liquid droplets with precise spatial and volumetric characteristics. A model is developed to describe the pick and place process, and the model is confirmed experimentally. An application for this process is then selected—that of the assembly of microlenses. It is shown that high-performance polymer microlenses can be fabricated both on stand-alone substrates and integrated in a self-aligned fashion with optical fibers. The microlenses are shown to have f#s as low as 1.45, and excellent surface qualities, deviating from spherical by as little as ±5 nm. It is further shown that arrays of such lenses have uniformities better than Δf/f∼±5.9%, and average f#s reproducible to within 3.5%.; The second pick and place scheme utilizes the hydrogen bond (in the form of DNA molecules) to allow the self-assembled pick and place of solid particles and devices. It is shown that by patterning DNA on substrates and attaching complementary DNA to particles, the particles can be assembled selectively through DNA hybridization. Particles ranging in size from 0.1–0.87 μm in diameter are shown to attach to DNA-coated substrates with excellent selectivity, (20:1) in a repeatable fashion. The number and orientation of DNA molecules involved in these hybridization events are inferred from experiments. Finally, the DNA-assisted pick and place scheme is extended to an active technique in which devices are first attracted by electrophoresis to the locations where they are expected to hybridize. Preliminary experiments with this technique are reported.