The effect of heat treatment rapid thermal annealing (RTA) or conventional thermal annealing on the electrical properties of polycrystalline silicon films implanted with boron in the intermediate concentration range is examined. A standard furnace anneal uniformly redistributes the dopant and results in an electrical activity of grain boundaries (GBs). On the contrary, a rapid thermal anneal does not activate GBs. Impurity gettering does not occur at GBs in RTA and implanted boron does not redistribute uniformly within the grains leading to a strong increase of the Hall mobility in small‐grained silicon films.