Chemical phase transitions of the HfO2/SiON/Si nanolaminate by high-temperature thermal treatments in NO and O2 ambient -: art. no. 262906

Temperature-dependent chemical phase transitions of the HfO2/SiON/Si(100) nanolaminate in O-2 and NO ambient have been investigated using high-resolution photoemission spectroscopy. Hf 4f, Si 2p, O 1s, and N 1s photoemission spectra were measured after annealing the nanolaminate at a temperature between 750 and 1150 degrees C. These spectra show that the chemical phase transitions of the nanolaminate strongly dependend on the ambient gases. The nanolaminate in an O-2 ambient is stable below 750 degrees C but the HfO2 and SiON layers dissociate by producing Hf silicides above 950 degrees C. In contrast, the nanolaminate in NO ambient does not transit into Hf silicides up to 1050 degrees C. Interestingly, the HfO2 and SiON layers transforms into HfOxNy and SiNx layers, respectively, with a high thermal stability, where the HfOxNy layers are a high-k dielectric material and the SiNx layers work as a barrier against both Si and O diffusion