The fabrication of PB(ZR,TI)O/sub 3/ films on a AL/AL/sub 2/O/sub 3/ structure employing a crack amendment process

Abstract

Pb(Zr,Ti)O/sub 3/ (PZT) thin films with lower gel concentration of 0.2 M to 0.3 M were deposited on Al/Al/sub 2/O/sub 3/ substrate via a sol-gel process, using lead acetate, zirconium n-propoxide and titanium isopropoxide as raw precursors, propyl alcohol as a solvent and acetate acid as a chelating agent and catalyst. After a batch of step (drying, pre-baking), sintered at higher temperature the amorphous PZT thin films were changed to perovskite-type crystal structure. The effect of variables such as gel solutions concentration and heating rate on morphology were investigated to conduct for preparing crack-free PZT thin films. The results showed that the cracking problem is reduced by employing for lower gel concentration 0.2 M with drying at 150/spl deg/C for 5 min and pre-baking at 350/spl deg/C for 10 min and then sintering at 700/spl deg/C for 30 min with heating rate 50/spl deg/C/min. We also measured P-E hysteresis loop using Sawyer-Tower circuit, the values of the remanent polarization (P/sub r/) and coercive field (E/sub c/) are around 11.39 c/cm/sup 2/ and 84.52 KV/cm, respectively. We also reported on the preparation and performance of a SAW resonator on PZT piezoelectric thin films coated on Al/Al/sub 2/O/sub 3/ substrate. Because of existing porous nature, crack-free PZT thin films were further surveyed for satisfactory SAW and FBAR devices on broadband application based on Al/Al/sub 2/O/sub 3/ structure.