26 June 2003 Evaluation of ArF CLM in the sub-100-nm DRAM cell
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Abstract
Process windows, MEEF (Mask Error Enhancement Factor), flare, aberration effect of the CLM (Cr-less PSM) were measured by the simulations and experiments for the various DRAM cell patterns compared with 6% transmittance HTPSM in the ArF lithography. We designed CLM layouts of sub 100nm node DRAM cells concerning the mask manufacturability, maximizing the NILS (Normalized Image Log Slope) and minimizing the MEEF with a semi-automatic OPC tool. Isolation, line and space and various contact patterns showed increasing process windows compared with HTPSM and this strongly depended on the layout design. Using a 0.75 NA ArF Scanner, CLM showed NILS reduction by about 10% in the presence of lens aberration and flare, which reduced DoF margin by about 0.1~0.2μm depending on the layer. So the critical layers in sub 100 nm node DRAM satisfied 10% of EL (Exposure Latitude) and 0.1 μm of DoF (Depth of Focus) margin. Also 3D mask topographic effect of CLM in the specific layer was discussed.
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Ju-Hyung Lee, Dong-Hoon Chung, Ho-Chul Kim, Dong-Seok Nam, Sang-Gyun Woo, Han-Ku Cho, Woo-Sung Han, "Evaluation of ArF CLM in the sub-100-nm DRAM cell", Proc. SPIE 5040, Optical Microlithography XVI, (26 June 2003); doi: 10.1117/12.485406; https://doi.org/10.1117/12.485406
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