A semiconductor substrate has a back face and a front face and includes a semiconductor well that is electrically isolated from the semiconductor substrate. A device is configured to detect a thinning of the semiconductor substrate from the back face. The device includes at least one trench that extends within the semiconductor well between two peripheral locations from the front face down to a location situated at a distance from a bottom of the semiconductor well. The trench is electrically isolated from the semiconductor well. A detection circuit is configured to measure a physical quantity representative of well electrical resistance between two contact areas respectively situated on either side of the at least one first trench.