Selective Cu growth on fine structures using a Cu-iodide precursor

Abstract

Selective Cu deposition by CVD using copper(I)-iodide (CuI) as the precursor is applied on 0.5 μm- and 1.0 μm-pitch Cu-lines/SiO2 -spaces (L/S) at 370 °C. A confocal laser microscope suggests that the Cu is selectively deposited on the Cu line, not on the space. The average Cu height provided by the cross-sectional profile across the 1.0 μm-pitch L/S, which is linearly increased with total CuI supply, evaluates that the dissociation efficiency of CuI is about 23%. Surface scanning electron microscopy and energy dispersive X-ray spectroscopy clearly show the selective deposition of Cu, but surface roughness on the deposited Cu is increases with the Cu-height. The feature of surface roughness is discussed on the coalescent Cu line at the deposition temperature and the rate-limiting step in the CVD. The selective Cu deposition is also performed on 0.5 μm-pitch L/S, in which the deposition rate is similar but the surface is rougher than on the 1.0 μm-wide line.