  We report detections of scintillation arcs for pulsars in globular clusters
M5, M13 and M15 for the first time using the Five-hundred-meter Aperture
Spherical radio Telescope (FAST). From observations of these arcs at multiple
epochs, we infer that screen-like scattering medium exists at distances
$4.1_{-0.3}^{+0.2}$ kpc, $6.7_{-0.2}^{+0.2}$ kpc and $1.3_{-1.0}^{+0.7}$ kpc
from Earth in the directions of M5, M13 and M15, respectively. This means M5's
and M13's scattering screens are located at $3.0_{-0.2}^{+0.1}$ kpc and
$4.4_{-0.1}^{+0.1}$ kpc above the galactic plane, whereas, M15's is at
$0.6_{-0.5}^{+0.3}$ kpc below the plane. We estimate the scintillation
timescale and decorrelation bandwidth for each pulsar at each epoch using the
one-dimensional auto-correlation in frequency and time of the dynamic spectra.
We found that the boundary of the Local Bubble may have caused the scattering
of M15, and detected the most distant off-plane scattering screens to date
through pulsar scintillation, which provides evidence for understanding the
medium circulation in the Milky Way.
