High resolution secondary ion mass spectrometry analysis of hydrogen behavior in SiO2/SiN/SiO2 films with thermal treatment

Abstract

The distribution and behavior of hydrogen in a SiO2/SiN/SiO2 (ONO) film stack structure with thermal treatment were investigated by high-resolution secondary ion mass spectrometry analysis. Hydrogen atoms were present in the poly-Si/top-SiO2 interface, SiN layer, and bottom-SiO2/Si-substrate interface. These hydrogen atoms decreased in number with annealing (1000 °C, 60 s) and spike annealing (1000 °C, about 1 s). However, when a SiN cap layer with hydrogen atoms was formed on a poly-Si/ONO film structure, hydrogen atoms in the ONO film did not decrease in number with spike annealing. It was considered that the SiN cap layer mainly performed a supply source of hydrogen into the ONO film during spike annealing, and that hydrogen atoms interdiffused between the SiN cap layer and the SiN layer of the ONO film. These results indicate that the amount of hydrogen in the ONO film can be controlled by annealing and the formation of a SiN cap layer.