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This paper presents the simulation of an SOI nano-flash memory device. The device is composed of a triangular quantum wire channel p-MOSFET with a self-aligned nano-floating gate embedded in the gate oxide. The simulation is carried out by combining TSUPREM-4 and a two-dimensional (2-D) self-consistent solution of the Poisson and Schrodinger equations. The fabrication process as well as quantum physics are taken into account. Hole distribution in the inversion layer of the triangular channel section is calculated in terms of wave functions and energy subbands. The threshold voltage shift between the programming and erasing of the device is investigated. In this paper, we show that the channel shape plays a crucial role in the programming voltage and the threshold voltage shift. Based on the fact that the holes are confined mainly at the top of the triangular channel section, we explain why our triangular channel device can be operated at relatively low programming voltage despite of a thick gate oxide and tunnel oxide. The threshold voltage shift in the triangular channel device is compared with that in a rectangular channel device. The result shows that the triangular channel device exhibits the larger threshold voltage shift.
Date of Publication: Aug 2002