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Proceedings Paper

Plasma technology for advanced quartz mask etching
Author(s): Munenori Iwami; Hirotsugu Ita; Yoshihisa Kase; Hidehito Azumano; Kazuki Nakazawa; Yoshie Okamoto; Hiroki Shirahama; Tomoaki Yoshimori; Makoto Muto; Ivan Ganachev
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Paper Abstract

We review the state-of-art and issues of dry etching of masks for nano-device photo lithography. After introducing the basics of photo-mask structures and their plasma etching, we discuss the specifics of mask etching as compared to the etching of silicon wafers, focusing on processes for the two most-challenging cases: phase-shift masks and NGL where it is achieved by etching the quartz exactly to the prescribed depth. State-of the art solutions for the etching of such masks must provide stringent etching uniformity and accurate end-point monitoring. This can be addressed by either reducing the lithography fields to half or even quarter of their present area, with two to four times worse productivity, or working with larger masks of 9 and later 12 inch. The pressure for such development is becoming stronger with the wider adoption of 450 mm wafers. The new masks may need to be thicker to prevent unwanted deformations. Etching uniformity will have to be sustained over much wider areas. Furthermore, RF bias control for thicker substrates is not straightforward due to the quartz impedance preventing effective RF coupling. Our etching experiments in Ar and Cl2 showed that well established mask etching conditions can be reproduced for moderately thicker substrates, while further increase of substrate thickness may require essentially different approach, such as a series resonance of the inductive plasma bulk and the capacitive sheath.

Paper Details

Date Published: 8 October 2014
PDF: 6 pages
Proc. SPIE 9235, Photomask Technology 2014, 92350D (8 October 2014); doi: 10.1117/12.2073069
Show Author Affiliations
Munenori Iwami, Shibaura Mechatronics Corp. (Japan)
Hirotsugu Ita, Shibaura Mechatronics Corp. (Japan)
Yoshihisa Kase, Shibaura Mechatronics Corp. (Japan)
Hidehito Azumano, Shibaura Mechatronics Corp. (Japan)
Kazuki Nakazawa, Shibaura Mechatronics Corp. (Japan)
Yoshie Okamoto, Shibaura Mechatronics Corp. (Japan)
Hiroki Shirahama, Shibaura Mechatronics Corp. (Japan)
Tomoaki Yoshimori, Shibaura Mechatronics Corp. (Japan)
Makoto Muto, Shibaura Mechatronics Corp. (Japan)
Ivan Ganachev, Shibaura Mechatronics Corp. (Japan)


Published in SPIE Proceedings Vol. 9235:
Photomask Technology 2014
Paul W. Ackmann; Naoya Hayashi, Editor(s)

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