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Proceedings Paper

Evaluation of a transmission CD-SEM for EB stencil masks
Author(s): Mikio Ishikawa; Hiroshi Fujita; Morihisa Hoga; Hisatake Sano
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Paper Abstract

Scanning-electron microscopes designed for critical dimension (CD) measurement (CD-SEMs), which operate in a reflection mode, are commonly used in photomask quality assurance. However, such CD-SEMs are not always suitable for CD measurement of electron beam (EB) stencil masks such as electron-beam projection lithography (EPL) masks and low-energy electron-beam proximity projection lithography (LEEPL) masks. A dual-mode CD-SEM, which can operate in a transmission mode besides in a reflection mode, was recently developed by HOLON. The performance of the tool will be reported. Two EPL test masks with a 2-μm-thick Si scatterer and one LEEPL test mask with about 1-μm-thick absorber were prepared. The EPL masks have 1:1 lines-and-spaces (L&S) patterns and isolated spaces, all varying from 200 to 1000 nm in designed size. The LEEPL mask has 1:1 L&S patterns ranging from 80 to 550 nm. The masks were observed at an acceleration voltage of 5.5 kV with no bias voltage and a current of 10 pA. The dual-mode CD-SEM is found to have the following characters: (1) short-term repeatability and long-term repeatability less than 2 nm in both modes, (2) compatibility with a photomask CD-SEM in the reflection mode, (3) coincidence of the CDs measured in the transmission mode from the front side and back side within 3.0 nm for stencil patterns with a sidewall angle larger than 89.8 deg, and (4) capability of measurement at least down to 80 nm. Therefore we conclude that the dual-mode CD-SEM is applicable for measurement of CDs of EB stencil masks.

Paper Details

Date Published: 28 August 2003
PDF: 9 pages
Proc. SPIE 5130, Photomask and Next-Generation Lithography Mask Technology X, (28 August 2003); doi: 10.1117/12.504237
Show Author Affiliations
Mikio Ishikawa, Dai Nippon Printing Co., Ltd. (Japan)
Hiroshi Fujita, Dai Nippon Printing Co., Ltd. (Japan)
Morihisa Hoga, Dai Nippon Printing Co., Ltd. (Japan)
Hisatake Sano, Dai Nippon Printing Co., Ltd. (Japan)

Published in SPIE Proceedings Vol. 5130:
Photomask and Next-Generation Lithography Mask Technology X
Hiroyoshi Tanabe, Editor(s)

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