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The possibility of 130-nm DRAM production with KrF lithography was investigated by simulation. First, the preferable exposure conditions that bring about sufficient exposure latitude (EL) for production were examined for each critical layer. Next, the effect of different mask errors of an attenuated phase shift mask (Att. PSM) on the EL was examined. In the experiments, a big difference was found on how much the errors reduced EL in the critical layers, and the EL of all patterns was found to change asymmetrically depending on the size comparison of completed mask and target design. In particular, if the contact hole size of Att. PSM is made smaller than design and exposure dosage becomes higher, EL decreases severely because ofthe sidelobe. As a result, selection ofa size that is robust against mask errors instead ofa size that exhibits the maximum exposure latitude without mask errors was found to maximize the practical EL in production. In this paper, we report on a novel methodology for 130-nm DRAM cell mask size optimization based on optical lithography simulation and dose-focus budget analyses. We also define the practical mask requirements for 130-nm DRAM production based on our simulation results.

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