How many excess electrons are in a modern SLC flash memory cell?

Question

A colleague told me that in a modern SLC flash memory cell there are about 400 electrons.

However, I can't find any reference to this.

Flash memory cells can be thought of as little buckets of electrons on the floating gate of a transistor. When they have enough excess electrons, the transistor switches. The gate floats, so the transistors don't drain away.

I'm looking for a reference to how many electrons are in a modern SLC flash memory cell.

EDIT: More references:

• bunnie's DRAM FAQ from 1996: http://web.mit.edu/rec/www/dramfaq/DRAMFAQ.html
• Wookhyun Kwon's PhD thesis from 2011: https://people.eecs.berkeley.edu/~tking/theses/whkwon.pdf

Answer 1

I found a paper, Direct Measurements of Charge in Floating Gate Transistor Channels of Flash Memories Using Scanning Capacitance Microscopy that says in its introduction:

Indeed, the recent technologies store fewer and fewer electrons, down to fewer than 1000 electrons for 90nm-node NAND Flash.

This paper is from 2006, so more modern chips may well be down in the range that your colleague mentioned. Both geometry sizes and voltages have shrunk since then.