• Proceedings of the KIEE Conference
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• 1998.07g
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• pp.2521-2523
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• 1998

Freestanding flexible microstructures fabricated from deposited thin films become mechanically unstable when internal stresses exceed critical values. The residual stress and stress gradient of aluminum thin film were examined to make sure of fabricating the reproduceable aluminium structure. For good shape of micro mirror array and microstructures, the experiment was done varying thickness and deposition rate. As the aluminium film thickness increased from 0.8${\mu}m$ to 1.6${\mu}m$, the stress gradient decreased from 11.62MPa/${\mu}m$ to 2.62MPa/${\mu}m$. The residual stress values are from 42.4MPa to 62.24MPa of tensile stresses.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.31 no.9
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• pp.74-81
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• 1982

One of the stable thin film transistor fabricated by cadmium suifide with the anodized aluminium oxide as gate material. The principle of the operation for the device is based on the control mechanism of injected majority carricrs to the wide band gap semiconductor, that is cadmium sulfide, by means of the function of the gate control. The fabricated device constructed by evaporating CdS layer in the form of microcrystalline on the oxided thin film characterized by ea, 80 as voltage amplification factor, 1/100 mho as transconductance, 8 kohm as dynamic output resistance, furthermore gain band width products is about 15 MHz.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.9
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• pp.863-867
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• 2008

In this paper, to increase the light current efficiency of photodiode, we fabricated aluminum-doped zinc oxide(AZO) thin films by RF magnetron sputtering. AZO thin films were deposited at low temperature of 100 $^{\circ}C$ and different RF powers of 50, 100, 150 and 200 W due to selective process technology. Then the AZO thin films were annealed at 400 $^{\circ}C$ for 1 hr in vacuum ambient to increase crystalline. The lowest resistivity of 1.35 ${\times}$ $10^{-3}$ ${\Omega}cm$ and a high transmittance over 90 % were obtained under the conditions of 3 mTorr, 100 'c and 150 W. The optimized AZO thin films were deposited as anti-reflection coating on PN junction of silicon photodiode. It was confirmed by the result of $V_r-I_{ph}$ curve that the efficiency of photodiode with AZO thin film was enhanced 17 % more than commercial photodiode.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.5
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• pp.471-478
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• 2010

Thin films play an important role in many technological applications including microelectronic devices, magnetic storage media, MEMS and surface coatings. It is well known that a thin film's material properties can be very different from the corresponding bulk properties and thus there has been a strong need for the development of a reliable test method to measure the mechanical properties of a thin film. We have developed an alternative and convenient test method to overcome the limitations of previous membrane deflection experiment and uniaxial tensile test by adopting a white light interferometer having sub-nanometer out-of-plane displacement resolution. The freestanding aluminium specimens are tested to verity the effectiveness of the test method developed and get the tensile properties. The specimens are 0.5 rum wide, $1{\mu}m$ thick and fabricated through MEMS processes including sputtering. 1 to 5 specimens are fabricated on Si dies. The membrane deflection experiments are carried out by using a homemade tester consisted of a motor-driven loading tip, a load cell, and 6 DOF alignment stages. The test system is compact enough to set it up beneath a commercial white light interferometric microscope. The white light fringes are utilized to align a specimen with the tester. The Young's modulus and yield point stress of the aluminium film are 62 GPa and 247 MPa, respectively.

• Journal of the Semiconductor & Display Technology
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• v.3 no.2
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• pp.17-21
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• 2004

Aluminum nitride(AlN) thin films were deposited on silicon substrate by reactive RF magnetron sputtering without substrate heating. We investigated the dependence of some properties for AlN thin film on sputtering conditions such as working pressure, $N_2$ concentration and RF power. XRD, Ellipsometer and AES has been measured to find out structural properties and preferred orientation of AlN thin films. Deposition rate of AlN thin film was increased with an increase of RF power and decreased with an increase of $N_2$ concentration. AES in-depth measurements showed that stoichiometry of Aluminium and Nitrogen elements were not affected by $N_2$ concentration. It has shown that low working pressure, low $N_2$ concentration and high RF power should be maintained to deposit AlN thin film with a high degree of (0002) preferred orientation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.224-225
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• 2009

Aluminium nitride thin film was deposited on Au electrode and Si substrate by radio frequency sputtering system. X-ray diffraction (XRD) was utilized to identify the AlN phase, and Atomic Force Microscope (AFM) was used to obtain the images of surface morphology and roughness value of AlN thin film. The result of XRD and AFM measurement showed that the AlN thin film has strong c-axs orientation and smooth surface. In order to investigate piezoelectric response and polarization properties along to the direction of electric field, PFM (Piezoresponse Force Microscope) system was used, and the images of piezoelectric response due to switching of polarization was observed by PFM.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1372-1374
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• 2001

This paper describes fabrication and characteristics of metal thin-film pressure sensor for working at high temperature. The proposed pressure sensor consists of a chrom thin-film, patterned on a Wheatstone bridge configuration, sputter-deposited onto thermally oxidized Si membranes with an aluminium interconnection layer. The fabricated pressure sensor presents a low temperature coefficient of resistance, high-sensitivity, low non-linearity and excellent temperature stability. The sensitivity is 1.097 $\sim$ 1.21 mV/V kgf/$cm^2$ in the temperature range of 25 $\sim$ $200^{\circ}C$ and the maximum non-linearity is 0.43 %FS.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.5
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• pp.405-409
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• 2001

This paper describes fabrication and characteristics of metal thin-film pressure sensor for working at high temperature. The proposed pressure consists of a chrom thin-film, patterned on a Wheat stone bridge configuration, sputter-deposited onto thermally oxidized Si membranes with an aluminium interconnection layer. The fabricated pressure sensor presents a low temperature coefficient of resistance, high-sensitivity, low non-linearity and excellent temperature stability. The sensitivity is 1.097∼1.21mV/V$.$kgf/$\textrm{cm}^2$ in the temperature range of 25∼200$^{\circ}C$ and the maximum non-linearity is 0.43%FS.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.77-78
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• 2006

We fabricated photonic crystals on GaAs and GaN substrates. After anodizing the aluminium thin film in electrochemical embient, the porous alumina was implemented to the mask for reactive ion beam etching process of GaAs wafer. And photonic crystals in GaN wafer were also fabricated using electron beam nano-lithography process. The coated PMMA thin film with 200 nm-thickness on GaN surface was patterned with triangular lattice and etched out the GaN surface by the inductively coupled plasma source. The fabricated GaAs and GaN photonic crystals provide the enhanced intensities of light emission for the wavelengths of 858 and 450 nm, respectively. We will present the detailed dimensions of photonic crystals from SEM and AFM measurements.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.5
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• pp.10-19
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• 1998

The erosion of electrode in spot welding of aluminium alloy by direct current is dependent on the electric polarity. The positive electrode is much more eroded than the negative one. To explain this phenomenon, Peltier effect has been generally accepted as a unique theory. In this study Peltier effect was evaluated by calculations on the basis of some references and experiments. The difference of heat generated by Peltier effect on both electrode surfaces was, however, only 4% of total heat generated during wel- ding. Because of insufficient explanation, Kohler theory, which is mainly affected by thin oxide film, was introduced. A theoretical calculation showed 17% of the temperature difference between the positive and negative electrode, in case "surface voltage" resulted from oxide film was 30% of total contact voltage. This revealed that the erosion of electrode could be more affected by Kohler theory than effect.an effect.