Erasable read-only semiconductor memory device

Abstract

Memory transistors are arranged in a plurality of rows and a plurality of columns. A source line is formed for every two bit lines formed in the column direction, each connected to the memory transistors of one column. A source region of each memory transistor is connected, on one side, to a source line adjacent thereto and, on the other side, to a source line through the source region of the adjacent memory transistor, through impurity regions respectively. A floating gate is formed to extend to a position under the corresponding source line. In another example, a source line is formed for each bit line formed in the column direction. The source region of each memory transistor is connected to the adjacent source lines on both sides thereof through impurity regions. The floating gate is formed to extend to positions under both adjacent source lines.