  We study the coherence of flux-tunable Josephson junction resonators made
with two different fabrication processes. In the first process, devices are
made using a single step of evaporation in which the resonator and the
junctions of the SQUID are made at the same time. In the second process,
devices are made with an identical geometry, but in which the resonators are
made from a MoRe superconding layer to which an the junctions are added later
in a second step. To characterize the coherence of the two types of SQUID
cavities, we observe and analyze the quality factor of their resonances as a
function of flux and photon number. Despite a detailed cleaning process applied
during fabrication, the single-step Al devices show significantly worse quality
factor than the hybrid devices, and conclude that a the hybrid technique
provides a much more reliable approach for fabricating high-Q flux-tunable
resonators.
