Chemical Vapor Deposition of Tantalum Oxide from Tetraethoxo(β-diketonato)tantalum(V) Complexes

Abstract

The complexes [Ta(OEt)4(β-diketonate)] (β-diketonate = acetylacetonate, 2; hexafluoroacetylacetonate, 3; 1,1,1-trifluoroacetylacetonate, 4; dipivaloylmethanate, 5; 2,2-dimethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octanedionate, 6) are established as volatile liquid precursors for low-pressure chemical vapor deposition (CVD) of films of tantalum(V) oxide. They give thermal CVD at a slightly lower temperature than the commonly used precursor [{Ta(OEt)5}2], 1. In all cases, the CVD at 300−450 °C gives amorphous films of Ta2O5, which crystallize on annealing at 800 °C under oxygen. Promotion of Ta2O5 film formation is established using catalyst-enhanced CVD with a palladium precursor as "catalyst" and the minimum CVD temperature is then reduced to 200 °C.