Heterogeneous Si 3N 4 growth during SiN x film deposition and thermal nitridation of Si(100): An X-ray photoemission spectroscopy study

Abstract

The nitriding adsorption of NH 3, both during SiN x film growth by reactive evaporation and during thermal nitridation of Si(100)-2×1 has been studied by X-ray photoemission spectroscopy (XPS) in the same range of substrate temperatures (0°C< T s<800°C) and with NH 3 pressures leading to equivalent exposures E in both processes (0 langmuirs < E<200 langmuirs). Such an exposure domain allows us to produce the complete range of possible nitride compounds SiN x with x between 0 and 1.33. In addition to the similarity of the successive chemisorption and desorption regimes in the entire T s range, we draw here a parallel, at T s>600°C, between the well-known phase segregation in silicon-and Si 3N 4-rich clusters during film deposition and island-like nitride growth on Si(100) in the initial stage. This growth model is supported by related angle-resolved XPS and coverage mesurements. They enable us to suggest a mechanism for cluster formation controlled not only by enhanced diffusion with increasing T s but also by enhanced desorption of many chemisorbed nitrogen atoms too far away from a nitride nucleation site.