  Angle-resolved photoemission spectroscopy (ARPES) measurements have
established the phenomenon of kink in band dispersion of high-$T_{\rm c}$
cuprate superconductors. However, systematic studies of the kink in
electron-doped cuprates are still lacking experimentally. We performed
$in$-$situ$ ARPES measurements on ${\rm La}_{2-x}{\rm Ce}_x{\rm
CuO}_{4\pm\delta}$ (LCCO) thin films over a wide electron doping ($n$) range
from 0.05 to 0.23. While the nodal kink is nearly invisible, an antinodal kink
around 45 meV, surviving above 200 K, is observed for $n\sim0.05-0.19$, whose
position is roughly independent of doping. The fact that the antinodal kink
observed at high temperatures and in the highly overdoped region favors the
phonon mechanism with contributions from the Cu-O bond-stretching mode and the
out-of-plane oxygen buckling mode. Our results also suggest that the antinodal
kink of LCCO is only weakly coupled to its superconductivity.
