The preparation methods of piezoelectric thin films mainly include the traditional vacuum coating method, including vacuum evaporation coating, sputtering coating, chemical vapor deposition coating, the thickness of 0~18μm, new Sol-gel method, hydrothermal method and electrophoretic deposition method are used to prepare 10~100μm piezoelectric thick film materials.
Piezoelectric thick film usually refers to the thickness of 10~100μm piezoelectric film, compared with the film, its piezoelectric, ferroelectric performance is less affected by the interface, surface and so on, because of its large thickness, so this material can also produce a large driving force, and has a wider operating frequency, compared with block materials, its operating voltage is low, the use of high frequency, Compatible with the semiconductor process.
Chemical vapor deposition is a chemical vapor-phase growth method called CVD (Chemical vapor deposition) technology. This method is to supply a substrate containing one or several compounds consisting of a thin film element, which uses the energy of heating, plasma, ultraviolet light and even laser to generate the required film by gas-phase action or chemical reaction on the substrate surface.
Because CVD is used to prepare thin films by various gaseous reactions, it is possible to control the composition of the film arbitrarily, so that many new membranes can be produced. When the film was prepared by CVD method, the growth temperature was significantly lower than the melting point of the film composition, the film layer had good uniformity, and it was suitable for the complex shape substrate.
The application range of chemical vapor deposition is very wide because of its advantages such as high deposition rate, little pinhole of membrane layer, high purity, compact and less defects in forming crystals. By using CVD method, dense, smooth surface, thickness in 0~18μm, and excellent performance of piezoelectric thick film materials can be prepared. Therefore, in the preparation of piezoelectric thick film, the CVD method develops rapidly and has been used by many researchers.
The new Sol-gel method is to add the prepared powder (the same ingredient and Sol) to the Sol, adding some organic solvents as dispersant in solution, adding other organic solvents to adjust the viscosity and ph of solution, and finally carrying out the discontinuous ultrasonic oscillation to disperse the nanometer powder in solution, and finally get the homogeneous powder solution, The membrane required for deposition of substrates by Sol-gel method. In this deposition process, the powder particles play the role of seed crystal.
This method can be used to make thick film thickness up to dozens of microns. It avoids the problem that the traditional Sol-gel method is used to produce the film cracking and even the membrane shedding in the thick film. The thick film composition is homogeneous, high purity and no need for high-temperature sintering, and the thick film can be compatible with the semiconductor fabrication process. And the equipment is simple, low-cost, membrane components can be controlled, so this method is currently used more than one method.
Piezoelectric thin films are widely used because of their excellent performance. Piezoelectric thick film can be used to create a variety of micro-devices, such as micro-pumps, ultrasonic motors, resonators, pyroelectric thick-film sensors, thick-film actuators, micro-energy picker and so on.
The piezoelectric film has a wide prospect in the application of antifouling. At present, the National Institute of the United States and the University of France Montelich to study the pollution of piezoelectric films. Piezoelectric films have been proven to be effective in measuring the vibrations of the shell polymers, so they can be used to prevent the proximity of most marine organisms that can cause ships to pollute. In addition, the Netherlands Del F T Institute of Science is extending its findings to larger metal structures, such as the hull of a merchant ship or a ship. At the same time, the same principle is being studied on how to produce antifreeze surfaces on airplanes.