Meniscus dynamics and melt solidification in the EFG silicon tube growth process

A comprehensive two-dimensional numerical model, which accounts for heat/mass transfer, solidification, and electromagnetic field, has been developed to simulate the silicon tube growth by the Edge-defined film-fed (EFG) method. A multi-block grid system has been employed to yield a high accuracy in the vicinity of die tip with relatively low CPU time, and the solution procedure is satisfied the flux conservation at the block interface. Selected results of magnetic and temperature fields have been presented for the silicon tube growth system of 30cm in diameter and 0.3mm in thickness. Two local models have also been developed to study the effect of the size of window opening and tube thickness on the maximum growth rate using the inner and outer heater temperature profiles as boundary conditions.

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A multi-block method and multi-grid technique for large diameter EFG silicon tube growth

Journal of Crystal Growth ◽

10.1016/j.jcrysgro.2004.02.042 ◽

2004 ◽

Vol 266 (1-3) ◽

pp. 167-174 ◽

Cited By ~ 6

Author(s):

Dawei Sun ◽

Chenlei Wang ◽

Hui Zhang ◽

Brian Mackintosh ◽

Doug Yates ◽

...

Keyword(s):

Large Diameter ◽

Tube Growth ◽

Block Method ◽

Silicon Tube ◽

Grid Technique

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Thermal Analysis and Buckling Behavior of Continuous Silicon Wafer Manufacturing by EFG Method

Heat Transfer, Volume 1 ◽

10.1115/imece2003-41990 ◽

2003 ◽

Author(s):

D. Sun ◽

C. Wang ◽

H. Zhang

Keyword(s):

High Accuracy ◽

Tube Growth ◽

Temperature Fields ◽

Two Dimensional ◽

Grid System ◽

Cpu Time ◽

Buckling Behavior ◽

Growth System ◽

Silicon Tube ◽

Wafer Manufacturing

A comprehensive two-dimensional numerical model, which accounts for heat/mass transfer, solidification, and electromagnetic field, has been developed to simulate the silicon tube growth by the edge-defined film-fed (EFG) method. A multi-block grid system has been employed to yield a high accuracy in the vicinity of die tip with relatively low CPU time. Selected results of magnetic and temperature fields have been presented for the silicon tube growth system of 30cm in diameter and 0.3mm in thickness. Based on elastic assumption, the mechanism of buckling behavior of the as-grown tube has been analyzed.

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An Integrated Model for Electromagnetic Field and Heat Transfer in a Cylindrical Silicon Tube Growth System

10.1115/imece1999-0911 ◽

1999 ◽

Author(s):

A. Roy ◽

Q.-S. Chen ◽

H. Zhang ◽

V. Prasad

Keyword(s):

Large Diameter ◽

System Optimization ◽

Tube Growth ◽

Magnetic Vector Potential ◽

Induced Magnetic Field ◽

Thermal Fields ◽

Growth System ◽

Silicon Tube ◽

Hollow Cylinders ◽

Different Shapes

Abstract Edge-defined Film-fed Growth (EFG) processes are widely used to grow silicon sheets and hollow cylinders of different shapes, e.g., octagon, nonagon and circular. Growth of large diameter silicon tube can bring further advancements in the photovoltaic technology. In the present investigation, a two dimensional axisymmetric numerical model has been developed for a cylindrical silicon tube growth system. The growth furnace is inductively heated. Magnetic vector potential equation and energy equation are solved to obtain the induced magnetic field and temperature distribution in the system. Selected results for magnetic and thermal fields have been presented for a range of parameters. The effect of using graphite afterheater in the system has also been investigated. The goal of the investigation is the system optimization with respect to the temperature field in the global system and the thermal profile in the grown tube.

