A high aspect ratio Si-fin FinFET fabricated with 193nm scanner photolithography and thermal oxide hard mask etching techniques

Abstract

A vertical double gate (FinFET) devices with a high Si-fin aspect ratio of height/width (H/W) = 87nm/11nm have been successfully fabricated on SOI wafers. Firstly, a 50nm-thick capping oxide layer was thermally grown upon the SOI crystalline silicon layer. Secondly, both 105nm-thick BARC and 265nm-thick photoresist were coated and a 193nm scanner lithography tool was used for the Si-fin layout patterning under high ASML exposure energy. Then, a deep sub-micron plasma etcher was used for an aggressive photoresist and BARC trimming down processing and the Si-fin capping oxide layer was subsequently plasma etched in another etching chamber without breaking the plasma etcher's loadlock vacuum. Continuously, the photoresist and BARC were removed with a plasma ashing and a RCA cleaning. Also, the patterned Si-fin capping oxide can be further trimmed down with an additional DHF cleaning and the remained ~22nm-thick capping oxide was still thick enough to act as a robust hard mask for the subsequent Si-fin plasma etching. Finally, an ultra thin Si-fin width 11nm and Si-fin height of 87nm can be successfully fabricated through the last silcon plasma etching.