On-chip high-Q solenoid inductors embedded in WL-CSP

On-chip Cu solenoid inductors on Si substrate with thick resin layer have been fabricated. These inductors were fabricated by dual Cu electroplating layers and separated more than 10 /spl mu/m from Si substrate by thick resin layer. The self-resonance frequency of 17.7 and higher than 20 GHz with peak-Q of 18.5 and 24.2 were obtained for a 5 turn solenoid inductor in the resistivity of 4, 1k /spl Omega/cm, respectively. This technology realizes that high performance inductors are embedded in wafer-level chip-scale packages.