A substrate includes an active region oriented along a crystallographic face (100) and limited by an insulating region. A MOS transistor includes a channel oriented longitudinally along a crystallographic direction of the type. A basic pattern made of metal and formed in the shape of a T is electrically inactive and situated over an area of the insulating region adjacent a transverse end of the channel. A horizontal branch of the T-shaped basic pattern is oriented substantially parallel to the longitudinal direction of the channel.