Investigation of Ligand Surface Chemistry: Implications for the Use of £]-Diketonate Copper(I) Complexes as Precursors for Copper Thin-film Growth
Two most useful families of copper CVD precursors that have been utilized widely are the Cu(I) and Cu(II) £]-diketone complexes. The Cu(II)precursors require the use of an external reducing agent such as hydrogen to
deposit copper films, i.e. CuII(£]-diketonate)2 + H2 ¡÷ Cu0+2 £]-diketonate.
The Cu(I) precursors deposit pure copper films without the use of an external
agent via a disproportionation reaction that produces a Cu(II)£]-diketonate in
conjunction with other organic byproducts, i.e. 2CuI(£]-diketonate)L ¡÷
Cu0+ CuII(£]-diketonate)2+2L where L is a typical Lewis base neutral ligand.
However, Do those ligands resulting from the dissociation of the precursors
simply desorb intact from the substrate or the growing films, or react further on the surface? To understand the surface chemistry of these ligands may provide better knowledge for designing more superior precursors and improvement of fabrication processes.
Cu(hfac)(VTMS) and Cu(hfac)(MHY) are the most promising Cu(I) precursors, as shown in Scheme 1.1. Here we report studies on the chemistry
of VTMS, MHY and hfacH on a Cu(111) surface. It should be noted that the hfacH is the simplest molecule containing the hfac, so we use it as a reference for £]-diketonate ligand. The Cu(111) single crystal was used to mimic the reactivity of these ligands on a growing Cu film during copper CVD. In situ analysis of ligand surface chemistry is carried out by TPD/R
(temperature-programmed desorption/reaction) and RAIRS (reflection adsorption infrared spectroscopy) to elucidate plausible reaction mechanisms by which ligands decompose and eventually lead to impurity incorporation
into the growing films, and to suggest means of minimizing such reactions.
Advisor:Chia-Chun Chen; Jong-Liang Lin; Chao-Ming Chiang
School:National Sun Yat-Sen University
School Location:China - Taiwan
Source Type:Master's Thesis
Keywords:tpd r mhy vtms hfach uhv cu 111 rairs
Date of Publication:07/24/2002