Papers by Keyword: Surface Defect

Abstract: This study investigates the effects of laser spot size and sizing threshold parameters in Surface Scanning Inspection Systems (SSIS) on defect cluster identification in 300 mm silicon wafers. Reducing the laser spot size enhances the detection of smaller point defects, increasing cluster counts by up to 45% depending on the scan mode. Similarly, lowering the sizing threshold improves point defect capture rates, raising cluster probability by over 30%. However, these optimizations involve trade-offs: smaller spot sizes limit the search distance, while lower thresholds encourage cluster merging, resulting in a net decrease in identified clusters by 10%-20% in some cases. These findings underscore the need for a precise balance between sensitivity and resolution in SSIS configurations to achieve effective defect management. This work offers critical insights for optimizing silicon wafer quality, an essential factor in advanced integrated circuit manufacturing. Furthermore, it establishes a foundation for integrating machine learning-based defect feature analysis, paving the way for next-generation automated and predictive inspection systems in semiconductor fabrication. By addressing the challenges of defect clustering and providing data-driven solutions, this study contributes to the advancement of more reliable and efficient inspection technologies for the evolving demands of the semiconductor industry.

Abstract: The sectional observations of 13Cr-2Ni-2Mo and SUS 440C stainless steel ball bearings were done. Two features were found from the observations: parabolic-shaped cracks generated the flaking failure of 13Cr-2Ni-2Mo stainless steel bearing; jellyfish-shaped wear affected the flaking failure of SUS 440C stainless steel bearing.

Abstract: This paper’s aim is to develop the tribological repair method in PEEK (Poly-ether-ether-ketone) polymer mechanical parts with surface damage. The radial rolling sliding contact tests were carried out by using a machined PEEK shaft with an artificial defect as surface damage. An alumina ball and a PTFE composite pin contacted a PEEK shaft specimen under cyclic compressive stress with friction. The particle as solid lubricant from a PTFE composite pin filled up the crevice of the artificial defect. After that, the artificial defect was covered with the deformed microgrooves on the PEEK shaft surface. Due to adhesion by compressive stress and friction, the crevice of the artificial defect was closed. In a running-in process, the artificial defect could be reduced by the adhesion repair.

Abstract: Ni-based single crystal superalloy turbine blades have excellent mechanical strength and resistance to corrosion and oxidation due to a uniformly distributed gamma prime phase in a gamma matrix. However, defect grains have been often found on the surface of turbine blades after manufacturing, which can be potential sites of crack initiation. In this study, several different types of surface defect grains formed in third generation Ni-based single crystal turbine blades, such as stray grains, freckle chain grains, equiax grains, and a new grain formed in surface scale, had been investigated. The grain boundary regions were observed by high resolution electron microscopy. Although the formation mechanism of each grain defect is different, secondary phases, such as rhenium-rich particles, have been always found in each grain boundary. In addition, depending on the existence of the secondary phases as well as the size of defect grains, different microstructures were observed even in the same defect grain boundary. Finally, the observed results suggest that if there is any boundary region in a turbine blade, secondary phases, such as Re-rich particles, can be found.

Abstract: SiC-powered devices which reduce the power loss, size, and weight of power converters are gradually appearing in the power electronics market. From now on, cost reduction and quality improvement of SiC epitaxial wafers is required to further increase their popularity. This paper describes the state of development of mass production of the epi-wafer at Showa Denko K. K.

Abstract: Bare spots defect of galvanealed (GA) in High Strength Dual Phase (DP) steel strip with 1.5 % Mn contain was studied in detail. The surface morphologies of spot defects before and after partial and complete removal of the Zn layer, as well as the interface between the outermost coating layer and the sheet substrate were analyzed by optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray Photoelectron spectroscopy (XPS), glow discharge optical emission spectrometry (GDOES) and laser scanning confocal microscope(LSCM). It was found that the bare spots defect was composed of a large number of pits with different sizes and depths. There were a lot of Fe - Zn alloy particles distributed in the pits, and many MnO formed on the surface, no effective Fe₂Al₅ inhibition layer formed. The results showed that the main reasons for the bare spots defect of the GA in High Strength DP steel strip are as follows: a silicon oxide film forms on the substrate during annealing prior to hot dipping because of Mn gathered on the surface of steel strip, thus strip surface wettability with liquid zinc is deteriorated and preventing the formation of the Fe₂Al₅ inhibition layer during hot dipping. In this paper, the dew point control process is introduced creatively, by increasing the dew point and the hydrogen content in the furnace area, and the bare spot defects on the surface of the high strength duplex steel galvanized sheet are solved.

Abstract: We investigated the carrot-defect reduction effect by optimizing the buffer layers of 4H-Silion Carbide (SiC) epitaxial wafers. The SiC epitaxial wafer with the 0.5 μm-thick optimized condition-B buffer layer show the carrot-defect density of 0.13 cm^-2, since that with the conventional-A buffer layer were 0.68 cm^-2. Although the average bunching length with the optimized condition-B buffer layer was 7-times longer than those with the conventional condition-A buffer layer, we could reduce the bunching length by applying the optimized condition-B only to the initial 0.05 μm-thick buffer layer. Finally, with the initial 0.05 μm-thick optimized condition-B buffer layers, we could achieve the SiC epitaxial wafers with only half the carrot-defect densities of those with the conventional condition-A buffer layers, while the average bunching lengths were less than 100 μm. With this condition, we could achieve the estimated yield of 90.1% with 4 x 4 mm chips, while that with the conventional condition-A buffer layer was 81.9%.

Abstract: Surface defects caused by damage or corrosion are major factor in petrochemical pressure vessels and line pipes failure. The characteristic size of typical surface defect is from micron to submillimeter which belongs to mesoscopic scale, leading to difficulties for inspection and evaluation. The instrumented indentation method has widely used in the characterization of micro-zone mechanical behavior which could be effective in surface defects analysis. This paper aims at investigating the correspondence between indentation experimental results and distribution characteristics of surface defects. Mechanical properties of pressure vessel steel with surface defects are measured by indentation, and corresponding finite element models are established. Finite element simulation results of equivalent mechanical properties under indentation and three dimensional deformations are compared, and the applicability of finite element models for indentation test of steel with surface defects is analyzed. The effect of randomized surface defects on measuring result is studied subsequently using stochastic finite element models. The relation of equivalent mechanical properties and description of surface defects is proposed. The achievement could used to estimate the degree of damage or corrosion by miniature indentation testing techniques for safety assessment.

Abstract: Alkaline blackening is one of the most popular surface treatment technology of components with the requirement for higher surface corrosion resistance, increased hardness, and the decorative appearance.This contribution deals with the appearance of surface defects on carburized steel components after the process of alkaline blackening, which appeared to be red shiny stains on an otherwise black matte surface of the component. The occurrence of defects on surface was observed several days after the alkaline blackening process. By means of metallographic methods, direct connection between surface defects and the microstructure of the material was found.Contribution further deals with the influence of microstructure and technological parameters on the quality of the final surface layer of the components.

Abstract: For the popularization of SiC power device, improvement on both productivity and quality of 150 mm diameter SiC epitaxial wafer is inevitable. With highly productive 8x150-mm CVD reactor, we have grown epitaxial layer on 4° off 4H-SiC wafer Si-and C-face. Modifying some reactor parts and optimizing growth conditions enabled us to achieve a good balance between high uniformity and smooth surface.