MANUFACTURING I MATERIALS CASE STUDY F2 for PV in EUROPE
Linde recently announced the signing of a long-term supply contract with Schüco TF, Germany’s largest thin-film silicon PV
module manufacturer, to deliver on-site fluorine (F2) to its new thin-film module mass production site in Großröhrsdorf, eastern Germany. One key area of focus was the development of PECVD cleaning recipes with fluorine to replace nitrogen trifluoride. The Schüco R&D facility was equipped with full size thin film tools allowing processes to be scaled up from the lab to manufacturing scale with confidence.
After achieving excellent results in terms of cleaning capability and faster cleaning time [5], the process was adopted successfully at production scale on the 40MW Osterweddingen site in 2009. For the new project at Großröhrsdorf, Linde will construct the largest electronics fluorine production plant in Europe. This will see the complete elimination of the use of nitrogen trifluoride from Schüco TF’s manufacturing process.
On-site fluorine technology will improve solar module production and increase profitability by removing any risk of unabated emissions, reducing non-productive cleaning time and improving throughput. This will help Schüco TF to reduce
its emissions by more than 100,000 tonnes of CO2 equivalent per year [see table 3]. As a result, the carbon payback time,
the time it takes the use of solar panels to offset the environmental impact of their manufacture, is reduced by up to one year. To help enhance performance and decrease costs of thin film silicon modules, Oerlikon Solar, a supplier of thin film silicon PV production equipment, launched a European Commission backed research project in September last year called “PEPPER” with Linde becoming one of the key partner companies in the project.
The EUR 16.7 million project, of which EUR 9.4 million is financed by the European Commission [6], is a landmark collaboration between Oerlikon Solar and the Photovoltaics Laboratory of the Institute of Microengineering at EPFL (IMT- Neuchâtel, Switzerland), the Universities of Northumbria (UK) and Patras (Greece), Bosch Solar Thin Film (Germany, module production), Heliosphera (Greece, module production) and Linde (Germany, gas supply).
The project tackles the major influences on Micromorph module efficiency and production cost by assessing the influences of glass, gas, transparent conductive oxide (TCO) and silicon deposition as part of the production process. The close cooperation between these organisations will help demonstrate, expand and statistically bolster the advantages of this technology on a broad scientific basis.
Reliable requirements
On-site generated fluorine must meet the very high industry standards for reliability. Beyond proper material and component selection, design and operation are essential to achieving high uptime and so moving parts are minimised in the system design, electrochemical duty is kept light, and preventative maintenance and monitoring leading indicators keep all performance parameters within controlled ranges.
Preventative maintenance and repairs can be performed quickly without compromising supply, and longer-term service can be done off-site. In addition to on-site operators, most fluorine plants for chamber cleaning take advantage of remote monitoring. This allows 24 hours a day coverage and diagnostics by fluorine plant experts located on three continents.
On-site generated fluorine offers significant cost efficiency benefits over the incumbent cleaning gases. Production throughput increases and equipment cost reduction options provide the necessary value-improvement incentives to make the
switch commercially attractive. Fluorine also offers elimination of the large and growing GWP risk from nitrogen trifluoride, while reducing the carbon footprint of the cleaning process. These advantages have already been realised by a number of PV manufacturers, and the trend is toward adoption of on-site fluorine generation for a wide section of the industry.
On-site generated fluorine is currently used in commercial scale thin-film processes at many sites in both Asia and Europe, and generators specifically designed to meet the requirements of the electronics industry have been supplying low pressure, high purity fluorine gas reliably to CVD tools for more than ten years. These continue to operate without a single safety incident and provide delivery reliability much greater than 99%. Production capacities ranging from 1 to 100+ tonnes per year have displaced high-pressure fluorine cylinder and bulk nitrogen trifluoride supplies.
© 2011 Angel Business Communications. Permission required.
REFERENCES [1] “ESH 2007 Chemical Restrictions Table,” in the International Technical Roadmap for Semiconductors 2007.
[2] M. J. Prather et al., “NF3, the greenhouse gas missing from Kyoto,” Geophysical Research Letters, vol. 35, June 2008. [3] R. F. Weiss et al., “Nitrogen trifluoride in the global atmosphere,” Geophysical Research Letters, vol. 35, October 2008. [4] M. Schottler et al., “The carbon footprint of PECVD chamber cleaning using fluorinated gases,” in Proceedings of the 23rd European Photovoltaic Solar Energy Conference., 1-5 September 2008.
[5]
S.Petri et al., “Fluorine chamber cleaning for AKT and KAI PECVD tools” presented at 25th EUPVSEC Sept 2010 [6] The research leading to these results has received funding from the European Community’s 7th Framework Programme under grant agreement n° 249782 (PEPPER Project)
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