Oxide-Nitride-Oxide Stack Having Multiple Oxynitride Layers

摘要

A semiconductor device including an oxide-nitride-oxide (ONO) structure having a multi-layer charge storing layer and methods of forming the same are provided. Generally, the method involves: (i) forming a first oxide layer of the ONO structure; (ii) forming a multi-layer charge storing layer comprising nitride on a surface of the first oxide layer; and (iii) forming a second oxide layer of the ONO structure on a surface of the multi-layer charge storing layer. Preferably, the charge storing layer comprises at least two silicon oxynitride layers having differing stochiometric compositions of Oxygen, Nitrogen and/or Silicon. More preferably, the ONO structure is part of a silicon-oxide-nitride-oxide-silicon (SONOS) structure and the semiconductor device is a SONOS memory transistor. Other embodiments are also disclosed.