• Particle and aerosol research
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• v.5 no.1
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• pp.17-27
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• 2009

Particle deposition on a semiconductor wafer larger than 100 mm was studied experimentally and numerically. Particularly the electrostatic effect on particle deposition velocity was investigated. The experimental apparatus consisted of a particle generation system, a particle deposition chamber and a wafer surface scanner. Experimental data of particle deposition velocity were obtained for a semiconductor wafer of 200 mm diameter with the applied voltage of 5,000 V and PSL particles of the sizes between 83 and 495 nm. The experimental data of particle deposition velocity were compared with the present numerical results and the existing experimental data for a 100 mm wafer by Ye et al. (1991) and Opiolka et al. (1994). The present numerical method took into consideration the particle transport mechanisms of convection, Brownian diffusion, gravitational settling and electrostatic attraction in an Eulerian frame of reference. Based on the comparison of the present experimental and numerical results with the existing experimental results the present experimental method for a 200 mm semiconductor wafer was found to be able to present reasonable data.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.6
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• pp.262-266
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• 2004

Rutile single crystals were grown by the skull melting method. Ti metal ring was used for initial RF induction heating. The grown crystals were cut into wafer of 5.5 mm diameter and 1mm thickness. The wafers were annealed in air at $1300^{\circ}C$ up to 15 hours and their transmittance spectra $(\lambda= 200~25000 nm)$ were obtained.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1196-1200
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• 2004

Micropump is very useful component in micro/nano fluidics and bioMEMS applications. In this study, a bubble-powered micropump was fabricated and tested. The micropump consists of two-parallel micro line heaters, a pair of nozzle-diffuser flow controller and a 1 mm in diameter, 400 ${\mu}m$ in depth pumping chamber. The two-parallel micro line heaters with 20 ${\mu}m-width$ and 200 ${\mu}m-length$ were fabricated to be embedded in the silicon dioxide layer of a wafer which serves as a base plate for the micropump. The pumping chamber, the pair of nozzle-diffuser unit and microchannels including the liquid inlet and outlet port were fabricated by etching through another silicon wafer. A glass wafer (thickness of $525{\pm}15$ ${\mu}m$) having two holes of inlet and outlet ports of liquid serve as upper plate of the pump. Finally the silicon wafer of the base plate, the silicon wafer of pumping chamber and the glass wafer were aligned and bonded (Si-Si bonding and anodic bonding). A sequential photograph of bubble nucleation, growth and collapse was visualized by CCD camera. Clearly liquid flow through the nozzle during the period of bubble growth and slight back flow of liquid at the end of collapsing period can be seen. The mass flow rate was found to be dependent on the duty ratio and the operation frequency. As duty ratio increases, flow rate decreases gradually when the duty ratio exceeds 60%. Also as the operation frequency increases, the flow rate of the micropump decreases slightly.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.4
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• pp.400-406
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• 2015

This study researched the structure of the source of an ion milling machine used to fabricate a scanning electron microscope (SEM) sample. An ion source is used to mill out samples of over 1 mm dimension using a broad ion beam to generate plasma between the anode and cathode using a permanent magnet. To mill the sample in the vacuum chamber, the ion source should be greater than 6 kV for a positive ion current over $200{\mu}A$. To discover the optimum operating conditions for the ion miller, the diameter of the extractor, anode shape, and strength of the permanent magnet were varied in the experiments. A silicon wafer was used as the sample. The sputter yield was measured on the milled surface, which was analyzed using the SEM. The wafer was milled by injecting 1 sccm of argon gas into the 0.5 mTorr vacuum chamber.

