This work reviews recent developments in the field of copper trace detection by advanced electrical techniques and presents new data on the behavior of copper in silicon. First the current understanding of copper in silicon is described. In addition, physical principles, assumptions, and limitations of electrical methods based either on minority carrier dynamics, or transient ion drift (TID) are discussed. In the second part new TID data obtained on quantitatively contaminated silicon are given. The influences of annealing temperature, cooling rate, and storage conditions on copper impurities are addressed. It is shown that in high quality silicon, copper impurities may remain on interstitial sites for several days at room temperature. Under illumination the surface photovoltage increases the out-diffusion rate considerably. In float-zone material, evidence for copper trapping by grown-in defects is given. The discussion focuses on the impact these results have on the copper trace detection methods. (C) 2003 The Electrochemical Society.