Selective and blanket copper chemical vapor deposition for ultra-large-scale integration

Abstract

Selective and conformal chemical vapor deposition (CVD) of copper from (hfac)Cu(VTMS), where hfac=1,1,1,5,5,5-hexafluoroacetylacetonate, VTMS=vinyltrimethylsilane, has been studied. The compounds (hfac)CuL, L=VTMS, 1,5-COD, and 2-butyne, deposited copper on both SiO2 and W, nonselectively, under the conditions employed. Selective CVD onto W in the presence of SiO2 was obtained by passivating SiO2 surface hydroxyl groups via reaction with Me3SiCl in the liquid phase. However, selective deposition was maintained only for short periods (1 min), and loss of selectivity was attributed to the desorption of hydrogen-bonded Me3SiCl groups which exposed the reactive SiO2 surface sites (hydroxyl groups). To avoid this problem, gaseous (CH3)2SiCl2 was introduced during Cu CVD and resulted in selective deposition for longer periods at respectable rates (≳2500 Å/min at 170 °C). Highly conformal deposition was demonstrated on test structures with keyhole geometries and trenches with widths of 2.8–0.45 μm and aspect ratios of 0.35–1.40. Deposition rates were 1000–2500 Å/min at temperatures of 160–170 °C with (hfac)Cu(VTMS) partial pressures of 10–17 mTorr.