Duk-Soo Eun

Fabrication of circular-type microchannel using photoresist reflow and isotropic etching for microfluidic devices

In this study, we fabricated circular channels using photoresist reflow and isotropic etching. A silicon substrate, using Si3N4 as a mask, was selectively etched using the hydrofluoric acid, nitric acid, acetic acid (HNA) etching system for fabricating the bottom hemisphere of the channels. Photoresist reflow was used to make the top of the channels round. Then Si3N4 was deposited on the reflowed photoresist. Since the deposited Si3N4 was approximately 6000 A thick, it was possible to observe the inside of the channel. We expect to apply such circular channels to simple bio-systems and microfluidic devices in which optical detection is required.

Fabrication of a Based Fluidic Chip Equipped with Porous Silicon Filter and Micro-Channels

In this paper, a new design and fabrication method for a micro electro mechanical system (MEMS)-based micro-fluidic system that includes an articulated filter with micro-channel is proposed. An anodic reaction that involves chemical etching is used to produce a porous silicon (PS) layer to be applied to a micro-fluidic filter. The micro-fluidic filter is fabricated with vertical micro-pores by an anodic reaction process using a (110) wafer. Physical etching based on a micro-sandblaster process, and wet chemical etching using either tetramethylammonium hydroxide (TMAH) or hydrofluoric, nitric, and acetic (HNA) acid solution are applied to form the micro-channels that function as an essential factor in the micro-fluidic system. These independently-fabricated filter and channel wafers are bonded using a dry film resist (DFR). The characteristics of the filter fabricated on a (100) wafer are analyzed. Moreover, the functional performances of the channels formed by different methods are compared. The proposed micro-fluidic system with porous silicon micro-filters might be applied to bio-material reaction chambers, such as polymerase chain reaction (PCR) chambers and DNA separation devices that require a filter.

Design and fabrication of a MEMS-based multi-sensor

In this paper, a newly-designed tamper detection multi-sensor with various functions is proposed. The multi-sensor consists of three different sensors, a piezoresistive sensor with and without mass, a proximity sensor, and a photodiode sensor, which use MEMS technology. The various components of the multi-sensor, could perceive different types of external tampers independently, resulting in more reliable responses. The multi-sensor could be applied to detect external tampers on various types of system and mobile units.

Characteristics of cantilever beam fabricated by silicon micromachining for flow sensor application

In this paper we report the thermal stress characteristics of multiarray cantilever beam and the result of experimental researches. The cantilever beam was fabricated using porous silicon micromachining techniques, surface tension and the difference in the thermal expansion coefficients between the two films on the cantilever beam. Then the height of the curled cantilever beam is measured as a function of the annealing temperature and time. Using these results, Piezoresistive flow sensors with micro cantilever structure were fabricated using (100), n/n/sup +//n three layer silicon wafer and their characteristics were then investigated. The proposed micro flow sensor consists of four identical silicon cantilever beam with piezoresistors. The total resistance and sheet resistance were obtained about 1K/spl Omega/ and 50/spl Omega/ respectively. The results show the dependence of the sensitivity on cantilever length and geometry.

Fabrication of Three-Dimensional Cu Coaxial Cable Using Porous Silicon Technology

This paper presents the fabrication of a three-dimensional Cu coaxial cable with a thick oxidized porous silicon (OPS) layer for application of microwave and RF integrated circuit technology. The structure was fabricated by hydrofluoric acid, nitric acid, acetic acid (HNA) etching, followed by the OPS process, electroplating and photoresist (PR) reflow. The return loss of the Cu coaxial cable on the OPS layer is -35.53 dB at 13 GHz and the insertion loss of Cu coaxial cable on OPS layer is -0.17 dB at 5.5 GHz. Therefore, the fabricated devices are expected to improve the characteristic of the insertion loss and the transmission line dispersion. Also, it is possible that the cable can be used as the microsize coaxial cable.

Fabrication of the multi-PCR chamber with inner heat-sink materials using a micro-blaster etching technique

In this paper, we propose a new design for a PCR (polymerase chain reaction) chamber with a temperature sensor under a top glass wafer and heaters on the bottom glass wafer. These chamber sensors are thermally isolated from the heater. The multi PCR chamber has an inner heat-sink material of etched silicon mass or glass mass using a micro-blaster. Then we will capture the image of the thermal mass temperature profile among the chambers by using the TIS (thermal imaging system). The performance of the inner heat-sink materials is analyzed during the PCR cycles and the thermal interference of the chamber, respectively.

Two Different Multisensors Fabricated by Various Manufacturing Methods

In this paper, we propose two different types of multisensor fabricated by various manufacturing methods. The first type of multisensor is fabricated all on the same chip. This type of the multi-sensor consists of three different sensors, a piezoresistive sensor, a capacitive proximity sensor, and a photodiode sensor for system units consisting of two different sensors, a capacitive proximity sensor and a photodiode sensor for mobile applications. The second type of multisensory, which is responsible for each function, is combined with a sandwich structure. This type of the multisensor consists of three different sensors: a piezoresistive sensor, a tilt sensor, and a photodiode sensor. The various components of the multisensor can perceive different types of external tamper independently, resulting in more reliable responses. The multisensor could be applied to detect external tampering on various types of system unit.

Fabrication of a micro-PCR chip with a heat-sink using TiO 2 nano-Fluid

In this paper, a newly-designed micro-PCR chip with a heat-sink using TiO2 nano-fluid is proposed. The chip consists of three parts; a top part with the micro channel including an integrated heater and sensor, a middle part of the micro chamber that specimens react in, and a bottom part of the micro-fluidic channel that the nano-fluid flows into as the role of a heat-sink. The nano-fluid made use of the TiO2 material. In order to investigate the heating of a micro chamber, an infrared thermal imaging system measured temperature changes in the chambers.

Fabrication of a Micro-Fluidic Filter/Channel using MEMS Technology

This paper investigates the design and fabrication of a micro-fluidic filter/channel using different methods. The micro-fluidic filter is fabricated by anodic reaction with (110) wafer. The most ideal micro-fluidic channel is fabricated by microblaster process, and HNA solution etching. It is expected that proposed micro-fluidic filter/channel would likely be applied micro-fluidic systems that could classify necessary materials to react and measure.

Solar cell surface texturing using a micro-blaster etching technique

In this paper, we describe a new fabrication method of texturing technology to use of micro-blaster for display process to develop surface texturing of new solar cell and to examine how to reduce reflection of solar ray.