Synthesis of Mg and Zn diolates and their use in metal oxide deposition

The synthesis of complexes [M(OCHMeCH(2)NMeCH(2))(2)] (5, M = Mg; 7, M = Zn) is described. Treatment of MeHNCH(2)CH(2)NMeH (1) with 2-methyloxirane (2) gave diol (HOCHMeCH(2)NMeCH(2))(2) (3), which upon reaction with equimolar amounts of MR(2) (4, M = Mg, R = Bu; 6, M = Zn, R = Et) gave 5 and 7. The thermal behavior and vapor pressure of 5 and 7 were investigated to show whether they are suited as CVD (= chemical vapor deposition) and/or spin-coating precursors for MgO or ZnO layer formation. Thermogravimetric (TG) studies revealed that 5 and 7 decompose between 80–530 °C forming MgO and ZnO as evidenced by PXRD studies. In addition, TG-MS-coupled experiments were carried out with 7 proving that decomposition occurs by M–O, C–O, C–N and C–C bond cleavages, as evidenced from the detection of fragments such as CH(4)N(+), C(2)H(4)N(+), C(2)H(5)N(+), CH(2)O(+), C(2)H(2)O(+) and C(2)H(3)O(+). The vapor pressure of 7 was measured at 10.4 mbar at 160 °C, while 5 is non-volatile. The layers obtained by CVD are dense and conformal with a somewhat granulated surface morphology as evidenced by SEM studies. In addition, spin–coating experiments using 5 and 7 as precursors were applied. The corresponding MO layer thicknesses are between 7–140 nm (CVD) or 80 nm and 65 nm (5, 7; spin-coating). EDX and XPS measurements confirm the formation of MgO and ZnO films, however, containing 12–24 mol% (CVD) or 5–9 mol% (spin-coating) carbon. GIXRD studies verify the crystalline character of the deposited layers obtained by CVD and the spin-coating processes.