Copper Oxide Films Grown by Atomic Layer Deposition from Bis(tri-n-butylphosphane)copper(I)acetylacetonate on Ta, TaN, Ru, and SiO[sub 2]

Abstract

The thermal atomic layer deposition (ALD) of copper oxide films from the non-fluorinated yet liquid precursor bis(tri-n-butylphosphane)copper(I)acetylacetonate, [( n Bu 3 P) 2 Cu(acac)], and wet O 2 on Ta, TaN, Ru and SiO 2 substrates at temperatures of < 160 C is reported. Typical temperature-independent growth was observed at least up to 125 C with a growth-per-cycle of 0.1 for the metallic substrates and an ALD window extending down to 100 C for Ru. On SiO 2 and TaN the ALD window was observed between 110 and 125 C, with saturated growth shown on TaN still at 135 C. Precursor self-decomposition in a chemical vapor deposition mode led to bimodal growth on Ta, resulting in the parallel formation of continuous films and isolated clusters. This effect was not observed on TaN up to about 130 C and neither on Ru or SiO 2 for any processing temperature. The degree of nitridation of the tantalum nitride underlayers considerably influenced the film growth. With excellent adhesion of the ALD films on all substrates studied, the results are a promising basis for Cu seed layer ALD applicable to electrochemical Cu metallization in interconnects of ultralarge-scale integrated circuits. Cu Dielectric cap SiO 2 or ULK Barrier PVD Seed ECD Cu Void Lower interconnect level Via level Upper interconnect level