Wet Chemical Etching Process of BST Thin Films for Pyroelectric Infrared Detectors

Ba0.8Sr0.2TiO3 (BST) thin films were prepared on Pt/Ti/SiO2/Si substrates by sol-gel processing. The BST thin films were patterned by wet chemical etching and the electrodes were shaped by lift-off technique. An improved etchant with the volume ratio of HF:HNO3:H2O2:H2O = 1:25:50:20 was developed for BST films etching. SEM graph shows that the unetched BST thin film is dense, crack-free and pore-free. EDS analyses indicate that Ba, Sr and Ti elements of etched areas are removed completely. XRD and AFM results show that the etchant-induced damage of the etched BST films could be partially recovered by post-annealing treatment.