Mechanical and Electrical Characterization of Benzocyclobutene Membrane Packaging

A whole benzocyclobutene (BCB) membrane zero-level packaging using a wafer level bonding technique is presented. Wafer-scale membrane transfer technique using silicon carrier wafers was used to make BCB membrane caps placed above the device wafers. BCB multiple coating process using CYCLOTENE 4026-46 was developed for an encapsulation cap. The average height of the implemented BCB cap was approximately 40 mum with a little curvature for the dimension of 2 mm x 3 mm. Hermeticity of BCB was improved by depositing 0.5 um-thick PECVD nitride on the membrane, which was verified by vacuum chamber test and the ANSYS model was developed to describe the BCB membrane movement depending on the vacuum level. Mechanical resonant frequency of the BCB membrane was also characterized 7.5 kHz with an optical measurement. In addition, RF characterization using coplanar waveguide (CPW) line and thin-film resonator were performed to estimate the effect of BCB film package from DC to 110 GHz. The packaged thin-film resonator showed a frequency change of 100 MHz at 62.5 GHz resonance frequency and 200 MHz at 104 GHz.