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Back Pressure Equal Channel Angular Pressing of Consolidate Pure Al Particles
Li Yinglong,
He Lizi,
Zhang Ling
Issue:
Volume 9, Issue 1, January 2020
Pages:
1-6
Received:
11 December 2019
Published:
3 February 2020
Abstract: In this study, pure aluminum particles were successfully consolidated to fully dense bulk material by back pressure equal channel angular pressing (BE-ECAP) at room temperature, the evolutions of microstructure and densification mechanism were systematically investigated using an FEI-TECNAI G20 transmission electron microscope (TEM) operating at 200kV, FEI field-emission scanning electron microscope (FE-SEM) and hardness testing. The results indicated that the strong bulk materials from particles were successfully produced. After 4 BE-ECAP passes, the present samples show finer grains with the average grain size of ~10μm, the density of the sample was considerably higher compared to those of the materials that had undergone ECAP without back pressure, and was approach to the theoretical density of pure Al. This was related to the combination of hydrostatic pressure, shear deformation and strain accumulation. The mechanisms of grain refinement was the dislocation generated inside grains moves towards the grain boundary continuously, and accumulates, tangles annihilates at the grain boundaries, which resulting in the grains continuously fragmented and refined.
Abstract: In this study, pure aluminum particles were successfully consolidated to fully dense bulk material by back pressure equal channel angular pressing (BE-ECAP) at room temperature, the evolutions of microstructure and densification mechanism were systematically investigated using an FEI-TECNAI G20 transmission electron microscope (TEM) operating at 20...
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Effect of Acid Etching Time and Concentration on Oxygen Content of Powder on the Microstructure and Elastic Properties of Silicon Carbide Densified by SPS
Zeynep Ayguzer Yasar,
Richard Haber
Issue:
Volume 9, Issue 1, January 2020
Pages:
7-13
Received:
27 January 2020
Accepted:
12 February 2020
Published:
28 February 2020
Abstract: In this current paper, oxygen content of a fine particle size SiC (H. C. Starck UF 25 Silicon Carbide) and coarser particle size SiC (Saint Gobain Silicon Carbide) were modified by using different concentrations of HF for etching. Fully dense silicon carbide ceramics (>99% th. density) were produced by the spark plasma sintering technique at 1950 °C under an applied pressure of 50 MPa for 5 min hold with boron carbide and carbon addition. Archimedes method, scanning electron microscopy, and the ultrasound analysis were used to examined density, microstructure, elastic (E), shear (G), and bulk (K) moduli of dense silicon carbide ceramics to investigate the effect of oxygen impurities on the densification and the properties of silicon carbide. The results showed that high oxygen content is detrimental to the final density of SPS silicon carbide. When the oxygen content increased from 0.60 to 5.92 wt.%, the relative density decreased from 99.99% to 96%. For both SiC powders, by increasing the etching time, the grain size of SiC decreased. It means that the high oxygen caused grain growth. Ultrasound analysis results showed that the high oxygen content affected the elastic properties. SiC samples with the high oxygen content had a lower elastic moduli, shear moduli and bulk moduli. It was clear that increasing the oxygen content decreased the elastic properties.
Abstract: In this current paper, oxygen content of a fine particle size SiC (H. C. Starck UF 25 Silicon Carbide) and coarser particle size SiC (Saint Gobain Silicon Carbide) were modified by using different concentrations of HF for etching. Fully dense silicon carbide ceramics (>99% th. density) were produced by the spark plasma sintering technique at 1950 °...
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Investigation of the Airborne Molecular Contamination Behavior in 300 mm Semiconductor Front - End Manufacturing
Peter Franze,
Germar Schneider,
Clara Zaengle,
Markus Pfeffer,
Stefan Kaskel
Issue:
Volume 9, Issue 1, January 2020
Pages:
14-24
Received:
6 January 2020
Accepted:
15 January 2020
Published:
6 March 2020
Abstract: Front-end manufacturing of power semiconductor devices requires numerous different processes and materials. To control the complexity of fully automated 300 mm manufacturing lines, which typically utilize closed wafer containers, so called FOUPs (Front Opening Unified Pod), a systematic FOUP management concept is mandatory. This concept has to fulfill the quality targets in terms of organic and inorganic contaminants to assure the highest yield level of the semiconductor products. The focus of this study is to understand the behavior of airborne molecular contaminations (AMC) and to define strategies to prevent yield loss driven by AMC. The first step was to achieve a comprehensive knowledge of the AMC level within the different process steps of a selected power technology. Sampling and analysis procedures based on laser spectroscopy, measurements of electrical conductivity and mass spectrometry systems were used to understand the AMC level of the investigated components. A special automated research platform to analyze the gas phase in the FOUPs was used within the 300 mm high volume power semiconductor fab at Infineon Technologies Dresden. A pronounced dependence of the investigated component level on the different production steps was found. First offline root cause analyses due to contaminations of FOUPs with boron were performed using mass spectrometry, and the air filter systems used within the 300 mm cleanroom could be identified as a second source for boron contaminations. Other special experiments investigated the time dependency of the AMC level in the FOUP atmospheres. With this work, Infineon Dresden has established methods and strategies to prevent AMC-caused yield losses.
Abstract: Front-end manufacturing of power semiconductor devices requires numerous different processes and materials. To control the complexity of fully automated 300 mm manufacturing lines, which typically utilize closed wafer containers, so called FOUPs (Front Opening Unified Pod), a systematic FOUP management concept is mandatory. This concept has to fulf...
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