the wafer inspection solution for silicon solar cell
TRANSCRIPT
1March 2014 BT Imaging Pty Ltd - Confidential Information
Product Update
QS-W2THE WAFER INSPECTION SOLUTION
FOR SILICON SOLAR CELL MANUFACTURERS
• The QS-W2 is an in-line inspection and sorting system utilized in solar cell factories
• Previously WIS only sorted the reject wafers
o QS-W2 sorts the good wafers into quality bins based on predictive cell efficiency measurements
• Modular architecture allows for any combination of available inspection modules
o Also can include wafer marking
o Allows for future expansion of inspection capability
• Allows a cell maker to:
o Check wafer supplier quality
o Reject poor wafers and identify cause of rejection
o Improve overall cell efficiency and decrease spread in efficiency
o Increase value of cells
o Differentiate their cell product from competitors
o Create close wafer supplier relationships based on product quality/efficiency
o Enables cost reductions and efficiency gains via continuous process improvement
o Enables cost reductions and efficiency gains via trialing and implementation of new process and material technologies
o Enables wafer-quality based process settings to be enabled
2March 2014 BT Imaging Pty Ltd - Confidential Information
3March 2014 BT Imaging Pty Ltd - Confidential Information
Load Station
WID-1Wafer Marker
iLS-W2PL Imaging
iS-G1Grain
Structure
Sorting Station
Lifetime, Sawmark
& TTV
Surface & Geometry
MicroCrack
• High throughput of 3,600 wafers per hour
• Wafer handling capability of >160m
• Low breakage specification of < 0.1%
• Coin stack, cassette, or integrated in-line loading options
• Modular metrology unit architecture
o Expandable to multiple inspection module options
o Add modules as production expands
o Also wafer marking available for product tracing and process improvement
• Expandable sorter units
o 6 unit base sorter expandable to 12, 20 or 24 bin configurations
• Powerful efficiency/electrical wafer sorting software available
o Customer configurable
• Yield management software and consulting available
o Powerful analysis tool
4March 2014 BT Imaging Pty Ltd - Confidential Information
• Available Wafer Inspection Options:
o BT Imaging
Wafer Electrical Quality by Photoluminescence
Micro Grains and Crystal Fraction
Thickness
o Qualified third party providers for
Wafer Lifetime
Thickness, TTV, Warp, Bow
Saw Marks
Geometry (Length, Width, Diagonals, Corners)
Surface defects (Stains, Finger Prints, Edge Chips)
Micro Cracks
• Plus BT Imaging wafer marking option
o For process improvement and debugging
o For root cause failure analysis
o For continued cell line calibration and optimization
5March 2014 BT Imaging Pty Ltd - Confidential Information
• BT Imaging has easy to use customer-configurable GUI software & unique algorithms that detect wafer defects
• Only BT Imaging has production-proven algorithms with
o High repeatability
o High accuracy of defect measurement
o Using ALL the WIS information for optimal solar cell efficiency correlations (inclusive of PL)
• We have algorithms optimized for
o All multi-crystalline wafers including high performance multi
o Mono-crystalline wafers
6March 2014 BT Imaging Pty Ltd - Confidential Information
• Only BT Imaging has a proprietary ‘algorithm calibration’ procedure
o Maximizes wafer sorting benefits
o Enables continuous process and material improvement
• The BT Imaging team is available to customize algorithms to a customer request
• The BT Imaging team is always adding new features to its software capability
• Includes
o Single coinstack wafer loader
o 6 bin unloader + 1 reject bin
o Laser-safe iQ unit containing a single iLS-W2 photoluminescence inspection module
o Onsite training
o Installation and FAT
o A one-seat license to BT Imaging patents
7March 2014 BT Imaging Pty Ltd - Confidential Information
o Automation servers and control software & electronics for the tool
o Display, Keyboard and Mouse for the GUI
o Standard one-year Warranty
o QS-W2 Software Package™ - An integrated wafer quality algorithm and sorting software package that has taken many man-years of R&D to develop and optimise. The W2 software package™ takes inputs from the iLS-W2™ and other inspection modules and outputs wafer grades, defect metrics and wafer reports and allows wafer sorting based on these metrics.
