Ve. Vamvakas et al., THERMODYNAMIC STUDY, COMPOSITIONAL AND ELECTRICAL CHARACTERIZATION OFLPCVD SIO2-FILMS GROWN FROM TEOS N2O MIXTURES/, Microelectronics and reliability, 38(2), 1998, pp. 265-269
The theoretical phase diagram describing the growth of SiO2 films from
TEOS and N2O mixtures within the temperature range 500-1100 degrees C
and pressure 0.3 Torr has been obtained, minimizing the total Gibbs e
nergy of the chemical system involved in the deposition. It was found
that at temperatures up to 900 degrees C and N2O/TEOS molar ratios up
to approximately 7, the SiO2 films deposited contained carbon impuriti
es. For higher N2O/TEOS molar ratios the obtained films are carbon fre
e. SiO2 films were grown from TEOS/N2O mixtures in a conventional hori
zontal low pressure chemical vapor deposition reactor at temperatures
of 710 degrees C and 820 degrees C and at a pressure of 0.3 Torr. Thes
e films were analyzed using X-ray photoelectron spectroscopy, Rutherfo
rd backscattering spectroscopy, atomic force microscopy and C-V measur
ements taken on metal-insulator-semiconductor structures formed with t
he deposited films as insulators. It was found that the films contain
carbon impurities the concentration of which decreases with the increa
se of N2O/TEOS molar ratio, in agreement with the results of the therm
odynamic study. Carbon atoms were 90% bonded to other carbon atoms and
only 10% to oxygen. It was found that the films are substoichiometric
in oxygen with O/Si atomic ratios ranging between 1.95 and 1.80. The
films were found to be positively charged, the charge increasing with
N2O flow and decreasing with deposition temperature. (C) 1998 Elsevier
Science Ltd.