Solar wafer emitter measurement by infrared reflectometry for process control: Implementation and results

Infrared reflectometry (IRR) is a method whereby physical characteristics of a sample are rapidly extracted from the spectrum of reflected IR radiation. In the case of solar cell characterization, this provides a useful technique for high-volume inline measurement of wafer dopant content, correlated to emitter sheet resistance. IRR measurements can be used for characterizing variations in volume production and for process verification, feedback and feed-forward control. We present recent developments and experience in making the IRR technique robust for applications in solar cell emitter dopant content measurement and quality control during volume manufacturing. The IRR technology has been embodied in a commercially available product, described herein.