High-speed metal-based optical microscanning devices with low production cost and simple fabrication process wre successfully fabricated by direct deposition of piezoelectric materials using the aerosol deposition method (ADM) onto the micro-structured metal scanner frame. Large optical scanning angle of 35° at high resonance frequency of 23.6 kHz was achieved in ambient air without vacuum package. The scanner is applicable to SVGA high-resolution display of 800 x 600 or more. This method is a powerful tool for realizing ceramic integration with metal components.
We developed a Fabry-Perot (FP) optical modulator with electro-optic (EO) films fabricated by aerosol deposition (AD). We found the ferroelectric Pb(Zr,Ti)O3 film by AD produced a fairly high EO coefficient (>150 pm/V), approximately 10 times larger than that of LiNbO3. Since thick EO films greater than 5 μm can be deposited on a transparent electrode layer or a metallic mirror layer of the FP optical modulator by AD, the FP optical modulator can achieve low capacitance, resulting in high modulation speed. Transmittance spectra of the FP optical modulator coincided with the optical simulation spectra, which indicated that optical scattering in AD films and at the surface/boundary were very small. We demonstrated an optical intensity modulation with applied electric field to EO film of ferroelectric Pb (Zr, Ti)O3. We obtained a 4-dB modulation with 50 V for the 10-μm-thick modulator with dielectric multilayer mirror on a glass substrate.
Aerosol deposition method (ADM) is a high performance technique for fabricating of piezoelectric 1-100- micron- thick film on various kinds of substrate. High deposition rate (over 30 micron/min for area 5 mm × 5 mm), low process temperature (less than 600 °C) as well as micropatterning of PZT during deposition (without etching) are very attractive for MEMS, and micro-TAS applications. In this presentation, the performance of a Si diaphragm driven by PZT thick film deposited by ADM was investigated from the point of view of applications for micro-diffuser. To find optimum conditions of diffuser, 4 ~ 60-micron-thick PZT films were directly deposited onto 10 ~ 140-micron-thick Si substrate. Displacement of 65-micron-thick Si diaphragm ( 6 mm × 6 mm) driven by 14-micron-thick PZT film was 1.2 micron at 40 V ac at non-resonance frequency and was 24 micron at resonance of 22.4 kHz driven by 8 V. The influence of liquid loads on resonance frequency shift and fluidic follow were investigated as the first report.
Using Aerosol Deposition Method it is possible directly deposited PZT 1~100-micron-thick films on different kinds of substrates. The mechanical, and piezoelectric properties of such piezoelectric films allowed applying it to the microactuator fabrication. In this presentation, 10-μm-thick PZT film was directly deposited on the stainless steel. After annealing and poling of PZT, the fatigue of such actuator was investigated applied bipolar electrical field of 30 kV/cm keeping actuator temperature at 100°C. After 109 cycles changing in the vibration amplitude was not observed, as well as the actuator tip’s shift. Applications of such actuator for preside positioning of hard disk drive are discussed.
Although piezoelectric thin films are of great interest for actuator application in MEMS, deposition of PZT films with thicknesses between 5 and 100 micrometers has been hardly possible. It is therefore the goal of this paper, to investigate the properties of PZT-films of this thickness deposited by the recently introduced Jet-Printing System, especially concerning an application in micro actuator devices. First, PZT layers of thicknesses between 5 and 80 micrometers have been Jet-Printed on different substrates to investigate the compatibility of the deposition method with standard materials used for MEMS. The relative dielectric constant of the layers could be determined between 20 and 550, depending on annealing and deposition conditions. Following, on thin beam-shaped steel substrates PZT layers of 10 to 40 micrometers thickness were deposited. SInce the samples showed deformation caused by technology-introduced stress, the stress value is calculated by means of FEM calculation, and methods for avoiding and compensation of the deformation are introduced. Using the beam-shaped samples, for the first time the piezoelectric constant of the Jet-Printed PZT-layer was calculated to 20...30 10-12 C/N from laser measurements of static and quasi-static beam deflection, and therefore piezoelectric actuation capability could be proofed directly.
To close the technological thickness gap between vary thin PZT-layer deposition and bulk PZT, a new technology called Jet Printing has been introduced recently, which can be used to deposit layers between 5 and 100 micrometers thickness. This technology is used for the first time to fabricate bimorph actuator elements suitable for actuation purposes in MEMS. At first, 10 to 40 micrometers thin PZT layers are deposited on beam shaped structures made of 30 micrometers thick steel. This basic actuator beams were stimulated by an AC voltage, and the reflected laser beam showed reasonable dynamic deflection angels of about 5 degrees maximum. Secondly, deposition on anisotropically etched silicon membranes with varying thickness from 25 to 125 micrometers was carried out. It appeared, that at a membrane thickness lower than 50 micrometers technologically effects can break the membrane. However, for membranes thicker than that, direct deposition after anisotropic etching could be applied successfully, and dynamic deflection of this membranes could be proofed by laser interferometric measurement. Finally, a small structure capable of diverting a laser beam and carrying out 2D scanning was designed and fabricated from 30 micrometers thick steel using laser ablation. The scanner is actuated by four actuator beams, on which 30 micrometers thick PZT has been Jet Printed as the actuating material. The electrodes on the beams can be stimulated separately, and therefore control the scanning direction. Experiments showed the capability of the structure to be actuated, and deflection angels up to 5 degrees could be measured.