Polymer-metal composite thin film microcap packaging technology using low temperature SU-8 bonding

This paper reports a packaging technology involving a lightweight, low temperature bonding process with a polymer-metal composite thin film microcap. A layer of SU-8, in the form of sealing rims, is used as an adhesive to bond the micro and nano-electromechanical systems (MEMS/NEMS) substrate with the microcap due to the excellent properties of SU-8 as a packaging material. A silicon oxide thin film layer is formed on the carrier wafer by using a furnace to separate the microcap from the carrier wafer once the bonding process between the host and the carrier wafer is complete. In addition, the thin-film polymer microcap retains its original shape and acts as a protective layer for the cavity after the carrier wafer is released. To characterize the bonding strength, tensile tests have been carried out, and the measurement results show that the bond strength is up to ∼15 MPa. This means that the proposed packaging method, with the thin-film polymer microcap on the host wafer, was successfully realized by the low temperature bonding and transfer process. Finally, to check and verify the mechanical conditions, such as stress and deflection, of the microcap in the atmosphere, finite element (FE) analysis has been performed.