| Abstract: | We report on atomic layer deposition of bismuth titanium oxide thin films for use in ferroelectric random access memory (FRAM). Bismuth titanium oxide thin films were grown on ruthenium and platinium coated silicon substrates respectively. We used tris(1-methoxy-2-methyl-2-propoxy)bismuth, Bi(mmp)3 and tetrakis(1-methoxy-2-methyl-2-propoxy)titanium, Ti(mmp)4 as metal organic precursors, which were mixed together in organic solvent, ethyl cyclo hexane (ECH), and then put through the vaporizer. The variations of the composition and growth rate with wafer temperature over 350～450 and 250～500C was investigated. The process window for ALD is below 350C and bismuth content in films starts to decrease above 425C. The as-grown films at 300C were amorphous. After post deposition annealing at 700C for 5 minitues we had well-cystallised Bi4Ti3O12 thin films. However, we didn't have well-saturated hysterisis curve, which the remenant polization is 8.9 uC/cm2 at 7 V. The dielectric constant is about 320 and the leakage current is below 10?8 A/cm2 at 0.8 MV/cm. |
