Evaluation of oxygen precipitation behavior in n-type Czochralski-Si for photovoltaic by infrared tomography: Effects of carbon concentration and annealing process conditions

ABSTRACTEffects of high carbon concentration upon oxygen precipitate formation in Cz silicon have been investigated by combining various furnace and rapid thermal annneals. Even though oxide precipitate density increases with increasing carbon levels, Cs, synchrotron radiation section topographs of processed high carbon content wafers (Cs ∼ 4ppma) exhibit Pendellosung fringes, indicating a strain free bulk state. Our optical microscopic data have also shown very few defect etch features inside the bulk. A model based upon a direct coupling of both SiO2 and Si-C complex formation reactions is used to explain rather unique oxygen precipitation characteristics in the high carbon content Cz Si materials.

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Mathematical Modeling of Carbon Flux Parameters for Low-Pressure Vacuum Carburizing with Medium-High Alloy Steel

Coatings ◽

10.3390/coatings10111075 ◽

2020 ◽

Vol 10 (11) ◽

pp. 1075

Author(s):

Haojie Wang ◽

Jing Liu ◽

Yong Tian ◽

Zhaodong Wang ◽

Xiaoxue An

Keyword(s):

Carbon Concentration ◽

Carbon Flux ◽

Carbon Fluxes ◽

Low Pressure ◽

Process Conditions ◽

Flux Method ◽

Vacuum Carburizing ◽

Initial Carbon ◽

Vacuum Carburization ◽

And Diffusion

Low-pressure vacuum carburizing adopts a pulse process mode to improve the carburizing efficiency and reduces gas and energy consumption. Carbon flux is the key to accurately control the time of strong infiltration and diffusion in each pulse. In order to obtain the carbon fluxes with various materials under diffident carburizing process conditions, an evenly segmented carbon flux method is proposed. A systematic study with each model using different materials (12Cr2Ni4A, 16Cr3NiWMoVNbE, and 18Cr2Ni4WA represent different initial carbon concentrations and different alloy compositions), carburizing temperatures, and carburizing pressures to determine the effect of these conditions on carbon flux is conducted. Compared with traditional segmented carbon flux method, an evenly segmented carbon flux method can predict the actual carbon flux more precisely and effectively in order to finely control the pulse carburization process. The paper also indicates that carbon fluxes increase with the increase of pressure. The optimal carburization pressure for low-pressure vacuum carburization is 300 Pa. Raising the carburization temperature to 980 °C instead of 920 °C can increase effective carbon flux by more than 30%. Among the material compositions, alloy content has the biggest impact over the carbon, initial carbon concentration the second, and saturated carbon concentration the third biggest impact.

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Diffusive steel scrap melting in carbon-saturated hot metal—phenomenological investigation at the solid–liquid interface

Materials ◽

10.3390/ma12081358 ◽

2019 ◽

Vol 12 (8) ◽

pp. 1358 ◽

Cited By ~ 2

Author(s):

Penz ◽

Schenk ◽

Ammer ◽

Klösch ◽

Pastucha ◽

...

Keyword(s):

Boundary Layer ◽

Carbon Concentration ◽

Steel Production ◽

Production Optimization ◽

Steel Scrap ◽

Process Conditions ◽

Hot Metal ◽

Scrap Melting ◽

Solid Liquid Interface ◽

Solid Liquid

The oxygen steelmaking process in a Linz-Donawitz (LD) converter is responsible for more than 70% of annual crude steel production. Optimization of the process control and numerical simulation of the LD converter are some of the current challenges in ferrous metallurgical research. Because of the process conditions and oxidation of impurities of the hot metal, a lot of chemical heat is generated. Therefore, steel scrap is charged as a coolant with the economical side aspect of its recycling. One of the more complex aspects is, among others, the dissolution and melting behaviour of the scrap in carbon-saturated hot metal. Heat and mass transfer act simultaneously, which has already been investigated by several researchers using different experimental approaches. The appearances at the interface between solid steel and liquid hot metal during diffusive scrap melting have been described theoretically but never investigated in detail. After an experimental investigation under natural and forced convective conditions, the samples were further investigated with optical microscopy and electron probe microanalysis (EPMA). A steep carbon concentration gradient in the liquid appeared, which started at an interface carbon concentration equal to the concentration on the solid side of the interface. Moreover, the boundary layer thickness moved towards zero, which symbolized that the boundary layer theory based on thermodynamic equilibrium was not valid. This fact was concluded through the prevailing dynamic conditions formed by natural and forced convection.

