Studies of Ni-B as an electrochemical metal migration barrier

The effectiveness of electroless Ni-B as a barrier metal to prevent the electrochemical migration between adjacent copper lines on a polyimide dielectric substrate was studied by measuring the resistance of the polyimide dielectric and by observing the electrochemical migration between the fine lines by reflective electron microscope after stress conditions. The rate-determining step associated with the electrochemical migration was also discussed.