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An Advanced Multiblock Solution Procedure and its Application to Silicon Tube Growth by EFG Technique

10.1115/imece2001/htd-24298 ◽

2001 ◽

Author(s):

D. Sun ◽

H. Zhang ◽

V. Prasad ◽

B. Mackintosh ◽

J. P. Kalejs

Keyword(s):

Radiation Heat Transfer ◽

Solution Procedure ◽

Tube Growth ◽

Grid System ◽

Structured Grid ◽

Fast Solver ◽

Photovoltaic Application ◽

Growth System ◽

Silicon Tube ◽

Hollow Cylinders

Abstract The Edge-defined Film-fed Growth (EFG) is a widely used technique for the growth of polycrystalline silicon from its melt in the form of ribbon and hollow cylinders. The current octagonal tube growth technique has been modified successfully to produce 50 cm diameter circular tube for photovoltaic application by ASE Americas, Inc. A comprehensive growth model has been developed that accounts for conduction, convection and radiation heat transfer in the growth system, electromagnetic heating, and solidification. To improve the efficiency and accuracy of the model, two sets of grid system have been employed. A single structured grid system is used to calculate the magnetic potential field generated by radio-frequency induction heater, and a non-matching multi-block grid system to solve the temperature field with fine grids in the vicinity of the die-tip and silicon tube. Two sets of grid system overlap each other. A multi-block solution procedure has been developed satisfying the flux conservation at the block interfaces. The new solution procedure is used to simulate the existing octagonal silicon tube growth. The results obtained by different solvers, e.g., TDMA, CGSTAB, BiCGSTAB, SIP solver, are compared. It is evident that the CPU time is reduced dramatically if a fast solver, such as SIP or multigrid method, is used in the multi-block system.

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Model based, pulling rate, thermal and capillary conditions setting for silicon tube growth

Journal of Crystal Growth ◽

10.1016/j.jcrysgro.2010.09.002 ◽

2010 ◽

Vol 312 (23) ◽

pp. 3549-3554 ◽

Cited By ~ 1

Author(s):

Loredana Tanasie ◽

Stefan Balint

Keyword(s):

Tube Growth ◽

Model Based ◽

Silicon Tube

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Experimental Study of Buckling Behavior of Octagonal Thin-Walled Silicon Tube Grown by Edge-Defined Film-Fed Method

Volume 8B: Heat Transfer and Thermal Engineering ◽

10.1115/imece2014-38434 ◽

2014 ◽

Author(s):

Guanghua Wei ◽

Ronghui Ma ◽

Hui Zhang ◽

Lili Zheng

Keyword(s):

High Temperature ◽

Temperature Gradient ◽

High Speed ◽

Thermal Stresses ◽

Tube Growth ◽

Random Fluctuation ◽

High Temperature Gradient ◽

Solid Interface ◽

Buckling Behavior ◽

Silicon Tube

Edge-defined Film-fed Growth (EFG) is a promising technology for production of silicon wafers with minimum loss of silicon material for photovoltaic applications. The growth of the hollow tubes by the EFG method is a very high temperature gradient along the direction of tube growth at the melt-solid interface. As this high temperature gradient is necessary to sustain the high speed of silicon growth through dissipating latent heat at the melt-solid interface, it generates substantial amount of thermal stresses that are associated with defect generation and deformation of the structure. With increase of the tube diameter and reduction of wall thickness, the large thermal stresses lead to significant buckling of the tube. In this study, the buckling behavior of the growing silicon tube is studied experimentally by monitoring deflection of two pairs of opposite faces of an octagonal tube during the growth. Four capacitance sensors were placed on a fixed plane normal to the translation of the tube to measure the varying thickness of the air between the sensor and the tube surface throughout the tube growth. The recorded data reveal the buckling behavior of tubes for several growth runs. Despite the different growth conditions in the EFG systems, similar patterns of buckling behavior have been observed in octagonal silicon tubes with face width of 12.5 cm. A typical buckling pattern observed can be divided into three distinctively different stages, namely seed holder-influenced stage, tube growth stage, and a random fluctuation stage. Each stage has different amplitude of deflection and covers different length of the tube. More interestingly, the recorded surface deflection reveals the displacement of the center of the tube, suggesting off-centered growth and possible instability of the meniscus. It is considered that these mechanisms may contribute to the special buckling pattern observed during growth.

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