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Title: Wafer screening device and methods for wafer screening

Abstract

Wafer breakage is a serious problem in the photovoltaic industry because a large fraction of wafers (between 5 and 10%) break during solar cell/module fabrication. The major cause of this excessive wafer breakage is that these wafers have residual microcracks--microcracks that were not completely etched. Additional propensity for breakage is caused by texture etching and incomplete edge grinding. To eliminate the cost of processing the wafers that break, it is best to remove them prior to cell fabrication. Some attempts have been made to develop optical techniques to detect microcracks. Unfortunately, it is very difficult to detect microcracks that are embedded within the roughness/texture of the wafers. Furthermore, even if such detection is successful, it is not straightforward to relate them to wafer breakage. We believe that the best way to isolate the wafers with fatal microcracks is to apply a stress to wafers--a stress that mimics the highest stress during cell/module processing. If a wafer survives this stress, it has a high probability of surviving without breakage during cell/module fabrication. Based on this, we have developed a high throughput, noncontact method for applying a predetermined stress to a wafer. The wafers are carried on a belt through a chambermore » that illuminates the wafer with an intense light of a predetermined intensity distribution that can be varied by changing the power to the light source. As the wafers move under the light source, each wafer undergoes a dynamic temperature profile that produces a preset elastic stress. If this stress exceeds the wafer strength, the wafer will break. The broken wafers are separated early, eliminating cost of processing into cell/module. We will describe details of the system and show comparison of breakage statistics with the breakage on a production line.

Inventors:
;
Issue Date:
Research Org.:
National Renewable Energy Laboratory (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1143680
Patent Number(s):
8780343
Application Number:
13/146,111
Assignee:
Alliance for Sustainable Energy, LLC (Golden, CO)
Patent Classifications (CPCs):
G - PHYSICS G01 - MEASURING G01N - INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
DOE Contract Number:  
AC36-08GO28308
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY

Citation Formats

Sopori, Bhushan, and Rupnowski, Przemyslaw. Wafer screening device and methods for wafer screening. United States: N. p., 2014. Web.
Sopori, Bhushan, & Rupnowski, Przemyslaw. Wafer screening device and methods for wafer screening. United States.
Sopori, Bhushan, and Rupnowski, Przemyslaw. Tue . "Wafer screening device and methods for wafer screening". United States. https://www.osti.gov/servlets/purl/1143680.
@article{osti_1143680,
title = {Wafer screening device and methods for wafer screening},
author = {Sopori, Bhushan and Rupnowski, Przemyslaw},
abstractNote = {Wafer breakage is a serious problem in the photovoltaic industry because a large fraction of wafers (between 5 and 10%) break during solar cell/module fabrication. The major cause of this excessive wafer breakage is that these wafers have residual microcracks--microcracks that were not completely etched. Additional propensity for breakage is caused by texture etching and incomplete edge grinding. To eliminate the cost of processing the wafers that break, it is best to remove them prior to cell fabrication. Some attempts have been made to develop optical techniques to detect microcracks. Unfortunately, it is very difficult to detect microcracks that are embedded within the roughness/texture of the wafers. Furthermore, even if such detection is successful, it is not straightforward to relate them to wafer breakage. We believe that the best way to isolate the wafers with fatal microcracks is to apply a stress to wafers--a stress that mimics the highest stress during cell/module processing. If a wafer survives this stress, it has a high probability of surviving without breakage during cell/module fabrication. Based on this, we have developed a high throughput, noncontact method for applying a predetermined stress to a wafer. The wafers are carried on a belt through a chamber that illuminates the wafer with an intense light of a predetermined intensity distribution that can be varied by changing the power to the light source. As the wafers move under the light source, each wafer undergoes a dynamic temperature profile that produces a preset elastic stress. If this stress exceeds the wafer strength, the wafer will break. The broken wafers are separated early, eliminating cost of processing into cell/module. We will describe details of the system and show comparison of breakage statistics with the breakage on a production line.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2014},
month = {7}
}

Works referenced in this record:

Semiconductor wafer heating chamber
patent, July 1988


Method and apparatus for substrate heating in an axially symmetric epitaxial deposition apparatus
patent, December 1988


Method and apparatus for inspection of a transparent container
patent, October 1989


Dry texturing of solar cells
patent, October 1994


Impurity gettering in semiconductors
patent, June 1995


High performance multi-zone illuminator module for semiconductor wafer processing
patent, August 1995


Apparatus for making optically fused semiconductor powder for solar cells
patent, March 1997


Method for monitoring surface stress
patent, December 1997


Optical method of detecting defect and apparatus used therein
patent, April 1999


Lid assembly for high temperature processing chamber
patent, February 2000


Furnace for rapid thermal processing with optical switching film disposed between heater and reflector
patent, April 2000


Wafer scale packaging scheme
patent, August 2000


Thermally developable material
patent, July 2001


Accelerated thermal stress cycle test
patent, August 2003


Edge flaw inspection device
patent, September 2004


Method and apparatus for detecting defects along the edge of electronic media
patent, November 2004


Wafer edge polishing system
patent, January 2005


Wafer processing method including formation of a deteriorated layer
patent, March 2010


Silicon wafer and process for the heat treatment of a silicon wafer
patent, November 2010


Screening of silicon wafers used in photovoltaics
patent, August 2011


Localized anneal
patent, September 2012


Rapid thermal processing chamber for processing multiple wafers
patent-application, January 2002


Defect inspection data processing system
patent-application, February 2002


Automated wafer defect inspection system and a process of performing such inspection
patent-application, January 2005


Method and apparatus for wafer mechanical stress monitoring and wafer thermal stress monitoring
patent-application, March 2005


Method and its apparatus for inspecting particles or defects of a semiconductor device
patent-application, December 2005


Wafer inspection system and method thereof
patent-application, December 2005


Monitoring semiconductor wafer defects below one nanometer
patent-application, February 2006


Apparatus and method for thermal processing
patent-application, August 2006


System for heat treatment of semiconductor device
patent-application, May 2007


Controlled process and resulting device
patent-application, May 2007


Structure and Method for Thermally Stressing or Testing a Semiconductor Device
patent-application, October 2007


Method of Scribing and Breaking Substrate Made of a Brittle Material and System for Scribing and Breaking Substrate
patent-application, December 2008


Screening of Silicon Wafers Used in Photovoltaics
patent-application, June 2010


Optical Cavity Furnace for Semiconductor Wafer Processing
patent-application, January 2011


Method to Reduce Dislocation Density in Silicon Using Stress
patent-application, March 2011


A high throughput, noncontact system for screening silicon wafers predisposed to breakage during solar cell production
conference, June 2011


High-flux solar furnace processing of silicon solar cells
conference, January 1994

  • Tsuo, Y. S.; Pitts, J. R.; Landry, M. D.
  • Proceedings of 1994 IEEE 1st World Conference on Photovoltaic Energy Conversion - WCPEC (A Joint Conference of PVSC, PVSEC and PSEC)
  • https://doi.org/10.1109/WCPEC.1994.520186

Graphic script provides quick classification of GaAs wafers
journal, March 2000


Non-destructive optical methods for assessing defects in production of Si or SiGe materials
journal, July 2004