Temperature coefficient of resistance (TCR) of as-deposited and annealed atomic beam-deposited polycrystalline copper films of 20 nm with chromium under-layer on SiOx substrate layers was measured. The copper resistivity for various chromium thicknesses was in situ measured during copper deposition. The TCR of the as-deposited films decreases with the chromium thickness to reach a minimum value at about 5 nm. The minimum TCR value for the annealed copper films exists at the chromium thickness equal to about 1 nm. When chromium thickness is less than 2 nm the annealing markedly decreases the TCR of the copper film.