• Title/Summary/Keyword: Thin film residual stress

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Observation of Size Effect and Measurement of Mechanical Properties of Ti Thin Film by Bulge Test (벌지 실험을 통한 Ti 박막의 크기 효과 관찰 및 기계적 물성 측정)

  • Jung, Bong-Bu;Lee, Hun-Kee;Hwang, Kyung-Ho;Park, Hyun-Chul
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.37 no.1
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    • pp.19-25
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    • 2013
  • In this study, the mechanical properties of a Ti thin film are measured by a bulge test. In the bulge test, uniform pressure is applied to one side of the film. Measurement of the membrane deflection as a function of the applied pressure allows one to determine the mechanical properties of the film. Ti thin films with thicknesses of 1.0, 1.5, and $2.0{\mu}m$ were deposited on a Si wafer by using an RF magnetron sputtering system. These specimens were annealed at $600^{\circ}C$ for 150, 300, and 600 s to investigate the effect of temperature on the yield stress and mechanical properties of the Ti films. The elastic modulus, residual stress, and yield stress of these membranes are measured by a bulge test. The experimental results suggest that the yield stress is sensitive to the film thickness and annealing time.

Study on Residual Stress in Viscoelastic Thin Film Using Curvature Measurement Method

  • Im, Young-Tae;Park, Seung-Tae;Park, Tae-Sang;Kim, Jae-Hyun
    • Journal of Mechanical Science and Technology
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    • v.18 no.1
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    • pp.12-19
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    • 2004
  • Using LSM (laser scanning method) , the radius of curvature due to thermal deformation in polyimide film coated on Si substrate is measured. Since the polyimide film shows viscoelastic behavior, i.e., the modulus and deformation of the film vary with time and temperature, we estimate the relaxation modulus and the residual stresses of the polyimide film by measuring the radius of curvature and subsequently by performing viscoelastic analysis. The residual stresses relax by an amount of 10% at 100$^{\circ}C$ and 20% at 150$^{\circ}C$ for two hours.

Microstructure and Residual Stress of Metallic Thin Films According to Deposition Parameters

  • Park, Byung-Jun;Kim, Young-Man
    • Journal of the Korean institute of surface engineering
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    • v.36 no.1
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    • pp.1-8
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    • 2003
  • In general, the microstructure in thin films was known to evolve in similar manner according to the energy striking the condensing film at similar homologous temperature, Th for the materials of the same crystal structure. The fundamental factors affecting particle energy are a function of processing parameters such as working pressure, bias voltage, target/sputtering gas mass ratio, cathode shape, and substrate orientation. In this study, Al, Cu, Pt films of the same crystal structure of face centered cubic (FCC) have been prepared under various processing parameters. The influence of processing variables on the microstructures and residual stress states in the films has been studied.

Fabrication of Nano-Size Specimens for Tensile Test Employing Nano-Indentation Device (나노 인장시험을 위한 압축 시험기용 인장시편 제작에 관한 연구)

  • Lim, Tae Woo;Yang, Dong-Yol
    • Journal of the Korean Society for Precision Engineering
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    • v.32 no.10
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    • pp.911-916
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    • 2015
  • In the nano/micro scale, material properties are dependent on the size-scale of a structure. However, conventional micro-scale tensile tests have limitations to obtain reliable values of nano-scale material properties owing to residual stress and elastic slippage in the gripping/aligning process. The indenter-driven nano-scale tensile test provides prominent advantages simple testing device, high-quality nano-scale metallic specimen with negligible residual stress. In this paper, two-types of specimens (a specimen with multi-testing parts and a specimen with a single-testing part) are discussed. Focused ion beam (FIB) is employed to fabricate a nano-scale specimen from a thin nickel film. Using the specimen with a single-testing part, we obtained a nano-scale stress-strain curve of electroplated nickel film.

