Atomic layer deposition of molybdenum oxide using (NtBu)2(NMe2)2Mo, hydrogen peroxide (H2O2), and ozone (O3) for DRAM application

Abstract

Molybdenum oxide (MoOx) films have the unique characteristics of a number of possible structures and high work functions. In DRAM using high-k dielectrics, MoOx can be used to reduce leakage current that originates from Schottky emission. High quality MoOx can be deposited using atomic layer deposition (ALD) that is advantageous in terms of the resulting film's high uniformity, high conformality, and precise thickness controllability. In this work, MoOx films were deposited using bis(tert-butylimido)-bis(dimethylamido)molybdenum ((NtBu)2(NMe2)2Mo) as a metal precursor, and hydrogen peroxide (H2O2) and ozone (O3) as oxidants. The MoOx films were deposited between 100 and 300 °C growth temperature. MoOx deposited at 200 °C using H2O2 and O3 shows different GPC values of 0.08 and 0.20 Å/cycle, respectively, due to the different reactivities of the oxidants. The O/Mo ratio, atomic concentration of impurities, crystallinity, optical properties, work function, and sheet resistance of TiN altered by MoOx fabricated using H2O2 and O3 were investigated. The reactivity of O3 is higher than that of H2O2, which increases the sheet resistance of TiN by 23.1%. Finally, a cross section of MoOx deposited with H2O2 on a trench wafer was investigated to demonstrate conformal deposition onto a complex structure.