Title: TiN nanocrystal flash memory devices

Authors: S. Maikap, P.J. Tzeng, C.H. Lin, Ting-Yu Wang, H.Y. Lee, Sheng-Shiung Tzeng, C.C. Wang, T.C. Tien, L.S. Lee, Pei-Wen Li, Jer-Ren Yang, M.J. Tsai

Addresses: Department of Electronic Engineering, Chang Gung University, Tao-Yuan, Taiwan, ROC. ' Electronic and Optoelectronic Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan, ROC. ' Electronic and Optoelectronic Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan, ROC. ' Department of Material Science Engineering, National Taiwan University, Taipei, Taiwan 310, ROC. ' Electronic and Optoelectronic Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan, ROC. ' Department of Electrical Engineering, National Central University, Chungli, Taiwan, ROC. ' Electronic and Optoelectronic Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan, ROC. ' Materials and Chemical Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan, ROC. ' Electronic and Optoelectronic Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan, ROC. ' Department of Electrical Engineering, National Central University, Chungli, Taiwan, ROC. ' Department of Material Science Engineering, National Taiwan University, Taipei, Taiwan 310, ROC. ' Electronic and Optoelectronic Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan, ROC

Abstract: Memory characteristics of TiN metal nanocrystals embedded by high-κ Al₂O₃ films have been investigated. The TiN (0.5 nm)/Al₂O₃ (1 nm) multilayers with high-κ Al₂O₃ film as a blocking oxide on SiO₂/p-Si substrates have been deposited by Atomic Layer Deposition (ALD). After subsequent annealing treatment (>900°C), tiny TiN nanocrystals with a diameter of ∼3 nm have been formed. The size and density of TiN nanocrystals have been measured by High-Resolution Transmission Electron Microscopy (HRTEM). The densities of TiN nanocrystals are found to be ∼1.6 × 10¹²/cm² at 950°C for 2 min and ∼5.3 × 10¹²/cm² at 900° for 2 min in N₂ (90%) + O₂ (10%) annealing ambient. X-ray Photoelectron Spectroscopy (XPS) shows the Ti-N bonds, suggesting that the TiN nanocrystals embedded in high-κ Al₂O₃ films can be formed. A high programming speed of threshold voltage shift (ΔV_t) ∼6.7 V @ 0.1 ms can be observed for the TiN nanocrystal memory devices. The erasing speed of ΔV_t ∼6.7 V @ 20 ms is slow, due to low work function poly-Si gate electrode. The charge loss of the TiN nanocrystal memory devices is ∼14% at 20°C and ∼17% at 85°C, which is better result as compared with the best published data in the literatures. A good programming speed, endurance and retention characteristics have been observed, due to small metal nano-dot, high density and deep level charge trapping as well as strong charge confinement in the TiN nanocrystals. The memory device performance can be improved with increasing the density of TiN nanocrystals. The TiN nanocrystal flash memory devices can be useful in future nanoscale high-performance applications.

Keywords: titanium nitride nanocrystals; flash memory devices; aluminium oxide film; ALD; atomic layer deposition; nanomanufacturing; nanotechnology.

DOI: 10.1504/IJNM.2008.023141

International Journal of Nanomanufacturing, 2008 Vol.2 No.5, pp.407 - 419

Published online: 11 Feb 2009 *

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