Growth of bismuth oxide films by direct liquid injection-metal organic chemical vapor deposition with Bi(tmhd) 3 (tmhd: 2,2,6,6-tetramethyl-3,5-heptanedione)

Abstract

Bismuth oxide films were deposited at 225–425 °C by direct liquid injection (DLI)-metal organic chemical vapor deposition (MOCVD) process with Bi(tmhd) 3 (tmhd : 2,2,6,6-tetramethyl-3,5-heptanedione) dissolved in n-butylacetate. The deposition rate of Bi 2O 3 film was determined by surface reaction with the apparent activation energy of 15 kcal/mol. The growth rate was decrease above 325 °C because of the gas phase dissociation of the precursor. The Bi 2O 3 film deposited at 300 °C was amorphous, while the film annealed at temperatures above 550 °C showed monoclinic α-phase. The grain size and surface roughness of the annealed film were increased with the increase of the annealing temperature up to 650 °C. At 750 °C, the monoclinic α-Bi 2O 3 film was changed into the cubic bismuth silicate due to the reaction with Si substrate. The dielectric constant of Bi 2O 3 films deposited at 300 °C was about 32 and the film showed a leakage current of 3.15×10 −7 A/cm 2 at 3 V (0.33 MV/cm). The thickness of Bi oxide Bi silicate films used in the C– V and I– V measurement was 92 and 140 nm, respectively.