METHOD OF PROGRAMMING READ-ONLY MEMORY BY ION IMPLANTATION AND NMOS READ-ONLY MEMORY OBTAINED BY THE METHOD

摘要

The method for ion implant programing NMOS read-only memories comprises the step of increasing the concentration of boron in the channel only proximate to the source junction of the NMOS devices of the memory which are to be programed 'off'. In this manner it is possible to increase the threshold voltage of these devices without reducing the breakdown voltage thereof, so as to obtain a reliable operation of the device or memory element even for very-large-scale-integration circuits, with a reduced thickness of oxide.