Low-Temperature Technique Produces Oxide Films

Most deposition techniques for crystalline oxide films involve subjecting amorphous films to high temperatures. This, however, can limit a film's ability to coalesce with thermally unstable substrates, and it substantially increases manufacturing costs. Researchers from Oregon State University and Hewlett-Packard Co., both in Corvallis, Ore., and ReyTech Corp. in Bend, Ore., have demonstrated a low-temperature method for the deposition and crystallization of oxide films.
The scientists combined a previously devised method for preparing anhydrous, crystalline oxide at temperatures as low as 400 K with a deposition technique called "successive ionic layer adsorption and reaction."

In this process, described in the July 5 issue of Science, they adsorbed the cation constituent of the oxide onto the substrate surface and rinsed it with water, which created an approximate monolayer of coverage. They transferred the substrate to a solution containing the anion, which caused a precipitation reaction at the substrate surface, and rinsed it again.

The team prepared approximately 250-nm-thick films of Zn₂SiO₄, ZrO₂ and MnO₂ by carrying out 700 robot-controlled repetitions of this process for each film.