Reactions of NH3 on high-temperature silicon surface and structure evolution during silicon nitride film growth

Abstract

Temperature and dosage-dependent reactions of NH3 on the Si(111)-(7 × 7) surface have been studied by low-temperature scanning tunneling microscopy. It was found that the surface reaction exhibited three different dissociative adsorption channels as the temperature increases at low exposure. Under the condition of high exposure, the amorphous structure of silicon nitride film gradually transformed into an ordered phase, with the increase of substrate temperature, and finally presented an 8/3 × 8/3 structure. This means that both exposure and temperature are critical for forming an ordered surface structure. Furthermore, many adsorbates were observed on the nitride region during the growth process, which is believed to be the intermediate reactants in the nitridation reaction and consumed in the subsequent annealing process to form an orderly and clean surface morphology.