Fabrication and characterization of a new EEPROM cell with spacer select transistor

Process technology and cell characteristics of a newly developed compact electrically erasable programmable read only memory cell are described. The cell has spacer select gates on both side walls of floating gate and this gives a very small cell size as well as relief of topology during contact formation. The cell size is 0.95 μm² with 0.18 μm logic process. The cells are programmed and erased by Fowler-Nordheim tunneling. It appears that programming requires 3 ms at 16 V while erasing requires 2 ms at 14 V. It is shown that the cells have very uniform distribution of both programmed and erased threshold voltage. It is also shown that the cell endures up to half million cycling tests.