Comparison of Bonding of Bulk PZT to Silicon by Intermediate Glass Layer and by Intermediate Au Layer

Abstract

As an energy conversion material, piezoelectric ceramic lead zirconate titanate (PZT) has been used in a wide range of areas. And a PZT wafer bonding with a silicon wafer technology is a promising method to fabricate micro-sensors and micro-actuators using well-established silicon machining techniques. In order to obtain the excellent piezoelectricity and suitable thickness from the bulk PZT, a method is presented. It is to bond a bulk PZT onto a silicon wafer via an intermediate layer. In this paper, two bonding methods are presented. One is to bond a bulk PZT with a silicon wafer by anodic bonding technique using a thin glass film as the intermediate layer. The other is to bond a bulk PZT with a silicon wafer by eutectic bonding using a thin gold film as the intermediate layer. The glass film is 2µm in thickness, deposited by sputtered method. Anodic bonding conditions are: 0.8MPa in pressure, 500 oC in temperature, 250V in voltage and different bonding time. The bonding strength test shows that the maximum bond strength is 13.93 MPa when the bonding time was 60 min. It is void-free structure in the interface of the PZT-Glass-Si structure. The gold film is 1.6µm in thickness, deposited by evaporation method. The eutectic bonding conditions are: 0.8MPa in pressure, 500 oC in temperature, and different bonding time. The bond strength of the PZT-Au-Si structure was tested and the maximum value was 13.19 MPa when the bonding time was 60 min.