Ring-Like Defect Formation in N-Type Czochralski-Grown Silicon Wafers during Thermal Donor Formation

This article presents experimental and simulation studies on the formation of recombination-active ring-like defects during thermal donor (TD) formation at 450 °C in n-type Czochralski-grown silicon wafers. With increasing anneal duration from 1 to 24 h, the resistivity and interstitial oxygen concentration of samples decrease, consistent with the formation of TDs. However, after a subsequent TD annihilation treatment, the resistivity recovers completely, while the interstitial oxygen concentration recovers only partially. Furthermore, the wafers exhibit ring-like defects in photoluminescence images after the TD generation and remain persistent even after annihilation treatment. By applying a tabula rasa (TR) treatment prior to TD generation anneals, the net loss of interstitial oxygen is reduced, and the incubation time of the ring-like defects is extended in comparison to as-grown wafers. Finally, to investigate the possibility of low-temperature precipitation, simulation of oxygen precipitation (OP) kinetics during the 450 °C annealing steps is performed using an enhanced effective diffusivity of oxygen. These simulations demonstrate that OP can occur simultaneously during TD formation, resulting in recombination-active ring-like defects.