Effect of phosphorus on the copper diffusion barrier properties of electroless CoWP films

• Published in: Thin solid films Vol. 519; no. 15; pp. 4958 - 4962
• Main Authors: Tsai, T.K., Wu, S.S., Hsu, C.S., Fang, J.S.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 31.05.2011; Elsevier
• Subjects: Annealing; Barriers; Chemical interdiffusion; diffusion barriers; Cobalt silicide; Condensed matter: structure, mechanical and thermal properties; Copper; Cu 3Si; Diffusion barrier; Diffusion barriers; Diffusion in solids; Diffusion; interface formation; Electroless CoWP; Exact sciences and technology; Failure; Phosphorus; Physics; Scanning electron microscopy; Silicon; Solid surfaces and solid-solid interfaces; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; Transport properties of condensed matter (nonelectronic); Cobalt silicide; Diffusion barrier; Electroless CoWP; Cu 3Si; Scanning electron microscopy; Interdiffusion; Phosphorus; Dispersive spectrometry; Cobalt; AES; Thin films; Cu; Transmission electron microscopy; Sheet resistivity; Diffusion barriers; Si; Silicon; Copper; Diffusion; Thermal annealing
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2011.01.061

The properties of electroless CoWP barrier films with different phosphorus contents in Cu/CoWP/Si stacked samples were explored. The Cu/CoWP/Si stacked samples with 30 nm CoWP films, contained about 5.7, 8.2 and 10.8 at.% P, were prepared by electroless deposition, and then annealed in a rapid thermal annealer at a temperature between 300 and 700 °C. The effect of phosphorus content in CoWP film on the barrier properties in preventing copper diffusion and the failure of the Cu/CoWP/Si stacked samples after thermal annealing were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrometer (EDS), Auger electron spectroscopy (AES), and sheet resistance measurement. Increasing the phosphorus content in the electroless CoWP film markedly improves the barrier properties. The failure temperature of Cu/CoWP/Si increased from 500 to 600 °C with the phosphorus content in CoWP film increasing from 5.7 to 10.8 at.%, and the failure of the Cu/CoWP/Si has mainly arisen from the interdiffusion of copper and cobalt during thermal annealing.