Method of manufacturing a semiconductor device having conductive and insulating portions formed of a common material utilizing selective oxidation and angled ion-implantation

摘要

A semiconductor device is manufactured by covering a semiconductor substrate of a predetermined conductivity type with a polycrystal layer of a semiconductor material. Selected portions of the polycrystal layer are oxidized into an insulating material during heat treatment. Remaining portions of the polycrystal layer which are left unoxidized act as conductive portions. On manufacturing a bipolar transistor, ion implantation is carried out in a predetermined solid angle to introduce an impurity of an opposite conductivity selectively in a preselected one of the remaining portions. During the heat treatment, the impurity diffuses into the substrate only from the preselected portion to form a PN junction in the substrate. For fabricating an MOS transistor, an oxide film is preliminarily formed on the substrate selectively on an area on which a predetermined one of the remaining polycrystal layer portions is to be formed. Ion implantation is carried out to introduce an impurity of the opposite conductivity in the respective remaining layer portions. The oxide film prevents the impurity from diffusing to the substrate. The impurity diffuses into the substrate only from the respective remaining portions, except the predetermined portion.