Feasibility study on the ArF attenuated phase shift mask for 100nm-node lithography

This paper describes the feasibility of 100nm-node lithography using ArF lithography and att-PSM (attenuated Phase Shift Mask). In the simulation approach, we can find that att-PSM can improve EL window more than 25% compared to BIM (Binary Intensity Mask) in both KrF and ArF lithography. Although the MEF (Mask Error Factor) values of att-PSM and BIM are almost same even in a higher NA region, the total CD variation of att-PSM is slightly lower than that of BIM because of the increase effect of EL window. Considering the total CD variation, it is necessary to use the ArF lithography machine with higher NA of more than 0.70NA for 100nm patterning. In the real patterning performance, the ArF lithography and att-PSM can improve EL windows more than 60% in comparison with KrF lithography and att-PSM for sub-120nm cell patterns. The case of att-PSM and annular aperture condition, especially small ring width annular condition shows the increasing effect of process windows compared to BIM for 100nm L/S patterns, For the direct C/H printing below 120nm feature, we can get about 9% EL window in the case of 120nm C/H feature. Although we have some technical issues for 100nm lithography such as the controllability of MEF and EL window extension, the lens quality enhancement for the higher NA and manufacturing defects of att-PSM, etc., there is a sufficient feasibility to obtain 100nm-node pattern with ArF lithography and att-PSM.