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Proceedings Paper

Deformation and stress in PMMA during hard x-ray exposure for deep lithography
Author(s): Nicolai A. Moldovan
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Paper Abstract

The availability of high-energy, high-flux, collimated synchrotron radiation has extended the application of deep X-ray lithography to thickness values of the PMMA resist of several millimeters. Some of the most severe limitations come from plastic deformation, stress, and cracks induced in PMMA during exposure and development. We have observed and characterized these phenomena quantitatively. Profilometry measurements revealed that the PMMA is subjected either to local shrinkage or to expansion, while compression and expansion evolve over time. Due to material loss and crosslinking, the material undergoes a shrinkage, while the radiation-induced decomposition generates gases expanding the polymer matrix. The overall dynamics of the material microrelief and stress during and after the exposure depend on the balance between compaction and outgassing. These depend in turn on the exposure conditions (spectrum, dose, dose rate, scanning, temperature), post-exposure storage conditions, PMMA material properties and thickness, and also on the size and geometry of the exposed patterns.

Paper Details

Date Published: 3 September 1999
PDF: 9 pages
Proc. SPIE 3875, Materials and Device Characterization in Micromachining II, (3 September 1999); doi: 10.1117/12.360466
Show Author Affiliations
Nicolai A. Moldovan, Argonne National Lab. (United States)

Published in SPIE Proceedings Vol. 3875:
Materials and Device Characterization in Micromachining II
Yuli Vladimirsky; Craig R. Friedrich, Editor(s)

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