Impact of Rapid Firing Thermal Processes on Meta-Stable Defects: Preformation of the LeTID and the Suppression of B-O Defects

Abstract

Rapid firing processes are shown to simultaneously impact the concentration of two common meta-stable defects in silicon that cause light- and elevated temperature-induced degradation (LeTID) and boron-oxygen related light-induced degradation. A high-temperature fast-firing process with a peak temperature of 850 °C can reduce the concentration of boron-oxygen (B-O) defects more than 50%. While no strong dependence on belt speed was observed, when peak firing temperature is above 750 °C, the total concentration of B-O defects increased with higher peak firing temperatures. On the other hand, increasing the belt speed or the peak firing temperature resulted in an increased preformation of LeTID during the firing process. The firing process reduced the effective lifetime from over 100 μs down to as low as 30μs, which is equivalent to the reduction in implied V OC of 36 mV, due to bulk recombination. This reduction was mainly contributed by the preformation of LeTID.