Through-silicon-via-based double-side integrated microsystem for neural sensing applications

This paper presents a Through-Silicon-Via (TSV) based double-side integrated microsystem for brain neural sensing applications. Figure 6.3.1 shows the structure of the double-side integrated microsystem. MEMS neural microprobe array and low-power CMOS readout circuit are fabricated on two sides of the same silicon substrate, and TSV´s are used to form a low impedance interconnection between the microprobe and CMOS circuitry, thus providing the shortest signal transmission distance from sensors to circuits. The low parasitic impedance of TSV minimizes transmission loss and noise. The overall chip is 5x5mm2, 350μm in thickness including 150μm probe height and 200μm TSV height, respectively. A total of 480 microprobes is divided into 4x4 sensing areas, forming 16channels. 16 TSV arrays are used to connect the microprobe outputs to 16 readout circuits fabricated on the opposite side of the silicon substrate. The proposed structure allows stacking of other CMOS chips onto the circuit side by TSV 3D IC technique.