A low voltage SANOS nonvolatile semiconductor memory (NVSM) device

Abstract

In this paper, we present a new Polysilicon-Aluminum Oxide-Nitride-Oxide-Silicon (SANOS) device structure suitable for future nonvolatile semiconductor memories. Replacing SiO2 with a high-K material, Al2O3 (Kf = 9) as the top blocking layer of the conventional SONOS device increases the electric field across the tunnel oxide, while reducing the electric field across the blocking layer with its dielectric constant during write and erase operations. Therefore, this new device can achieve lower programming voltages and faster programming speed than the conventional SONOS device. We have fabricated SANOS capacitors with 2 nm tunnel oxide, 5 nm silicon nitride and 8 nm aluminum oxide and studied the programming speed and charge retention characteristics of the new devices. These new SANOS devices achieve a 2 V reduction in the programming voltages with 2.1 V initial memory window. © 2006 Elsevier Ltd. All rights reserved.