KLAC FabVision Solar: Getting to the root of yield issues

KLA-Tencor (KLAC) debuted an integrated product to help solar photovoltaics (PV) cell manufacturers improve production yield. FabVision Solar captures all the measurement inspection data throughout the manufacturing process including measured data, images, and defect information, according to David Kallus, senior director in KLA-Tencor’s Process Control Information Division.

By Debra Vogler, senior technical editor

June 6, 2011 — KLA-Tencor (KLAC) debuted an integrated product to help solar photovoltaics (PV) cell manufacturers improve production yield. FabVision Solar captures all the measurement inspection data throughout the manufacturing process including measured data, images, and defect information, according to David Kallus, senior director in KLA-Tencor’s Process Control Information Division.

In a podcast interview, Kallus explained that manual analytical methods can take as much as a half a day, 3-4 times a week, manually scanning through log files and analyzing the data to get to the root cause of a yield loss. The new product automatically collects all the data in real time and automatically sends the reports to production managers, and so forth.

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Figure 1:Analysis of defect count after coating — a comparison between two lines. (Source: KLA-Tencor)

Kallus provided an example of what the product can do to control finger-width (Figs. 1 and 2). Finger-width is important because as it decreases, the cell’s efficiency goes down. Having a clear real-time understanding of finger width, the end user can take proactive active to minimize those cells that would have minimum finger width, which leads to a below specification efficiency, said Kallus.

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Figure 2: Comparison of print finger-width when new (at the
beginning of a shift) vs. after 8 hours. (Source: KLA-Tencor)

Listen to Kallus’ interview:

 

  • Format: mp3
  • Length: 6:12
  • Size: 5.68 MB
  • Date: 06/06/11

Figures 1 and 2 provide an analysis that looks at efficiency for a print screen cell over a period of time and identifies patterns in print finger-width. “While the trend for an extended period of time shows little variation around the mean, honing in on the specific time segments, such as shift changeover points, shows a pattern of variation that is useful to track,” Kallus told Photovoltaics World. The data in the figures, he noted, show a higher print finger-width when the print screen is new (at the beginning of a shift) but after eight hours, the finger-width becomes smaller. “The availability of such information enables process engineers to optimize the print screen replacement cycles to maintain the best balance between maximizing cell efficiency and production costs.”

Click to Enlarge

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