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Proceedings Paper

Improvement of depth of focus control using wafer geometry
Author(s): Honggoo Lee; Jongsu Lee; Sangmin Kim; Changhwan Lee; Sangjun Han; Myoungsoo Kim; Wontaik Kwon; Sung-Ki Park; Sathish Veeraraghavan; JH Kim; Amartya Awasthi; Jungho Byeon; Dieter Mueller; Jaydeep Sinha
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Paper Abstract

For several decades, the semiconductor industry has been controlling site flatness of the starting wafer material by defining tight specs on industry-standard site flatness metrics such as SFQR (Site Frontsurface-referenced least sQuares/Range) and ESFQR (Edge Site Frontsurface-referenced least sQuares/Range) that scale with technology nodes. The need for controlling site flatness of the starting material stems from previous research that shows that site flatness directly impacts lithography defocus. The wafer flatness variation changes significantly due to wafer processing downstream such as CMP, etch, and film deposition. Hence, for 2X nm and smaller technology nodes with very stringent focus process windows, it is critical to control wafer flatness variations at critical steps along the semiconductor process flow. In this paper, the capability of an interferometer-based patterned wafer metrology tool to predict lithography defocus is validated by comparison to scanner leveling data. The patterned wafer metrology tool is used to characterize the impact of near-edge flatness changes on the critical dimension (CD) of the contact holes due to different edge CMP process conditions. The results of the characterization illustrate how a site flatness specification or threshold can be developed for critical patterning steps. The paper also illustrates how the patterned wafer metrology tool can be used to identify processes causing site flatness variations. Finally, the site flatness variation at these processes can be monitored using the pattern wafer metrology tool to detect process drifts and excursion before patterning.

Paper Details

Date Published: 19 March 2015
PDF: 6 pages
Proc. SPIE 9424, Metrology, Inspection, and Process Control for Microlithography XXIX, 942428 (19 March 2015); doi: 10.1117/12.2085848
Show Author Affiliations
Honggoo Lee, SK Hynix, Inc. (Korea, Republic of)
Jongsu Lee, SK Hynix, Inc. (Korea, Republic of)
Sangmin Kim, SK Hynix, Inc. (Korea, Republic of)
Changhwan Lee, SK Hynix, Inc. (Korea, Republic of)
Sangjun Han, SK Hynix, Inc. (Korea, Republic of)
Myoungsoo Kim, SK Hynix, Inc. (Korea, Republic of)
Wontaik Kwon, SK Hynix, Inc. (Korea, Republic of)
Sung-Ki Park, SK Hynix, Inc. (Korea, Republic of)
Sathish Veeraraghavan, KLA-Tencor Corp. (United States)
JH Kim, KLA-Tencor Corp. (United States)
Amartya Awasthi, KLA-Tencor Corp. (United States)
Jungho Byeon, KLA-Tencor Corp. (Korea, Republic of)
Dieter Mueller, KLA-Tencor Corp. (United States)
Jaydeep Sinha, KLA-Tencor Corp. (United States)


Published in SPIE Proceedings Vol. 9424:
Metrology, Inspection, and Process Control for Microlithography XXIX
Jason P. Cain; Martha I. Sanchez, Editor(s)

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