Homogeneous and heterogeneous reactions in the decomposition of precursors for the MOCVD of high- k and ferroelectric films

Abstract

The present paper reports on the role of heterogeneous and homogeneous reactions in the MOCVD of Sr(hfac) 2tetraglyme (H-hfac =1,1,1,5,5,5-hexafluoroacetylacetone) and Ta(OC 2H 5) 5 precursors. Hints of the precursor decomposition during MOCVD processes in hot wall reactors have been obtained through in situ FT-IR monitoring of the gas phase composition. Two different reaction pathways have been proposed for the MOCVD of Sr(hfac) 2tetraglyme. A heterogeneous decomposition mechanism is the most relevant process at low temperatures and/or in the presence of reactive surfaces (metal), while a homogeneous decomposition leading to CF 2O and acylketenes is evident at high temperature and/or adopting less reactive surfaces. In the case of Ta(OC 2H 5) 5, the main pathway involves a heterogeneous process leading to C 2H 5OH, enhanced in presence of metallic surfaces.