Investigation on Defects in Czochralski Silicon with High-Sensitive Laser/Microwave Photoconductance Technique

Abstract

High sensitivity of a noncontact laser/microwave photoconductance (LM-PC) technique for defects in heat-treated Czochralski (CZ) silicon crystals was confirmed in comparison with other diagnostic techniques such as Fourier transform infrared spectroscopy (FT-IR) and deep-level transient spectroscopy (DLTS). The energy levels of recombination centers (ET) in samples subjected to a three-step intrinsic gettering (IG) thermal process were obtained with LM-PC although no significant oxygen reduction in the samples was observed with FT-IR. The defect density detection limits of LM-PC and DLTS for samples after the three-step IG process are estimated to be ≤1×107 cm-3 and ∼1×1010 cm-3, respectively. Moreover, the dependence of effective minority-carrier recombination lifetime on defect density was found to be influenced greatly by carbon concentration through the enhancement effect on oxygen precipitation.