MODIFIED TOP ELECTRODE STRUCTURE FOR THIN FILM CAPACITORS.

The decoupling thin film capacitor comprises a bottom electrode, a dielectric (thin) layer and a top electrode which is covered by a suitable insulator, e. g. , quartz. To reduce contact resistance between the solder mount and Al-Cu metallurgy, a dc or rf sputter cleaning is employed. When the capacitors were subjected to rf sputter cleaning, most of them broke down. The origin of the solder-mound contact resistance is the thin Al//2O//3 that is ever present in aluminum. In this new approach, the top electrode is modified to form a sandwich structure so that a non-oxidizing surface is exposed to the terminal metallurgy. The sandwich structure consists of a layer layer of Pt, Pd, or Au in the thickness range of 1000-5000 A along with a thin layer of thin Cr or Ti.