3D-IPD with High Aspect Ratio Cu Pillar Inductor

In this paper, a novel high performance 3D-IPD (Integrated Passive Devices) solution has been demonstrated by 2 RDL combined with the key element - tall Cu pillar. It doesn't required expensive TSV or TGV process to achieve the 3.5~7 aspect ratio vertical connection, and meet the demand of high quality value wafer level processed 3D inductor. The proposed inductors formed by 20um/140umt (pillar diameter to pillar height ratio) type pillars are used for high inductance, and 40um/140umt type pillars are used for better power handling. Moreover, the proposed structure has been adopted to design and fabricate 3D-IPD diplexer (1.0mm*0.5mm size) to reach better performance of lower insertion loss (0.31dB and 0.70dB) and larger attenuation (28dB and 26dB) than 2D-IPD diplexer done. According to the design simulation, physical confirmation and electrical measurement results, the proposed high aspect ratio tall Cu pillar technology has been verified on RF inductors and IPD diplexer with good agreement and performance.