Evaluation of Oxalyl Fluoride for a Dielectric Etch Application in an Inductively Coupled Plasma Etch Tool

The goal of the work presented in this article was to provide a preliminary screening for a novel fluorinated compound, oxalyl fluoride, as a potential replacement for perfluorocompounds in dielectric etch applications. Both process and emissions data were collected and the results were compared to those provided by a process utilizing a standard perfluorinated etch chemistry In this evaluation, oxalyl fluoride produced very low quantities of global warming compounds under the conditions in which it was tested, as compared to the process. A preliminary evaluation of the compound's process performance was also carried out. Patterned tetraethoxysilane-deposited silicon oxide masked with deep UV photoresist having 0.6, 0.45, and 0.35 μm via hole features was used as the test vehicle. Although was capable of etching silicon dioxide, low oxide etch rate and poor selectivity to the mask layer were observed. Finally, in addition to the experimental work performed, a set of ab initio quantum chemical calculations was undertaken to obtain enthalpies of dissociation for each of the bonds in the oxalyl fluoride molecule in order to better understand its dissociation pathways in plasma environments.