• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.04b
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• pp.147-151
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• 2000

This paper presents the electrochemical etch-stop characteristics of single-crystal silicon in a tetramethyl ammonium hyciroxide(TMAH):isopropyl alcohol(IPA):pyrazine solution. Addition of pyrazine to a TMAH:IPA etchant increases the etch-rate of (100) silicon, thus the elapsed time for etch-stop was shortened. The current-voltage(I-V) characteristics of n- and p-type silicon in a TMAH:IPA:pyrazine solution were obtained, respectively. Open circuit potential(OCP) and passivation potential(PP) of n- and p-type silicon, respectively, were obtained and applied potential was selected between n- and p-type silicon PP. The electrochemical etch-stop is applied to the fabrication of 801 microdiaphragms having $20\;{\mu}m$ thickness on a 5-inch silicon wafer. The averge thicknesses of 801 microdiaphragms fabricated on the one wafer were $20.03\;{\mu}m$ and standard deviation was ${\pm}0.26{\mu}m$. The silicon surface of the etch-stopped microdiaphragm was extremely flat without noticeable taper or other nonuniformities. The benefits of the electrochemical etch-stop in a TMAH:IPA:pyrazine solution become apparent when reproducibility in the microdiaphragm thickness for mass production is considered. These results indicate that the electrochemical etch-stop in a TMAH:IPA:pyrazine solution provides a powerful and versatile alternative process for fabricating high-yield silicon microdiaphragms.

• Journal of the Korean institute of surface engineering
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• v.20 no.4
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• pp.144-153
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• 1987

In the case of dipping the Ni-Resist cast iron into molten aluminum with iron content, the thickness of intermetallic compound was remarkably increased with increasing iron content. The thickness was shown by following equation in the range of 1-3% iron content; $x=22.5t^{1/2}+4.47{\cdot}t{\cdot}(Fe%)$. where, x is thickness(${\mu}m$), t the time (minute), Fe% the iron w/o. When the Ni-Resist cast iron was dipped into the molten aluminum containing zinc content, the intermetallic compound thickness was also increased with increasing zinc contents. And thickness was represented by the following equation in the range of 2-10% zinc content; $x=3.46t^{1/2}+0.27{\cdot}t{\cdot}(Zn%)$. However, in the case of dipping the Ni-resist cast iron into molten aluminum with silicon content, the thickness of intermetallic compound was decreased with increasing silicon content, as shown in the following equation; $x=7.17t^{1/2}-0.15{\cdot}t{\cdot}(Si%)$. The intermetallic compound formed onto Ni-Resist cast iron was identified to be $FeAl_3\;and\;Fe_3Al$. As the result of hardness measurement, the peak hardness appeared in the intermetallic compound at near interface of the cast iron and the compound.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.2
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• pp.142-147
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• 2021

We present a subthreshold swing model for a symmetric junctionless double gate MOSFET. The scale length λ1 required to obtain the potential distribution using the Poisson's equation is a criterion for analyzing the short channel effect by an analytical model. In general, if the channel length Lg satisfies Lg > 1.5λ1, it is known that the analytical model can be sufficiently used to analyze short channel effects. The scale length varies depending on the channel and oxide thickness as well as the dielectric constant of the channel and the oxide film. In this paper, we obtain the scale length for a constant permittivity (silicon and silicon dioxide), and derive the relationship between the scale length and the channel length satisfying the error range within 5%, compared with a numerical method. As a result, when the thickness of the oxide film is reduced to 1 nm, even in the case of Lg < λ1, the analytical subthreshold swing model proposed in this paper is observed to satisfy the error range of 5%. However, if the oxide thickness is increased to 3 nm and the channel thickness decreased to 6 nm, the analytical model can be used only for the channel length of Lg > 1.8λ1.

• Journal of Applied Reliability
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• v.16 no.1
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• pp.26-31
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• 2016

Purpose: The purpose of this study was to investigate the effect of grinding process and thickness on the fracture strength of silicon die used for semiconductor substrate. Method: Silicon wafers with different thickness from $200{\mu}m$ to $50{\mu}m$ were prepared by chemical mechanical polishing (CMP) and dicing before grinding (DBG) process, respectively. Fracture load was measured by point load test for 50 silicon dies per each wafer. Results: Fracture strength at the center area was lower than that at the edge area of the wafer fabricated by DBG process, while random distribution of the fracture strength was observed for the CMPed wafer. Average fracture strength of DBGed specimens was higher than that of the CMPed ones for the same thickness of wafer. Conclusion: DBG process can be more helpful for lowering fracture probability during the semiconductor fabrication process than CMP process.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.7
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• pp.1434-1437
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• 2011

Precision measurement of silicon wafer resistivity has been using single-configuration Four-Point Probe(FPP) method. This FPP method have to applying sample size, shape and thickness correction factor for a probe pin spacing to precision measurement of silicon wafer. The deference for resistivity measurement values applied correction factor and not applied correction factor was about 1.0 % deviation. The sample size, shape and thickness correction factor for a probe pin spacing have an effects on precision measurement for resistivity of silicon wafer.

