Stability Study of a Magnesium beta-Diketonate As Precursor for Chemical Vapor Deposition of MgO

On the basis of the study of the thermal behavior of [Mg(tmhd)(2)(TMEDA)] (1; tmhd = 2,2,6,6-tetramethyl-3,5-heptanedionate; TMEDA = N,N,N',N'-tetramethylethylenediamine), a novel procedure for magnesium oxide thin film growth has been developed for chemical vapor deposition (CVD) applications. Complementary studies (thermogravimetric measurements and IR and NMR spectroscopy) enabled revelation of the dissociation of TMEDA from 1, confirmed by the detection of both free TMEDA in the vapor phase and less volatile [Mg-2(tmhd)(4)] (2) as a residue after sublimation. The effect of this dissociation is an unwanted changeable sublimation rate of the precursor 1 during the CVD process. The endeavor of a constant deposition rate by simultaneously exploiting the good volatility of 1 was achieved through its synthesis in situ by using 2 with a diamine enriched carrier. Laser reflectance interferometry (LRI) measurements testified that such a method ensured a good and constant deposition rate throughout the growth experiment, independently of the adopted processing conditions. In addition, X-ray diffraction (XRD) measurements revealed the obtainment of textured and polycrystalline MgO coatings on sapphire and on Si(100). The system chemical composition was investigated by X-ray photoelectron spectroscopy (XPS).