Effect of Purge Time on the Properties of HfO2 Films Prepared by Atomic Layer Deposition

Takaaki KAWAHARA  Kazuyoshi TORII  

IEICE TRANSACTIONS on Electronics   Vol.E87-C    No.1    pp.2-8
Publication Date: 2004/01/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on High-κ Gate Dielectrics)
CMOSFET,  high-κ gate dielectric,  HfO2,  atomic layer deposition,  long purge,  impurity,  gate leakage current,  

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The process mapping of the ALD process of HfO2 using HfCl4 and H2O is reported. A thickness uniformity better than 3% was achieved over a 300 mm-wafer at a deposition rate of 0.52 Å/cycle. Usually, H2O purge period is set less than 10 sec to obtain reasonable throughput; however, the amounts of residual impurities (Cl, H) found to be in the order of sub%, and these impurities are piled up near the HfO2/Si interface. In order to reduce the piled up impurities, we proposed a 2-step deposition in which purge period for initial 10-20 cycles was set to be 90 sec and that for remaining cycles was usual value of 7.5 sec. The leakage current is reduced to 1/10 by using this 2-step deposition.