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Impact of Rapid Thermal Oxidation at Ultrahigh-Temperatures on Oxygen Precipitation Behavior in Czochralski-Silicon Crystals III

ECS Solid State Letters ◽

10.1149/2.0071508ssl ◽

2015 ◽

Vol 4 (9) ◽

pp. P63-P65 ◽

Cited By ~ 4

Author(s):

K. Araki ◽

H. Sudo ◽

S. Maeda

Keyword(s):

Thermal Oxidation ◽

Precipitation Behavior ◽

Czochralski Silicon ◽

Rapid Thermal Oxidation ◽

Silicon Crystals ◽

Oxygen Precipitation

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Systematic Analyses of Practical Problems Related to Defects and Metallic Impurities in Silicon

MRS Proceedings ◽

10.1557/proc-510-3 ◽

1998 ◽

Vol 510 ◽

Cited By ~ 7

Author(s):

Y. Kitagawara ◽

H. Takeno ◽

S. Tobe ◽

Y. Hayam Izu ◽

T. Koide ◽

...

Keyword(s):

Thermal Process ◽

High Sensitivity ◽

Wafer Surface ◽

Process Time ◽

Precipitation Behavior ◽

Oxygen Precipitation ◽

High Temperature Process ◽

Diffusion Dynamics ◽

High Sensitivity Detection ◽

Low Temperature Process

AbstractSystematic approaches are introduced for (i) oxygen precipitation behavior, which is important for internal gettering, and (ii) segregation induced gettering behaviors of p/p+ epitaxial wafers and Poly-Si Back Seal (PBS) wafers. (i) Oxygen precipitation behavior during a whole sequence of a thermal process is predicted by a practical computer simulation technique involving a novel empirical function. The predicted oxygen precipitation behavior agrees with the corresponding experimental results reasonably well. (ii) For a systematic description of Fe segregation gettering, explicit expressions of the Fe segregation coefficients are obtained as functions of temperature and time. Using the determined expressions of the segregation coefficients and introducing diffusion dynamics, one can predict [Fe] behavior as a function of process time during a whole sequence of a thermal process. For both behaviors of(i) oxygen precipitation and (ii) segregation induced gettering, experimentally observed characteristics of a high-temperature process and a low-temperature process are well understood by aids of those simulations. (iii) For a high-sensitivity detection of an important heavy metal impurity Cu, we present a novel bulk impurity collection technique using a room-temperature Cu drift phenomenon accelerated by Corona charge showering on a Si wafer surface

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The Engineering of Silicon Wafer Material Properties Through Vacancy Concentration Profile Control and the Achievement of Ideal Oxygen Precipitation Behavior

MRS Proceedings ◽

10.1557/proc-510-27 ◽

1998 ◽

Vol 510 ◽

Cited By ~ 30

Author(s):

R. Falster ◽

D. Gambaro ◽

M. Olmo ◽

M. Cornara ◽

H. Korb

Keyword(s):

