AVS 52nd International Symposium
    Electronic Materials and Processing Monday Sessions
       Session EM-MoM

Paper EM-MoM6
Physical and Electrical Properties of LaAlO@sub 3@, Potential Candidate for High K Gate Dielectric

Monday, October 31, 2005, 10:00 am, Room 309

Session: Electronic Properties of High-k Dielectrics and their Interfaces
Presenter: M.C. Hugon, Universite Paris Sud, France
Authors: V. Edon, Universite Paris Sud, France
M.C. Hugon, Universite Paris Sud, France
O. Voldoire, Universite Paris Sud, France
B. Agius, Universite Paris Sud, France
I.J.R. Baumvol, Universidade Federal do Rio Grande do Sul, Brazil
L. Miotti, Universidade Federal do Rio Grande do Sul, Brazil
K.P. Bastos, Universidade Federal do Rio Grande do Sul, Brazil
Correspondent: Click to Email
There is currently an extensive research effort to find an alternative gate dielectric to replace SiO@sub 2@ in metal oxide semiconductor field effect transistors (MOSFETs). LaAlO @sub 3@ is a promising material: it has a dielectric constant in the range 20-27. RuO@sub 2@ is proposed as a gate electrode. LaAlO@sub 3@ films were deposited by rf magnetron sputtering of a LaAlO@sub 3@ target in argon atmosphere. Thin film properties are studied as a function of deposition parameters (rf power, process pressure) and thermal annealings (in @super 16@O@sub 2@ or @super 18@O@sub 2@ atmospheres - temperatures from 450 to 1000 °C). Physical properties of as deposited material (composition, density), as determined by RBS, NRA, and X-ray reflectometry, are seen to depend slightly on deposition parameters. The films are stoichiometric and present a density of 5.5 ± 0.5g.cm@super -3@ close to the bulk material one (6.5g.cm@super -3@). The thermal stability of LaAlO@sub 3@ has been investigated under typical conditions of a MOSFET processing. O and Al transport during annealings are investigated with sub-nanometric depth resolution via the narrow resonances of @super 18@O(p,@alpha@)@super 15@N at 151 keV (fwhm=100eV) and @super 27@Al(p,@gamma@)@super 28@Si at 404.9keV (fwhm=40eV) respectively. The interfacial characteristics of LaAlO@sub 3@/Si were measured by spectroscopic ellipsometry, X ray reflectometry. The initial measurements subject the presence of an interfacial layer. We have performed high frequency (1MHz, 100kHz) C-V and I-V characteristics on RuO@sub 2@/LaAlO@sub 3@/Si MIS structure. After a thermal treatment at 600°C, the C-V curves exhibit well defined accumulation, depletion and inversion regimes which indicate a low interface state density. With the device biased in accumulation regime, a permittivity of 15 was deduced. Low leakage current is detected for films deposited at 0.5Pa or 5Pa and annealed at 600°C under 1 atm of oxygen.