SEMICONDUCTOR INTEGRATED CIRCUIT DEVICE AND MANUFACTURE THEREOF

摘要

PURPOSE: To make more fine memory cells of a semiconductor integrated circuit device having a mask ROM. CONSTITUTION: In an As ion implanting step to form an n<+> -type semiconductor region 8 forming sources 8s and drains 8d of a mask ROM 1, a photoresist pattern is used. Using this mask, a B ion implanting step is made to form a p<+> -type semiconductor region 9 and then a semiconductor substrate 7 is heat treated.