Mechanism of Plasma Nitridation of Silicon Dioxide Employing Surface-Wave and Inductively Coupled Plasma Sources

Abstract

A thin silicon dioxide (SiO2) film was nitrided with nitrogen plasma generated through a surface-wave plasma (SWP) or inductively coupled plasma (ICP) source. The plasma and nitridation characteristics were compared in both plasma sources. We found that large amounts of nitrogen atomic ions (N+) and neutral radicals (N•) were included in the SWP; however, the dominant species were nitrogen molecular ions (N2+) in the ICP. Nitrogen areal density in the nitrided SiO2 film is correlated with ion dose in the SWP, which suggests that the main reactants are ions. Also, there exists a large nitrogen loss in the ICP, but a small loss in the SWP. To understand these differences, we performed molecular dynamics (MD) simulations based on a semi-empirical molecular orbital (MO) method. We investigated reactions by irradiating N+ or N2+ to a SiO2 molecule, thermal stability of the reaction products, and reactions between the reaction products and N•. Consequently, we found that the reaction products are stable for N+, but are unstable for N2+, which is consistent qualitatively with experimental results. Finally, we conclude that stable reaction products are formed by N+ and N• irradiation, and that the SWP source that we employed is the appropriate plasma source for generating these species efficiently.

Area-Selective Molecular Layer Deposition of a Silicon Oxycarbide Low-k Dielectric

“…As the example illustrated in the dashed box in Figure 6 suggests, the N 2 plasma can be used to remove ODPA from the Al surface and, in the process, convert surface SiOC to a silicon oxynitride etch stop layer. 39 Besides the nitridation strategy to create an etch stop layer on SiOC, the SAMs exploited in this work have also been shown to block deposition of thin etch stop layers by ALD, for example, 1.5−3 nm of Al 2 O 3 . 18,40 Thus, a scheme including area-selective SAM deposition, SiOC ALD, Al 2 O 3 ALD, and finally SAM removal can be an alternative option for fabrication of fully aligned vias.…”