Atomic Layer Deposition of Al₂O₃ Thin Films from a 1-Methoxy-2-methyl-2-propoxide Complex of Aluminum and Water

Al 2 O 3 thin films were grown by atomic layer deposition (ALD) using the novel volatile complex Al(mmp) 3 (mmp = 1-methoxy-2-methyl-2-propoxide, OCMe 2 CH 2 OMe) and water vapor in the temperature range of 200−450 °C on p-type Si or Ru/SiO 2 /Si substrates. Al 2 O 3 films were formed at 250 °C through the typical self-limiting mechanism of ALD, wherein the saturated growth rate was about 0.6 Å/cycle. The resultant films were amorphous, and the refractive index of the films varied between 1.53 and 1.62, which was dependent on the growth temperature and water pulse length. The aluminum-to-oxygen ratio of the Al 2 O 3 film grown at 250 °C was 2:3.1, and the carbon content was 2.4%. With capacitance−voltage measurements of Al/Al 2 O 3 /SiO 2 /Si structures, the dielectric constant of Al 2 O 3 grown at 250 °C is evaluated to be 7.7, and the flat band voltage appears at 1.05 V, which corresponds to a negative fixed charge on the order of 10 11 /cm 2 . The leakage current density of the Al 2 O 3 films is on the order of 10 - 7 A/cm 2 at 1 MV/cm, and the dielectric breakdown voltage is about 6.5 MV/cm.