Precursor with (alkyloxy)(alkyl)-silylolefin ligand to deposit copper

Abstract

A method is provided for applying chemical vapor deposition (CVD) copper (Cu) to integrated circuit substrates using a Cu(hfac)(ligand) precursor with a silylolefin ligand including combinations of C1-C8 alkyl groups with at least one C2-C8 alkyloxy group. The alkyloxy groups include, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, and aryloxy, while the alkyl groups include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, and aryl. The oxygen atoms of the alkyloxy groups, and the long carbon chains of both the alkyl and alkyloxy groups, increase the stability of the precursor by contributing electrons to the Cu(hfac) complex. The improved bond helps insure that the ligand separates from the (hfac)Cu complex at consistent temperatures when Cu is to be deposited. Combinations of alkyloxy and alkyl groups allow the molecular weight of the precursor to be manipulated so that the volatility of the precursor is adjustable for specific process scenarios. Other embodiments provide a precursor blend made from additional silylolefins, hexafluoroacetylacetone (H-hfac), H-hfac dihydrate, and water, either separately, or in combinations, to enhance deposition rate, conductivity, and precursor stability. A Cu precursor compound including silylolefin ligands having at least one alkyloxy group is also provided. Combinations of ethyl groups with ethoxy groups are specifically disclosed.