The effect of annealing atmosphere of Ar, N2, or O2 on the recombination activity of copper (Cu) precipitates, formed by the rapid thermal process (RTP), in conventional Czochralski (CZ) silicon and nitrogen-doped CZ (NCZ) silicon wafers have been investigated. It was revealed that the recombination activity of Cu precipitates formed under N2, Ar, and O2 atmospheres decreased in turn. Moreover, the RTP under O2 atmosphere led to a higher critical temperature for Cu precipitation in comparison with the RTP under Ar or N2 atmosphere. Furthermore, it was found that the Cu precipitates formed under the same conditions possessed stronger recombination activity in CZ silicon than in NCZ silicon. The above results have been tentatively explained.