The disclosure concerns a method of stressing a semiconductor layer comprising: depositing, over a semiconductor on insulator (SOI) structure having a semiconductor layer in contact with an insulating layer, a stress layer; locally stressing said semiconductor layer by forming one or more openings in said stress layer, said openings being aligned with first regions of said semiconductor layer in which transistor channels are to be formed; and deforming second regions of said insulating layer adjacent to said first regions by temporally decreasing, by annealing, the viscosity of said insulator layer.