• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.15 no.3
• /
• pp.82-90
• /
• 2006

Recently the electrostatic 2-axis MEMS stages have been fabricated for the purpose of an application to PSD (Probe-based Storage Device). However, all of the components(platform, comb electrodes, springs, anchors, etc.) in those stages are placed in-plane so that they have low areal efficienceis, which is undesirable as data storage devices. In this paper, we present a novel structure of an electrostatic 2-axis MEMS stage that is characterized by having large area platform. for obtaining large area efficiency, the actuator part consisting of mainly comb electrodes and springs is placed right below the platform. The structure and operational principle of the MEMS stage are described, followed by a design procedure, structural and modal analyses using FEM(Finite Element Method). The areal efficiency of the MEMS stage was designed to be about 25%, which is very large compared with the conventional ones having a few percentage.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.373-378
• /
• 2004

Recently the electrostatic 2-axis MEMS stages have been fabricated for the purpose of an application to PSD (Probebased Storage Device). However, most of them have low area efficiency, which is undesirable as data storage devices, since all of the components (springs, comb electrodes, anchors, platform, etc.) are placed in-plane. In this paper, we present a novel structure of electrostatic 2-axis MEMS stage that is characterized by having large area platform. For large area efficiency, the actuator part consisting of mainly comb electrodes and springs is placed right below the platform. In this article, the structures and operational principle of the MEMS stages are described, followed by design procedure, structural and modal analysis using FEM(Finite Element Method). The area efficiency of the MEMS stage was designed to be about 55％, that is very large compared with conventional ones having a few percentage.

• Journal of the Korean Society for Precision Engineering
• /
• v.23 no.9 s.186
• /
• pp.179-189
• /
• 2006

Recently the electrostatic 2-axis MEMS stages have been fabricated f3r the purpose of an application to PSD (Probe-based Storage Device). However, all of the components (platform, comb electrodes, springs, anchors, etc.) in those stages are placed in-plane so that they have low areal efficiencies such as a few percentage, which is undesirable as data storage devices. In this paper, we present a novel structure of an electrostatic 2-axis MEMS stage that is characterized by having a large areal efficiency of about 25%. For obtaining large area efficiency, the actuator part consisting of mainly comb electrodes and springs is placed right below the platform. The structure and operational principle of the MEMS stage are described, followed by a design and analysis, the fabrication and measurement results. Experimental results show that the driving ranges of the fabricated stage along the x and y axis were 27$\mu$m, 38$\mu$m at the supplied voltages of 65V, 70V, respectively and the natural frequencies along x and y axis were 180Hz, 310Hz, respectively. The total size of the stage is about 5.9$\times$6.8mm$^2$ and the platform size is about 2.7$\times$3.6mm$^2$.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.11 s.176
• /
• pp.173-181
• /
• 2005

We report on the design and fabrication of an electrostatic 2-axis MEMS stage possessing a platform with a size of $5{times}5mm^2$. The stage, as a key component, would be used in developing probe-based storage devices in the future. It was fabricated by forming numerous $5{\times}5{\mu}m^2$ etching holes in the central platform, as a result, reducing the total number of masks to 1, thereby simplifying the whole fabrication process. Experimental results show that the driving range of the stage was $32{\mu}m$ at the supplied voltage of 20V and the natural frequency was approximately 300Hz. The mechanical coupling between x- and y-motion was also measured and verified to be $25\%$.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.1 no.1
• /
• pp.84-93
• /
• 2001

An electromagnetic micro x-y stage for probe-based data storage (PDS) has been fabricated. The x-y stage consists of a silicon body inside which planar copper coils are embedded, a glass substrate bonded to the silicon body, and eight permanent magnets. The dimensions of flexures and copper coils were determined to yield $100{\;}\mu\textrm{m}$ in x and y directions under 50 mA of supplied current and to have 440 Hz of natural frequency. For the application to PDS devices, electromagnetic stage should have flat top surface for the prevention of its interference with multi-probe array, and have coils with low resistance for low power consumption. In order to satisfy these design criteria, conducting planar copper coils have been electroplated within silicon trenches which have high aspect ratio ($5{\;}\mu\textrm{m}$in width and $30{\;}\mu\textrm{m}$in depth). Silicon flexures with a height of $250{\;}\mu\textrm{m}$ were fabricated by using inductively coupled plasma reactive ion etching (ICP-RIE). The characteristics of a fabricated electromagnetic stage were measured by using laser doppler vibrometer (LDV) and dynamic signal analyzer (DSA). The DC gain was $0.16{\;}\mu\textrm{m}/mA$ and the maximum displacement was $42{\;}\mu\textrm{m}$ at a current of 180 mA. The measured natural frequency of the lowest mode was 325 Hz. Compared with the designed values, the lower natural frequency and DC gain of the fabricated device are due to the reverse-tapered ICP-RIE process and the incomplete assembly of the upper-sided permanent magnets for LDV measurements.

