Pattern matching, simulation, and metrology of complex layouts fabricated by electron beam lithography Proximity exposure effect analysis using the phenomenon of resist debris formation in electron beam lithography

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This paper describes the feasibility of lOOnm-node lithography using ArF lithography and att-PSM (aUenuated 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 aU-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 O.7ONA for lOOnm 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-l2Onm cell patterns. The case of att-PSM and annular aperture condition, especially small ring width annular condition shows the increasing effect ofprocess windows compared to BIM for lOOnm L/S patterns. For the direct C/H printing below l2Onm feature, we can get about 9% EL window in the case of l2Onm C/H feature. Although we have some technical issues for lOOnm 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 lOOnm-node pattern with ArF lithography and att-PSM.

This paper describes the effect of the mask errors such as mask critical dimension (CD) variation, phase and transmission error of attenuated phase shifting mask (att-PSM) on wafer CD in ArF lithography and also analyzes these errors quantitatively. Mask CD requirement using ELF and MEF is estimated firstly and mask CD should be controlled within about 7nm assuming O.7ONA ArF system with 1% illumination uniformity. Transmission error induces larger CD variation than phase error. However, phase error should be considered otherwise in that it reduces depth of focus (DOF). To control DOF degradation less than 10% in case of O.l4um and O.l6um isolated contact hole(C/H), the phase should be controlled within the range of Considering O.l4um isolated contact hole, transmission error of occupies 10% of CD tolerance. Finally, the budget of these factors are calculated in view of total wafer CD variation quantitatively except lens aberration, resist process, and etc. To reduce wafer CD variation, we should control mask CD more tightly.