AVS 51st International Symposium
    Electronic Materials and Processing Monday Sessions
       Session DI-MoA

Paper DI-MoA5
Nitrided Hafnium Silicates for Gate Dielectrics

Monday, November 15, 2004, 3:20 pm, Room 304B

Session: High-k Dielectrics: Electronic Properties
Presenter: C.-G. Wang, ASM America Inc.
Authors: C.-G. Wang, ASM America Inc.
H. Velasco, ASM America Inc.
M. Verghese, ASM America Inc.
E. Shero, ASM America Inc.
G. Wilk, ASM America Inc.
J.W. Maes, ASM International, Belgium
O. Laitinen, ASM International, Belgium
W. Deweerd, IMEC, Belgium
A. Delabie, IMEC, Belgium
R.L. Opila, University of Delaware
A. Mathew, University of Delaware
K. Demirkan, University of Delaware
J. Morais, Universidade Federal do Rio Grande do Sol, Brazil
I.J.R. Baumvol, Universidade Federal do Rio Grande do Sol, Brazil
Correspondent: Click to Email
Nitrided hafnium silicate (HfSiON) gate dielectric films deposited by atomic layer chemical vapor deposition (ALCVD@super TM@) show excellent capacitor and transistor characteristics with both poly-Si and metal gates, which are directly correlated with local physical and chemical properties. A wide range of compositions are demonstrated, with Si/(Hf+Si) percentages from 0 to 75% and uniformly distributed N levels up to 30 at. %. XPS is used to distinguish the local bonding arrangements of N to Hf, Si and O. The distribution and depth profile of these N bonds is directly attributable to the observed electrical and physical properties of these films as measured by TOF-SIMS, TEM, EELS, nuclear reaction analysis and angle-resolved XPS. Using poly-silicon gate electrodes with chemical or thermal oxide underlayers, EOT values down to 1.3 nm with substantial leakage reduction vs. SiO@sub 2@ have been achieved using stacks with ultrathin HfSiON. Hysteresis and midgap interface density (D@sub it@) are less than 10 mV and 5X10@super 10@ cm@super -2@eV@super -1@, respectively. Transistors (gate length of 110nm) with these ALD HfSiON films display excellent V@sub T@ stability and channel electron mobility > 90% of SiO@sub 2@ at high E@sub eff@. Detailed analysis on silicate compositions, the distribution of nitrogen in the interface layers, and corresponding impact on device performance will be presented.