Self-Assembly and Self-Tiling of Miniaturized Semiconductor Dies Across Length Scales and 3D Topologies

This thesis presents work focusing on the development of novel methods for enabling the heterogeneous integration of increasingly small inorganic components over wide areas on flexible, curved, and inexpensive substrates by fluidic self-assembly. These processes are potential building blocks for facilitating the future development of printable and macroelectronics, including distributed sensors, displays, solar cells, and flexible logic and memory units. We demonstrate a new approach to assembling sub-100 µm semiconductor components by combining solder-based surface tension-driven self-assembly with a liquid-liquid component confinement technique that resembles a Langmuir-Blodgett film, a common nanotechnology tool. The assembly is driven by a stepwise reduction of interfacial free energy where chips are first collected and pre-oriented at an oil-water interface before they assemble on a solder-patterned substrate that is pulled through the interface. Patterned transfer of components as small as 3 µm occurs in a progressing linear front as the liquid layers recede. By increasing the size of the receptor domains and allowing components to close-pack on them, we have also developed a process we refer to as "self-tiling." This process greatly increases the area coverage of assembly on a given substrate. We have demonstrated such self-tiling on planar and curved surfaces over increasingly large domains. Additionally, we have applied these technologies to the fabrication of a number of fault-tolerant monocrystalline silicon solar cells, including a microconcentrator solar module. We expect that this work will be extended to include roll-to-roll processing in order to enable the wide-area assembly/printing of very small active components.