Carbon Rich Plasma-Induced Damage in Silicon Nitride Etch

Abstract

Conventional and semi-recessed localized oxidation of silicon (LOCOS) processes have been compared in terms of junction current leakage. Three different Si 3 N 4 etch chemistries, SF 6 /CHF 3 -SF 6 /HBr/O 2 , CHF 3 /CF 4 /Ar, and CHF 3 /CF 4 /Ar/CO, have been used to etch active Si 3 N 4 with two types of plasma etchers, conventional silicon nitride and silicon oxide etchers. It has been found that the junction leakage current with CHF 3 /CF 4 /Ar in the semi-recessed LOCOS has slightly higher value than that with the conventional LOCOS. However, with CO addition to CHF 3 /CF 4 /Ar gases, the junction leakage current resulted from plasma-induced damage on silicon substrate is much higher. The results obtained from X-ray photoelectron spectroscopy and atomic force microscopy indicate that carbon-rich perfluoronated polymers and plasma etch induced silicon substrate roughness with CHF 3 /CF 4 /Ar/CO gases contribute to the higher junction leakage.

Ultralow-loss tightly confining Si3N4 waveguides and high-Q microresonators

“…Also, the CHF 3 has been added to CF 4 since it has a high C/F ratio so it could form polymers that compensate the highly isotropic etching of CF 4 . Moreover, adding argon enhances the straight waveguides profiles by strong bombardment as well as the higher RF [24].…”

Patterning of silicon nitride for CMOS gate spacer technology. I. Mechanisms involved in the silicon consumption in CH3F/O2/He high density plasmas

“…5 In this work, we used surface analysis techniques to characterize the silicon surface after the nitride silicon etching in order to explain the etch mechanisms involved in silicon loss in S/D regions. 5 In this work, we used surface analysis techniques to characterize the silicon surface after the nitride silicon etching in order to explain the etch mechanisms involved in silicon loss in S/D regions.…”

Silicon nitride etching in high- and low-density plasmas using SF6/O2/N2 mixtures

“…However, carbon rich plasmas may create damage due to implantation and postprocess diffusion of carbon into the silicon substrate. 6 Another concern in using fluorocarbon gases is related to their environmental impact. 7,8 To minimize the latter, various approaches are currently being explored, including process optimization and alternative chemistries.…”