Characterization of low-k dielectric trench surface cleaning after a fluorocarbon etch

The cleaning process of low-k dielectric trench structures used in sub-0.13 mum. technology was investigated. These trenches were fabricated from silicon carbide, silicon oxide and CVD SiCOH low-k film using a fluorocarbon etching chemistry. The compared cleaning methods include N-2/H-2 plasma treatment, semi-aqueous organic strippers, dilute HF and combinations of plasma treatment and the aforementioned chemicals. Angle-resolved X-ray photoelectron spectroscopy (XPS) was used to investigate the nature and quantity of the contaminants deposited on the copper surfaces at the bottom of the trenches and on the dielectric sidewalls. Significant Cu-, C-, F- and O-containing contaminants were found on both the copper surface at the trench bottoms and the dielectric sidewalls after etching. The cleaning treatments were generally found to be ineffective when used individually. On the contrary, a two-step approach, viz. N-2/H-2 plasma treatment followed by wet clean was found to give favorable removal of contaminants. (C) 2004 Elsevier B.V. All rights reserved.