Jong-oh Kwon

6B-6 An Ultra Small SAW RF Filter using Wafer Level Packaging Technology

Since a multitude of surface acoustic wave (SAW) filters are the key components for wireless communications, they play an important role in todays mobile phone evolution. Increasing the levels of functional integration and size reduction are therefore the major driving forces in recent SAW radio frequency (RF) filter development. This paper presents a pioneering work for design and fabrication of ultra small SAW filter package. A novel wafer level packaging technology based on through-wafer interconnection and wafer-to-wafer bonding is designed to achieve highly miniaturized SAW RF filters. Based on this technology, SAW RF filters for mobile phone systems are developed in the worlds smallest size of 1.0 times 0.8 times 0.25 mm3. It is shown that our newly developed SAW RF filter offers equal frequency characteristics compared with the conventional chip-sized package. And the reliability test result of hermetically sealed SAW filter package will be presented to verify its application to mobile phones. As a result of these developments, wafer-level packaged SAW RF filters will offer considerable advantages over conventional chip-sized packages in many aspects of performance and production, including size, cost, and further integration

Three-dimensional imaging using fast micromachined electro-absorptive shutter

Abstract. A 20-MHz switching high-speed light-modulating device for three-dimensional (3-D) image capturing and its system prototype are presented. For 3-D image capturing, the system utilizes a time-of-flight (TOF) principle by means of a 20-MHz high-speed micromachined electro-absorptive modulator, the so-called optical shutter. The high-speed modulation is obtained by utilizing the electro-absorption mechanism of the multilayer structure, which has an optical resonance cavity and light-absorption epilayers grown by metal organic chemical vapor deposition process. The optical shutter device is specially designed to have small resistor–capacitor–time constant to get the high-speed modulation. The optical shutter is positioned in front of a standard high-resolution complementary metal oxide semiconductor image sensor. The optical shutter modulates the incoming infrared image to acquire the depth image. The suggested novel optical shutter device enables capturing of a full high resolution-depth image, which has been limited to video graphics array (VGA) by previous depth-capturing technologies. The suggested 3-D image sensing device can have a crucial impact on 3-D–related business such as 3-D cameras, gesture recognition, user interfaces, and 3-D displays. This paper presents micro-opto-electro-mechanical systems-based optical shutter design, fabrication, characterization, 3-D camera system prototype, and image evaluation.

Newly Developed High Q FBAR with Mesa-Shaped Membrane

In this paper, the authors present the newly developed high Q film bulk acoustic resonator (FBAR) which has the piezoelectric AlN film sandwiched between two electrode films and mesa-shaped membrane structure by utilizing poly-Si and XeF2 as a sacrificial layer and dry release gas, respectively. By controlling the etching profile of bottom electrode and sacrificial layer, the poor formation of AlN in the edge region of mesa-shaped membrane could be eliminated. In addition, by reducing the parasitic overlap which both of the electrodes and the piezoelectric layer resides directly on the substrate, the authors improve the characteristics of resonator and filter. When we compare with the typical surface micromachined FBAR, such as resonator having its own Bragg reflector or cavity, we could greatly reduce the needs for tight control of chemical mechanical polishing (CMP) of the layer underneath the resonator. The measured Q value and effective electromechanical coupling coefficient of the resonator with the area of 120times120 mum2 were 1450 and 6.43%. The peak insertion loss (IL) and bandwidth of filter were 0.60 dB and 70 MHz, respectively

Multilayered relaxor ferroelectric poly(vinylidene fluoride-trifluoroethylene-clorotrifluoroethylene) actuators to operate a varifocal liquid-filled microlens

We designed and fabricated the multilayered P(VDF-TrFE-CTFE) actuators, which can be operated by the applied voltage of only 40 V. To fabricate P(VDF-TrFE-CTFE) films having a thickness of about 1∼2 µm, we also developed a new film transfer method, with which the P(VDF-TrFE-CTFE) films of about 1.5 µm thickness were fabricated and stacked. The deflection of the fabricated P(VDF-TrFE-CTFE) actuator was measured as a function of applied voltage, showing that with the applied voltage of 40 V the varifocal lens can change the optical power of more than 50 diopters. The response time of the actuator was also measured to be less than 20 ms. Therefore, we showed that the multilayered P(VDF-TrFE-CTFE) actuators can be used to operate the varifocal liquid-filled microlens to realize the auto-focus function in mobile phone cameras.