Microstructural Evolution of Metal-Insulator-Metal Capacitor Prepared by Atomic-Layer-Deposition System at Elevated Temperature

The rougher surface and raised-hollow holes were observed in the TiN/Al2O3/HfO2/Al2O3/TiN/SiO2/Si multi-stack metalinsulator-metal (MIM) capacitor sample after 1000 degrees C, 60s rapid thermal annealing (RTA) process in N-2. The surface became rougher partially resulted from the nucleation of TiN layer after RTA. Experimental results also indicated that the oxygen content in the HfO2 was desorbed and the remaining Hf was crystallized. Also, the TiN and Al2O3 layers were intermixed and partially re-crystallized at this high temperature. Very clear morie fringes could be observed in the high-resolution transmission electron microscopy (HR-TEM) micrographs. Also, the energy dispersive spectroscopy (EDS) results indicated that the nitrogen in TiN was desorbed and the TiN was phase transformed to TiO2. This phenomenon might result from the TiN oxidation process during the high-temperature thermal annealing.