HETEROGENEOUS SI3N4 GROWTH DURING SINX FILM DEPOSITION AND THERMAL NITRIDATION OF SI(100) - AN X-RAY PHOTOEMISSION SPECTROSCOPY STUDY

The nitriding adsorption of NH3, both during SiNx 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<Ts<800°C) and with NH3 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 SiNx with x between 0 and 1.33. In addition to the similarity of the successive chemisorption and desorption regimes in the entire Ts range, we draw here a parallel, at Ts>600°C, between the well-known phase segregation in silicon-and Si3N4-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 Ts but also by enhanced desorption of many chemisorbed nitrogen atoms too far away from a nitride nucleation site. © 1990.