Chemical-Vapor-Deposited Tantalum Pentoxide and Titanium Dioxide Thin Films for High-Density DRAM Storage Capacitor Applications

• Main Authors: Chen, Tsai-Fu, 陳再富
• Other Authors: Shyang Su, Shi-Chung Sun
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/26672904563259867245

博士 === 國立交通大學 === 電子工程學系 === 85 === Two promising high dielectric constant materials for advanced DRAM storage capacitors: tantalum pentoxide (Ta2O5) and titanium dioxide (TiO2), were investigated in this thesis. These thin films were deposited by low pressure chemical vapor deposition (LPCVD). Post-deposition thermal treatments by rapid thermal annealing in N2O and furnace annealing in N2O are the most important contributions in our study. An in-situ sequential CVD deposition of multilayer TiO2/Ta2O5 composite films was proposed to achie both high dielectric constant and low leakage current simultaneously. CVD Ta2O5 films using tantalum pentaethylate(TaO(C2H5)5) source and O2 gas were deposited on phorphous-doped polycrystallinesilicon (n+ poly-Si) substrates and n- bare silicon wafers. Prior to filmdeposition, a rapid thermal nitridation (RTN) process had been taken to maximizethe charge storage efficiency and improve the electrical properties. The growth kinetic is thought to be a surface- reaction limited case due to an observed dependence of the deposition rate on the deposition temperature (350 ~ 580 C). A cross-sectional scanning electron microscopy (SEM) image shows anexcellent step coverage (~ 90 %) for CVD Ta2O5 film. Both the surface topography of as-deposited and annealed Ta2O5 films look rather smooth by AFM investigation. XRD pat