SGER: Shape-Dependent, Selective Self-Assembly for Nanomanufacturing

Massachusetts Institute Of Technology, Cambridge MA

Investigators

Abstract

This project will provide an initial demonstration and characterization of techniques to manufacture complex systems of nanocomponents rapidly, effectively, and inexpensively to meet a wide array of future nanomanufacturing needs. The proposed technique uses geometrically-selective self-assembly from fluid to organize nanoscale components precisely into arbitrary, pre-determined, non-periodic systems. The technology will enable the creation of integrated nanosystems from separately fabricated functional nanocomponents in the 10 nm to greater than 1 mm size range. The substrate is patterned so that its topography at a given location is the exact inverse of the shape of the desired component at that location. Both substrate and components are chemically functionalized with a blanket coating of a hydrophobic self-assembled monolayer (SAM) to promote component-substrate attachment. The components and substrate are immersed in an appropriate fluid; components then contact the substrate randomly and stick. Because component-substrate binding energy scales with contact area, components attach much more strongly in shape-matched holes than on non-shape-matched surfaces. Megasonic excitation selectively dislodges the incorrectly-placed, more weakly-bound components while retaining the correctly placed, more strongly-bound components. Random contact and selective removal occur simultaneously, and the assembled configuration approaches the desired configuration. The benefits of this approach include high positioning precision, simultaneous and selective assembly of diverse nanostructures, and a means of avoiding layer-to-layer alignment steps. The project has three primary goals. First is to characterize assembly yield and defect density vs. assembly time, megasonic excitation strength, hydrophobicity, and quality of particle/hole match using 1 mm-scale particles. Second is to demonstrate repeatable self-assembly into lithographically-defined shape-matched binding sites. Third is to relate the measured assembly yields to differences in binding energy in order to identify limits on selectivity and component size. Creating rapid, effective, widely-applicable nanomanufacturing technologies such as the one described here is important. There is a vast amount of existing research on nanocomponents, but more research on incorporating such nanocomponents into larger systems will be needed to convert them into practical systems and new products. Such systems could range from single electronics to physical, chemical, and biological sensors.