MOSFET semiconductor device - having ion-implanted regions with impurity ion concn. profile

摘要

(A) A semiconductor device with a MOSFET has (i) a semiconductor substrate with a first conductivity region at least in the neighbourhood of the substrate surface; (ii) source and drain regions of second conductivity type on the left and the right of a channel region extending from the substrate surface down to a given depth; (iii) a transfer gate electrode (5) covering the channel region, an insulating gate film (3) being provided between the transfer gate electrode (5) and the substrate; and (iv) ion-implanted regions (4) of first conductivity type, formed at least in the neighbourhood of the channel region, for controlling the threshold voltage of the channel region. The novelty is that the ion-implanted regions (4) have a higher impurity atom concn. distribution in the right and left side regions adjacent the source and drain regions than in the region near the central section of the channel region. (B) Also claimed is prodn. of the device, in which the ion-implanted regions (4) are formed by ion implantation in a sloping direction with a predetermined inclination angle w.r.t. the substrate surface, at least the transfer gate electrode (5) being used as mask and the substrate being rotated in a plane parallel to its surface, followed by heat treatment to activate the ion-implanted regions. USE/ADVANTAGE - The device is esp. a MOSFET of lightly doped drain type. Source/drain breakdown voltage or the like is not reduced even when the device is highly integrated, short circuit of the depletion layer between the source and drain regions is inhibited so that breakdown voltage is increased and intermittent source / drain breakdown by the Alpen effect is avoided