Effects of polymer/metal interaction in thin-film multichip module applications

The effects of different polyimide/metal combinations on structures similar to those used in thin-film multichip module applications were studied. Three different metal structures and three commercially available spin-on polyimide materials with differing molecular structures were examined. Transmission electron microscopy (TEM) was used to study the polyimide/metal interfaces. Measurements of the electrical signal propagation through the different polyimide/metal structures were compared. It was found that the extent of interaction of polyimide with copper is dependent on the type of polyimide used. The use of an electroless nickel layer over copper structures was found to retard copper/polyimide interaction during the curing cycle. The use of aluminum conductor lines with various polyimides was also examined. No significant interaction occurred between aluminum and any of the tested polyimides