[en] The influence of heat treatment (85-180 deg. C) on latent tracks (LTs) in poly(ethylene terephthalate) (PET) films irradiated by Xe ions with energy of 1 MeV/nucleon was studied. The kinetics of the alkaline etching (layer-by-layer technique) was investigated. Thermal annealing rises the time of through-pore formation. The etching of through pores, investigated by Hagen-Poiseuille and atomic force microscopy (AFM) methods, was found to be nonlinear: steps were discovered at the etching diagram. They were associated with earlier detected zones of high chemical stability around the track (with the diameters of approximately 10 and 20 nm). Using the AFM method an appearance of surface craters after the irradiation was found. After the annealing the shape of these defects changed to the hillock form. From the analysis of the Raman and electron paramagnetic resonance (EPR) spectra it is supposed that the polymer structure in the LT area was changed towards carbonaceous phase with graphite-like inclusions, which are evolving under the annealing and affecting the sequential etching process