DLI-MOCVD 법을 이용한 Pb계 강유전막의 저온 증착

Abstract

In order to apply for three-dimensional capacitors of high-density ferroelectric random access memories (FRAMs), the low temperature direct liquid injection metalorganic chemical vapor deposition (DLI-MOCVD) of Pb-based ferroelectric films has been investigated. The combination of Pb(TMHD)₂/Zr(TMHD)(O-i-Pr)₃/Ti(TMHD)₂(Oi- Pr)₂ was selected for metalorganic precursors and n-butylacetate was also selected for solvent. The lowest temperature to grow Pb-based films using those metalorganic precursors was found to be 360℃ at which Ti(TMHD)₂(O-i-Pr)₂ could be sufficiently decomposed. The film grown at 380℃ exhibited the good step coverage characteristic. However, the small variation in the precursor input flow rate ratios led to the large variation in film compositions, which means that the composition control is difficult at the low temperature. The application of pulsed plasma expanded the process window to obtain the stoichiometric films, thereby making the control of film composition somewhat easier.