With excellent piezoelectric and dielectric properties and a high Curie temperature compared to other piezoelectric films, lead zirconate titanate (PZT) films have been used in many fields, from micro-electromechanical systems (MEMS) to ultrasonic sensors to energy collectors, where it plays a key role [1]. In the process of material preparation, how to improve the uniformity and performance stability of materials has been a constant pursuit of the problem.
Youcao Ma et al. [2] successfully integrated a micron-thick PZT film onto a 3-inch silicon wafer through a combination of medium temperature magnetron sputtering and rapid heat treatment (RTP). In particular, the uniformity of PZT film on the whole wafer after RTP is discussed, including the difference of crystal orientation, surface morphology and element composition at different positions.
Figure 1 illustrates that PZT films have similar (001) lattice orientation, surface morphology, and element distribution at different locations, indicating that RTP treatment helps to achieve uniformity of PZT films. It can be found that before RTP treatment, only Py phase in PZT film, and after RTP treatment, mainly (001) oriented Pe phase appears in PZT film. In addition, the surface of PZT films treated by RTP showed closely arranged columnar grains without obvious cracks or holes.
The dielectric and ferroelectric properties of PZT films at different positions on the wafer after RTP treatment are shown, including relative dielectric constant, ferroelectric hysteresis loop and dielectric loss. Among them, the surface morphology is very smooth and there are no obvious defects, which indicates that the PZT film has good surface quality. The relative dielectric constant and dielectric loss change with the change of electric field, showing a typical ferroelectric butterfly ring, which proves that PZT films have good ferroelectric properties. The polarization-electric field curves also show typical ferroelectric characteristics, indicating that PZT films have good ferroelectric properties.
Therefore, RTP treatment helps to improve the microstructure and properties of PZT films, so that they have similar (001) lattice orientation, surface morphology and element distribution at different locations, which is conducive to improving the uniformity and performance of the films.