Design and fabrication of micromachined pyroelectric infrared detector array using lead titanate zirconate (PZT) thin film

Pyroelectric infrared detector array using lead zirconate titanate (PbZr_0.3Ti_0.7O₃, PZT) thin film as a sensing layer was fabricated on Si₃N₄/SiO₂/Si substrate by a microelectromechanical system (MEMS) technique. Si₃N₄/SiO₂ layers, used as the etching mask and supporting layer, were grown on both sides of 4-in. double-side polished silicon wafer(100, p-type). The silicon-window was etched by a series of processes for photoetching, dry-etching and wet-etching. Pt/TiO₂ bottom electrode was deposited and patterned by using photoetching and RF magnetron sputtering. 800 nm-thick PZT thin film was deposited at 600 °C by RF magnetron sputtering. Au top electrode and the infrared absorption layer of black-gold were deposited and patterned by photoetching and DC sputtering. The dielectric constant and loss tangent of PZT film are 440 and 0.021 at 1 kHz, respectively. The remnant polarization (P_r) and the coercive field (E_c) are 25 μC/cm² and 40 kV/cm, respectively. The pyroelectric coefficient of the film was measured by a quasi-static method and is 300 μC m⁻² K⁻¹. The pyroelectric infrared detector array has potential applications on safety monitoring and smart appliances.