Challenge for Sub-100-nm DRAM Gate Printing Using ArF Lithography with Combination of Moderate OAI and attPSM

摘要

Mask error effects of attenuated PSM wafer CD and process windows were analyzed by simulation, and proven experimentally for dense line applications. Among possible mask errors, mask CD variations dominate wafer CD control like a conventional binary mask, but phase and transmission errors are also significant especially when a defocus condition is applied. There is an apparent trend of MEEF versus mask bias. It is increased as mask bias goes towards the positive direction, i.e., overexposure condition, where process window can be maximized. Therefore mask bias should be chosen carefully on the basis of small MEEF as well as large process window.