In this manner, Watkins and his colleagues have coated surfaces with an array of metals, including platinum, palladium, rhodium, and nickel. At the AIChE meeting, Jason M. Blackburn, a graduate student in Watkins' group, reported on depositing nickel and platinum films on silicon substrates that uniformly coat features 100 nm wide by 1 m deep. As for industrial feasibility, the cost of maintaining a vacuum environment for the vapor may balance the cost of pressurization needed in the supercritical fluid technique. In some processes, selected portions of the coating are exposed to ultraviolet light, and the light-sensitive compound, known as a photoacid generator, produces an acid that reacts with the polymer, rendering it insoluble. The remaining, unexposed portion of the coating can be washed away.
Centrifugal force spreads the material out into a thin, even layer.
Hoggan reported the development of the group's unique process at the AIChE meeting. After the creation of the film, the next steps can be performed with supercritical CO 2 . Industrial use of liquid CO 2 to spin-coat films is still a few years away, Hoggan noted, in part because researchers still need to improve film quality. Supercritical CO 2 may offer itself as a tool for controlling the processing and behavior of nanocrystals. These metal particles, usually between 20 and 100 in diameter, have electronic and optical properties that are different from bulk materials and have numerous potential applications in areas such as microelectronics or biological tagging.