Thin film resistors and capacitors for advanced packaging

Integrated passive components are important for high frequency hybrid microelectronics. We have fabricated resistors using reactively sputtered TaN_x (x<0.5) and Ta₂Si thin films. We report on the resistivity, temperature coefficient of resistance (TCR), microstructure, composition, and thermal stability as a function of deposition conditions. The resistivity can be tuned, for example, by varying the nitrogen concentration. We have also fabricated capacitors with high capacitance density (70 nF/cm²) using Ta₂O₅ dielectric films. The Ta₂O₅ dielectric films were prepared by various methods such as reactively sputtered Ta₂O₅, anodization of reactively sputtered TaN,, and anodization of Ta,Si films. We report on the capacitance density, leakage current, breakdown voltage, and dissipation factor up to high frequencies. We also report on the temperature coefficient of capacitance (TCC) and thermal stability of these capacitors during subsequent processing. A variety of analytical techniques were used to characterize the film properties. These anodic Ta₂O₅ capacitors have exceptionally low leakage currents (<1 nA/cm² at 10 V), high breakdown fields (>4 MV/rm), and high capacitance densities (70 nF/cm²). The ac measurements of the capacitors showed ideal behavior up to 10 MHz Generally, anodic capacitors degrade upon subsequent processing above 200°C due to dielectric and electrode metal interaction. By engineering the dielectric and the electrode materials, we have fabricated anodic Ta₂O₅ capacitors that are stable up to 350°C with excellent capacitor properties. These capacitors are useful as integrated passive components for advanced packaging applications