(Na, Bi)TiO sub(3) based lead-free ferroelectric thin films on Si substrate for pyroelectric infrared sensors

In this study, we report ferroelectric and pyroelectric properties of (Na sub(0.5)Bi sub(0.5))TiO sub(3)BaTiO sub(3) (NBT-BT) thin films on Si substrates using chemical solution deposition for the first time. The NBT-BT thin films deposited on Pt/Ti/SiO sub(2)/Si substrates have exhibited a typical hysteresis loop with remnant polarization of 5 mu C/cm super(2) and coercive field of 80 kV/cm. Furthermore NBT-BT films showed pyroelectricity with pyroelectric coefficient of 0.6x10 super(-8) C/cm super(2)K. Monolithic-integration of Si electronics and lead-free ferroelectric NBT thin films has been archived using SiN passivation layer. It was previously believed that LSI processes could not incorporate any sodium-containing material which would cause characteristic degradation, such as threshold voltage shift. In this work, no threshold voltage shift in MOS characteristics was observed using this SiN layer. The SiN layer not only blocked diffusion from NBT chemistry, but also from crystallized NBT films during NBT formation process.