SRAM and flash memory

Which electron injection mechanism is mainly used for writing (programming) NAND flash memory?

  1. AFowler-Nordheim (FN) tunneling current
  2. BExcitation of electrons by light
  3. CMovement of electrons by a magnetic field
Show answer and explanation

Answer: A. Fowler-Nordheim (FN) tunneling current

In NAND flash, a high voltage is applied to the control gate to inject electrons from the channel into the charge-storage layer through a thin tunnel oxide. This quantum-mechanical tunneling current is called FN tunneling current. Because the current is small, many cells can be programmed at once. NOR flash also often uses channel hot-electron injection.

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More SRAM and flash memory questions

  1. In NAND flash, what is the phenomenon in which repeatedly reading the same block gradually shifts the threshold voltages of cells that are not being read?
  2. In QLC (4 bits per cell) NAND flash, how many threshold voltage states must one cell distinguish?
  3. In TLC and QLC SSDs, what is the main purpose of using part of the space as SLC to absorb writes temporarily?
  4. What problem tends to occur as the supply voltage of SRAM is lowered?
  5. What is the advantage of an 8T SRAM cell, which adds read-only transistors to a 6T SRAM cell?