Layer-by-layer growth of silicon nitride films by NH3 and SiH4

Layer-by-layer growth of silicon nitride by NH, and SM, was investigated using an ultraclean low-pressure CVD system with a Xe flash lamp. Thermal nitridation on Si(100) in an NH3, environment with and without the flash lamp light irradiation is explained assuming Langmuir-type physical adsorption of NH, and reaction of the adsorbed NH,. The reaction can be enhanced by Xe flash lamp light irradiation, and the N atom concentration tends to saturate to similar to 2.7x10(15)cm(-2). In Si deposition on the ultrathin silicon nitride, it is found that N desorption from the Si nitride films hardly occurs, and the deposited Si atom concentration increases up to about the single atomic layer concentration (6.8x10(14) cm(-2)), and then the Si deposition rate drastically increases. From FTIR/ATR and RHEED measurements, the structures of the Si film on Si and the Si nitride are found to be different. Layer-by-layer growth control of Si nitride is proposed by combining atomic-layer nitridation on Si and atomic-layer growth of Si on the Si nitride.