Copper(I), silver(I) and gold(I) carboxylate complexes as precursors in chemical vapour deposition of thin metallic films

Abstract

Volatile precursors of copper, silver and gold for chemical vapour deposition (CVD) of metallic layers are described. There is considerable research interest in CVD because it provides advantages such as selective deposition, control of film density and thickness, etc. over other physical deposition techniques. Copper, silver, and gold compounds used as CVD precursors can be divided into three types: inorganic, coordination and organometallic. Organometallic compounds are often used as CVD precursors, however they usually are air and moisture sensitive, moreover they are characterized by low thermal stability. Inorganic compounds, which are usually air stable and easy to obtain, exhibit low volatility and require lower deposition pressures and higher vapourization temperatures. Therefore, we present here results on: (a) synthesis and characterization of inorganic and coordination precursors, (b) applications in CVD of metallic layers, (c) studies on the impact of CVD parameters on the quality of nanolayers, (d) gas phase composition and reactions during fabrication of the metallic films. Carboxylates of copper(I), silver(I) and gold(I) and their complexes with tertiary phosphines are described as a new class of CVD precursor. The molecular structures have been discussed based on X-ray structural analysis and spectroscopic methods. 1H, 13C, 31P, 19F, 63Cu NMR 31P CP MAS NMR, along with variable temperature NMR and IR were used for characterization of new Cu(I), Ag(I) and Au(I) complexes of general formula [M (COOR)(L)] where R = CH 3, C(CH 3) 3, C 2F 5, C 2H 5, (CH 3) 3SiCH 2, C 3H 7, C 3F 7, (CH 3) 3SiC 2H 4, C 4H 9, C 6F 13, C 7F 15, C 8F 17, C 9F 19, C 6F 5, C 6H 2(CH 3) 3, L = PR′ where R′ = Me, Et, Ph, OMe, OEt, OPh, or L = diphosphines—dppm, dppe. The analyses of thermal decomposition and MS data have been used for elucidation of the decomposition mechanisms, description of the transport in the gas phase and deposition processes. The molecular structures of the precursors have been discussed in relation to the quality of the obtained metallic nanolayers.