Copper precipitation on extrinsic defects in silicon

Abstract

The gettering of impurity copper in silicon has been investigated for over a decade because of its technological importance in electronic device fabrication.it is known that Cu can be extrinsically gettered in silicon at deliberately introduced nucleation sites. However, its reaction mechanism and the nature of the reaction product are not well understood. Here we report the interaction of Cu with dislocations in Si created by mechanical abrasion.A damaged region was introduced into CZ{001} silicon wafers on one side by abrasion. A Cu layer 200nm thick was deposited onto the abraded surface in a UHV chamber at room temperature. After Cu deposition the wafers were sealed immediately into quartz ampules under vacuum and annealed at 1000 C for 24 hrs, followed by quenching. Cross section specimens were prepared by mechanical dimpling and Ar beam ion milling. Diffraction contrast imaging and microdiffraction experiments were done in a JEM-2000FX at 200kV, and a Philips 400TEM/STEM/FEG at 100kV.