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Proceedings Paper

Resist compacting under SEM E-Beam
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Paper Abstract

Resist critical dimensions (CD) and thickness are usually obtained by in-line CD SEM or in-line optical metrology measurements but varification or calibration of these is typically achived by cross sectional SEM. As we push CDs to 100nm and beyound, descrepencies between these two sources data can constitute a large percentage of the target dimension. Particularly for 193nm resists, the CD shrinkage under SEM has been well characterized, but the vertical and horizontal compaction behavior in across sectional SEM has not been explored. In this paper, the discussion is divided into two parts. One is for bulk resist and another is for patterned resist. For bulk case, the the only variable is vertical thickness. The experiments for I-line, 248nm and 193nm resist indicated that the resist thickness from the cross sectional image is strongly dependent on the resist polymer structure, the SEM conditions and the interrogration time under SEM E-beam. Therefore, the thickness comparison between optical and electronic is not always meaningful because the cross sectional thickness often shows a low thickness than the optically determined value. We have determined the optimum SEM condition to minimize vertical compaction. There are two variables for patterned resist, vertical thickness and lateral CD size. Our experiments for I-line and 248nm resists exhibited that the patterned resist thickness can be 30% lower than the optical thickness. However, the lateral CD sizes showed less variation relative to the different SEM conditions. The unique behaviors of 193nm patterned resist are also displayed and discussed in this paper. Based on all experimental data, different SEM conditions are recommended based on different purposes to generate accurate cross sectional resist images.

Paper Details

Date Published: 2 June 2003
PDF: 9 pages
Proc. SPIE 5038, Metrology, Inspection, and Process Control for Microlithography XVII, (2 June 2003); doi: 10.1117/12.483432
Show Author Affiliations
Yiming Gu, Integrated Device Technology, Inc. (United States)
Dyiann Chou, Integrated Device Technology, Inc. (United States)
John L. Sturtevant, Integrated Device Technology, Inc. (United States)

Published in SPIE Proceedings Vol. 5038:
Metrology, Inspection, and Process Control for Microlithography XVII
Daniel J. Herr, Editor(s)

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