Fabrication of integrated microwave passive devices using thick BCB as dielectric at wafer level

This paper presents a wafer-level integration technology of micro/millimeter-wave integrated passive devices utilizing thick photo-BCB layer as dielectrics. Maximum three layers of metal and two layers of BCB are included in the specimen. Several kinds of RF integrated passive devices (IPDs) such as microwave resonator, low-pass filter (LPF) as well as bandpass filter, are fabricated on 25um/layer thick dielectrics. The RF transmission performances are measured on wafer. The S₁₁ and S₂₁ of the λ₀/4 resonator are -0.774dB and -25.48dB, and the S₁₁ and S₂₁ of the stepped impedance resonator achieve -0.394dB and -27.42dB respectively at 24GHz. The cut-off frequency of the low pass filter is measured to be 13 GHz. The measured pass-band range of the BPF is 13.15GHz-13.75 GHz where the return loss is better than 11 dB. The pole point appears at 13.4GHz, and the return loss is 18.4dB.