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10 May 2005 90nm technology contact CD performance characterization via ODP scatterometry
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Contact hole lithography presents a variety of challenges for process development. Measurement of the bottom of the hole presents the most difficulty, and metrology error has traditionally been much larger for contact (3D) metrology than for line/space structures. In light of process windows being significantly smaller for contact holes than for line/space structures, it is difficult to maintain good Contact CD characterization of novel methods requires CD correlation to existing metrology tools including CD linearity across a range of pitches and target CDs. In this paper, we will present contact CD linearity results as characterized by integrated ODP scatterometry, where measurements of hole CD and profile have been made following the lithography process, in a method nondestructive to the 193nm resist pattern on the wafer. The CD linearity is characterized for a 90nm technology device film stack of patterned photoresist (PR), bottom anti-reflective coating (BARC), oxide, and SiC on top of a silicon (Si) substrate. The pattern densities range from dense to semi-dense to isolated, and the grating structures include circular holes aligned in an orthogonal pattern on the wafer. Measurement stability results are also shown, and correlation to CD-SEM and cross-section SEM is provided as a reference metrology. The results of the experiment show that ODP can be used successfully to not only characterize contact CD linearity, but to also monitor film thickness and profile variation, providing a valuable solution for contact hole process development.
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Kelly Barry, Shaunee Cheng, and Greet Storms "90nm technology contact CD performance characterization via ODP scatterometry", Proc. SPIE 5752, Metrology, Inspection, and Process Control for Microlithography XIX, (10 May 2005);

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