The effect of plasma treatment prior to hydrogenated amorphous silicon nitride (a-SiN:H) deposition on the a-SiN:H/Si interface was studied. NH3, NH3+N2, and NH3+H2 were used as source gases for plasma treatments. Nitridation of silicon surfaces after plasma treatment was observed by X-ray photoelectron spectroscopy (XPS). Fourier transform infrared spectroscopy (FTIR) measurement revealed that the stoichiometry of the thin nitrided layer varied depending on the source gas. After the plasma treatment and subsequent a-SiN:H deposition on the silicon substrate, capacitance–voltage (C–V) characteristics of the metal–insulator–semiconductor (MIS) structure were measured. As a result, it was found that the interface trap density (D IT) of the plasma-treated sample decreased compared with that of the nontreated sample, whereas the type of source gas did not affect D IT. On the other hand, flatband voltage (V FB) of MIS structure shifted along with the type of source gas, and this phenomenon indicates that the fixed charge at the a-SiN:H/Si interface depends on the stoichiometry of the thin nitrided layer. Finally, the passivation effect of plasma treatment was evaluated quantitatively on the basis of the extended Shockley–Read–Hall (SRH) theory.

Reduction of impurities such as gels and metals is one of the critical requirements in chemistries used in directed self assembly lithography (DSAL). In this study, we focused on elucidating the forms of the gels and metals in block copolymer (BCP) solution to effectively reduce these impurities. As a result, particles or gels, and ions are suggested as forms of metals. To reduce these multiple forms of metals, multistep filtrations such as repetitive filtration of single filter material and combination of different type of filters are conducted. As a result, more than 99.99% of Li and more than 99.9% of Al are reduced with a combination of Nylon 6,6 10 nm filtration and ion exchange filtration. The order of the filtration steps does not impact the removal efficiency. The results should contribute realizing DSAL in semiconductor device fabrication.

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