Atomic layer deposition of SiO2 at room temperature using NH3-catalyzed sequential surface reactions

Ultrathin SiO2 films were deposited at 300-338 K with atomic layer control using NH3-catalyzed sequential surface reactions. The SiO2 deposition was a chieved by splitting the reaction SiCl4 + 2H(2)O-->SiO2+4HCl into two separ ate SiCl4 and H2O half-reactions. Successive application of the half-reacti ons in an ABAB... sequence produced atomic layer controlled SiO2 growth. Th e NH3 catalyst dramatically lowered the necessary deposition temperature fr om > 600 to 300 K and reduced the required reactant fluxes from similar to 10(9) to similar to 10(5) L. In situ spectroscopic ellipsometry monitored t he SiO2 deposition versus reaction temperature and SiCl4, H2O and NH3 parti al pressures. The ellipsometric measurements obtained a maximum SiO2 growth rate of 2.16 Angstrom per AB reaction cycle at 303 K. Atomic force microsc opy images of the deposited surface topography indicated smooth SiO2 films with a roughness similar to the starting Si(100) substrate. Catalysis of th e sequential surface reactions that yield atomic layer controlled growth ma y be general and could facilitate the low temperature deposition of other b inary materials. (C) 2000 Elsevier Science B.V. All rights reserved.