  We demonstrate enhanced relaxation and dephasing times of transmon qubits, up
to ~ 60 \mu s by fabricating the interdigitated shunting capacitors using
titanium nitride (TiN). Compared to lift-off aluminum deposited simultaneously
with the Josephson junction, this represents as much as a six-fold improvement
and provides evidence that previous planar transmon coherence times are limited
by surface losses from two-level system (TLS) defects residing at or near
interfaces. Concurrently, we observe an anomalous temperature dependent
frequency shift of TiN resonators which is inconsistent with the predicted TLS
model.
