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Proceedings Paper

Measurement of hard pellicles for 157-nm lithography using Fourier transform phase-shifting interferometry
Author(s): Leslie L. Deck; Chris Van Peski; Richard D. Eandi
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Paper Abstract

Though phase-shifting interferometry (PSI) is widely regarded as the method of choice for precision measurements of the surface and bulk characteristics of optical components, conventional PSI suffers from severe distortions in the presence of multiple reflections caused from co-parallel surfaces. The optical and physical characteristics of hard pellicles used for 157nm lithography mean that they are essentially parallel plates and the use of standard PSI techniques to evaluate the optical quality of these components will suffer from these problems. We describe a measurement method called Fourier Transform phase-shifting interferometry (FTPSI) that can overcome the disadvantages of standard PSI by the use of wavelength tuning and special analysis techniques. The technique can measure several surfaces simultaneously without distortion from multiple interference effects and is applied to the measurement of mounted and unmounted pellicles. Additionally, bulk properties of the pellicle, such as index homogeneity, can be easily measured with high precision. By spectrally separating the interference produced by different surfaces in the cavity during a wavelength chirp, each surface is identified and measured individually. In this paper, we describe the technique and give examples of measurements of hard pellicles provided by International SEMATECH.

Paper Details

Date Published: 28 August 2003
PDF: 8 pages
Proc. SPIE 5130, Photomask and Next-Generation Lithography Mask Technology X, (28 August 2003); doi: 10.1117/12.504217
Show Author Affiliations
Leslie L. Deck, Zygo Corp. (United States)
Chris Van Peski, International SEMATECH (United States)
Richard D. Eandi, Zygo Corp. (United States)


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

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