Analysis of Handling Stresses in Thin Solar Silicon Wafers Generated by a Rigid Vacuum Gripper

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Hao Wu ◽  
Shreyes N. Melkote
Keyword(s):  
Stress Distribution ◽  
Dominant Role ◽  
High Stress ◽  
Surface Profile ◽  
Silicon Wafers ◽  
Wafer Surface ◽  
Initial Surface ◽  
Fe Modeling ◽  
Solar Silicon ◽  
Surface Profiles

Breakage of thin solar silicon wafers during handling and transport depends on the stresses imposed on the wafer by the handling/transport device. In this paper, the stresses generated in solar silicon wafers by a rigid vacuum gripper are analyzed via a combination of experiments and numerical modeling. Specifically, stresses produced in monocrystalline (Cz) and multicrystalline (Cast) silicon wafers of different thicknesses when handled by a vacuum gripper are analyzed using the finite element (FE) method. With the measured surface profiles of the wafer and the gripper as input, the handling process is simulated using FE modeling and the stress distribution obtained. The FE modeling results are validated by experimental data of wafer surface profile during handling. The results show that while the vacuum level does not have significant impact on the stress distribution, the initial surface profiles of the thin wafer and gripper play a dominant role in producing regions of high stress in the wafer.

Modeling the Tensile Strength and Crack Length of Wire-Sawn Silicon Wafers

2009 ◽  
Vol 131 (1) ◽  
Author(s):  
Claudia Funke ◽  
Susann Wolf ◽  
Dietrich Stoyan
Keyword(s):  
Stress Distribution ◽  
Crack Length ◽  
Fracture Stress ◽  
Quantitative Description ◽  
Silicon Wafers ◽  
Wafer Surface ◽  
Truncation Parameter ◽  
Solar Silicon ◽  
Intensity Functions ◽  
The Impact

Solar silicon wafers are mainly produced through multiwire-sawing. This sawing implies microcracks on the wafer surface, which are responsible for brittle fracture. In order to reduce the sawing-induced cracks, the wafers are damage etched after sawing. This paper develops a model for the impact of crack length manipulation on fracture stress distribution. It investigates the effect of damage-etching on the mechanical properties of solar silicon wafers. The main idea is to transform the fracture stress distribution into a crack length intensity function and to model the effect of etching in terms of crack lengths. The fracture stress distribution is determined statistically by fracture tests of wire-sawn and sawn and etched wafers. The Griffith criterion then enables the transition to crack lengths and crack length intensity functions. Two numerical parameters, called truncation parameter and scaling parameter, determine this relationship and enable a quantitative description of the effect of etching. They turn out to be dependent on etchant and geometry of load and thus tested crack population.

scholarly journals How surface stress transforms surface profiles and adhesion of rough elastic bodies

2020 ◽  
Vol 476 (2243) ◽  
pp. 20200477
Author(s):  
Chung-Yuen Hui ◽  
Zezhou Liu ◽  
Nicolas Bain ◽  
Anand Jagota ◽  
Eric R. Dufresne ◽  
...  
Keyword(s):  
Surface Stress ◽  
Periodic Structures ◽  
Surface Profile ◽  
Initial Surface ◽  
One Dimensional ◽  
Patterned Substrate ◽  
Soft Solids ◽  
Elastic Bodies ◽  
Surface Profiles ◽  
Qualitative Changes

The surface of soft solids carries a surface stress that tends to flatten surface profiles. For example, surface features on a soft solid, fabricated by moulding against a stiff-patterned substrate, tend to flatten upon removal from the mould. In this work, we derive a transfer function in an explicit form that, given any initial surface profile, shows how to compute the shape of the corresponding flattened profile. We provide analytical results for several applications including flattening of one-dimensional and two-dimensional periodic structures, qualitative changes to the surface roughness spectrum, and how that strongly influences adhesion.

Fracture Analysis and Distribution of Surface Cracks in Multicrystalline Silicon Wafers

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
S. Saffar ◽  
S. Gouttebroze ◽  
Z. L. Zhang
Keyword(s):  
Failure Probability ◽  
Surface Crack ◽  
Silicon Wafers ◽  
Multicrystalline Silicon ◽  
Wafer Surface ◽  
Surface Cracks ◽  
Property Variation ◽  
Micro Cracks ◽  
Solar Silicon ◽  
Sawing Process

Solar silicon wafers are mainly produced through multiwire sawing. The sawing process induces micro cracks on the wafer surface, which are responsible for brittle fracture. Hence, it is important to scrutinize the crack geometries most commonly generated in silicon wafer sawing or handling process and link the surface crack to the fracture of wafers. The fracture of a large number of multicrystalline silicon wafers has been investigated by means of 4-point bending and twisting tests and a failure probability function is presented. By neglecting the material property variation and assuming that one surface crack is dominating the wafer breakage, 3D finite element models with various crack sizes (depth, length, and orientation) have been analyzed to identify the distribution of surface crack geometries by fitting the failure probability from the experiments. With respect to the 63% probability, the existing surface cracks in the wafers studied appear to have depth and length ratios less than 0.042 and 0.19, respectively. Furthermore, it has been shown that the surface cracks with depth in the range from 10 to 20 μm, length up to 10 mm and angles in the range of 30 deg–60 deg, can be considered as the most common crack geometries in wafers we tested. Finally, it has been found that the mechanical strength of the wafers tested parallel to the sawing direction is approximately 15 MPa smaller than those tested perpendicular to the sawing direction.

