A plasmaless, photochemical etch process for porous organosilicate glass films
A plasmaless, photochemical etch process using ultraviolet (UV) light in the presence of NH3 or O2 etched porous organosilicate glass films, also called pSiCOH films, in a two-step process. First, a UV/NH3 or UV/O2 treatment removed carbon (mostly methyl groups bonded to silicon) from a pSiCOH film...
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Published in | Journal of applied physics Vol. 122; no. 24 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
28.12.2017
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Online Access | Get full text |
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Summary: | A plasmaless, photochemical etch process using ultraviolet (UV) light in the presence of
NH3 or O2 etched porous organosilicate glass films, also called
pSiCOH films, in a two-step process. First, a UV/NH3 or UV/O2
treatment removed carbon (mostly methyl groups bonded to silicon) from a pSiCOH film by
demethylation to a depth determined by the treatment exposure time. Second, aqueous HF was
used to selectively remove the demethylated layer of the pSiCOH film leaving the
methylated layer below. UV in the presence of inert gas or H2 did not
demethylate the pSiCOH film. The depth of UV/NH3 demethylation followed
diffusion limited kinetics and possible mechanisms of demethylation are presented. Unlike
reactive plasma processes, which contain ions that can damage surrounding structures
during nanofabrication, the photochemical etch contains no damaging ions. Feasibility of
the photochemical etching was shown by comparing it to a plasma-based process to remove
the pSiCOH dielectric from between Cu interconnect lines, which is a critical step during
air gap fabrication. The findings also expand our understanding of UV photon interactions
in pSiCOH films that may contribute to plasma-induced damage to pSiCOH films. |
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ISSN: | 0021-8979 1089-7550 |
DOI: | 10.1063/1.5008388 |