Analysis and modeling of low pressure CVD of silicon nitride from a silane-ammonia mixture - II. Deposition modeling

This paper, Part II of this series of two articles, is devoted to two-dimen sional modeling of silicon nitride low pressure chemical vapor deposition f rom a silane-ammonia mixture. In that aim, the CVD2 model previously develo ped in our laboratory, which takes into account hydrodynamics, mass transpo rt, and chemical reactions, is adapted to this special kind of deposition. The gas phase mechanism described in Part I is integrated in the model. The concentration profiles of NH3, SiH4, SiH2, SiHNH2, SiH3NH2, and H-2 have b een computed and the contribution of the different species to deposition ra te have been evaluated. The results obtained confirm the importance of the entrance zone length of the reactor, which conditions the formation of the stable species SiH3NH2, generating SiH2 and SiHNH2, which are responsible f or the strong overthicknesses observed at the wafer periphery. (C) 1999 The Electrochemical Society. S0013-4651(98)10-088-5. All rights reserved.