Effects of conform, non-conform, and hybrid conformity toward stress distribution at the glenoid implant and cement: A finite element study

2021 ◽  
pp. 039139882199939
Author(s):  
Abdul Hadi Abdul Wahab ◽  
Nor Aqilah Mohamad Azmi ◽  
Mohammed Rafiq Abdul Kadir ◽  
Amir Putra Md Saad
Keyword(s):  
Stress Distribution ◽  
Daily Living ◽  
3D Model ◽  
Promising Result ◽  
High Stress ◽  
Constant Load ◽  
Posterior Region ◽  
Implant Stability ◽  
Eccentric Load ◽  
Standing Up

Glenoid conformity is one of the important aspects that could contribute to implant stability. However, the optimal conformity is still being debated among the researchers. Therefore, this study aims to analyze the stress distribution of the implant and cement in three types of conformity (conform, non-conform, and hybrid) in three load conditions (central, anterior, and posterior). Glenoid implant and cement were reconstructed using Solidwork software and a 3D model of scapula bone was done using MIMICS software. Constant load, 750 N, was applied at the central, anterior, and posterior region of the glenoid implant which represents average load for daily living activities for elder people, including, walking with a stick and standing up from a chair. The results showed that, during center load, an implant with dual conformity (hybrid) showed the best (Max Stress—3.93 MPa) and well-distributed stress as compared to other conformity (Non-conform—7.21 MPa, Conform—9.38 MPa). While, during eccentric load (anterior and posterior), high stress was located at the anterior and posterior region with respect to the load applied. Cement stress for non-conform and hybrid implant recorded less than 5 MPa, which indicates it had a very low risk to have cement microcracks, whilst, conform implant was exposed to microcrack of the cement. In conclusion, hybrid conformity showed a promising result that could compromise between conform and non-conform implant. However, further enhancement is required for hybrid implants when dealing with eccentric load (anterior and posterior).

Dislocation Nucleation and Growth in MOCVD GaN/AlN Films on Stepped and Step-free 4H-SiC Mesa Substrates

2008 ◽  
Vol 1090 ◽  
Author(s):  
Mark E. Twigg ◽  
Yoosuf N. Picard ◽  
Nabil D. Bassim ◽  
Joshua D. Caldwell ◽  
Michael A. Mastro ◽  
...  
Keyword(s):  
Dominant Role ◽  
High Stress ◽  
Chemical Vapor ◽  
Misfit Strain ◽  
Nucleation And Growth ◽  
Dislocation Nucleation ◽  
Threading Dislocations ◽  
Surface Steps ◽  
Half Loop ◽  
Edge Dislocations

AbstractUsing transmission electron microscopy, we have analyzed dislocations in AlN nucleation layers and GaN films grown by metallorganic chemical vapor deposition (MOCVD) on the (0001) surface of epitaxially-grown 4H-SiC mesas with and without steps. For 4H-SiC substrates free of SiC surface steps, half-loop nucleation and glide parallel to the AlN/SiC interfacial plane play the dominant role in strain relief, with no mechanism for generating threading dislocations. In contrast, 4H-SiC mesa surfaces with steps give rise to regions of high stress at the heteroepitaxial interface, thereby providing an environment conducive to the nucleation and growth of threading dislocations, which act to accommodate misfit strain by the tilting of threading edge dislocations.

scholarly journals A Simple Model to Predict Machined Depth and Surface Profile for Picosecond Laser Surface Texturing

2018 ◽  
Vol 8 (11) ◽  
pp. 2111 ◽  
Author(s):  
Jieyu Xian ◽  
Xingsheng Wang ◽  
Xiuqing Fu ◽  
Zhengwei Zhang ◽  
Lu Liu ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Surface Texturing ◽  
Surface Profile ◽  
Picosecond Laser ◽  
Scanning Speed ◽  
Laser Surface ◽  
Laser Surface Texturing ◽  
Micro Channels ◽  
Surface Profiles ◽  
Simulation Parameters

A simple mathematical model was developed to predict the machined depth and surface profile in laser surface texturing of micro-channels using a picosecond laser. Fabrication of micro-craters with pulse trains of different numbers was initially performed. Two baseline values from the created micro-craters were used to calculate the estimated simulation parameters. Thereafter, the depths and profiles with various scanning speeds or adjacent intervals were simulated using the developed model and calculated parameters. Corresponding experiments were conducted to validate the developed mathematical model. An excellent agreement was obtained for the predicted and experimental depths and surface profiles. The machined depth decreased with the increase of scanning speed or adjacent interval.