Silicon Wafer ◽

Integrated Circuit ◽

Defect Formation ◽

Electronic Device ◽

Vacancy Concentration ◽

Silicon Wafers ◽

Precipitation Behavior ◽

Oxygen Precipitation ◽

Profile Control ◽

Zone Depth

AbstractA new kind of silicon wafer and a new class of materials engineering techniques for silicon wafers is described. This wafer, called the “Magic Denuded Zone” or MDZ wafer, is produced through the manipulation of the vacancy concentration and, in particular, vacancy concentration depth profiles in the wafer prior to the development of oxygen precipitates in subsequent heat treatments. The result is a wafer with ideal oxygen precipitation behavior for use in all types of integrated circuit applications. The methods used to prepare such wafers combine Frenkel pair generation with injection and the use of surface sinks. Simulations of the vacancy profiles produced by these techniques are presented and discussed. It is shown that within the range of vacancy concentration accessible by these techniques (up to ca. 1013 cm−3) the rate and oxygen concentration dependence of oxygen clustering can be substantially modified. Such techniques can be used to precisely engineer unique and desirable oxygen-related defect performance in silicon wafers both in terms of distribution and rate of defect formation. One result of the application of such techniques is an ideally precipitating silicon wafer in which the resulting oxygen precipitate profile (denuded zone depth and bulk density of precipitates) is independent of the concentration of oxygen of the wafer, the details of the crystal growth process used to prepare the wafer and, to a very large extent, the details of thermal cycles used to process the wafer into an electronic device. Optimal, generic and reliable internal gettering performance is achieved in such a wafer

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Correlation of defect densities in semiconductors measured by TEM and optical profiling instruments

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100138609 ◽

1995 ◽

Vol 53 ◽

pp. 446-447

Author(s):

L. Mulestagno ◽

J.C. Holzer ◽

D.E. Hill ◽

P. Fraundorf

Keyword(s):

Electronic Devices ◽

Device Layer ◽

Precipitation Behavior ◽

Laser Scattering ◽

Oxygen Precipitation ◽

Ir Laser ◽

Oxygen Precipitate ◽

And Control ◽

Non Destructive ◽

Defect Densities

The measurement of oxygen precipitate defect densities in Czochralski (CZ) Silicon wafers after standard heat cycles, or at strategic points in the device manufacturing process is often used as a tool to understand the oxygen precipitation behavior of the wafers on which electronic devices will be manufactured and to measure variability in the precipitation . The relevance of these measurements arises from the fact that controlled oxygen precipitation in the bulk of the wafer is used as a means to ‘getter’ unwanted impurities from the device layer of the wafer, and control of oxygen precipitation can be an important factor in device yields.Typically the density of oxygen precipitate in a given wafer and the depth profile is determined by physically counting defects on cleaved slices after preferential etch to reveal the defects . This is a fairly time-consuming and a destructive test. However in the last few years a number of companies have developed computerized, non-destructive IR laser scattering instruments which rely on the fact that silicon is transparent to IR., and a precipitate (having a different refractive index from silicon ), will scatter some of the laser beam which can be detected.

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Study on Continuous Annealing Process for Ultrathin Cold-Rolled SPCC Steel

Materials Science Forum ◽

10.4028/www.scientific.net/msf.817.268 ◽

2015 ◽

Vol 817 ◽

pp. 268-272

Author(s):

Wu Yan Fan ◽

Ren Bo Song ◽

Ru Wen Zheng ◽

Pei Sheng Yao

Keyword(s):

Annealing Temperature ◽

Annealing Process ◽

Continuous Annealing ◽

Precipitation Behavior ◽

Transmission Electron ◽

Batch Annealing ◽

Thin Steel ◽

Cold Rolled ◽

R Value ◽

General Specification

The continuous annealing process was simulated on the heat treatment system for thin steel sheet (CCT-AY-II). As the recrystallization was known, the annealing temperature and holding time were taken into account to study the influence on microstructure and mechanical properties of 0.08mm ultrathin cold-rolled SPCC steel. Combined with transmission electron microscope (TEM), the precipitation behavior was analyzed. The optical micrographs show that the microstructure of the samples are more similar to batch-annealing steel rather than general specification SPCC steel through continuous annealing. With 5°C/s heating rate and annealed at 860°C for 80s, the sample performs best: the yield strength is 161MPa, the elongation is 29% and the r-value is 1.51. AlN and MnS precipitations are observed in the inner grain and at grain boundary. The annealed textures mostly composed of {111} texture. The highest intensity is centered around the {111}<110> orientation.

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