We have carried out deep and very high angular resolution polarimetric ALMA observations toward the massive protostar driving the HH 80-81 radio jet. The observations clearly resolve the disk oriented perpendicular to the radio jet, with a radius of 290 au. The continuum brightness temperature, the intensity profile, and the polarization properties clearly indicate that the disk is optically thick inside a radius of 170 au. The linear polarization of the dust emission is detected almost all along the disk and its properties suggest that dust polarization is produced mainly by self-scattering. However, the polarization pattern presents a clear differentiation between the inner (optically thick) part of the disk and the outer (optically thin) region of the disk, with a sharp transition that occurs at about 170 au. The polarization characteristics of the inner disk suggest that dust settling has not occurred yet with a maximum dust grain size between 50 and 500 µm. The outer part of the disk has a clear azimuthal pattern but with a significantly higher polarization fraction compared to the inner disk. Although this pattern is consistent with self-scattering of a radiation field that is beamed radially outward, as expected in the optically thin outer region, a contribution from non-spherical grains aligned with respect to the radiative flux cannot be excluded.