A SIMPLE EEPROM CELL USING TWIN POLYSILICON THIN-FILM TRANSISTORS

A planar twin polysilicon thin film transistor (TFT) EEPROM cell fabri cated with a simple low temperature (less-than-or-equal-to 600-degrees -C) process is demonstrated in this work. The gate electrodes of the t wo TFT's are connected to form the floating gate of the cell, while th e source and drain of the larger TFT are connected to form the control gate. The cell is programmed and erased by Fowler-Nordheim tunneling. The threshold voltage of the cell can be shifted by as much as 8 V af ter programming. This new EEPROM cell can dramatically reduce the cost of production by reducing manufacturing complexity.