STRUCTURE AND CHEMISTRY OF SILICON-NITRIDE AND SILICON CARBONITRIDE THIN-FILMS DEPOSITED FROM ETHYLSILAZANE IN AMMONIA OR HYDROGEN

Amorphous silicon nitride or silicon carbonitride thin films were deposited on (100) silicon substrates by the pyrolysis of ethylsilazane, [CH2CH3SiHNH]n, in ammonia or hydrogen in the temperature range 873-1073 K at 0.1 MPa. Studies by means of Auger electron spectroscopy, Rutherford backscattering spectroscopy, and nuclear reaction analysis indicated the removal of carbon species present in the precursor to yield silicon nitride when the deposition was carried out in ammonia. Carbon-related bonds were, however, partially ruptured in the precursor when hydrogen was used, resulting in the formation of silicon carbonitride. The hydrogen content was determined by elastic recoil detection to decrease from 18 to 10 +/- 1 % in silicon nitride and from 21 to 8 +/- 1 % in silicon carbonitride with increasing deposition temperature. Fourier transform infrared spectroscopy analysis showed only Si-Hn bonds (n = 1, 2, 3) in silicon carbonitride and only N-Hn bonds (n = 1, 2) in silicon nitride. The refractive index increased with the deposition temperature from 1.86 to 2.10 for silicon nitride and from 1.81 to 2.09 for silicon carbonitride. The average deposition rate measured by ellipsometry increased with temperature from 1.9 to 49 nm/min. The apparent activation energies calculated from the slopes of the Arrhenius plot were equal to 19 and 43 kJ/mol in the mass transport regime and to 181 and 197 kJ/mol in the kinetic regime for silicon carbonitride and silicon nitride, respectively.