The Evolution of Contact Stress and Surface Profile in Press-Fitted Shaft under Partial Slip Conditions

2006 ◽  
Vol 321-323 ◽  
pp. 1495-1498 ◽  
Author(s):  
Dong Hyung Lee ◽  
Seok Jin Kwon ◽  
Chan Woo Lee ◽  
Jae Boong Choi ◽  
Young Jin Kim
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Surface Profile ◽  
Contact Stresses ◽  
Fretting Wear ◽  
Partial Slip ◽  
Initial Surface ◽  
Slip Conditions ◽  
Bending Load ◽  
Element Method

In this paper the fretting wear of press-fitted specimens under partial slip conditions was simulated using finite element method and numerical analysis based on Archard's equation. An elasto-plastic analysis of contact stresses in a press-fitted shaft in contact with a boss was conducted with finite element method and the amount of microslip and contact pressure due to bending load was estimated. The predicted wear profile of press-fitted specimens at the contact edge was compared with the experimental results. It is found that the depth of fretting wear by repeated slip between shaft and boss reaches the maximum value at the contact edge. The initial surface profile is continuously changed by the wear at the contact edge, and then the corresponding contact stresses and strain are redistributed.

Geometrical consideration for mechanical contact between rolling circle and surface roughness as an improvement to the surface profile

2021 ◽  
Vol 15 (1) ◽  
pp. 7846-7859
Author(s):  
Tsuyoshi Shimizu ◽  
Yasutake Hramiishi ◽  
Takaaki Ishii ◽  
Yuzairi Abdul Rahim ◽  
Mohd Fadzil Ali Ahmad ◽  
...  
Keyword(s):  
Contact Point ◽  
Surface Profile ◽  
Displacement Sensor ◽  
Nose Radius ◽  
Rolling Circle ◽  
Actual Surface ◽  
Contact Type ◽  
Measurement Surface ◽  
Surface Profiles ◽  
Tip Radius

This paper describes measurement methods of surface profiles that improve contact-type displacement sensor outputs by focusing on the contact point between the sphere tip of the sensor and the rough surface. We examined the geometry of a surface profile model and compared measurements using various methods with the measurement using a roughness meter. The spherical tip of the contact type displacement sensor touches the measurement surface and detects the displacement. The sphere tip radius of a typical contact-type displacement sensor ranges from 1–3 mm, causing the roughness curve to be “filtered” by the radius of the sphere.  Three methods for estimating the valley portion of the surface profile are evaluated in this study: a) linear approximation of the concave portion of the surface profile, b) function approximation of the concave portion, and c) using the known nose radius of the machining tool. The following sphere tip radii were used to measure actual surface profiles: 0.25 mm, 0.5 mm, 1.0 mm and 1.5 mm. Given the conditions of the experimental model, we found that surface profiles with a roughness that approximates a predictable curve can be measured with a high degree of accuracy.

Research on Digital Filters for Si Wafer Surface Profile Measurement - Design of Filters by Total Variation

2012 ◽  
Vol 565 ◽  
pp. 656-661
Author(s):  
Hirotaka Ojima ◽  
Kazutaka Nonomura ◽  
Li Bo Zhou ◽  
Jun Shimizu ◽  
Teppei Onuki
Keyword(s):  
Total Variation ◽  
Digital Filter ◽  
Digital Filters ◽  
Large Population ◽  
Surface Profile ◽  
Wafer Surface ◽  
Profile Measurement ◽  
Actual Measurement ◽  
True Value ◽  
New Tv

The underlying data form of a wafer is a matrix of length (or height) measurements. In the presence of noise, evaluation parameters are normally biased. The expectation value such as peak-to-valley and GBIR (global backside ideal range) is systematically larger than the “true” value. Correction and compensation need a large population of measurements to analytically estimate both bias and the uncertainty. In this study, approach to obtain the true value is to extract a “true” profile by filtering noise from the measured data. In previous paper, the digital filter with wavelet transformation (WT) is proposed and efficiency to remove the noise, however, the method is introduced the pseudo-Gibbs effect. Then, we propose the digital filter with new algorithm of total variation (TV). In this paper, the new algorithm of TV is proposed and the digital filter by new TV indicate that data is filtered without the pseudo-Gibbs effect. The digital filters by WT and new TV are applied on the sample data of actual measurement system to investigate their performance of noise reduction.

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