In this work, silicon nitride films containing terbium were deposited by reactive magnetron co-sputtering in a nitrogen enriched plasma and subjected to rapid thermal annealing treatments. The influence of annealing temperature on the emission and absorption properties of these films was investigated by photoluminescence, photoluminescence decay and photoluminescence excitation measurements. An increase in the photoluminescence intensity and photoluminescence decay time was observed upon annealing for the main D-5(4)-F-7(5) transition of Tb3+ ions. This observation was attributed to decrease of the non-radiative recombination and increase of the number of excited Tb3+ ions upon annealing. Moreover, high temperature annealing was found to shift the spectral position of absorption bands observed in the photoluminescence excitation spectra. In general, these excitation spectra were shown to have a rather complicated structure and were decomposed into three Gaussian bands. It was suggested that two of these excitation bands might be due to indirect excitation of Tb3+ ions via defects and the third excitation band could be due to direct 4f-5d transition.