Pattern wiggling investigation of self-aligned double patterning for 2x nm node NAND Flash and beyond

Abstract

Double patterning technology (DPT) has been identified as the extension of optical photolithography technologies to 3x nm half-pitch and below to fill in the gap between Immersion and EUV lithography. Self-aligned double patterning (SADP) technology utilized mature process to reduce risk and faster time to support the continuation of Moore’s Law. As for the SADP process, the suitable hard mask (HM) material as following core pattern selection is quite important. Usually, the severe pattern deformation –wiggling, is easy to happen as the line/space patterns scaled down to below 35nm, and it ultimately prevents the successful pattern transfer. In this paper, using the amorphous carbon as HM, it was found that wiggling was caused by serious chemical side-etch during SADP dry etch process. However, an effective of advanced carbon material with high etch selectivity and low etch rate by appropriate film modification can be successful in SADP without wiggling side effect for 2x nm node NAND Flash application. This extraordinary HM can be considered as a potential choice for SADP process continual performing.