16.6 Double-side CMOS-CNT biosensor array with padless structure for simple bare-die measurements in a medical environment

CMOS sensors using nanomaterials on the surface are very effective for early detection of diseases. Among the nanomaterials, carbon nanotube (CNT) is an ideal biosensor material since it has a small diameter (∼1nm) directly comparable to the size of biomolecules and excellent electrical characteristics. Because CNT is formed chemically in a special environment, to use it in a CMOS process, many electrodes are formed as an array and the CNT solution is coated on the electrode array. However, to prevent electrical shorts between bonding pads, very complicated area-selective CNT coating processes are required. Furthermore, chip packaging steps — such as wire bonding, chip passivation against reactions to the wire, microfluidic channels on the chip, etc. — should be carefully applied [1].