Wafer Level Package for the X-Band Microwave Power Sensor

A wafer level packaging solution for the X-band microwave power sensor is described based on through wafer via technology in silicon substrate in this paper. The connection between chip and external pin is the critical part of the packaging. A pre-processed silicon capping wafer containing recesses and vertical Cu-plated TWV interconnect is bonded to the microwave power sensor wafer providing environmental protection and easy signal access. In order to reduce the parasitic effects introduced by the capping wafer, TWV radius is optimized using Ansoft HFSS electromagnetic simulator for three materials (Al, Au and Cu). The optimization results show that the performance of the Au and Cu is a little better than that of the Al, and the optimum dimension of the TWV radius is all 10 mu m for the three materials. The S11 parameter is between -23.48 dB and -23.73 dB for the uncapped microwave power sensor, and -13.59 dB and -13.65 dB for the capped microwave power sensor. Although the cap has a little great effect on the microwave power sensor, but the wafer level packaging solution has a low loss after package and satisfies the design.