Laser transferred sol-gel PZT thin films
In order to achieve the integration compatibility with silicon microelectronics, ferroelectric lead zirconate titanate (PZT) thin films have been prepared by combining a sol-gel process and a laser transfer process. PZT films with thickness ranging from 1 to 10ìm are first deposited and annealed on sapphire substrates using an acetic acid based sol-gel method. Then they are bonded to silicon substrates and subsequently released from the sapphire substrates through excimer laser exposure from the backside of the sapphire substrates. These laser transferred PZT thin films have dielectric constants ranging from 526 to 1273, remnant polarizations of more than 32 ìC/cm2, and maximum polarizations of more than 52 ìC/cm2. The laser exposure induces a surface damage layer on the PZT films which shows a glassy phase structure, has a dielectric constant less than 67 and thickness less than 0.1ìm, but the laser exposure does not induce electric defects in the films as the laser transferred films have very high dielectric strength. While the laser induced surface damage layer can significantly affect the measurement and calculation of the dielectric constants and coercive fields of the PZT film, it is not necessary to remove this surface damage layer to make sensor and actuator devices because we still can effectively re-orient the domains and thus pole the films even with the existence of the surface damage layer.
Xu, B.; Rodkin, A.; Zesch, J.; White, D.; Buhler, S.; Fitch, J.; Littau, K. Laser transferred sol-gel PZT thin films. (Invited paper) Proceedings of the 107th Annual Meeting of the American Ceramic Society; 2005 April 10-13; Baltimore MD. In Ceramic Transactions. 2006; 174: 77-87.