| 摘要 |
PROBLEM TO BE SOLVED: To provide a mask ROM and a method for manufacturing the same which enable reduction in the numbers of steps by programming concurrently with formation of a source region and a drain region. SOLUTION: After a first gate 35 and a second gate 36 are formed on a P type semiconductor substrate 31, side walls 37 are formed respectively on the sides of the first gate 35 and the second gate 36. And the side wall 37 formed on the side of the second gate 36 is removed, N type impurity ions are then implanted into an exposed portion of the semiconductor substrate 31 to form an impurity region 41, thus forming a first channel 43 and a second channel 45 having a different effective channel length from each other. Therefore ON transistors and OFF transistors having different effective channel lengths are formed concurrently with formation of a source region and a drain region in one ion implantation step to program data, thus simplifying the steps. |
