  We have prepared two kinds of Al resonators using thin films made by
evaporation or sputtering and studied temperature behavior of their quality
factors and resonance frequencies with the help of the extended Mattis-Bardeen
(M-B) equations and its approximated analytical expressions. We have found that
temperature behavior of both the internal quality factor and resonance
frequency shift measured in evaporated Al thin-film resonators are well agreed
with those calculated by the analytical expressions of the complex conductivity
given by the M-B theory. In the Al thin film resonators made by sputtering, the
internal quality factor and resonance frequency shift show a peak and a bump
near 0.17 K in the respective temperature dependence. It is found that inverse
of the internal quality factor is well approximated by a-b*log(T) below 0.15 K,
where T is the temperature. This type of temperature dependence strongly
indicates the existence of the magnetic impurity scattering of residual
quasiparticles due to the Kondo effect. It is shown that temperature dependence
of the internal quality factor and resonance frequency shift observed in the
sputtered Al resonators can be well fitted by the theory taking the Kondo
effect and kinetic inductance of the residual quasiparticles into account.
