A New Method for the Determination of the Dopant-Related Base Resistivity Despite the Presence of Thermal Donors

During cooling of Czochralski grown silicon ingots, thermal donors can be formed. These oxygen clusters influence the measurement of the base resistivity in the as-cut state. Thermal donors distort the calculation of the emitter sheet resistance during inline control because two measurements-one before and one after emitter diffusion-are needed. In this paper, we quantify the negative influence of the thermal donors on the base resistivity measurements, as well as on the calculation of the emitter sheet resistance, and present a new photoluminescence-based method for the determination of the dopant-related base resistivity, despite the presence of thermal donors in the as-cut state of Czochralski grown silicon wafers. With the photoluminescence base resistivity method, the dopant-related base resistivity and, therefore, the emitter sheet resistivity can be calculated with significantly higher accuracy than standard base resistivity measurements.