Optimized Characterization and Processing of Thin Silicon Oxynitride Dielectric Films

Silicon oxynitride (SiO
_x
N
_y
) films are a promising candidate for replacing conventional SiO
₂
as gate dielectrics in current and future metal oxide semiconductor devices. However, characterization and optimization of the processing of these thin films for appropriate use in devices is not trivial. In this paper, we studied a group of ~80-100Å SiO
_x
N
_y
films deposited under different process conditions by using several surface analysis techniques, as required for new device development. Mercury (Hg) probe metrology was used to characterize the gate current leakage, charge trap density, and dielectric breakdown aspects to identify the most promising films with the least electrical leakage and breakdown. Optimized secondary ion mass spectroscopy (SIMS) analysis was used to study the impurity depth profile changes in order to distinguish the chemical distribution differences between the films. By combining the Hg probe and SIMS characterization results, it was found that a lower nitrogen concentration at the SiO
_x
N
_y
/Si substrate interface, as well as other impurity incorporation produce promising SiO
_x
N
_y
films.