Charge trap flash

Charge trap flash (CTF) is a semiconductor memory technology used in creating non-volatile NOR and NAND flash memory. It is a type of floating-gate MOSFET memory technology, but differs from the conventional floating-gate technology in that it uses a silicon nitride film to store electrons rather than the doped polycrystalline silicon typical of a floating-gate structure. This approach allows memory manufacturers to reduce manufacturing costs five ways:

1. Fewer process steps are required to form a charge storage node
2. Smaller process geometries can be used (therefore reducing chip size and cost)
3. Multiple bits can be stored on a single flash memory cell
4. Improved reliability
5. Higher yield since the charge trap is less susceptible to point defects in the tunnel oxide layer

While the charge-trapping concept was around earlier, it wasn't until 2002 that AMD and Fujitsu produced high-volume charge-trapping flash memory. They began the commercial production of charge-trapping flash memory with the introduction of the GL NOR flash memory family. The same business, now operating under the Spansion name, has produced charge trapping devices in high volume since that time. Charge trapping flash accounted for 30% of 2008's $2.5 billion NOR flash market. Saifun Semiconductors, who licensed a large charge trapping technology portfolio to several companies, was acquired by Spansion in March 2008. From the late 2000s, CTF became a core component of 3D V-NAND flash memory developed by Toshiba and Samsung Electronics.