In-situ monitoring of dopant concentration variation in a silicon melt during Czochralski growth

In-situ monitoring of dopant concentration variation in a silicon melt during Czochralski growth was performed using an X-ray radiography system. Indium was used as a dopant. The dopant concentration variation in the melt as a function of fraction solidified and of time lapse after growth interruption was also observed experimentally. It is shown that the time constant for dopant concentration variation in the bulk melt just after growth interruption is some tens of minutes. The time constant for variation of convective mode and for temperature oscillation of the melt is also several minutes. Therefore, the time constant for dopant concentration variation is attributed to its diffusion from an accumulated layer just beneath the solid-liquid interface.