2022-11-21 17:27 Tags: # floating gate  Has the normal MOS structure, but the normal gate is not connected to anything (burrowed). Another gate sits on top of it and is capacitively coupled to the floating gate. When there is a large electric field between the two gates, electrons can tunnel from the either the top gate or the substrate to the floating gate. Example: A very negative top gate voltage will force the electrons to tunnel to the floating gate and get stuck there. . Adding negative charge to the floating gate will cause the threshold voltage to increase.  If we do this long enough, normal voltages applied at the gate won't turn the transistor on at all. To remove electrons from the floating gate, we can apply a high positive voltage to the top gate and remove electrons from the floating gate. The electrons are retained near perfectly (years or decades) since there is no reverse-bias leakage current. However these memories wear out with use - 10k to 100k programming cycles (beyond this, not reliable). [^1] --- # References [^1]: [vr-4602-wk10-sc04-romcell](../../Spaces/University/ELEC4602%20–%20Microelectronics%20Design%20and%20Technology/Lectures/W10/vr-4602-wk10-sc04-romcell.mp4)