Full-chip curvilinear inverse lithography technology (ILT) requires mask writers to write full reticle curvilinear mask patterns in a reasonable write time. We jointly study and present the benefits of a full-chip, curvilinear, stitchless ILT with mask-wafer co-optimization (MWCO) for variable-shaped beam (VSB) mask writers and validate its benefits on mask and wafer at Micron Technology. The full-chip ILT technology employed, first demonstrated in a paper presented at the 2019 SPIE Photomask Technology Conference, produces curvilinear ILT mask patterns without stitching errors, and with process windows enlarged by over 100% compared to the OPC process of record, while the mask was written by multibeam mask writer. At the 2020 SPIE Advanced Lithography Conference, a method was introduced in which MWCO is performed during ILT optimization. This approach enables curvilinear ILT for 193i masks to be written on VSB mask writers within a practical, 12-h time frame, while also producing the largest process windows. We first review MWCO technology, then curvilinear ILT mask patterns written by VSB mask writer, and then show the corresponding 193i process wafer prints. Evaluations of mask write times and mask quality in terms of critical dimension uniformity and process windows are also presented.
In advanced semiconductor memory manufacturing, mask and lithography are critical for patterning. In this paper we jointly study the benefits of a full-chip, curvilinear, stitchless inverse lithography technology (ILT) with mask-wafer cooptimization (MWCO) for memory applications. The full-chip ILT technology employed in this study, first demonstrated in a paper presented at the 2019 SPIE Photomask Technology Conference[20], produces curvilinear ILT mask patterns without stitching errors, and with process windows enlarged by over 100% compared to the OPC process of record. At the 2020 SPIE Advanced Lithography conference, a new method was introduced, in which mask-wafer cooptimization (MWCO) is performed during ILT optimization[22]. This new approach enables curvilinear ILT for 193i masks to be written on variable-shaped beam (VSB) mask writers within a practical, 12-hour time frame, while also producing the largest process windows. This new study presents the mask and wafer results using MWCO. Curvilinear ILT mask patterns written by VSB mask writer and the corresponding 193i process wafer prints are shown. Evaluations of mask write times, and mask quality in terms of CD uniformity and process windows are also presented.
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