FLASH MEMORY AND DATA PROCESSOR

摘要

PURPOSE:To provide a flash memory whose memory cells can be made uniform in erasure characteristics even if memory cells which share a source have variance in source coupling capacity. CONSTITUTION:A couple of memory cells Q21 and Q31 share the source S1 of a flash memory cell; and only one memory cell is erased and then the other memory cell is erased. Namely, memory cells in an even-numbered row A2 are erased and memory cells in an odd--numbered row A3 are erased. While the even-numbered row is erased, an erasure preventing voltage is applied to the odd-numbered row and while the odd-numbered row is erased, the erasure preventing voltage is applied to the even-numbered row. Consequently, a difference in the capacity coupling ratio between the source between the couple of memory cells and a floating gate can be ignored.