Barrier properties of ALD1,5N thin films

W1.5N films grown by ALD from WF6, NH3, C2H4 and SiH4 as precursors were tested as Cu diffusion barriers in p+/n diodes and capacitors with SiO2 as a dielectric. I-V and C-V, C-t characteristics were measured before and after anneal. The layers exhibit excellent barrier properties against both Cu and Al interaction with silicon. No changes of current and capacitance attributed to a barrier failure were observed after annealing at 400°C. Samples without the barrier showed a drastic change of the I-V characteristics. The composition of the films was W1.5N as determined with RBS, being a mixture of WN and W2N phases The RMS- roughness was as low as 0.5-0.7 nm for a film with a thickness of 25 nm. © 2005 Materials Research Society