Que Duanlin

Minority Carrier Lifetime in As-Grown Germanium Doped Czochralski Silicon

The minority carrier lifetime of as-grown germanium-doped Czochralski (GCZ) silicon wafers doped with germanium concentrations [Ge]=1016−1018 cm−3 is investigated in comparison with conventional CZ silicon samples. It is found that the lifetime distribution along the ingot changes with the variation of [Ge]. There is a critical value of [Ge] = 1016 cm−3 beyond which Ge can obviously influence the lifetime of as-grown ingots. This phenomenon is considered to be associated with the competition or combination between the oxygen related thermal donors (TDs) and electrically active Ge-related complexes. The related formation mechanisms and distributions are also discussed.

Oxygen Precipitation within Denuded Zone Founded by Rapid Thermal Processing in Czochralski Silicon Wafers

Oxygen precipitation within the magic denuded zone (MDZ) founded by rapid thermal processing in Czochralski silicon (CZ-Si) wafers is investigated. After the standard MDZ process, the CZ-Si wafers are further subjected to two specific oxygen precipitation annealing, respectively. It is found that the MDZs in CZ-Si wafers shrunk notably because oxygen precipitation occurs within the MDZs. However, a width of substantial DZ still remains within the wafer. Therefore, it is believed that the outer region of the MDZs, which corresponds to the oxygen denuded zone formed in the course of rapid thermal process and high temperature annealing, is a substantial defect-free zone which acts as the active area for semiconductor devices.