Abstract
Intrinsic gettering and thermally induced microdefects in CZ silicon wafers taken from various portions of seed to tail of crystal ingots have been studied by means of infrared absorption, an etching procedure, and transmission electron microscopy. Thermal history dependence and critical annealing conditions to enhance intrinsic gettering were evaluated. Two standard crystals grown under the same conditions except the thermal history after growth were investigated. It is found that the thermal behavior of inner defects and the effectiveness of intrinsic gettering strongly depend on the thermal history of crystal ingots. It also follows that the effectiveness of intrinsic gettering can be enhanced even in low oxygen wafers taken from the tail portion, when the first annealing procedure is appropriately carried out.