Effects of Ni Concentration on Residual Stress in Electrodeposited Ni Thin Film for 63Ni Sealed Source (63Ni 밀봉선원용 Ni 전기도금 박막에서 Ni 농도가 잔류응력에 미치는 영향)

  • Yoon, Pilgeun;Park, Deok-Yong
    • Journal of the Korean institute of surface engineering
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    • v.50 no.1
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    • pp.29-34
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    • 2017
  • Chloride plating solution was fabricated by dissolving metal Ni powders in a mixed solution with HCl and de-ionized water. Effects of $Ni^{2+}$ and saccharin concentrations in the plating baths on current efficiency, residual stress, surface morphology and microstructure of Ni films were studied. In the case of $0.2M\;Ni^{2+}$ concentration, current efficiency was decreased to about 65 % with increasing saccharin concentration, but, in the case of $0.7M\;Ni^{2+}$ concentration, it was shown more than 90 % with the increase of saccharin concentration. Residual stress of Ni thin film was appeared to be about 400 MPa up to 0.0244 M saccharin concentration at the $0.2M\;Ni^{2+}$ concentration and surface morphology with severe cracks was observed in the range of 0.0487~0.0975 M saccharin concentration. Residual stress of Ni thin films was measured to be about 750 MPa without saccharin addition and 114~148 MPa at the range of 0.0097~0.0975 M saccharin concentration for the $0.7M\;Ni^{2+}$ concentration. Relatively low residual stress values (114~148 MPa) of the Ni films at the range of 0.0097~0.0975 M saccharin concentration may be resulted from codeposition of S from saccharin. Ni films at $0.7M\;Ni^{2+}$ concentration showed smooth surface morphology and were independent of saccharin concentration. Ni films at $0.7M\;Ni^{2+}$ concentration consist of FCC(111), FCC(200), FCC(220) and FCC(311) peaks and the intensities of FCC(111) and FCC(200) peaks increased with increasing saccharin concentration. Also, the average grain size decreased with increasing saccharin concentration from about 30 nm to about 15 nm.

Measurement of Mechanical Properties of a Thermally Evaporated Gold Film Using Blister Test (블리스터 시험법을 이용한 열증착 금박막의 기계적 성질 측정)

  • Moon, Ho-Jeong;Ham, Soon-Sik;Earmme, Yun-Young;Cho, Young-Ho
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.3
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    • pp.882-890
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    • 1996
  • Mechanical properties, including Young's modulus, residual stress and rupture strength, of a thermally evaporated gold film have been measured form a blister test. In a theoretical study, the priniple of minimum potential energy and that of virtual work have been applied to the pressurized circular membrane problem, and load-deflection relations have been derived for typical membrane deflection mode of spheroidal shape. In an experimental study, circular gold membranes of 4800 A-thickness and 3.5mm diameter were fabricated by the silicon electropolishing technique. Mecahnical properties of the thin gold films were deduced from the load-deflection curves obtained by the blister test, Young's moduli, obtianed from blister test, have been in the range of 45-70 GPa, while those of bulk gold have been in the range of 78-80 GPa. Residual stresses in the evaporated gold films have been measured as 28-110MPa in tension, The rupture strength of the gold film has turned out to be almost equal to that of dental gold alloy (310-380MPa). It has been demonstrated that the present specimen fabrication method and blister test apparatus have been effective for simultaneous measurement of Young's modulus, residual stress and repture strength of thin solid films. Especially, the electropolishing technique employed here has provided a simple and practical way to fabricate thin membranes in a circular or an arbitrary shape, which could not be obtained by the conventional anisotropic silicon mecromachining technique.

Annealing Effect on the Characteristics of Thin Film Inductors with Inner Coil Type (내부 코일형 박막 인덕터의 특성에 미치는 열처리 효과)

  • Min, Bok-Gi;Kim, Hyeon-Sik;Song, Jae-Seong
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.48 no.5
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    • pp.333-338
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    • 1999
  • Thin film inductors of $10 mm \times 10 mm$ with inner coil type of 14 turns were fabricated by sputtering, photo-masking, and etching processes. Their characteristics of impedances and annealing after were investigated. The properties of impedances of the thin film magnetic core inductors with inner coil type were improved by magnetic field annealing due to the removal of residual stress and the improvement magnetic properties of magnetic films. But the characteristics of frequency of the thin film magnetic core inductors were not improved by magnetic field annealing due to properties of the spiral pattern and inner coil type. The thin film magnetic core inductor annealed by uniaxal field annealing method showed an inductance of 1000 nH and resistance of$ 6 \Omega$ of 1 at 2 MHz.

