Thin films used in microelectronic and other microsystems are metastable. If heated at sufficiently high temperatures they will agglomerate or dewet to form islands while remaining in the solid state. The temperature at which solid state dewetting occurs decreases as the thickness of a film is decreased and dewetting can occur well below a material’s melting temperature. The dewetting temperature also decreases as other dimensions are decreased, as in the case of the diameters of nanowires. Scaling of feature sizes in microelectronic systems has led to increasing problems with dewetting during circuit fabrication. At the same time, a range of applications have been developed for which structures made through controlled solid-state dewetting are a key component.
Solid state dewetting typically occurs through capillary-driven surface diffusion and is strongly affected by crystalline anisotropy. The results of detailed experimental and modeling studies of dewetting of lithographically patterned single crystal thin films will be discussed. Dewetting studies can guide approaches for optimization of the morphological stability of thin films and nano-structures. It has also been found that patterning of films can provide a means of templating of the solid-state dewetting process to reproducibly form complex structures with sub-lithographic length scales.
Professor Thompson received his S.B. in Materials Science and Engineering from MIT and Ph.D. in Applied Physics from Harvard University. He joined the MIT faculty in 1983. He is the Director of MIT’s Materials Research Laboratory and co-directs the Skoltech Center for Electrochemical Energy Storage. He previously directed the MIT Materials Processing Center, co-chaired the Materials for Micro- and Nano-systems program of the Singapore-MIT Alliance and is a past president and Fellow of the Materials Research Society. Professor Thompson’s research interests include processing of thin films and nanostructures for applications in microelectronic, microelectromechanical and electrochemical systems. Current activities focus on development of thin film batteries for autonomous microsystems, the reliability of IC interconnects and GaN-based electronic devices, and morphological stability of thin films and nano-scale structures.