  Scandium aluminum nitride (ScAlN) has recently emerged as an attractive
material for integrated photonics due to its favorable nonlinear optical
properties and compatibility with CMOS fabrication. Despite the promising and
versatile material properties, it is still an outstanding challenge to realize
low-loss photonic circuits on thin-film ScAlN-on-insulator wafers. Here, we
present a systematic study on the material quality of sputtered thin-film ScAlN
produced in a CMOS-compatible 200 mm line, and an optimized fabrication process
to yield 400 nm thick, fully etched waveguides. With surface polishing and
annealing, we achieve micro-ring resonators with an intrinsic quality factor as
high as $1.47\times 10^5$, corresponding to a propagation loss of 2.4 dB/cm.
These results serve as a critical step towards developing future large-scale,
low-loss photonic integrated circuits based on ScAlN.