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Effects of the Changes of Current Density and Additive Concentration on Ni Thin Films in Ni Sulfamate-chloride Electrodeposition Baths (Ni Sulfamate-chloride 전기도금 용액에서 전류밀도와 첨가제의 농도 변화가 Ni 박막에 미치는 영향)

  • Yoon, Pilgeun;Park, Deok-Yong
    • Journal of the Korean institute of surface engineering
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    • v.51 no.1
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    • pp.62-70
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    • 2018
  • Sulfamate plating solution containing a small amount of chloride bath was fabricated to study the properties of the electrodeposited Ni thin films. Effects of the changes of current density and additive concentration on current efficiency, residual stress, surface morphology and microstructure of Ni thin films electrodeposited from Ni sulfamate-chloride baths were investigated. The current efficiency was measured to be more than about 95%, independent of the changes of current density and saccharin concentration in the baths. Residual stress of Ni thin film was appeared to be the compressive stress modes in the range of $5{\sim}30mA/cm^2$ current density. Maximum compressive stress was observed at the current density of $10mA/cm^2$. Compressive stress values of Ni thin/thick films were increased to be about -85~-100 MPa with increasing saccharin concentration from 0 to 0.0195 M(4 g/L). Surface morphology was changed from smooth to nodule surface appearance with increasing the current density. Smooth surface morphology of Ni thin films electrodeposited from the baths containing saccharin was observed, independent of the saccharin concentration. Ni thin/thick films consist of FCC(111), FCC(200), FCC(220), FCC(311) and FCC(222) peaks. It was revealed that the FCC(200) peak of Ni thin films is the preferred orientation in the range of $5{\sim}30mA/cm^2$ current density. The intensity of FCC(200) peak was gradually decreased and the intensity of FCC(111) peak was increased with increasing saccharin concentration in the baths.

Fatigue Life Analysis on Multi-Stacked Film Under Thermal and Residual Stresses (열응력과 잔류응력하의 다층박막의 피로수명 해석)

  • Park Jun-Hyub
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.4 s.235
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    • pp.526-533
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    • 2005
  • Reliability problem in inkjet printhead, one of MEMS devices, is also very important. To eject an ink drop, the temperature of heater must be high so that ink contacting with surface reaches above $280^{o}C$ on the instant. Its heater is embedded in the thin multi-layer in which several materials are deposited. MEMS processes are the main sources of residual stresses development. Residual stress is one of the factors reducing the reliability of MEMS devices. We measured residual stresses of single layers that consist of multilayer. FE analysis is performed using design of experiment(DOE). Transient analysis for heat transfer is performed to get a temperature distribution. And then static analysis is performed with the temperature distribution obtained by heat transfer analysis and the measured residual stresses to get a stress distribution in the structure. Although the residual stress is bigger than thermal stress, thermal stress is more influential on fatigue life.

C-axis Orientation and Growth Structure of AIN Thin Films on $SiO_2$/Si Substrates Deposited by Reactive RF Magnetron Sputtering

  • Joo, Han-Yong;Lee, Jae-Bin;Kim, Hyeong-Joon
    • The Korean Journal of Ceramics
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    • v.3 no.4
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    • pp.257-262
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    • 1997
  • Aluminum nitride(AIN) thin films were deposited on SiO$_2$/Si substrates by reactive sputtering for the application of SAW devices. The major deposition parameters such as pressure, nitrogen fraction, rf power, substrate distance were changed to find out the optimal condition for c-axis oriented thin films on an amorphous substrate. The effects of deposition parameters on the crystal structure, residual stress, and growth morphology of thin films were characterized by XRD, SEM, and TEM. The FWHM of (002) rocking curve of the films deposited at the proper condition was lower than 2.2$^{\circ}$(C=0.93$^{\circ}$). Cross-sectional TEM showed that self-aligned structure was developed just after slightly random growth at the initial stage. The frequency characteristics of test device fabricated from AIN thin films confirmed their piezoelectric property and applicability for SAW devices.

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