engleski

Application of spacer hard-masks for sub-100 nm wide silicon fin-etching

The use of spacers as a hard mask allows the wafer patterning in sub-100 nm range without the use of lithography tools with such high resolution. The patterned line width is determined by the thickness of the deposited spacer material and subsequent etching steps. The conformal deposition of the spacer material with precise thickness control is required for narrow spacer processing. Additionally, the sacrificial island and spacer etching steps need to be highly anisotropic. Silicon oxide and nitride layers deposited by LPCVD were examined for island/spacer combinations for silicon fin-etching. Excellent selectivity of buffered-HF solutions to silicon and silicon nitride makes silicon oxide the preferred island material. Consequently, silicon nitride was used for the spacers. The silicon nitride spacers with widths of 100 nm, 50 nm, and 30 nm were processed and used as a hard mask for silicon etching. Reactive-ion etching with HBr/Cl2 chemistry achieved high silicon fins with sloped sidewalls. Wet silicon etching in 25% TMAH done on <110> wafers created vertical silicon fins with smooth sidewalls. Both processes resulted in silicon fins with high aspect-ratio.

silicon fin; nitride spacer; TMAH

nije evidentirano