Carbonate formation during post-deposition ambient exposure of high-k dielectrics

• Published in: Applied physics letters Vol. 83; no. 17; pp. 3543 - 3545
• Main Authors: Gougousi, Theodosia, Niu, Dong, Ashcraft, Robert W., Parsons, Gregory N.
• Format: Journal Article
• Language: English
• Published: 27-10-2003
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.1623316

When thick films of group-III (La, Y)- and group-IV (Hf, Zr)-based high-k dielectrics are exposed to ambient for several months, Fourier transform infrared spectroscopy shows formation of carbonate species in the film bulk, likely due to reaction with atmospheric CO2. Group-III-based films show signs of carbonate feature growth within 10 min of air exposure, especially in films processed at relatively low temperatures (<600 °C). Carbonate formation is verified also for group-IV-based films, but at a significantly reduced concentration. Post-exposure annealing can reduce the carbonate observed in the IR spectra. However, post-exposure annealing likely does not remove carbon contamination, and it results in interface silicon oxide growth. The observed reactions of high-k films with the ambient may impose significant constraints on the post-deposition handling of high-k films.