28 June 2005 Stencil pattern accuracy of EPL masks
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Proceedings Volume 5853, Photomask and Next-Generation Lithography Mask Technology XII; (2005); doi: 10.1117/12.617279
Event: Photomask and Next Generation Lithography Mask Technology XII, 2005, Yokohama, Japan
Abstract
Stencil masks for electron projection lithography (EPL) require peculiar patterns as perforations in a thin membrane. The stencil pattern accuracy of a conventional mask with 1-mm subfields and a new geometry mask with 4-mm subfields was evaluated and compared. No significant influence of the mask geometry on most of critical dimension (CD) specifications was observed. The stencil patterns in both geometry masks had vertical sidewalls ~ 90° with angle range less than 0.3° and CD uniformity of ~12 nm (3σ) across the mask. CD linearity is also similar for both geometry masks. On the other hand, enlarging the membrane windows considerably increased CD deterioration and image placement (IP) distortion within individual membranes. A practical 4 mm-window mask requires solution to this issue. The stencil pattern accuracy is, however, acceptable level for not only the 1 mm-window mask but also the 4 mm-window mask at current EPL development status. According to the evaluation of the stencil pattern accuracy, pattern specification of the EPL mask for 45-nm node would be achieved with further process optimization despite of its peculiarity in pattern structure.
© (2005) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Hiroshi Sugimura, Tsukasa Yamazaki, Takashi Susa, Yoshiyuki Negishi, Takashi Yoshii, Hideyuki Eguchi, Akira Tamura, "Stencil pattern accuracy of EPL masks", Proc. SPIE 5853, Photomask and Next-Generation Lithography Mask Technology XII, (28 June 2005); doi: 10.1117/12.617279; https://doi.org/10.1117/12.617279
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KEYWORDS
Photomasks

Reactive ion etching

Critical dimension metrology

Lithography

Etching

Mask making

Silicon

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