• Ingenium
• /
• v.8 no.2
• /
• pp.51-57
• /
• 2001

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.6 no.4
• /
• pp.293-298
• /
• 2006

Thermopiezoelectric method, using poly silicon heater and a piezoelectric sensor, was proposed for writing and reading in a probe based data storage system. Resistively heated tip writes data bits while scanning over a polymer media and piezoelectric sensor reads data bits from the self-generated charges induced by the deflection of the cantilever. 34${\times}$34 array of thermopiezoelectric nitride cantilevers were fabricated by a single step wafer level transfer method. We analyzed the noise level of the charge amplifier and measured the noise signal. With the sensor and the charge amplifier 20mn of deflection could be detected at a frequency of 10KHz. Reading signal was obtained from the cantilever array and the sensitivity was calculated.

• Smart Structures and Systems
• /
• v.2 no.2
• /
• pp.115-126
• /
• 2006

The Terra-Scope system is an affordable 4-D down-hole seismic monitoring system based on independent, microprocessor-controlled sensor Pods. The Pods are nominally 50 mm in diameter, and about 120 mm long. They are expected to cost approximately $6000 each. An internal 16-bit, extremely low power MCU controls all aspects of instrumentation, eight programmable gain amplifiers, and local signal storage. Each Pod measures 3-D acceleration, tilt, azimuth, temperature, and other parametric variables such as pore water pressure and pH. Each Pod communicates over a standard digital bus (RS-485) through a completely web-based GUI interface, and has a power consumption of less than 400 mW. Three-dimensional acceleration is measured by pure digital force-balance MEMS-based accelerometers. These accelerometers have a dynamic range of more than 115 dB and a frequency response from DC to 1000 Hz with a noise floor of less than $30ng_{rms}/{\surd}Hz$. Accelerations above 0.2 g are measured by a second set of MEMS-based accelerometers, giving a full 160 dB dynamic range. This paper describes the system design and the cooperative shared-time scheduler implemented for this project. Restraints accounted for include multiple data streams, integration of multiple free agents, interaction with the asynchronous world, and hardened time stamping of accelerometer data. The prototype of the device is currently undergoing evaluation. The first array will be installed in the spring of 2006.

• Proceedings of the KIEE Conference
• /
• 2003.07c
• /
• pp.1903-1905
• /
• 2003

전자기력을 이용하여 탐침형 정보저장장치의 미디어를 제어할 수 있는 초정밀 구동기를 제작하였다. 탐침형 정보저장장치는 데이터 비트의 크기가 10nm 수준이고, 단일 캔틸레버가 점유하는 영역의 크기가 수십 ${\mu}m$${\times}$수십${\mu}m$ 수준이므로, 미디인 구동기는 수 nm의 위치 정확도 및 수십 ${\mu}m$ 수준의 변위 그리고 100Hz이상의 공진 주파수를 확보하여야한다. 본 연구에서 제작한 탐침형 정보저장장치의 미디어 구동기는 고저항 Si wafer 표면을 Deep RIE로 patterning한 후 그 내부를 도금으로 채워 구리 코일을 형성하고 이를 영구자석과 결합시킨 후, 구리 코일에 전류를 흘려 미디어를 구동하는 방식이다. 사용된 영구자석은 SmCo 자석이며 코일의 폭은 $100{\mu}m$이고 간격은 $20{\mu}m$, 높이는 $70{\mu}m$로 결정하였으며, 100Hz 이상의 공진 주파수를 확보하기 위하여 스프링 재질은 구리보다 상대적으로 stiff한 Si을 사용하였다. 미디어의 크기는 $20{\times}20mm^2$, 전체 구동기의 크기는 $30{\times}30mm^2$이며 측정결과 최대변위는 140mA 인가 시 약 ${\pm}127{\mu}m$이다.

• Journal of the Korean Society for Precision Engineering
• /
• v.23 no.6 s.183
• /
• pp.166-173
• /
• 2006

In this study, a probe array has been developed for use in a data storage device that is based on scanning probe microscope (SPM) and MEMS technology. When recording data bits by poling the PZT thin layer and reading them by sensing its piezoresponse, commercial probes of which the tip heights are typically shorter than $3{\mu}m$ raise a problem due to the electrostatic forces occurring between the probe body and the bottom electrode of a medium. In order to reduce this undesirable effect, a poly-silicon probe with a high aspect-ratio tip was fabricated using a molding technique. Poly-silicon probes fabricated by the molding technique have several features. The tip can be protected during the subsequent fabrication processes and have a high aspect ratio. The tip radius can be as small as 15 nm because sharpening oxidation process is allowed. To drive the probe, electrostatic actuation mechanism was employed since the fabrication process and driving/sensing circuit is very simple. The natural frequency and DC sensitivity of a fabricated probe were measured to be 18.75 kHz and 16.7 nm/V, respectively. The step response characteristic was investigated as well. Overshoot behavior in the probe movement was hardly observed because of large squeeze film air damping forces. Therefore, the probe fabricated in this study is considered to be very useful in probe-based data storages since it can stably approach toward the medium and be more robust against external shock.