Memory device having additional selection transistors and main bit lines

Abstract

A semiconductor memory device has an element isolation region between rewrite units of memory cells. A plurality of memory cells are memory cell groups arranged in a row direction, and each memory cell group consists of (8×N) memory cells arranged in a row direction as a unit to be used as a storage region. The number of a plurality of selection word lines is at least eight, and the number of selection transistors corresponding to at least N is connected to each of the plurality of selection word lines. At least one selection transistor in addition to (8×N) selection transistors are connected in total to the plurality of selection word lines. A plurality of main bit lines includes at least one main bit line in addition to (4×N) main bit lines connected to the common drain of a pair of selection transistors.