AVS 50th International Symposium
    Electronic Materials and Devices Thursday Sessions
       Session EM-ThM

Paper EM-ThM9
Low Temperature Chemical Vapor Deposition and Characterization of Ultra-thin Ruthenium for Copper Diffusion Barriers in ULSI Interconnects

Thursday, November 6, 2003, 11:00 am, Room 321/322

Session: Materials for Interconnects and Contacts to Semiconductors
Presenter: Q. Wang, University of Texas at Austin
Authors: Q. Wang, University of Texas at Austin
Y.-M. Sun, University of Texas at Austin
D. Gay, University of Texas at Austin
J.M. White, University of Texas at Austin
J.G. Ekerdt, University of Texas at Austin
Correspondent: Click to Email
Ultra-thin ruthenium (Ru) films covering Ta were investigated as part of a Cu diffusion barrier with enhanced adhesion of Cu that potentially enables seedless Cu plating on the barrier surface in ULSI interconnect processes. A low temperature thermal chemical vapor deposition (CVD) of ultra-thin Ru films on Ta and SiO@sub 2@ surfaces using ruthenium carbonyl [Ru@sub 3@(CO)@sub 12@] as a precursor was developed. Films deposited at substrate temperatures between 423 and 593 K were characterized using in-situ X-ray photoelectron spectroscopy (XPS), atomic force microscopy and in-situ four-point probe resistance measurements. A pure Ru ultra-thin film with low resistivity of ~50 µ@Ohm@@super .@cm was deposited without any reactive gas at temperatures as low as 423 K. In-situ ion scattering spectrometry and Ta 4f XPS peak attenuation indicated that the minimum thickness to form a continuous Ru film on Ta is ~2.5 nm. The pure Ru film also showed good thermal stability at elevated temperatures (up to 593 K). This Ru film also inhibited oxidation of the Ta film when the sample was exposed to air. Compared with poor wettability of Cu on Ta, only ~0.3 nm of Cu fully covers Ru indicating excellent wetting.