Method of programming a non-volatile memory cell to eliminate or to minimize program deceleration
View Patent ↗A method to eliminate program deceleration and to enhance the resistance to program disturbance of a non-volatile floating gate memory cell is disclosed. This method eliminates or minimizes the impact of the hole displacement current. This can be done, for example, by increasing the rise time of the high programming voltage applied to the high voltage terminal. Alternatively, the transistor of the non-volatile floating gate memory cell can be turned off until the voltage applied to the high voltage terminal has reached the programming voltage. This can be done, for example by delaying the voltage applied to either the low voltage terminal or to the control gate to turn on the transistor until the voltage at the high voltage terminal has past the ramp up voltage and has reached a level programming voltage.
1. A method of programming a floating gate storage transistor having a first region and a second region in a semiconductor substrate with a channel region between the first region and the second region, a floating gate spaced apart from the channel region for controlling the flow of current therein, wherein said floating gate is programmed by either channel hot electron injection or by source side injection, wherein said method comprising:
applying a first voltage to said first region; and
applying a second voltage to said second region, wherein said second voltage has a rise period that reduces displacement current between said second region and said first region, wherein said second voltage is characterized by a rise time and a trail time after the rise time and wherein said displacement current is reduced by increasing the rise time and the trail time.
2. The method of claim 1 wherein said displacement current (Idis) is proportional to
dVsp/dt
where Vsp is the second voltage.
3. The method of claim 1 wherein the rate of said second voltage applied during said rise time is less than or equal to approximately 1v/50 ns.
4. The method of claim 1 wherein the rate of said second voltage applied during said trail time is less than or equal to approximately 1v/20 ns.