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, C2O2F2 (F-(C= O)-(C=O)-F), as a potential replacement for perfluorocompounds in dielectri c 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 (C2F6). In this evaluation, oxalyl fluoride p roduced very low quantities of global warming compounds under the condition s in which it was tested, as compared to the C2F6 process. A preliminary ev aluation of the compound's process performance wa's also carried out. Patte rned tetraethoxysilane-deposited silicon oxide masked with deep UV photores ist having 0.6, 0.45, and 0.35 mum via hole features was used as the test v ehicle. Although C2O2F2 was capable of etching silicon dioxide, low oxide e tch rate and poor selectivity to the mask layer were observed. Finally, in addition to the experimental work performed, a set of ab initio quantum che mical calculations was undertaken to obtain enthalpies of dissociation for each of the bonds in the oxalyl fluoride molecule in order to better unders tand its dissociation pathways in plasma environments. (C) 2001 The Electro chemical Society. All rights reserved.