Chemically Conformal ALD of SrTiO[sub 3] Thin Films Using Conventional Metallorganic Precursors

Abstract

(STO) thin films were grown on Si wafer, Pt- and Ru-coated Si wafers, respectively, by an atomic layer deposition (ALD) technique using conventional metallorganic precursors, and (TTIP) as Sr- and Ti-precursors, respectively, with a remote-plasma activated vapor as the oxidant at a wafer temperature of 250°C. Patterned Si wafers with contact holes having a diameter of 0.13 and 1 μm depth (aspect ratio of 8) was used in order to test the film-thickness and cation-composition conformalities over the contact hole surface. The ALD behavior of the STO film was critically dependent on the source heating temperature. When the Sr source temperature was [ melting temperature] stoichiometric STO films were deposited with a good process reliability. Excellent film thickness and cation composition conformalities (nonuniformity ) over the severe contact hole structure were obtained by the optimized precursor supply and deposition conditions. It was also observed that most of the input TTIP precursor molecules did not chemically adsorb on the SrO surface, possibly due to oversaturation of the SrO surface by the molecules or thermally modified molecules as a result of the heating process of the when the Sr-source temperature was . This difficulty resulted in a nonuniform cation composition ratio along the contact hole.