• JSTS:Journal of Semiconductor Technology and Science
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• 제5권1호
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• pp.52-57
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• 2005

This paper describes a fabrication method of a circular diaphragm using boron etching stop method. It will be applied to acoustic transducers such as microphones or microspeakers and so on. The sensitivity is expected to be increased with the circular diaphragm through the simulation results to compare with a general rectangular diaphragm. The borondoped layer which is doped with solid source is sufficient for achieving an etching stop in 20 wt% TMAH, and the thickness is about $7.4{\mu}m$. The diameter of the circular silicon nitride diaphragm was measured to be 2 mm with $1{\mu}m$ thickness. The fabrication of piezoelectric acoustic devices was completed.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 하계종합학술대회 논문집(2)
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• pp.477-480
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• 2004

We studied the characteristics of impedance and electromechanical coupling coefficient in ZnO and AIN thin films by using resonance frequency spectrum method. The response peak of impedance decreased with the decrease of thickness of piezoelectrics, the number of mode of response peak increased with the increase of substrate thickness. An error of $k_{t}^{2}$ estimated from input $k_{t}^{2}$ increased as the thickness of piezoelectrics decreased and the thickness of substrate increased. Also, the error was increased in case of a large acoustic impedance of substrate. It was found that the composite resonator operating in optimized condition could be designed through the resonance frequency spectrum analysis of composited resonator consisted of piezoelectric thin film and substrate.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.543-546
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• 2001

So far, the design methods of quartz crystal resonator have been developed. Recently, as the electronic package and semiconductor modules become smaller, the need to minimize the sizes of crystal components grows larger. but Minimizing crystal plate sizes has limitations because its temperature-frequency characteristics is worse and unwanted resonances occur. so appropriate design of electrode size and crystal plates is necessary. In this palter, Two-dimensional governing equations for electroded piezoelectric crystal plates with general symmetry have been solved from deduced equations from three-dimensional equations of linear piezoelectricity in most cases. In practice, electroded piezoelectric crystal plates have three-dimensional geometry, so simplified 2-dimensional equations and 2-D modeling are insufficient for explaining its resonance modes and characteristics. So, three-dimensional FEM(finite element method) analysis is done and its effectiveness is verified from analyzing practical crystal resonator model.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권12호
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• pp.597-600
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• 2002

Film Bulk Acoustic wave Resonator (FBAR) using thin piezoelectric films can be made as monolithic integrated devices with compatibility to semiconductor process, leading to small size and low cost, high Q RF circuit elements with wide applications in communications area. This paper presents a MMIC compatible suspended FBAR using surface micromachining. Membrane is composed $Si_3N_4SiO_2Si _3N_4$ multi layer and air gap is about 50${\mu}{\textrm}{m}$. Firstly, We perform one dimensional simulation applying transmission line theorem to verify resonance characteristic of the FBAR. Process of the FBAR is used MEMS technology. Fabricated FBAR resonate at 2.4GHz, $K^2_{eff}$ and Q are 4.1% and 1100.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.156-159
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• 2002

Film Bulk Acoustic wave Resonator (FBAR) using thin piezoelectric films can be fabricated as monolithic integrated devices with compatibility to semiconductor process, leading to small size, low cost and high Q RF circuit elements with wide applications in communications area. This paper presents a MMIC compatible Suspended FBAR using surface micromachining. It is possible to make Si$_3$N$_4$/SiO$_2$/Si$_3$N$_4$membrane by using surface micromachining and its good effect is to remove the substrate silicon loss. FBAR was made on 2$\mu\textrm{m}$ multi-layered membrane using CVD process. According to our result, Fabricated film bulk acoustic wave resonator has two adventages. First, in the respect of device Process, our Process of the resonator using surface micromachining is very simple better than that of resonator using bull micromachining. Second, because of using the multiple layer, thermal expansion coefficient is compensated, so, the stress of thin film is reduced.

• 한국공작기계학회논문집
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• 제15권3호
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• pp.111-119
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• 2006

The ultra-precision stage is demanded for some industrial fields such as semiconductor lithography, ultra-precision machining, and fabrication of nano structure. A new stage was developed for those applications in order to obtain nano meter resolution. This stage consists of symmetric double parallelogram mechanism using flexure hinges. The mechanical properties such as strength of the flexures and deformations along the applied force were analyzed using FEM. The stage is actuated by a piezoelectric actuator and its movement was measured by a ultra-precision linear encoder. In order to improve positioning performance, a PID controller was designed based on the identified second order transfer function. Experimental results showed that this stage could be positioned within below 5 nm resolution irrespective of hysteresis and creep by the controller.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제50권12호
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• pp.593-598
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• 2001

Transient liquid phase processing was investigated to decrease processing temperatures while maintaining useful piezoelectric properties in the lead zirconate titanate (PZT) system. Niobium oxide$(Nb_2O_5)$ modified crystalline PZT (PZTN) powder was combined with lead silicate $(PS; PbO-SiO_2)$ glass powder and crystalline titania, zirconia, and niobia. Firing above the melting temperature of the lead silicate $(PS; Tm \risingdotseq\; 714^{\circk}C)$ resulted in liquid phase densification of the PZTN followed by dissolution of the titania, zirconia, and niobia into the liquid phase, and crystallization of additional PZTN. The addition of crystalline titania, zirconia, and niobia to react with the lead oxide from the lead silicate phase resulted in an increase in the dielectric and Piezoelectric properties.

• 한국정밀공학회지
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• 제21권3호
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• pp.147-154
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• 2004

This paper presents a procedure for analysis and design of a fine positioning stage, which has many applications in industries for machine tools, semiconductor, LCD and so forth. The stage considered here is based on a single module with 3 axes which is composed of flexures hinges, piezoelectric actuators and their peripherals. Through a series of analysis, the structural analysis model is simplified as a rigid body(the moving part) and springs(the flexures hinges). An experimental design procedure is applied to determine the dimension of flexures hinges. A sensitivity analysis on the notch positions is also performed to obtain a guideline of fabrication accuracy for the stage. An actual fine stage is made and verified through an experiment on the dynamic characteristics.

• 반도체디스플레이기술학회지
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• 제4권2호
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• pp.21-24
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• 2005

Ink-jetting characteristics of pulse width and pulse amplitude for a piezoelectric ink jet printer driver have been mapped with various polymer EL ink. In this study, the jetting characteristics have been classified into 4 regime; no Jetting, unstable jetting, stable jetting, and spraying, and the importance of fluid viscosity on the scope of the stable jetting regime has been emphasized. The relation between jetting speed and the width and amplitude of driving signal has also been investigated and the effect of the speed on the jetting characteristics has been discussed.

• 반도체디스플레이기술학회지
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• 제17권4호
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• pp.62-65
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• 2018

We will provides a micro-pump infusion injector with the cloud networking for remote control. The existing infusion injector with controlled manually have an uncomfortable to use it inconveniently. The proposed remote control infusion, infusion system enables the identification and control of injected amount through the IOT function on th WEB. The micro-pump used is a piezo electric pump manufactured by using MEMS technology, and the amount of charge is varied depending on the frequency magnitude through the micro-controller. The micro-pump can adjust the speed of the fluid depending on the frequency and can be from 0.1ml / min to 7ml / min when the frequency is from 3 to 110Hz.