• Sorter options - downgrade
o Single coinstack unloader
o 2 bin +1 reject bin unloader
o Cassette unloader
• Sorter options - upgrade
o 12 bin + 1 reject bin unloader
o 12 bin + 1 reject bin + 2 indexerunloaders
o 20 bin + 1 reject bin unloader
o 20 bin + 1 reject bin + 2 indexer unloader
• Loader options – upgrade
o Twin auto loader
o Single cassette loader
• Chiller for laser system
8March 2014 BT Imaging Pty Ltd - Confidential Information
• Inspection module options - upgrade
o iLS-G1
o MDP lifetime
o E+H thickness and resistivity
o Wafer ID reader for QS-W2
o Wafer ID reader for IV Sorter
o Wafer ID Marker WID-1
o Vivitek optical inspection modules
• Q-Analyser™
o Offline data analysis & statistics package gives customers the ability to
Automatically create wafer sorting recipes for emailing to wafer suppliers
Continuous process & product improvement
o Requires wafer ID marker
• Overall tool is sold by BT Imaging
o Over 50 tools sold
o More than 15 WIS systems sold with PL Imaging
• Preferred automation provided by and supported by Delta Automation
o We can use customer-preferred automation – adds cost
o We have Fortix as a second-source automation provider
o Three other WIS automation vendors also available
• Proprietary Inspection Modules by BT Imaging
o iLS-W2 - Wafer Electrical Quality by Photoluminescence
o iS-G1 - Micro Grains and Crystal Fraction
o WID-1 wafer marker
• Qualified third party inspection module vendors
o Vivitek (Delta Automation subsidiary)
o Freiberg Instruments
o E&H Metrology
o Other third party vendors as requested by customers
9March 2014 BT Imaging Pty Ltd - Confidential Information
• BT Imaging has dedicated support staff for
o China, Taiwan & Europe
o Supported by highly trained distributors in
Japan
Korea
South East Asia
USA
10March 2014 BT Imaging Pty Ltd - Confidential Information
• Delta Automation has dedicated support staff to support the automation
o All of Asia
• Inspection modules supported by
o Delta Automation for Vivitek
o BT Imaging and third-party vendors for third party Inspection Modules
Head-Office
Country-Office
Distributor
11March 2014 BT Imaging Pty Ltd - Confidential Information
Cell IV Performance, Cell $
Wafer properties-induced variation
Cell processing-induced variation
Ideal Cell Population
We measure thisAllows you to optimize this
And this…
12March 2014 BT Imaging Pty Ltd - Confidential Information
Solar cell efficiencies are continuously increasing due to• Higher quality wafers with less defects and impurities• New advanced cell designs with higher conversion efficiencies• New and/or modified cell line processing steps• Improved materials (e.g. screen printing pastes)
High efficiency cell designs and process steps are more sensitive to as-cut wafer defects and impurities that can be detected by
Photoluminescence Imaging in the QS-W2
Poor quality wafers need to be sorted for rejection, remediation
or lower wafer purchasing price
High quality wafers need to be sorted for high efficiency lines
All wafers can be sorted into quality bins
for optimal cell processing & pricing
Wafer and cell linesneed to be constantly
monitored for continuousprocess improvement,
debug, advanced QA & QC, & R&D
The biggest impact on cell efficiency
is wafer defects thatwe can measureby PL Imaging!
