Title:
Measurement and analysis of wire sawing induced residual stress in photovoltaic silicon wafers

dc.contributor.advisor Melkote, Shreyes N.
dc.contributor.author Pogue, Vanessa Ann
dc.contributor.committeeMember Danyluk, Steven S.
dc.contributor.committeeMember Rohatgi, Ajeet
dc.contributor.department Mechanical Engineering
dc.date.accessioned 2016-05-27T13:25:34Z
dc.date.available 2016-05-27T13:25:34Z
dc.date.created 2016-05
dc.date.issued 2016-05-06
dc.date.submitted May 2016
dc.date.updated 2016-05-27T13:25:34Z
dc.description.abstract The manufacturing process of a photovoltaic Si wafer comprises of first a high temperature heating process to produce a Si ingot from polycrystalline Silicon, which is then cut into bricks and subsequently sawn into wafers using a wire saw. These processes create residual stresses both from the thermal gradient induced by solidification and from either the rolling-indenting or scratching-indenting processes caused by the type of wire saw used. The objective of this research is to study silicon wafer residual stress as a result of the typical industry manufacturing processes and by doing so, better understand the mechanical properties that lead to increased fracture. This thesis aims to quantify the amount of residual stress generated by the solidification/thermal gradient produced during the casting of Si ingots separately from the residual stress generated by the wire sawing process. Samples from industry are used to compare the effects of the manufacturing processes on residual stress in multi-crystalline silicon (mc-Si) wafers including the effects of fixed abrasive diamond wire sawing (DWS) vs. loose abrasive (LAWS) slurry wire sawing used in the wafering process. Near-infrared birefringence polariscopy and polarized micro-Raman spectroscopy are used to study wafer residual stresses within grains and at grain boundaries in mc-Si as a function of etch-depth. While near-infrared birefringence polariscopy allows for the measurement of full-field maximum shear stress, micro-Raman spectroscopy provides decomposition of the stress tensor into both principal and shear in-plane stress components. Consequently, regions of high tensile stress, which are detrimental to the mechanical integrity of the wafer, can be easily identified. In addition to the mechanical characterization, the residual stress produced by the thermal gradient/solidification process for multi-crystalline Si wafers was also correlated to electrical performance of mc-Si wafers using photoluminescence.
dc.description.degree M.S.
dc.format.mimetype application/pdf
dc.identifier.uri http://hdl.handle.net/1853/55071
dc.language.iso en_US
dc.publisher Georgia Institute of Technology
dc.subject residual stress
dc.subject silicon
dc.subject photovoltaic
dc.subject wire-sawing
dc.subject Near-infrared birefringence polariscope
dc.subject Raman spectroscopy
dc.title Measurement and analysis of wire sawing induced residual stress in photovoltaic silicon wafers
dc.type Text
dc.type.genre Thesis
dspace.entity.type Publication
local.contributor.advisor Melkote, Shreyes N.
local.contributor.corporatename George W. Woodruff School of Mechanical Engineering
local.contributor.corporatename College of Engineering
relation.isAdvisorOfPublication e78c9d4f-2d4a-4337-9739-f9179a9fd7fb
relation.isOrgUnitOfPublication c01ff908-c25f-439b-bf10-a074ed886bb7
relation.isOrgUnitOfPublication 7c022d60-21d5-497c-b552-95e489a06569
thesis.degree.level Masters
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