• Journal of the Korean Ceramic Society
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• v.33 no.10
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• pp.1170-1176
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• 1996

Porous silicon was prepared by anodic reaction. The process was controlled by current density and etching time an the thickness change and the room temperature PL was measured. The thickness of porous silicon was increased with etching time and was decreased after critical time. It was the same as increasing current density. It needed only 15 sec to electropolish the surface of porous silicon above current density 70 mA/cm2. We can understand that increasing etching time leads narrow size of Si column by porous silicon formation mechanism. And the sample with narrow Si column revealed PL blue shift. The specimens were heated in the range of 300-1000$^{\circ}C$ in order to see PL changes. The heat treatment was proceeded in H2 atmosphere vacuum system to avoid oxidation. The PL was disappeared above 600$^{\circ}C$. In high temperature some sintered Si columns were observed in SEM photography. There was no difference of -Hx bonds which was suggested as evidence of hydride compounds luminescence between 500$^{\circ}C$ and 600$^{\circ}C$. Thus it is concluded that quantum confinement is major factor of PL of porous silicon.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.4
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• pp.185-189
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• 2004

The temporal variation of a secondary electron emission coefficient (${\gamma}$ coefficient) of hydrogenated amorphous silicon (a-Si:H) was investigated in a dc silane plasma. Estimated ${\gamma}$ coefficients have a value of 2.73 ${\times}$ 10$^{-2}$ on the pure aluminum electrode and 1.5 ${\times}$ 10$^{-3}$ after 2 hours deposition of -Si:H thin films on a cathode. It showed an abrupt decrease for about 30 minutes before saturation. The variation of the ${\gamma}$ coefficient was estimated as a function of the thin film thickness, and the film thickness was about 80 nm after 30 minutes deposition time. These results are compared with the results of a computer simulation for ion penetration into a cathode.

• Journal of Korea Foundry Society
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• v.32 no.5
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• pp.211-218
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• 2012

The effects of thickness, silicon and manganese contents on the mechanical properties of 3.3 wt%C-0.1 wt%S thin-section gray cast iron plates were investigated. The eutectic cell counts and volume fraction of pearlite in the matrix decreased with increased thickness and therefore the strength and hardness decreased with it. Even though the eutectic cell count increased with increased silicon content, the volume fraction of pearlite decreased and the strength and hardness decreased with it. The pearlite was refined more with increased manganese content and therefore the strength and hardness increased with it.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.4
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• pp.187-191
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• 2004

In this work, we used the PCID simulator for simulation of solar cell and examined the effect of front-back surface recombination velocity, minority carrier diffusion length, junction depth and emitter sheet-resistance. As the effect of base thickness, the efficiency decreased by the increase in series resistance with the increase of the thickness and found decrease in efficiency by decrease of the current as the effect of the recombination. Also, as the effect of base resistivity, the efficiency increased somewhat with the decrease in resistivity, but when the resistivity exceeded certain value, the efficiency decreased as a increase in the recombination ratio. The optimum efficiency was obtained at the resistivity 0.5 $\Omega$-cm, and thickness $100\mu\textrm{m}$. We have successfully achieved 10.8% and 13.7% efficiency large area($103mm{\times}103mm$) mono-crystalline silicon solar cells without and with PECVD silicon nitride antireflection coating.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.1
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• pp.93-99
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• 1996

The formation properties and oxidation mechanism of electrochemically oxidized porous silicon(OPS) films have been studied. To examine the humidity-sensitive properties of OPS films, surface-type and bulk-type humidity sensors were fabricated. The oxidized thickness of porous silicon layer(PSL) increases with the charge supplied during electrochemical humidity sensor shows high sensitivity at high relative humidity in low temperature. The sensitivity and linearity can be improved by optimizing a porosity of PSL. (author). refs., figs.