  Kepler's observation shows that many of the detected planets are
super-Earths. They are inside a range of critical masses overlapping the core
masses (2-20 $M_{\bigoplus}$), which would trigger the runaway accretion and
develop the gas giants. Thus, super-Earths/sub-Neptunes can be formed by
restraining runaway growth of gaseous envelopes. We assess the effect of
planetary rotation in delaying the mass growth. The centrifugal force, induced
by spin, will offset a part of the gravitational force and deform the planet.
Tracking the change in structure, we find that the temperature at the
radiative-convective boundary (RCB) is approximate to the boundary temperature.
Since rotation reduces the radiation energy densities in the convective and
radiative layers, RCB will penetrate deeper. The cooling luminosity would
decrease. Under this condition, the evolutionary timescale can exceed the disk
lifetime (10 Myr), and a super-Earth/sub-Neptune could be formed after
undergoing additional mass loss processes. In the dusty atmosphere, even a
lower angular velocity can also promote a super-Earth/sub-Neptune forming.
Therefore, we conclude that rotation can slow down the planet's cooling and
then promote a super-Earth/sub-Neptune forming.
