Impact of photo-induced species in O2-containing gases on lithographic patterning at 193-nm wavelength

Uzodinma Okoroanyanwu; Peter Kunze; Katharina H.B. Al-Shamery; Jeremias Romero; Joffre Bernard

doi:10.1117/12.474623

30 July 2002 Impact of photo-induced species in O₂-containing gases on lithographic patterning at 193-nm wavelength

Uzodinma Okoroanyanwu, Peter Kunze, Katharina H.B. Al-Shamery, Jeremias Romero, Joffre Bernard

Proceedings Volume 4691, Optical Microlithography XV; (2002) https://doi.org/10.1117/12.474623
Event: SPIE's 27th Annual International Symposium on Microlithography, 2002, Santa Clara, California, United States

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.

Citation Download Citation

Uzodinma Okoroanyanwu, Peter Kunze, Katharina H.B. Al-Shamery, Jeremias Romero, and Joffre Bernard "Impact of photo-induced species in O₂-containing gases on lithographic patterning at 193-nm wavelength", Proc. SPIE 4691, Optical Microlithography XV, (30 July 2002); https://doi.org/10.1117/12.474623

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available