PURPOSE: To obtain a semiconductor memory of large capabity which satisfies both speed and yield by a method wherein a structure of good yield is used for a memory cell part transistor, etc., and a transistor of a structure which enables high speed actions is used for the transistor of peripheral circuits which influence the speed.

CONSTITUTION: A memory is composed of a memory cell part 62 and the peripheral circuit part 63 containing input-output circuits on an N type Si substrate 61. A transistor L1 of large bird beak is used for the memory cell part 62, and while a transistor L2 of small bird beak is used for the peripheral circuit part 63. Since the transistors are so selected that the equation L2/L1=70% is effective, i.e. each differs by 30%, the memory of high speed the access time is 0.6 in opposition to 1 of conventional one and of high yield that it is approx. 85% can be obtained.