Studies of metallic thin film growth in an atomic layer epitaxy reactor using M(acac)(2) (M = Ni, Cu, Pt) precursors

Feasibility of metallic thin film growth by atomic layer epitaxy (ALE) was studied in the case of divalent metal beta-diketonate-type precursor M(acac )(2) (M = Ni, Cu and Pt) at 250 degrees C and 1 mbar. Metallic films were o btained by two different approaches: (i) direct layer-by-layer reduction of the adsorbed precursor by H-2, and (ii) by first depositing a metal oxide thin film by ALE and then converting it to the metallic form by a separate reduction step. The latter case was demonstrated by converting a NiO thin f ilm, deposited at 250 degrees C on glass substrate with O-3 as an oxygen so urce, to metallic Ni at 260 degrees C and 1 atm by 5% H-2. AFM study indica ted, however, pinhole formation and, thus, deformation of the initial dense structure of NiO. In the case of direct layer-by-layer reduction by H-2, a ttention was focused on the effects of the substrate on the film growth by applying Ti, Al, Si(100) and glass substrates. X-ray photoelectron spectros copy (XPS) and X-ray diffraction (XRD) studies indicated that metallic Ni, Cu and Pt film growth proceeded preferably on Ti and Al substrates. On Si s ubstrate, the film growth was restricted by interdiffusion and silicide for mation; whereas on the glass substrate, the dim growth was related to the g as phase stability of the precursors and proceeded mainly by pyrolysis. (C) 2000 Elsevier Science B.V. All rights reserved.