Optical and electrical characterization methods of plasma-induced damage in silicon nitride films

Research paper by Tomohiro Kuyama, Koji Eriguchi

Indexed on: 01 Jun '18Published on: 28 May '18Published in: Japanese journal of applied physics (2008)


We proposed evaluation methods of plasma-induced damage (PID) in silicon nitride (SiN) films. The formation of an oxide layer by air exposure was identified for damaged SiN films by X-ray photoelectron spectroscopy (XPS). Bruggeman’s effective medium approximation was employed for an optical model consisting of damaged and undamaged layers, which is applicable to an in-line monitoring by spectroscopic ellipsometry (SE). The optical thickness of the damaged layer — an oxidized layer — extended after plasma exposure, which was consistent with the results obtained by a diluted hydrofluoric acid (DHF) wet etching. The change in the conduction band edge of the damaged SiN films was presumed from two electrical techniques, i.e., current–voltage ( I–V ) measurement and time-dependent dielectric breakdown (TDDB) test with a constant voltage stress. The proposed techniques can be used for assigning the plasma-induced structural change in an SiN film widely used as an etch-protecting...