Effects of heavy plasma atoms on spin centers in reactively sputtered sin films

The effects of heavy atoms on spin centers and microstructures in SiN films produced by reactive radio-frequency sputtering in Kr-N₂ plasmas are clarified by electron spin resonance (ESR) spectroscopy and high-resolution transmission electron microscopy (HRTEM). Rutherford backscattering spectroscopy suggests that the film-constituent elements have uniform depth profiles with the atomic ratio of SiN_1.21. The films produced in the Kr/N₂ = 0.5 and 2 plasmas show triplet-character ESR curves with a zero crossing of g = 2.0036. High-temperature measurements (> 400°C) reveal that their ESR curves have an additional spin center at g = 2.0018, which disappears in room-temperature measurement. At 590°C, the ESR curve becomes a simple featureless curve similar to the silicon K^o spin center. The Kr/N₂= 10 film exhibits a simple featureless curve with g = 2.0016, which is mainly attributed to the oxidized silicon spin centers. This film also shows a novel weak signal at g = 2.126 which disappears in vacuum. This signal probably originates from a volatile species, such as oxygen-related small radicals. ESR curves of this Kr/N₂= 10 film measured in vacuum are unchanged up to 590°C. HRTEM reveals that the fibrous voids are uniformly scattered and make the open columnar structure. These salient structures induced by heavy atom effects are consistent with the structure zone model and should be effective for strong adsorption of paramagnetic species.