Low-temperature silicon wafer-scale thermocompression bonding using electroplated gold layers in hermetic packaging

Abstract

We describe a low-temperature wafer-scale thermocompression bonding using electroplated gold layers. Silicon wafers were completely bonded at 320 C at a pressure of 2.5 MPa. The interconnection between the packaged devices and external terminal did not need metal filling and was made by gold films deposited on the sidewall of the via-hole. Helium leak rate was measured for application of thermocompression bonding to hermetic packaging and was 2.74 +/- 0.61 x 10(-11) Pa m(3)/s. Therefore, Au thermocompression bonding can be applied to high quality hermetic wafer level packaging of radio-frequency microelectromechanical system devices. (c) 2005 The Electrochemical Society.