Effect of mask critical dimension error for subquarter-micron contact hole

Abstract

The effect of mask critical dimension (CD) error for binary mask and attenuated phase shift mask (PSM) are investigated by simulation and experimental based data. For the large features, mask error factor (MEF) is approximately unit. But as the CD is closed to the resolution limit, the MEF value is rapidly increased. The MEF was dependent on the contact density. For example, dense contact has larger MEF value than isolated contact. Attenuated PSM has smaller MEF value comparing with binary mask because it is applied the positive mask bias in order to reduce the sidelobe printing. The sensitivity of mask CD error for NA and sigma variation was different from the contact density. For the isolated contact, MEF value was almost independent on the sigma value. However, the MEF was improved by high NA lines at the resolution limits both for the isolated and for the dense contact. According to these data, the mask CD control budget for the sub-quarter micron contact was considered.