MEMORIA FLASH EPROM CANCELLABILE PER BLOCCHI DI CELLE MEDIANTE INTERRUZIONE DELLE LINEE DI CONNESSIONE SOURCE E COLLEGAMENTI ATTRAVERSO LINEE ORTOGONALI AUSILIARIE DI INTERCONNESSIONE SOURCE IN METAL 1 ED INCROCI IN POLY 2 PER LA CONTINUITA' DELLE BIT LINES

摘要

A FLASH-EPROM memory with a single metal architecture may be erased by selectable banks of cells. The diffused source lines are not interconnected in the silicon but contacted by means of a set of PRIMARY source connection lines, purposely patterned in metal 1, through contacts which may be formed together with the drain contacts. The PRIMARY source connection lines are parallel to and alternate with a plurality of BIT LINES which are patterned in the same metal 1. The PRIMARY source connection lines are segmented and the aligned segments are intercepted by orthogonal SECONDARY source interconnection lines patterned also in the same metal 1 and extending through interruptions of the patterned BIT LINES. The electrical continuity of the BIT LINES in the interruption zones is realized by means of "crosses" patterned in the underlying poly 2 layer. The SECONDARY source interconnection lines are brought out of the matrix and may be individually selected through a dedicated circuitry for erasing selected groups of cells having their sources connected in common to the particular SECONDARY source line, without affecting the other cells of the matrix.