Atomic layer deposition- and chemical vapor deposition-TiN top electrode optimization for the reliability of Ta2O5 and Al2O3 metal insulator silicon capacitor for 0.13 mu m technology and beyond

TiCl4-based atomic layer deposition (ALD)- and chemical vapor deposition (C VD)-TiN films are applied as the metal top electrode for Ta2O5 and Al2O3 me tal insulator silicon (MIS) capacitor. The effects of factors such as CI co ntent, step coverage, deposition temperature of the TiN top electrode proce sses and pre-NH3 flushing on the electrical properties and reliability of t he Ta2O5 and Al2O3 MIS capacitor are studied. Among these factors, poor ste p coverage shows distinctly degraded electrical properties of MIS capacitor , and high deposition temperature of TiN processes also degraded electrical properties, particularly those of Ta2O5. Although similar capacitance and leakage characteristics are measured with high chlorine content and pre-NH3 flushing, TiN processes, a difference in the orders of magnitude is observ ed in time dependent dielectric breakdown (TDDB) measurements. Regarding th e deposition temperature and pre-NH3 flushing effect, the electrical and TD DB characteristics of Ta2O5 degrade even more severely than those of Al2O3. Degradation of TDDB in TiN films with NH3 flushing prior to deposition is attributed to the reduction effect of the dielectric material by NH3 gas. B ased on the X-ray photoelectron spectroscopy (XPS) analysis results, Al2O3 is chemically more inert than Ta2O5. In addition, the degradation of TDDB c haracteristics is directly correlated to the early generation of V-p-depend ent solid "0" fail bit counts. Due to the relatively low deposition tempera ture as well as to the excellent step coverage and low resistivity, the ALD -TiN process is ideal for enhancing the reliability of a MIS capacitor.