Properties of [Mg₂(thd)₄] as a Precursor for Atomic Layer Deposition of MgO Thin Films and Crystal Structures of [Mg₂(thd)₄] and [Mg(thd)₂(EtOH)₂]

Abstract

Complexes [Mg2(thd)4] (1) and [Mg(thd)2(EtOH)2] (2) (Hthd = 2,2,6,6-tetramethyl-3,5-heptanedione) were prepared and characterized using various techniques, viz. X-ray diffraction, NMR and mass spectroscopy, and thermal analysis. Crystal structures of compounds 1 and 2 were determined. Complex 1 crystallizes as a dimer where three oxygen atoms from three different thd ligands join the Mg atoms together. Crystallization from ethanol results in a monomeric complex having solvent coordinated to Mg. Both complexes volatilize completely, but in 2, coordinated ethanol molecules do not stay intact in the gas phase. Complex 1 was used with H2O2 as precursors in the growth of MgO thin films by atomic layer deposition techniques. A rather constant growth rate of 0.10−0.14 Å/cycle was observed at 325−425 °C.