engleski

Sub-100 nm Silicon Nitride Hard-Mask for High Aspect Ratio Silicon Fins

A method for using hard-masks to achieve sub-100 nm patterning of silicon is described. The process flow involves anisotropic etching of the silicon with spacers forming the hard-mask. Silicon dioxide and silicon nitride are investigated as possible materials. Silicon nitride is shown to have advantages due to better etch selectivity during the removal of the sacrificial island around which the spacers are formed. It is demonstrated that nitride spacers can be used as hard-masks for the reactive-ion etching (RIE) of silicon. Vertical silicon fins 690 nm high and processed with an aspect ratio of 29:1 and smooth sidewalls, were achieved on <110> bulk silicon wafers when silicon wet etching with TMAH was applied. A planarized oxide trench isolated of the base of the TMAH-etched fins is demonstrated. It opens the possibility of processing FinFETs with different channel-widths.

hard-mask; silicon nitride; etching; RIE; FinFET

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