• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1568-1570
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• 2009

Nanocrystalline silicon thin films were deposited using an internal-type inductively coupled plasma-chemical vapor deposition at room temperature by varying the bias power to the substrate and the structural characteristics of the deposited thin film were investigated. The result showed that the crystalline volume fraction was decreased with the increase of bias power. At the low bias power range of 0~60 W, the compress stress in the deposited thin film was in the range of -34 ~ -77 Mpa which is generally lower than the residual stress observed for the nanocrystalline silicon thin films deposited by capacitively coupled plasma.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.5
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• pp.249-252
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• 2001

The paper represents the design and fabrication of an electrostatic micro actuator with $p^+$,/TEX> Si cantilevers. The micro actuator consists of a plate suspended by four $p^+$,/TEX> silicon cantilevers and an electrode on a glass substrate. The $p^+$,/TEX> Si structure is fabricated by the boron diffusion process and the anisotropic wet etch process. The cantilevers of the micro actuator curl down because of the residual stress gradient in $p^+$,/TEX> silicon. When the electrostatic forec is applied to the $p^+$,/TEX> cantilevers, the vertical displacement of the plate can be achieved. The deflection of the cantilever due to the residual stress gradient and the vertical displacement by electrostatic force were calculated. The displacement of the plate was measured with a laser displacement meter for various input voltages and frequencies. The feasibility of the proposed micro actuator for the applications to optical pickup devices or optical communication devices was confirmed by the experiments.

• Korean Journal of Materials Research
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• v.16 no.10
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• pp.656-662
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• 2006

We fabricated thermal evaporated 10 nm-$Ni_xCo_{1-x}$ (x=0.2, 0.5 and 0.8) /(poly)Si films to form nanothick cobalt nickel composite silicides by a rapid thermal annealing at $700{\sim}1100^{\circ}C$ for 40 seconds. A field emission scanning electron microscope and a micro-Raman spectrometer were employed for microstructure and silicon residual stress characterization, respectively. We observed self-aligned micro-pinholes on single crystal silicon substrates silicidized at $1100^{\circ}C$. Raman silicon peak shift indicates that the residual tensile strain of $10^{-3}$ in single crystal silicon substrates existed after the silicide process. We propose thermal stress from silicide exothermic reaction and high temperature silicidation annealing may cause the pinholes. Those pinholes are expected to be avoided by lowering the silicidation temperature. Our results imply that we may use our newly proposed composite silicides to induce the appropriate strained layer in silicion substrates.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.820-823
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• 2002

MEMS structures Generally have been fabricated using surface-machining, but the interface failure between silicon substrate and evaporated thin film frequently takes place due to difference of linear coefficient of thermal expansion. Therefore this paper studied the effect of the residual stress caused by variable external loads. This study did not analyzed accurate quantity of the residual stress but trend for the effect of residual stress. Several specimens were fabricated using other material(Al, Au and Cu) and thermal load was applied. The residual stress was measured by nano-indentation using AFM. The results showed the existence of the residual stress due to thermal load. The indentation area of the thermal loaded thin film reduced about 3.5% comparing with the virgin thin film caused by residual stress. The finite element analysis results are similar to indentation test.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.9
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• pp.135-141
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• 2003

MEMS structures generally have been fabricated using surface-machining method, but the interface failure between silicon substrate and evaporated thin film frequently takes place due to the residual stress inducing by the applied the various loads. And the very important physical property in the heated environment is the linear coefficient of thermal expansion. Therefore this paper studied the residual stress caused the thermal loads in the thin film and introduced the simple method to measure the trend of the residual stress by the indentation. Specimens were made of materials such as Al, Au and Cu and thermal load was applied repeatedly. The residual stress was measured by nano-indentation using AFM and FEA. The existence of the residual stress due to thermal load was verified by the experimental results. The indentation length of the thermal loaded specimens increased minimum 11.8％ comparing with the virgin thin film caused by tensile residual stress. The finite element analysis results are similar to indentation test.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.1007-1009
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• 1998

In this paper, the effects of the drive-in process parameters on the residual stress profile of the p+ silicon film has been investigated. All the residual stress profile has been estimated by the second-order polynomial. All the coefficients of the polynomial have been determined from the measurement of the deflections of cantilevers and a rotating beam by using a surface profiler meter and by means of focusing a calibrated microscope. As the drive-in temperature or the drive-in time increases, the boron concentration decreases and the magnitude of the average residual stress decreases. If the boron concentration decreases the tensile residual stress decreases except near the surface where the magnitude of compressive residual stress increases.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.220-223
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• 1996

Mechanical properties of Plasma-Enhanced Chemical Vapor Deposited (PECVD) silicon nitride thin film was studied to determine the feasibility of the film as a passivation layer over the aluminum bonding areas of integrated circuit chips. Ultimate strain of the films in thicknesses of about 5 k${\AA}$ was measured using four-point bending method. The ultimate strain of these films was constant at about 0.2% regardless of residual stress. Intrinsic and residual stresses of these films were measured and compared with thermal shock and cycling test results. Comparison of the results showed that more tensile films were more susceptible to crack- induced failure.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.725-730
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• 1996

The key process in silicon surface micromachining is the selective etching of a sacrificial layer to release the silicon microstructure. The newly developed anhydrous HF/$CH_3$OH gas phase etching of TEOS (teraethylorthosilicate) sacrificial layers onto the polysilicon and the nitride substrates was employed to release the polysilicon microstructures. A residual product after TEOS etching onto the nitride substrate was observed on the surface, since a SiOxNy layer is formed on the TEOS/nitride interface. The polysilicon microstructures are stuck to the underlying substrate because SiOxNy layer does not vaporize. We found that the only sacrificial etching without any residual product and stiction is TEOS etching onto the polysilicon substrate.

• Journal of the Korean Vacuum Society
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• v.1 no.1
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• pp.145-152
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• 1992

Si surfaces exposed to CHF3/C2F6 gas plasmas ih reactive ion etching (RIE) have been characterized by X-ray photoelectron spectroscopy (XPS). CHF3/C2F6 gas plasma exposure of Si surface leads to the deposition of residual film containing carbon and fluorine. The narrow scan spectra of C 1s show various bonding states of carbon as C-Si, C-F/H, C-CFx(x $\leq$ 3), C-F, C-F2, and C-F3. The chemical bonding states of fluorine are described with F-Si, F-C and F-O. And the oxygen and silicon are also detected. The effects of parameters for reactive ion etching as CHF3/C2F6 gas ratio, RF power, and pressure are investigated.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.1
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• pp.13-19
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• 2015

Among the various possible factors affecting the Minority Carrier Life Time (MCLT) of the mc-Si crystal, dislocations formed during the cooling period after solidification were found to be a major element. It was confirmed that other defects such as grain boundary or twin boundary were not determinative defects affecting the MCLT because most of these defects seemed to be formed during the solidification period. With a measurement of total thickness variation (TTV) and bow of the silicon wafers, it was found that residual stress remaining in the mc-Si crystal might be another major factor affecting the MCLT. Thus, it is expected that better quality of mc-Si can be grown when the cooling process right after solidification is carried out as slow as possible.