A novel 3D packaging concept for RF powered sensor grains

We present a novel three-dimensional (3D) embedded wafer-level ball grid array (eWLB) system in package (SiP) solution for biochips and micro labs. This 3D SiP includes three major components, a complementary metal oxide semiconductor (CMOS)-tunnel magneto resistance (TMR) sensor biochip for magnetic bead-sensing stacked on a radio frequency identification (RFID) microchip and a 13.56 MHz coil antenna for wireless energy and data transfer. The power supply and the serial peripheral interface (SPI) chip interconnections between the CMOS-TMR sensor biochip (slave) and the RFID microchip (master) are implemented with a novel embedded Z-line (EZL) vertical contact technology through the mold compound. The 13.56 MHz antenna is embedded into the fan-out area of the bottom redistribution layer of the eWLB. With this setup we are able to maximize the RFID reading distance and to ensure a displacement to the TMR sensor surface. We achieve an overall volume of the 3D SiP of only 5.6 mm × 3.6 mm × 0.7 mm applying the eWLB technology. Due to the RFID technology the developed 3D SiP does not need any external contacts and cabling. Therefore it can be encapsulated into harsh environments. In addition the top fan-out surface of the eWLB can be used for adhesive bonding to higher level analyzing setups. The results demonstrate that innovative SiP technology using the eWLB technology combined with chip and antenna design allow to realize modern subsystems e.g. for medical applications.