Seungeun Lee

Dielectric Properties and RF characterisitics of Bismuth-Zinc-Niobium Thin Films for Embedded Capacitor in PCB

The BZN thin films on copper clad laminate substrate by RF sputtering were studied for embedded capacitor application in PCB. The deposition was performed without substrate heating and the deposited films are composed of an amorphous phase. The dielectric properties of BZN thin films were dependent on the deposition parameters. The dielectric constant of the BZN thin films decreases with oxygen addition from 113 to 30. However, the leakage characteristics were improved by the oxygen addition, probably due to the removal of metallic bismuth in the film. By optimizing the lyaer structure, amorphous BZN thin film provides a capacitance density as high as 280 nF/cm2. Dielectric loss was below 1.5% and the capacitor shows excellent leakage current behavior. In addition, thin film embedded capacitor showed much lower impedance at high frequencies above ~ 150 MHz when compared with LICC and IDC.

Dielectric Properties of PCB Embedded Bismuth-Zinc-Niobate Films Prepared by RF Magnetron Sputtering

A novel bismuth zinc niobate (Bi1.5Zn1.0Nb1.5O7, BZN) thin film was studied as an embedded capacitor. The BZN thin films were prepared on copper based substrate by RF sputtering, which is compatible with low-temperature PCB processing. The films without any heat treatment were composed of an amorphous phase. Dielectric properties of the BZN thin films measured using Au/BZN/Cu structure were strongly dependent on deposition conditions. Very high dielectric constant of 87 was obtained for the BZN thin films even though they are in amorphous phase. The capacitance density and leakage current were 218 nF/cm2 and less than 1 uA/cm2 at 3 V, respectively. The process-compatibility of BZN thin films with PCB process was also studied.