Effects of alignment accuracy on CMP process for overlay control

Jong-Kyun Hong; GuChul Joung; Hyun-Jo Yang; Jinwon Park; Jeong Soo Kim; Bong-Ho Kim

doi:10.1117/12.386500

2 June 2000 Effects of alignment accuracy on CMP process for overlay control

Jong-Kyun Hong, GuChul Joung, Hyun-Jo Yang, Jinwon Park, Jeong Soo Kim, Bong-Ho Kim

Proceedings Volume 3998, Metrology, Inspection, and Process Control for Microlithography XIV; (2000) https://doi.org/10.1117/12.386500
Event: Microlithography 2000, 2000, Santa Clara, CA, United States

Abstract

As design rule shrinks down, the role of CMP process is important for obtaining available depth of focus margin in optical lithography. However, the alignment mark deformed by CMP process contributes to the total overlay error budget. This study examines the effect of alignment accuracy with various CMP polishing targets in STI process and optimizes for stable overlay control in gate pattering. At first, polishing uniformity was monitored as polishing targets in STI process and results show that uniformity is getting worse as increasing polishing target. Also, the signal contrast of alignment mark becomes lower and thus, modeled alignment residual is increased. The investigations of modeled alignment residual with signal profile and overlay result as alignment mark type show that convex alignment mark is more sensitive than concave in varying a polishing target. And, the effect of Tungsten gate film stack was considered. In order to make alignment topology, oxide between alignment marks was removed by wet etching process. Then, gate film stack materials, poly, Tungsten, Nitride, oxide, were successively deposited over alignment mark. For stable overlay control, alignment mark type and the optimization of the width of segment alignment mark with concave was examined using modeled alignment residual with signal profile and overlay result. From this study, it is found that narrow width with segment alignment mark and concave type is better than normal bar alignment mark with convex type for overlay control in Tungsten gate patterning.

Citation Download Citation

Jong-Kyun Hong, GuChul Joung, Hyun-Jo Yang, Jinwon Park, Jeong Soo Kim, and Bong-Ho Kim "Effects of alignment accuracy on CMP process for overlay control", Proc. SPIE 3998, Metrology, Inspection, and Process Control for Microlithography XIV, (2 June 2000); https://doi.org/10.1117/12.386500

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