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Proceedings Paper

Evaluation of overlay accuracy of phase-shift image for 65-nm node masks
Author(s): Tadashi Komagata; Norio Kimura; Kaoru Funaki; Yasutoshi Nakagawa; Nobuo Gotoh
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Paper Abstract

A 65 nm node mask is required to have total alignment accuracy of 20 nm (3σ) or less for 1st and 2nd layers, including the positional accuracy of each layer. We have developed a new electron beam mask lithography process using “alignment-and-height” marks to minimize the displacement between two layers resulting from additional bowing and contraction on the blank surface after the 1st layer exposure. The new process consists of the following steps: 1. Write “alignment-and-height” marks on the edge of a mask simultaneously with the pattern of the 1st layer. 2. Measure the position and height of “alignment-and-height” marks before writing the 2nd layer. 3. Create a position/height correction map to write the 2nd layer. 4. Write the 2nd layer with reference to the correction map. Basic system attributes, such as beam origin and positional drift of mask blank, are monitored and adjusted throughout the process. We tested the process and achieved an alignment accuracy of 20 nm (3σ) between 1st and 2nd layers regardless of the density of the pattern area ratio, confirming that the process is effective for 65 nm node phase shift mask exposure.

Paper Details

Date Published: 6 December 2004
PDF: 8 pages
Proc. SPIE 5567, 24th Annual BACUS Symposium on Photomask Technology, (6 December 2004); doi: 10.1117/12.568784
Show Author Affiliations
Tadashi Komagata, JEOL USA, Inc. (United States)
Norio Kimura, JEOL Ltd. (Japan)
Kaoru Funaki, JEOL Ltd. (Japan)
Yasutoshi Nakagawa, JEOL Ltd. (Japan)
Nobuo Gotoh, JEOL Ltd. (Japan)

Published in SPIE Proceedings Vol. 5567:
24th Annual BACUS Symposium on Photomask Technology
Wolfgang Staud; J. Tracy Weed, Editor(s)

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