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Modified Top Electrode Structure for Thin Film Capacitors

IP.com Disclosure Number: IPCOM000041284D
Original Publication Date: 1984-Jan-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 69K

Publishing Venue

IBM

Related People

Herdzik, RJ: AUTHOR [+3]

Abstract

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. The top electrode is Al-Cu. Via holes are etched in the insulator (quartz) and used to make contacts between electrodes and a solder mound. To reduce contact resistance between the solder mound and Al-Cu metallurgy, a DC or RF sputter cleaning (in situ) is employed. These capacitors have a breakdown voltage of 10-20 V. When they were subjected to RF sputter cleaning, most of the capacitors broke down. The origin of the solder-mound contact resistance is the thin Al2O3 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.

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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. The top electrode is Al-Cu. Via holes are etched in the insulator (quartz) and used to make contacts between electrodes and a solder mound. To reduce contact resistance between the solder mound and Al-Cu metallurgy, a DC or RF sputter cleaning (in situ) is employed. These capacitors have a breakdown voltage of 10-20 V. When they were subjected to RF sputter cleaning, most of the capacitors broke down. The origin of the solder-mound contact resistance is the thin Al2O3 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 of Pt, Pd, or Au in the thickness range of 1000-5000 ~ along with a thin layer of thin Cr or Ti, as shown in Fig. 2. In Fig. 2, the function of Cr, Ti or NICHROME* is to provide an adhesion layer to sputtered quartz. After the vias are opened by wet etch of sputtered quartz, using a dry or wet etch the thin layer of Cr, Ti or NICHROME is removed, leaving non-oxidizing Pt, Pd or Au surface. Now, the solder-mound contact metallurgy evaporation and PbSn evaporation can be carried out without sputter cleaning and without concern for high contact resistance....