Precise control of nitrogen profiles and nitrogen bond states for highly reliable N2O-grown oxynitride

Gate dielectrics formed by N2O oxynitridation using a rapid thermal anneale r (RTA) and a furnace were developed and evaluated. The oxynitrides formed by RTA show very large time-to-breakdown (T-bd) values and small stress-ind uced leakage current, as compared with pure oxides and oxynitrides formed b y furnace annealing. The depth profile of the N-1 delta peak For oxynitride s was analyzed by X-ray photoelectron spectroscopy. Nitrogen atoms in the o xynitrides formed by RTA are localized at the Si/SiO2 interface, and those in the oxynitrides formed during furnace annealing exist uniformly througho ut the film. The differences in nitrogen bond state in the oxynitride betwe en the RTA and the furnace are due to the decomposition of N2O gas. A nitro gen atom at the Si/SiO2 interface bonds with one oxygen and two silicon ato ms (Si-2=N-O), or bonds with three silicon atoms (Si-3=N). A nitrogen atom located In the bull of the film, however, bonds with two oxygen atoms and o ne silicon atom (Si-N=O-2). We clarified that the electrical and chemical c haracteristics of the oxynitride depend on the location of N2O gas decompos ition. Thus, precise control of the nitrogen profile and the nitrogen bond states is very important for the formation of highly reliable N2O oxynitrid e. (C) 2000 The Electrochemical Society. S0013-4651(99)04-038-0. Ail rights reserved.