Studies on thin film integral passive components for mixed mode multichip module (MCM) applications

There is a need to incorporate integral passive elements into the MCM interconnect structure to reduce the component count, decrease the substrate area and improve the electrical performance. In this study, advanced material and processing technologies for the in-situ formation of capacitor and resistor components during the fabrication of multilayer polymer/copper MCM interconnect structures are investigated. Amorphous BaTiO₃ thin film having a dielectric constant of 10 to 40 depending on stoichiometry was deposited on a surface roughness controlled metallized polyimide surface at room temperature for capacitor applications. Hundreds of pF capacitor with <10^-6 Amp leakage current were obtained depending on the top metal electrode size, dielectric thickness, and stoichiometry of dielectric film. After preliminary reliability testing, it was proved that thin film integral capacitor was good to be used as a practical MCM application. For integral resistors, thin film tantalum nitride resistor material was deposited on various polyimide films using a reactive DC magnetron sputtering machine with N₂ and Ar gas mixture at room temperature. The resistivity of the resistor film was about 250 μohm.cm with -200~-100 TCR values. Thin film resistor with power density of 0.3 mW/mil² was demonstrated on a polyimide surface, and the resistivity of the patterned resistor lines were not changed for more than 150 hours at 0.15 mW/mil² power density which was 12 times of their intended usage in power