Characterization of Ultrathin Dielectrics Grown by Microwave Afterglow Oxygen and N₂O Plasma

Abstract

Ultrathin dielectrics, oxides and oxynitrides were grown using microwave afterglow oxygen and N2O plasma at low temperature. N2O plasma annealing and pretreatment improved the breakdown properties of O2 plasma oxides. From secondary ion mass spectroscopy (SIMS) analysis, nitrogen was found to be incorporated into oxides effectively by this low-temperature method. Nitrogen content was highest at the oxide surface and decreased toward the oxide/Si interface. This indicates a nitridation mechanism different from the conventional N2O gas annealing or oxidation processes. The relationships among interface state densities, tunneling current and nitrogen profiles were also investigated by C-V and I-V measurements.

Plasma-assisted oxidation, anodization, and nitridation of silicon

“…With N,0, nitrogen was incorporated throughout the 7-8-nm oxide layer, but the concentration was highest at the SiOj surface and decreased to the Si/SiO^ interface [79]. This distribution is similar to that observed in oxides thermally (furnace) nitrided with NH,.…”

“…This distribution is similar to that observed in oxides thermally (furnace) nitrided with NH,. Nitrogen in the bulk oxide gave high tunneling currents, but MBDF ~8 MV/cm; the effective charge density was ~3 X lO' /cm , while the interface state density was >2 X 10''/cm'/eV [79].…”

“…Downstream microwave discharges have been used to grow silicon oxynitride layers using N,0 at 3 Torr with a substrate temperature of 600°C [79] and using N^/Oj mixtures at 1 Torr with a substrate temperature of 550°C [80]. With N,0, nitrogen was incorporated throughout the 7-8-nm oxide layer, but the concentration was highest at the SiOj surface and decreased to the Si/SiO^ interface [79].…”

The investigation of an amorphous SiOx system for charge storage applications in nonvolatile memory at low temperature process

“…Therefore, the tunneling thickness strongly influences the leakage current of the trapped charges from the storage layer through the tunneling layer. In addition, the thicker tunneling layer guarantees a continuous film and less defect density [16]. In this case, the retention properties of a device using the richest silicon storage layer can be improved by employing a thicker tunneling layer.…”

Electrical characterization of ultrathin oxides of silicon grown by N2O plasma assisted oxidation

“…The NH 3 -nitrided oxides have a disadvantage of often having a large amount of electron traps induced by hydrogen inherent in NH 3 . [18][19][20][21] Masuda et al 17 reported the growth of ultrathin SiO 2 films by N 2 O plasma oxidation technique using a PECVD reactor. 16 In the case of direct oxynitridation in N 2 O or NO, the process temperature required is very high (1000°C to 1150°C), which makes the control of the oxynitride thickness, and nitrogen content and distribution in the bulk of the oxide and at the Si/SiO 2 interface more difficult.…”