GROWTH AND CHARACTERIZATION OF THIN SIN FILMS GROWN ON SI BY ELECTRON-CYCLOTRON-RESONANCE NITROGEN PLASMA TREATMENT

Thin silicon nitride films have been fabricated on Si at a low substrate temperature (about 450-degrees-C) by means of the direct exposure of Si wafers to an electron cyclotron resonance nitrogen plasma generated at 2.45 GHz. The film thickness can be controlled in the range 40-400 angstrom by suitably changing the nitrogen pressure, microwave power and substrate bias voltage. The activation energy characteristic of the growth is 0.42 +/- 0.11 eV. The refractive indices of the films are 1.9-2.0 and the N-to-Si atomic ratio obtained by Rutherford backscattering spectrometry ranged from 1.35 to 1.43, indicating a nitrogen-rich film (stoichiometric value of 1.33). The average breakdown voltage of Al-SiN-Si capacitors is 11.9 +/- 0.2 MV cm-1 and a typical leakage current density is about 10(-9) A cm-2 at a 2 V positive bias stressing for films 16 nm thick. Ion channelling experiments show that silicon nitride films form sharper interfaces (about 5 angstrom) on the Si substrate than chemically vapour-deposited nitrides do, Optical emission spectra measured during the film growth indicate that the nitrogen molecular ions are closely related to the growth rate and film quality.