Virtual Single Wafer Tracking Enables Complex Analysis, While Sustainably Increasing Process Quality

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Quality control in cell production lines gains importance due to increasing production capacities and efficiencies. On the basis of a virtual single wafer tracking technology the Manufacturing Execution System FabEagle®MES has been in the technology portfolio of AIS Automation Dresden, a member of Meyer Burger Technology Ltd., since 2005. Since 2014 the FabEagle®MES is successfully in production at First Solar in Malaysia.

The FabEagle®MES contains a range of modules for improvement of production quantity and quality. The base of PV production in Malaysia is a comprehensive virtual single wafer tracking, which allows to monitor the processing of each single wafer without physically marking it. In August 2016 First Solar has presented the opportunities and benefits of virtual single wafer tracking at the Silicon Workshop in Colorado. A unique ID is assigned to each wafer only virtually and then passed on between subsequent pieces of process equipment. In this project a continuous tracking rate of 97% could be achieved which provides reliable data correlations for process analysis and improvement, even from small samples or experiments. Compared to tracking systems relying on physical markings of the wafer the virtual tracking is cheaper (no marking or reading devices required), does not damage the material and provides data correlations between process steps just as reliably. Cheaper batch tracking systems on the other hand do not provide the required data quality and reliability.

The presented paper from First Solar gives details on the scientific approach of analyzing and improving the production process and how the FabEagle®MES with single wafer tracking successfully contributed to that process. The key points are that small sample sizes deliver sufficient data because every single material is tracked and measured. Furthermore the experiments can be processed with the production material, no gaps or separation from the production material is required and the throughput is not effected.