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Nanoscale Observation of Dielectric Damage to Low k MSQ Interconnects from Reactive Ion Etching and Ash Treatment

Published online by Cambridge University Press:  01 February 2011

Todd S. Gross  and
Shaoning Yao
Todd S. Gross
Affiliation:
University Of New Hampshire, Department of Mechanical Engineering, Materials Science Program, Durham, NH Sri Satyanarayana SEMATECH, Austin, TX
Shaoning Yao
Affiliation:
University Of New Hampshire, Department of Mechanical Engineering, Materials Science Program, Durham, NH Sri Satyanarayana SEMATECH, Austin, TX
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Abstract

Electrostatic force microscopy (EFM) was used to measure the extent of dielectric damage from plasma processing of nanoporous, low k methyl silsesqioxane (MSQ) interconnect structures with approximately 50 nm spatial resolution. Single level patterns were formed in 200 nm thick MSQ films by reactive ion etching (RIE) and were subsequently backfilled with an MSQ layer that was not exposed to plasma to act as a reference. The backfill was performed on as-etched structures with the photoresist intact and on structures in which the photoresist was removed by an oxygen plasma (ash) treatment. The EFM images on cross sections and feather sections show that the damage from the RIE penetrated ∼100 nm in from the sidewall and that the redeposited polymer had a higher k than the MSQ (k∼2.2). The etched and ashed MSQ exhibits a higher dielectric constant than the reference MSQ if it was exposed to water and has nearly the same dielectric constant as the reference with no water exposure. This suggests that the damage from the ash acts to make the MSQ hydrophilic.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 863: Symposium B – Materials, Technology and Reliability of Advanced Interconnects , 2005 , B2.4
Copyright
Copyright © Materials Research Society 2005

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