New pulsed laser deposition technique speeds search for high-tech thin films. (General Developments).

A new rapid prototyping technique developed by two NIST scientists could speed up the search for thin films with properties optimized for next-generation memory devices and wireless communications circuits. The novel method--called dual-beam, dual-target, pulsed-laser deposition--can be used to create libraries of inorganic thin films that vary, predictably, in thickness and chemical composition. Mass producing samples of films composed of two or more compounds opens the way to high-throughput screening that can narrow the hunt for new materials.

NIST scientists demonstrated their new technique by creating libraries of barium strontium titanate (BST) films, a candidate to replace silicon-dioxide insulators in future dynamic random access memories. The technique splits a laser beam so that the high-energy light strikes two sets of starting materials simultaneously. Both target materials vaporize, creating gas plumes that mix before depositing and crystallizing on a silicon wafer nearby. By adjusting the laser's energy and the spacing between the targets, the researchers can control both the composition and thickness of the film deposited on the substrate. For example, the researchers created samples with narrow bands of uniform thickness, while the relative amounts of barium, strontium, and titanium varied systematically across each band.

Data gathered automatically after the process are used to map film thickness. Using a model that they developed, the scientists then can estimate the chemical composition at hundreds of points in a sample, eliminating a time-consuming chore. They now are extending the technique to other combinations of inorganic materials.

CONTACT: Peter Schenck, [phone]; [e-mail].