• BT Imaging QS-W2 WIS can measure and reject low efficiency multi-crystalline wafers
o All types including high-performance multi wafers
• Typical results below
o Measured efficiency versus proprietary wafer-measured single Q-factor™
o Mean absolute error of efficiency predictions on wafers less than 0.1%
13March 2014 BT Imaging Pty Ltd - Confidential Information
• Example: Customer wants to reject wafers with Q-factor™ >1.4
Avoids processing of a large fraction of wafers with Q-factor™ larger than 1.4 which in this cell line result in low efficiency cells (<16.7%)
Small fraction of false positives
• BT Imaging uses PL Imaging to detect and alert manufacturers to a range of known defect types in mono-crystalline wafers
o Defect types
Low lifetime (dark) edges and centers
Rings and other structures
Slip-lines
Cracks
o BT Imaging has proven algorithms that provide manufactures with
Overlay images of defects
Quantitative measurement of defects
o For monocrystalline wafers BT Imaging also can
Measures and reports defects after diffusion that correlate very highly with low performance cells
Measures and reports cracks and defects in finished mono-crystalline solar cells
14March 2014 BT Imaging Pty Ltd - Confidential Information
• Incoming wafers are measured by the BT Imaging QS-W2 WIS and then sorted into quality bins based on their expected solar cell efficiency
o Three bin example given below (green-best, blue-middle, purple-worst)
• BT Imaging can support up to 24 sorting bins
• Use cases
o Allows worst wafers to be rejected
o Best wafers to be used for high-efficiency lines
o Allows wafers to be processed by bin quality to optimize cell efficiency
o Lower quality can be remediated with better cell processing
15March 2014 BT Imaging Pty Ltd - Confidential Information
• Optional advanced data handling and statistics package that enables use-case decision making for cell makers
16March 2014 BT Imaging Pty Ltd - Confidential Information
17March 2014 BT Imaging Pty Ltd - Confidential Information
Cell maker runs weekly batch of test wafers through QS-W2 with wafer markingThese wafers can also go to module production – no lost production
QS-W2 PL-WIS properties of Marked Wafers and IV-performance of Marked Cells are automatically correlated by the Q-Analyser™ software
Cell makers decides on preferred wafer quality mix based on required cell IV histogramQ-Analyser™ automatically generates wafer sorting recipe
Wafer sorting recipe emailed to wafer supplierWafer supplier runs recipe on QS-W2 PL-WIS and supplies desired wafers
• Cell customer wants a specific band of cell efficiencies to fill a large order of specific solar module powers, and does not want to keep solar cells in inventory
o Runs a marked wafer trial on QS-W2 and uses Q-Analyser™ to develop a specific wafer sorting recipe that is sent to the wafer suppliers
o Only wafers that will give the required cell efficiencies are supplied
• Cell customer negotiates with wafer supplier to purchase low, medium and high efficiency wafers at a variable price per grade
o Cell maker run weekly marked wafer trial and uses Q-Analyser™ to generate a weekly sorting recipe into 3 grades of low, medium and high for emailing to wafer supplier
o The weekly run of this process is required to keep up to date with continuous process and materials changes on the cell lines
• Cell customer wants a specific low defect and low impurity wafer grade for a high-efficiency cell line process
o Runs a marked wafer trial on QS-W2 and uses Q-Analyser™ to develop a specific wafer sorting recipe that is sent to the wafer suppliers
o Only wafers that will give the required cell efficiencies are supplied
18March 2014 BT Imaging Pty Ltd - Confidential Information
• Advanced BT Imaging wafer inspection allows the development of ‘closed loop’ process control
• By monitoring and measuring wafer impact on cell efficiency a wafer or cell manufacturer can tighten incoming material specifications and outgoing product performance
• Examples
o Monitoring, control and improving process tool impact on cell efficiency by removing the impact of unknown and/or varying wafer quality
o Alarms when a wafer or batch of wafers underperforms and does not achieve efficiency entitlement
• BT Imaging can provide software tools to enable these and other use-cases
19March 2014 BT Imaging Pty Ltd - Confidential Information
• Continuous process & product improvement
• Monitor and report week-to-week variations in
o Incoming wafer quality as measured by defects and impurities
o Process ‘conversion’ efficiency
The change in cell efficiency delivered on a specific wafer qualities
o Process ‘spread’
The change in error contour maps of the cell efficiency delivered on a specific wafer qualities
• Use of the metrics above to
o Find and fix process errors
o Continuous process and product improvement
o Commission changes to lines or materials
o Bring all lines up to top line specification
20March 2014 BT Imaging Pty Ltd - Confidential Information
21March 2014 BT Imaging Pty Ltd - Confidential Information
Information sharing and NDA
Customer wafer samples measured & binned by BT Imaging
Customer processes batches of wafers and reports batch or marked-wafer IV results
BT Imaging generates report demonstrating value of use cases to customer
Customer purchases QS-W2 WIS
BT Imaging remains available to assist cell line customer
22March 2014 BT Imaging Pty Ltd - Confidential Information