OREANDA-NEWS. Ricoh Company, Ltd., has succeeded in crystallizing PZT, produced in inky form by CSD method, using unique technology. The technology applies a semiconductor laser and has proved that the film obtained exhibits the displacement characteristics proper to PZT. Ricoh is the first in the world (as of May, 2013) to obtain the PZT film, which has displacement characteristics, with its original irradiation technology using a semiconductor laser among laser annealing technologies.

This technology, when combined with the piezo element formation technology by IJP method (an ink-jet printing technique) that Ricoh announced in May, 2012, makes it possible to plot an actuator of a minute size (several to several hundred microns) as a 3D modeling pattern on a silicon substrate. It uses piezo material crystallized with laser annealing technology for molding. In addition to the field of MEMS that includes imaging equipment, hard disk drives, and displays requiring a displacement function in minute area, these technologies can evolve for use in the field of sensors, capable of measuring minute pressure and acceleration.

Although PZT material is used for many piezo elements, such as sensors and actuators, what Ricoh developed this time applies laser annealing technology to produce PZT film using the CSD method in the crystallization process. Until now, this crystallization process was made by heating to about 750 ? in an electric furnace, where almost all heat capacity was used to raise and lower the temperature of the substrate and furnace itself, resulting in significant waste of heat capacity and run time. With the laser annealing technology, because only the section irradiated by the laser beam is heated locally, there is no wasted energy, as only the PZT film on the substrate is heated.

The problem with crystallization annealed by laser lay in how to uniformly improve crystallinity without causing cracking and peeling. To solve this problem, there was a need to make the temperature at the time of irradiation uniform, even with the laser beam. Ricoh achieved the solution by developing a unique optical system capable of (1) making the geometry of the laser beam spot rectangular (circular in usual) to conform with the device form, and (2) making the intensity distribution of laser beam (beam profile) oblong (Gaussian distribution in usual). Beyond that, the cracking and peeling problem was solved by rationalizing laser power and irradiation time.