Hydrogen-related memory traps in thin silicon nitride films

Abstract

The internal photoelectric-effect technique in combination with multiple internal reflection measurements has been used for quantitative measurement of impurities and defect-related traps in the thin Si3N4 insulating film of a metal–nitride–oxide–semiconductor device, and their correlation with film processing conditions. The hydrogen content in the film showed an increase of approximately 3% for a decrease of deposition temperatures from 950 to 700 °C and corresponding increase in trapped electron density from 0.55×1018 to 2.0×1018 cm3. The multiple internal reflection measurements indicated that the variation in the hydrogen content in the Si3N4 film was predominantly related to a variation in hydrogen-to-silicon bonding while the hydrogen bonded to nitrogen was relatively constant. The results suggest that hydrogen, in addition to excess silicon, and perhaps other structural defects, plays a role in determining trapped electron densities in silicon nitride.