Method for improving erasing speed of SONOS (Silicon Oxide Nitride Oxide Silicon) by utilizing strained silicon technology

Abstract

The invention discloses a method for improving an erasing speed of an SONOS (Silicon Oxide Nitride Oxide Silicon) by utilizing a strained silicon technology. The method is characterized by comprising the following steps of: after manufacturing a sidewall of a grid electrode on a P-type substrate forming a plurality of shallow channel isolation regions, (1) depositing a baffle layer to cover a transistor; (2) etching to remove the baffle layer covering above an NMOS (N-channel Metal Oxide Semiconductor) region to expose the NMOS region; (3) etching silicon of active regions on two sides of the grid electrode of the NMOS region; (4) depositing silicon carbide at the active regions through a selectivity epitaxy process; and (5) carrying out high-temperature annealing to enable the silicon carbide to generate tensile stress on a channel. According to the method for increasing the erasing speed of the SONOS by utilizing the strained silicon technology, disclosed by the invention, an energy band of silicon is broken up so that effective mass of electron in the direction of the channel is reduced; simultaneously, energy valley scattering probability of the electron is also reduced, and mobility of the electron of the SONOS unit transistor is remarkably improved, thus the SONOS programming efficiency and speed of a hot electron injection mechanism are improved.

Description

technical field [0001] The invention relates to a silicon-silicon oxide-silicon nitride-silicon oxide-silicon (SONOS) memory, in particular to a method for improving the erasing and writing speed of the SONOS by utilizing strained silicon technology. Background technique [0002] The basic working principle of non-volatile semiconductor memory is to store charge in the gate dielectric of a MOSFET. Devices in which charges are stored in discrete trapping centers in a suitable dielectric layer are called charge-trapping devices. The most common of these devices is silicon-silicon oxide-nitride-silicon oxide-silicon (SONOS) memory. [0003] The main two storage mechanisms for storing data in flash memory cells are channel hot electron (CHE) injection and F-N tunneling. Channel hot electron injection is considered to be quite reliable after long-term cycling because it does not place significant stress on the tunnel oxide. But the disadvantage of CHE is that the programming e...

AI Technical Summary

Problems solved by technology

When some electrons get enough high energy, hot electron injection occurs, but since only a small part of the channel is effective for programming, hot electron injection programming is not efficient

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