28 August 2003 Extension of Cr-less PSM to sub 90-nm-node DRAM and logic device
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Proceedings Volume 5130, Photomask and Next-Generation Lithography Mask Technology X; (2003) https://doi.org/10.1117/12.504280
Event: Photomask and Next Generation Lithography Mask Technology X, 2003, Yokohama, Japan
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 and logic patterns compared with 6% transmittance HTPSM in the ArF lithography. We designed CLM layouts of sub 90 nm node DRAM and logic layers 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. We also introduced concept of checkerboard CLM to apply zigzag L/S and semi dense contact in the logic layer. Using 0.75 NA ArF Scanner, CLM showed NILS reduction by 10~15% in the presence of lens aberration and flare, which reduced DoF margin by about 0.1~0.2 μm depending on the layer. So the critical layers in sub 90 nm node DRAM satisfied 8% of EL (Exposure Latitude) and 0.3 μm of DoF (Depth of Focus) margin. Also 3D mask topographic effect of CLM in the specific contact layer was discussed.
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Ju-Hyung Lee, Ju-Hyung Lee, Hyung-Do Kim, Hyung-Do Kim, Dong-Hoon Chung, Dong-Hoon Chung, Sang-Gyun Woo, Sang-Gyun Woo, Han-Ku Cho, Han-Ku Cho, Woo-Sung Han, Woo-Sung Han, "Extension of Cr-less PSM to sub 90-nm-node DRAM and logic device", Proc. SPIE 5130, Photomask and Next-Generation Lithography Mask Technology X, (28 August 2003); doi: 10.1117/12.504280; https://doi.org/10.1117/12.504280

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