We investigated low temperature out-diffusion of Cu impurity from the bulk of p- and n-type silicon wafers after contamination followed by diffusion of Cu into silicon during annealing. We show that Cu impurity in the bulk after low-temperature out-diffusion can be measured at the surface by total x-ray fluorescence and graphite furnace atomic absorption spectroscopy 10(10) atom/cm(3). In addition, a benefit of low-temperature annealing is the removal of Cu contamination from the bulk by surface cleaning. We also find that Cu contamination in the bulk of p-type Si wafers out-diffuses at room temperature after removing the surface oxide, but this does not happen in the case of n-type Si material.