The Development of Novel-Single Source Precursors for the Growth of Zinc Oxide Thin Films via Atmospheric Pressure Metal Organic Chemical Vapor Deposition (AP-MOCVD) For Applications in Microelectronic Devices

A series of free ligands were synthesized by reacting the appropriate primary amine or primary alkoxy amine with β-ketoimines, β-ketoamides or β-ketoesters. The isolated product was characterized using GC/MS, FT-IR, 1H-NMR and 13C-NMR. Each free ligand was reacted with diethylzinc under an inert atmosphere in a 2:1 mole ratio to afford the Zn complexes. These complexes were isolated via recrystallization from hexane as either white or light yellow solids or a viscous yellow oil. Compounds 10, 21 and 23 afforded single crystals that were suitable for X-ray analysis. The molecular structure of these compounds revealed monomeric compounds with distorted tetrahedral metal center. The volatility and thermal stability of the complexes were assessed using thermogravimetric analysis (TGA). The bis (enaminoamidate) and the bis (enaminoalkoxyesterate) zinc precursors were not thermally stable and as a result they were not utilized to grown ZnO thin films. The bis (ketoiminato) zinc complexes however, possessed favorable properties for MOCVD and were successfully employed in the growth of ZnO films on Si wafer at temperatures between 350°C-700°C. The morphology of the thin films was investigated using scanning electron microscope (SEM) and atomic force microscope (AFM) and the elemental composition was obtained using x-ray photoelectron spectroscopy (XPS). The % carbon content of the ZnO thin films depends on the substrate temperature and the precursor structure. We successfully fabricated metal oxide semiconductor field effect transistors (MOSFET) from ZnO thin films that were deposited below 500°C.