Share Email Print
cover

Proceedings Paper

Impact of photo-induced species in O2-containing gases on lithographic patterning at 193-nm wavelength
Author(s): Uzodinma Okoroanyanwu; Peter Kunze; Katharina H.B. Al-Shamery; Jeremias Romero; Joffre Bernard
Format Member Price Non-Member Price
PDF $14.40 $18.00
cover GOOD NEWS! Your organization subscribes to the SPIE Digital Library. You may be able to download this paper for free. Check Access

Paper Abstract

In order to prevent contaminants and impurities from being deposited on the optical elements of the tool, ArF lithographic patterning of photoresists is currently done in the exposure chamber of a scanner or stepper that is purged with clean dry air. Unfortunately, the 6.4 eV (193 nm) ArF laser photons can dissociate molecular oxygen in air into atomic oxygen, form ozone, form singlet molecular oxygen and atomic oxygen from the photodissociation of ozone, and mediate singlet molecular oxygen formation in polymers by energy transfer mechanisms from impurities or specially added sensitizers (S) (e.g. dyes). Once formed, these species mediate photo-oxidative degradation processes of resist polymers, including cross-linking, chain scission, oxidation, and other secondary reactions by free radical mechanisms, resulting in resist feature erosion, poor resist feature profiles, particularly under bright field illumination in full field scanners and steppers. The occurrence of these photo-oxidative degradation processes has been experimentally verified in photoresist films exposed in commercially available ArF laser scanners and steppers that are purged with clean dry air. Using a custom-built ultra-high vacuum (UHV) chamber equipped with ArF laser beam line, mass spectrometer, and infra-red spectrometer, as well as an ex-situ X-ray photo-electron spectrometer and a Fourier Transform infra-red spectrometer, the effects of different exposure environments (dry air, nitrogen, oxygen, ozone/oxygen mixture, and vacuum) in either contributing to or mitigating these photo-oxidative degradation processes during exposure of photoresist films were studied. The effects of these photo-oxidative degradation processes have been quantified, and it was observed that the processes are initiated at the surface of resist polymers by photo-induced species, and proceed inwards, giving rise to a gradient of deteriorated material across the specimen thickness.

Paper Details

Date Published: 30 July 2002
PDF: 19 pages
Proc. SPIE 4691, Optical Microlithography XV, (30 July 2002); doi: 10.1117/12.474623
Show Author Affiliations
Uzodinma Okoroanyanwu, Advanced Micro Devices, Inc. (United States)
Peter Kunze, Carl von Ossietzky Univ. Oldenburg (Germany)
Katharina H.B. Al-Shamery, Carl von Ossietzky Univ. Oldenburg (Germany)
Jeremias Romero, Advanced Micro Devices, Inc. (United States)
Joffre Bernard, Advanced Micro Devices, Inc. (United States)


Published in SPIE Proceedings Vol. 4691:
Optical Microlithography XV
Anthony Yen, Editor(s)

© SPIE. Terms of Use
Back to Top