A double-bit junction-free flash memory and its programming, erasing and reading methods

Abstract

The invention discloses a double-bit junction-free flash memory, which is a SONOS flash memory using a junction-free transistor structure, and its substrate has a source terminal, a drain terminal and a channel region uniformly and heavily doped with N-type impurities without using PN Junction, whose silicon nitride layer includes two storage bits for storing charge, whose heavily doped region has a thickness that enables the SONOS flash memory to completely deplete the region of electrons when it is turned off; its programming utilizes band tunneling hot space The method of hole injection is used for erasing, and the channel FN tunneling erasure mechanism is used for erasing, and the reverse reading method is used for reading, which can solve the complex circuit structure existing in traditional floating gate multi-bit storage technology. In addition to the defects of slower speed and higher reliability requirements.

Description

technical field [0001] The present invention relates to the technical field of semiconductors, more specifically, to a dual-bit junctionless flash memory and programming, erasing and reading methods thereof. Background technique [0002] As the distance between the PN junctions of modern CMOS devices has reached the sub-50nm stage, extremely high doping concentration gradients are necessary, which greatly increases the difficulty of process manufacturing. When the channel length of the device is less than 50nm, the ultra-shallow junction technology is very effective in suppressing the short-channel effect, but it is difficult to control the depth and profile of the PN junction. Moreover, due to the high cost of thermal annealing, the formation of ultra-shallow junctions is a bottleneck for future 3D multilayer stacked device processes. [0003] SONOS (Silicon-Oxide-Nitride-Oxide-Silicon, Silicon-Oxide-Nitride-Oxide-Silicon) is a non-volatile memory that is closely related t...

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Problems solved by technology

[0012] The purpose of the present invention is to overcome the above-mentioned defects existing in the prior art, and provide a double-bit junction-free flash memory and its programming, erasing and reading methods, which can solve the complex circuit structure of the traditional floating gate multi-bit storage technology. Defects with slow reading, writing, and erasing speeds and high reliability requirements

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