6097.1:
Nanostructered Piezo-Ceramic PZT Thin Films for Adaptive Materials using Sputter Deposition Technique
Abstract
During the last few years great effort has been made to produce piezoelectric lead zirconate-titanate (PbZrxTi1-xO3, PZT) thin films which can be utilized as sensors, actuators and transducers. Based on physical coating technologies, the deposition of PZT-films on substrates (i.e. Si-Wafer, mostly coated with a seed-layer such as Pt) is usually carried out by means of single- or multiple-target RF-magnetron sputtering. The RF-mode is used especially for electrically insulating targets and leads unintentional to low deposition rates and a high substrate strain: In Industry, where nanocrystalline thin PZT-films would have a high market potential in the field of non-volatile FRAM (Ferroelectrically random access memory), the RF-sputtering process employed from one or more targets is therefore not applicable in mass production lines.
The aim of this work is to develop a thin nanocrystalline PZT-film on Pt(111)-coated Si-Wafer by using pulsed reactive single-target DC-magnetron sputtering. We will study a series of candidate targets provided by our industrial partner UNAXIS and evaluate and optimize the process parameters. In the course of the project, it is crucial to control the chemical, structural, electrical and mechanical properties of produced PZT-films.
It should be emphasized that the project is not only basic research but is strongly focused on the development and optimization of nanocrystalline thin piezoelectric devices with a future industrial application of FRAM. Such devices are based on PZT-material and are applicable to the field of communications, military, info tech, biomedical, medical and automotives. We could also produce MEMS (microelectro mechanical systems) if the transition from the nm to mm-range can be achieved.
As a general rule, due to the high volatility of Pb, the deposition process under low pressure conditions and high substrate temperature leads to Pb-deficient non-stochiometric films that are not useful. Hence, the development of well-defined stoichiometric nanocrystalline thin PZT-films can be classified as challengeing and risky.