Abstract
Contact hole patterning for half pitch 51nm can be achieved by single exposure for mass production and for half pitch 39nm can be achieved by Litho-Etch-Litho-Etch (LELE). Currently for half pitch 32nm there is no promising solution so far, but ouble patterning and extreme ultraviolet lithography (EUV) are still competing each other for this target. In the current situation of contact hole patterning, single exposure negative tone development (NTD) shows excellent contact hole performance on fidelity, process window and CD uniformity compared to positive tone development (PTD) and finally enables to define half pitch below 50nm. In this paper, we describe necessity for circle patterning on 3-D flash, optimization of exposure condition, upgrade status of resist and device speed of 3-D flash on negative tone development (NTD) process.
