Integral thin film capacitors: Fabrication and integration issues

Although integral passive components have been used for over ten years, only recently has there been significant impetus to integrate. This is being driven by the need for miniaturization, increased performance and potentially lower costs. Discrete passives traditionally used in electronic products for decoupling, by-passing and line termination are becoming the speed bottleneck due to their size and distance from the active circuits. This problem can be circumvented by moving some of the function to the integrated chip. The passive devices can also be integrated into the printed wire board or part of a multichip module. Important integration issues involve the use of barrier metal layers and patterning. Metal migration under the influence of thermal or electric fields may produce shorts and render the entire device ineffective. Further more improved wetting can lead to decreased defect density and improved electrical characteristics and yield. To produce both test structures and working assemblies the electrodes and dielectric layers need to be compatible with standard photopatterning methods. In this paper we present our work on the fabrication of capacitor arrays by top electrode patterning, development of a photoimageable polymer-ceramic nanocomposite and copper metallization issues controlling integration.