Flicker (1/f) noise in copper films due to radiation-induced defects

Changes were measured in the 1/f noise and resistivity in polycrytalline Cu films due to defects induced by 500-keV - 1.1-MeV electron irradiation or 1-MeV Kr+ ion irradiation. The films were irradiated while maintained at 90 K on a cold stage of an electron microscope, and all noise and resistivity measurements were made in-situ. Irradiation with 500-keV electrons increased the voltage noise level in the films by more than an order of magnitude, while the resistivity increased by at most 10%. When the films were annealed at progressively higher temperatures, both the 1/f noise and the resistivity were reduced; however, at lower annealing temperature, the fractional reduction in the induced noise was substantially more than in the added resistivity. These results suggest that a large fraction of the induced noise may be generated by certain mobile added defects that are more readily annealed than the majority of the added defects. The temperature dependence of the noise after irradiation and partial annealing indicated that the induced noise was thermally activated in a manner consistent with the Dutta-Dimon-Horn model. Isolated defects created by 1.1-MeV electron irradiation were found to produce substantially higher noise levels than clustered defects resulting from 1 MeV Kr+ irradiation