Technology Advances
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TECHNOLOGY ADVANCES
Rapid Deposition Technique Developed for High-Quality Metal Oxide Films A method called laser-assisted molecularbeam deposition (LAMBD) has been developed by the AMBP Tech Corporation, in Amherst, N.Y. LAMBD creates uniform, high-purity thin films whose film growth can be controlled, with thicknesses ranging from a monolayer to several micrometers thick. These coatings all possess exceptionally flat, conformal morphologies. LAMBD is a high-temperature reactive process that simplifies the production of complex films such as metal oxide nitrides, carbides, and alloys. Metal oxides such as CeO2 or HfO2 are employed in the microelectronics industry for silicon-on-insulator (SOI) devices and also used to create buffer layers for superconducting tapes. LAMBD has advantages over other fabrication methods such as chemical vapor deposition (CVD), physical vapor deposition (PVD), and molecular-beam epitaxy (MBE). CVD offers high deposition rates, but often requires costly precursors and high temperatures and produces undesirable byproducts. PVD and MBE, although relatively simple in principle, have deposition rates typically lower than CVD, and comparable film qualities cannot be achieved. In addition, many materials, such as oxides or insulators, cannot be efficiently deposited using conventional PVD and MBE techniques. In contrast, the LAMBD process can generate a wide variety of metal oxides with rapid deposition rates and the ability to directly control the growth of the film. As in pulsed laser deposition, the LAMBD source uses an excimer laser to rapidly heat a pure metal target rod, generating a cloud of evaporated target material. However, PLD simply transfers an existing target material to a substrate. The LAMBD technique uses the laser pulse to chemically react a metal with oxygen gas
Technology Advances provides upto-date reports of materials developments that show potential to bridge the gap between research innovation and application of advanced materials technologies. If you encounter or are involved with materials research that shows potential for commercialization and would like to present these developments, contact Renée G. Ford, PDS Communications, Inc., tel. 914-967-0955; fax 914-967-7927; or e-mail [email protected].
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1 µm 20,000 × Figure 1. Edge view of a 1-µm thick hafnium oxide (HfO2 ) film on silicon deposited by laserassisted molecular-beam deposition (LAMBD).
to generate the metal oxide molecules. The resulting plasma of ablated metal atoms reaches temperatures as high as 15,000°C. A pulse of reagent gas, such as oxygen or nitrogen, is then injected into this cloud of vaporized material. The ablated metal target material and the gas pulse form a high-temperature chemical reactor. The reactions within this plasma occur with 100% efficiency, creating a stoichiometric product. For example, a titanium or gallium target rod can be used along with nitrogen gas to create titanium nitride or gallium nitride films; a Ce or Hf rod can be used with oxygen to generate cerium ox
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