Abstract: Laser scattering characteristics of typical CMP-induced defects such as particles and microscratches with the size of sub-micron order are investigated using a developed automated scattered light measurement system. The measurement system has an ability to detect three-dimensional distribution of scattered light from the defects with high sensitivity. The angular distributions of scattered light from the standard PSL (Polystyrene latex) spheres and microscratches reveal that scattering characteristics of microscratches are quite different from those of Particles. The scattered light from the PSL sphere is detected mainly ahead. In contrast, the scattered light from the microscratches only exists in the direction perpendicular to its length dimension at an oblique incidence maintaining the sheet-shaped pattern, even if its orientation relative to the incident direction is changed. Optical arrangement for defect detection and classification is suggested based on the experimental results.
Abstract: A novel measurement system, the multi-functional Tribological Probe Microscope (TPM), has been developed to provide multi-function measurements of surface and surface properties. These properties are topography, friction, Young’s modulus, and nano-hardness. They are measured, point-by-point, in a single scan set up. The four function maps of surface topography, friction, hardness and Young’s modulus are correlated in space and time. In this paper we will brief the TPM system and demonstrate the capability of the multi-function evaluation of engineering surfaces and their correlated nature between these functions. It is believed that such direct correlated measurements will help scientist and engineers to understand surface and surface related properties and eventually to design and optimise a surface for a better performance.
Abstract: In order to reduce and control yield loss in the fabrication process of next generation ULSI devices, nano-defects inspection technique for polished Silicon (Si) wafer surface becomes more essential. This paper discusses a new optical nano-defects detection method, which is applicable to silicon wafer surface inspection for next-generation semiconductors. In our proposed method, the evanescent light is emerged on the wafer surface with total internal reflection (TIR) of infrared (IR) laser at the Si-air interface. By scanning the surface where the evanescent light is emerging with a very shaped fiber probe, it enables to detect nanometer scale defects in the vicinity of Si wafer surface without diffraction limit to resolution. To experimentally verify the feasibility of this method, an evanescent light measurement system was developed and several fundamental experiments were performed. The results show that the proposed Si wafer microdefects detection method can detect the microdefect with 10nm scale on and beneath the surface based on evanescent light distribution.
Abstract: A comparison of strain measurement results, from an embedded fibre-optic Bragg grating (FBG) sensor and surface mounted strain gauge, at different vibration frequency ranges and using a clamped-clamped glass fibre composite beam, is presented. It is shown that the FBG sensor is able to precisely measure the peaks at the first-two natural frequency modes compared with the spectrum captured from the strain gauge. The results also demonstrate that the strains measured from the FBG sensor agreed well with the strain gauge at frequencies below 100 Hz. Beyond this value, the actual strain on the beam surface was less than 3µe, and the data extracted from the strain gauge are no longer valid. For a clamped-clamped structure, the longitudinal strain of the beam correlates to its vibration amplitude and excitation frequency. Increasing the frequency results in decreasing the longitudinal strain of the beam and erroneous measurements from the strain gauge resulted. This study provides important information on the feasibility of using embedded FBG sensors as vibration monitoring devices to measure mechanical performance of composite structures.
Abstract: A method of the thermovision study for solving the problems of the experimental mechanics is presented. The method of the experimental study of deformation and fracture is based on the registration and interpretation of the infrared radiation pattern of a sample, which is caused by plastic deformations and material fracture. The thermofilm shows the kinetics of the sample deformation. Thermograms allow estimation of the plastic deformation zones. The characteristic changes in the temperature of a sample correspond to the limiting states of the material. Examples of studying the deformation and fracture of constructional steels under the conditions of the homogeneous and heterogeneous limiting states with the use of the thermovision method are given.
Abstract: A study on the use of modal parameter analysis for damage detection of structures made of composites is conducted. The damage-induced variations of modal parameters are investigated both numerically and experimentally. An appropriate finite element model is proposed to analyze the dynamic characteristics of different types of structures made of composites, such as honeycomb sandwich plates and multi-layer composite plates, with internal cracks and delamination. The numerical results are in good agreement with experimental results available in the literature. Natural frequencies, modal displacements, strains and energy are analyzed for the determination of damage severity and location. Vibration measurements are carried out using piezoelectric patch actuators and sensors for comparison and verification of the FEM model proposed in this study. Energy spectrum for wavelet packets decomposition of structural dynamic responses is used to highlight the features of damaged samples. The mechanism of mode-dependent energy dissipation of composite plates due to delamination is revealed for the first time. Experimental results clearly show the dependence of changes of modal parameters on damage size and location. The results obtained in this study show that the measured modal damping change combined with the computed modal strain energy distribution can be used to determine the location of delamination in composite structures. Both numerical and experimental findings in this study are significant to the establishment of guideline for size and location identification of damage in composite structures.
Abstract: Nonisothermal crystallization behaviors of PVA and poly (vinyl alcohol) and Silica (PVA/SiO2) nanocomposites prepared via a self-assembly monolayer (SAM) technique are investigated in this study. Differential scanning calorimetry (DSC) is used to measure the crystallization temperature and enthalpy of PVA and nanocomposites in nitrogen at various cooling rate. The results show that the degree of crystallinity of PVA and nanocomposites decreases when
the SiO2 content increases but increases with an increasing cooling rate. The peak crystallization temperature decreases with an increasing cooling rate.
Abstract: Structural and optical properties of MBE-grown GaAs(001) surface have been studied by reflection high-energy electron diffraction and single-wavelength ellipsometry under dynamic conditions of ramp heating after desorption of passivating As-cap-layer with and without As4 beam applied to the surface. For a number metastable reconstruction transitions, a clear correlation is established between diffraction and optical data. Boundary lines for transitional superstructures are determined as a function of As flux and corresponding activation energies are estimated. For the first time it is ellipsometrically shown that optical response of the surface is drastically different for transitions of the order-order and order-disorder type.
Abstract: This study aims to investigate the temperature effect on particle size of copper oxide
nanofluid produced under optimal parameters of the Arc Spray Nanoparticle Synthesis System (ASNSS) developed in this research. The purpose is to understand the aggregation feature of copper oxide nanofluid in a higher-than-room-temperature environment and to analyze its size change and the motion behavior of suspended nanoparticles. This study employs an ambient temperature controller to maintain the environment temperature within the scope of normal fluid work temperature to obtain data on the change in suspended particles of copper oxide nanofluid under varying temperatures and through change of time. Experimental result shows that the particle size distribution of copper oxide nanofluid changes when the temperature rises due to the slight absorption and aggregation phenomena between particles, and that the change in environmental temperature can accelerate the aggregation of copper oxide nanofluid, which can affect its stability in application. However, the change in particle size distribution will gradually stabilize for a longer duration of constant temperature.
Abstract: The Young’s modulus of micromechanical silicon films is very different from bulk
silicon structures. It is very meaningful to test Young’s modulus of micromechanical silicon films in related studies. Owing to its small and fragile characterstics, a suitable non-contact and nondestructive method is needed to test the Young’s modulus of micromechanical silicon films with plate-like and beamlike structures. Utilizing acoustic excitation and optical detection method based on theoretical analysis, a new resonant method is presented to determinate Young’s modulus of micromachined silicon films. By using this novel method, more accurate results have been achieved and the measuring error is 11%, better than the reported 14%.