Flicker (1/F) Noise in Copper Films Due to Radiation-Induced Defects

摘要

Changes were measured in the 1/f noise and resistivity in polycrystalline Cu films due to defects induced by 500 keV - 1.1 MeV electrons or 1 MeV Kr sup + ions. 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 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. This suggests that a large fraction of the induced noise may be generated by 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 electrons produced higher noise levels than clustered defects resulting from 1-MeV Kr sup + irradiation. Isolated In and Be impurities in Cu are known to trap radioinduced interstitial defects. Data on several films indicate that the induced 1/f noise is not sensitive to the type and quantity of interstitial traps. A simple local interference model is presented, which uses calculations by Martin to estimate the 1/f noise magnitude generated by moving defects. This model can account for the induced noise, with enough mobile defects. Several simple models are examined concerning the defects responsible for the induced noise. A model which attributes the noise to the motion of vacancy-type defects close to surfaces, grain boundaries, or dislocations is most consistent with experiment and theory. (ERA citation 13:018584)