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Chemical and Morphological Characterization of Low‐ k Dielectric Films Deposited From Hexamethyldisiloxane and Ethylene RF Glow Discharges
Author(s) -
Coclite Anna Maria,
Milella Antonella,
Palumbo Fabio,
Fracassi Francesco,
d'Agostino Riccardo
Publication year - 2010
Publication title -
plasma processes and polymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 74
eISSN - 1612-8869
pISSN - 1612-8850
DOI - 10.1002/ppap.201000091
Subject(s) - hexamethyldisiloxane , plasma enhanced chemical vapor deposition , dielectric , materials science , permittivity , annealing (glass) , ethylene , analytical chemistry (journal) , siloxane , x ray photoelectron spectroscopy , chemical engineering , plasma , thin film , chemistry , composite material , organic chemistry , nanotechnology , polymer , optoelectronics , physics , quantum mechanics , engineering , catalysis
Low‐ k dielectric films were deposited by PECVD from mixtures of hexamethyldisiloxane (HMDSO), ethylene, and oxygen. After deposition the films were thermally annealed in order to reduce their permittivity. Different deposition conditions were investigated in order to accomplish the best trade‐off between low permittivity and low thickness loss upon annealing. Soft plasma conditions were required in order to allow organic species incorporation in the film and achieve dielectric constant as low as 2.2 with a thickness loss of 14% upon thermal annealing treatment. Results were also compared to those obtained with divinyltetramethyldisiloxane, which is similar in structure to HMDSO but with two vinyl groups replacing methyl ones. The morphological analysis showed that feeding the plasma with a large amount of ethylene, CH x ‐enriched nanodomains were obtained over a siloxane matrix. Finally, the plasma phase composition was also investigated by infrared spectroscopy and correlated with the film chemistry.