• International Journal of Precision Engineering and Manufacturing
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• v.8 no.2
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• pp.44-48
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• 2007

In recent years, the size of plane substrates and semiconductor wafers has increased. As conventional contact transportation systems composed of, for example, carrier rollers, belt conveyers, and robot hands carry these longer and wider substrates, the increased weight results in increased potential for fracture. A noncontact transportation system is required to solve this problem. We propose a new noncontact transportation system combining acoustic viscous and aerostatic forces to provide damage-free transport. In this system, substrates are supported by aerostatic force and transported by acoustic viscous streaming induced by traveling wave deformation of a disk-type stator. A ring-type piezoelectric transducer bonded on the stator excites vibration. A stator with a high Q piezoelectric transducer can generate traveling vibrations with amplitude of $3.2{\mu}m$. Prior to constructing a carrying road for substrates, we clarified the basic properties of this technique and stator vibration characteristics experimentally. We constructed the experimental equipment using a rotational disk with a 95-mm diameter. Electric power was 70 W at an input voltage of 200 Vpp. A rotational torque of $8.5\times10^{-5}Nm$ was obtained when clearance between the stator and disk was $120{\mu}m$. Finally, we constructed a noncontact transport apparatus for polycrystalline silicon wafers $(150(W)\times150(L)\times0.3(t))$, producing a carrying speed of 59.2 mm/s at a clearance of 0.3 mm between the stator and wafer. The carrying force when four stators acted on the wafer was $2\times10^{-3}N$. Thus, the new noncontact transportation system was demonstrated to be effective.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.1
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• pp.45-50
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• 2009

By Laser Through-Silicon-Via process, debris and particles occur when you are forming. Therefore the research of TSV cleaning become important to remove those particles and debris. Both chemical cleaning method that uses a surfactant and physical cleaning method that uses a brush were studied with the via of $30{\mu}m$ diameter and $100{\mu}m$ depth on the 8 inch CMOS Image Sensor wafer. On the DI water and a surfactant in mixture ratio of 2:1, debris show $73{\mu}m^2$ per $0.054mm^2$. Cleaning is superior by lower mixture ratio of DI water and surfactant. In addition, It is less than 5% of debris distribution in the laser condition changed by Laser's frequency and its speed and cleaning had no effect. In the physical cleaning, there are no crack and damage when the system condition is set by $1000{\sim}3000rpm$ strip, $50{\sim}3000rpm$ rinsing, and $200{\sim}300rpm$ brushing Therefore, debris and particles can be removed by enforced chemical method and physical method.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.454-454
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• 2014

Silicon microwire array is one of the promising platforms as a means for developing highly efficient solar cells thanks to the enhanced light trapping efficiency. Among the various fabrication methods of microstructures, deep reactive ion etching (DRIE) process has been extensively used in fabrication of high aspect ratio microwire arrays. In this presentation, we show precisely controlled Si microwire arrays by tuning the DRIE process conditions. A periodic microdisk arrays were patterned on 4-inch Si wafer (p-type, $1{\sim}10{\Omega}cm$) using photolithography. After developing the pattern, 150-nm-thick Al was deposited and lifted-off to leave Al microdisk arrays on the starting Si wafer. Periodic Al microdisk arrays (diameter of $2{\mu}m$ and periodic distance of $2{\mu}m$) were used as an etch mask. A DRIE process (Tegal 200) is used for anisotropic deep silicon etching at room temperature. During the process, $SF_6$ and $C_4F_8$ gases were used for the etching and surface passivation, respectively. The length and shape of microwire arrays were controlled by etching time and $SF_6/C_4F_8$ ratio. By adjusting $SF_6/C_4F_8$ gas ratio, the shape of Si microwire can be controlled, resulting in the formation of tapered or vertical microwires. After DRIE process, the residual polymer and etching damage on the surface of the microwires were removed using piranha solution ($H_2SO_4:H_2O_2=4:1$) followed by thermal oxidation ($900^{\circ}C$, 40 min). The oxide layer formed through the thermal oxidation was etched by diluted hydrofluoric acid (1 wt% HF). The surface morphology of a Si microwire arrays was characterized by field-emission scanning electron microscopy (FE-SEM, Hitachi S-4800). Optical reflection measurements were performed over 300~1100 nm wavelengths using a UV-Vis/NIR spectrophotometer (Cary 5000, Agilent) in which a 60 mm integrating sphere (Labsphere) is equipped to account for total light (diffuse and specular) reflected from the samples. The total reflection by the microwire arrays sample was reduced from 20 % to 10 % of the incident light over the visible region when the length of the microwire was increased from $10{\mu}m$ to $30{\mu}m$.