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Title: Effects of ultraviolet (UV) irradiation in air and under vacuum on low-k dielectrics

Abstract

This work addresses the effect of ultraviolet radiation of wavelengths longer than 250 nm on Si-CH{sub 3} bonds in porous low-k dielectrics. Porous low-k films (k = 2.3) were exposed to 4.9 eV (254 nm) ultraviolet (UV) radiation in both air and vacuum for one hour. Using Fourier Transform Infrared (FTIR) spectroscopy, the chemical structures of the dielectric films were analyzed before and after the UV exposure. UV irradiation in air led to Si-CH{sub 3} bond depletion in the low-k material and made the films hydrophilic. However, no change in Si-CH{sub 3} bond concentration was observed when the same samples were exposed to UV under vacuum with a similar fluence. These results indicate that UV exposures in vacuum with wavelengths longer than ∼250 nm do not result in Si-CH{sub 3} depletion in low-k films. However, if the irradiation takes place in air, the UV irradiation removes Si-CH{sub 3} although direct photolysis of air species does not occur above ∼242 nm. We propose that photons along with molecular oxygen and, water, synergistically demethylate the low-k films.

Authors:
; ;  [1];  [2]
  1. GLOBALFOUNDRIES, Albany, NY 12203 (United States)
  2. Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States)
Publication Date:
OSTI Identifier:
22611457
Resource Type:
Journal Article
Journal Name:
AIP Advances
Additional Journal Information:
Journal Volume: 6; Journal Issue: 7; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 2158-3226
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ABUNDANCE; CONCENTRATION RATIO; DIELECTRIC MATERIALS; FILMS; FOURIER TRANSFORMATION; INFRARED SPECTRA; IRRADIATION; OXYGEN; PHOTOLYSIS; PHOTONS; POROUS MATERIALS; SILICON; ULTRAVIOLET RADIATION; WAVELENGTHS

Citation Formats

Choudhury, F. A., Nguyen, H. M., Shohet, J. L., E-mail: shohet@engr.wisc.edu, Ryan, E. T., and Nishi, Y. Effects of ultraviolet (UV) irradiation in air and under vacuum on low-k dielectrics. United States: N. p., 2016. Web. doi:10.1063/1.4959277.
Choudhury, F. A., Nguyen, H. M., Shohet, J. L., E-mail: shohet@engr.wisc.edu, Ryan, E. T., & Nishi, Y. Effects of ultraviolet (UV) irradiation in air and under vacuum on low-k dielectrics. United States. https://doi.org/10.1063/1.4959277
Choudhury, F. A., Nguyen, H. M., Shohet, J. L., E-mail: shohet@engr.wisc.edu, Ryan, E. T., and Nishi, Y. 2016. "Effects of ultraviolet (UV) irradiation in air and under vacuum on low-k dielectrics". United States. https://doi.org/10.1063/1.4959277.
@article{osti_22611457,
title = {Effects of ultraviolet (UV) irradiation in air and under vacuum on low-k dielectrics},
author = {Choudhury, F. A. and Nguyen, H. M. and Shohet, J. L., E-mail: shohet@engr.wisc.edu and Ryan, E. T. and Nishi, Y.},
abstractNote = {This work addresses the effect of ultraviolet radiation of wavelengths longer than 250 nm on Si-CH{sub 3} bonds in porous low-k dielectrics. Porous low-k films (k = 2.3) were exposed to 4.9 eV (254 nm) ultraviolet (UV) radiation in both air and vacuum for one hour. Using Fourier Transform Infrared (FTIR) spectroscopy, the chemical structures of the dielectric films were analyzed before and after the UV exposure. UV irradiation in air led to Si-CH{sub 3} bond depletion in the low-k material and made the films hydrophilic. However, no change in Si-CH{sub 3} bond concentration was observed when the same samples were exposed to UV under vacuum with a similar fluence. These results indicate that UV exposures in vacuum with wavelengths longer than ∼250 nm do not result in Si-CH{sub 3} depletion in low-k films. However, if the irradiation takes place in air, the UV irradiation removes Si-CH{sub 3} although direct photolysis of air species does not occur above ∼242 nm. We propose that photons along with molecular oxygen and, water, synergistically demethylate the low-k films.},
doi = {10.1063/1.4959277},
url = {https://www.osti.gov/biblio/22611457}, journal = {AIP Advances},
issn = {2158-3226},
number = 7,
volume = 6,
place = {United States},
year = {Fri Jul 15 00:00:00 EDT 2016},
month = {Fri Jul 15 00:00:00 EDT 2016}
}