| Summary: | 碩士 === 元智大學 === 電機工程學系 === 94 === In the semiconductor process field, the control of the critical dimension (CD) is a major task, specially in the processes of mask manufacturing and wafer exposure. If the linewidth cannot be well controlled, then the resultant patterns on the wafer may shrink or bridge. It is getting more critical as the technology node is pushed into smaller feature size. One of the difficult problems is that sometimes the linewidth variation on wafer is out of specification even though the linewidth on mask is in specification. The linewidth discrepancy may come from the process control during the chrome film etching, which will influence the sidewall profile of the chrome film pattern. We can get the angular variation of the profile by analyzing the cross-section of the mask. In this study, the masks used in the 130 nm technology node are investigated. Through the simulation done by AIMS fab 248 exposure system, the energy distribution on the photoresist, affected by the sidewall angular variation (90 deg +/- 5%) of the mask, is analyzed with the intensity distribution across the simulated exposure images. The result shows that within 3% of the exposure latitude the process window is acceptable if the linewidth variation is less than 4 nm and the 3 sigma of the depth of the focus (DOF) is 17 nm. The established process window can help the engineers to avoid the linewidth discrepancy between the wafer and the mask, even with the inevitable chrome sidewall angular variation of the mask.
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