Self-assembly from milli- to nanoscales: methods and applications

Abstract

The design and fabrication techniques for microelectromechanical systems (MEMS) and nanodevices are progressing rapidly. However, due to material and process flow incompatibilities in the fabrication of sensors, actuators and electronic circuitry, a final packaging step is often necessary to integrate all components of a heterogeneous microsystem on a common substrate. Robotic pick-and-place, although accurate and reliable at larger scales, is a serial process that downscales unfavorably due to stiction problems, fragility and sheer number of components. Self-assembly, on the other hand, is parallel and can be used for device sizes ranging from millimeters to nanometers. In this review, the state-of-the-art in methods and applications for self-assembly is reviewed. Methods for assembling three-dimensional (3D) MEMS structures out of two-dimensional (2D) ones are described. The use of capillary forces for folding 2D plates into 3D structures, as well as assembling parts onto a common substrate or aggregating parts to each other into 2D or 3D structures, is discussed. Shape matching and guided assembly by magnetic forces and electric fields are also reviewed. Finally, colloidal self-assembly and DNA-based self-assembly, mainly used at the nanoscale, are surveyed, and aspects of theoretical modeling of stochastic assembly processes are discussed.

Spectral analysis and experimental study of lateral capillary dynamics for flip-chip applications

“…Dry self-assembly (Park and Bohringer 2008), hydrophillic-hydrophobic interactions (Onoe et al 2007) are being employed. Mastrangeli et al (2009a) reviews shape matching, magnetic, electrophoretic, dielectrophoretic, and capillary mechanisms, the latter one falling into two categories. The first category is the fluid-driven capillary self-assembly, which has the advantage of accurate self-alignment, and the second category is the molten solder-driven self-assembly, which allows mechanical and electrical connections simultaneously.…”

High aspect ratio TSVs fabricated by magnetic self-assembly of gold-coated nickel wires

“…Magnetic fields can have high energy densities and can influence feature sizes from macro-to nano-scale. These advantageous characteristics are very attractive and have been reported in various assembly approaches [24]. A proof-of-concept of selfassembled pure nickel-TSVs has been shown by the authors earlier [17].…”

Anisotropic surface properties of micro/nanostructured a-C:H:F thin films with self-assembly applications

“…The most widely studied and used colloidal particles are silica beads and polymer latexes. 13 In the past decades, the formation of highly ordered structures of colloidal particles with sufficiently large domain sizes has attracted a wide research interest, also given the ample range of possible applications for this novel class of materials. 14 Several selforganizing techniques have been devised to assemble highquality arrays of monodispersed colloids.…”

“…15 colloids of highly uniform size and shape (monodisperse) is very important for the self-assembly of crystalline arrays in large areas, since uniformity and order affect the electronic, optical, magnetic, and electrokinetic properties of the resulting aggregates. 13 Arrangement and adhesion of these silica particles will depend on the chemical state of the surface and its topography. In this first work, nanoparticles would be like "inert cells" in order to test a-C:H:F surface properties.…”