Ge nanocrystals embedded in Hf-aluminate high-k gate dielectric for floating gate memory application

Pui Fai Lee; Wei Li Liu; Zhi Tang Song; Ji Yan Dai

doi:10.1117/12.582062

23 February 2005 Ge nanocrystals embedded in Hf-aluminate high-k gate dielectric for floating gate memory application

Pui Fai Lee, Wei Li Liu, Zhi Tang Song, Ji Yan Dai

Proceedings Volume 5650, Micro- and Nanotechnology: Materials, Processes, Packaging, and Systems II; (2005) https://doi.org/10.1117/12.582062
Event: Smart Materials, Nano-, and Micro-Smart Systems, 2004, Sydney, Australia

Abstract

Recently, many efforts have been made to improve the device performance of nanocrystal memory by replacing the SiO₂ with various high dielectric constant (high-k) materials, especially embedded with Ge nanocrystals. This paper demonstrates the floating gate memory effect by embedding nanometer-sized Ge nanocrystals in hafnium aluminate (HfAlO) high-k gate dielectric. A 5 nm-thick amorphous thin film of HfAlO was first deposited on (100) p-Si substrates as a tunneling gate oxide layer by laser molecular beam epitaxy deposition using a HfO₂ and Al₂O₃ composite target. Well-defined (~10 nm in diameter) nanometer-sized Ge dots were subsequently deposited on this thin tunneling gate oxide followed by a 30 nm-thick top control gate oxide of HfAlO. Transmission electron microscopy has been carried out for a detailed study of structural properties of the Ge nanocrystals embedded in the HfAlO films, and their relationships to electrical properties. Electrical properties have been characterized by means of high-frequency capacitance-voltage (C-V) and current-voltage (I-V) measurements on the metal-oxide-semiconductor capacitors. A counter-clockwise hysteresis C-V loop has been obtained and a threshold voltage shift of 1.0 V has been achieved indicating stored electrons (up to a density of 2x10¹² cm^-2) in the Ge-nanodots floating gate and thus the memory effect. Time-dependent I-V measurement also showed low leakage current of floating gate system. These results suggest that the Ge nanocrystals embedded in HfAlO are promising for floating gate memory device application.

Citation Download Citation

Pui Fai Lee, Wei Li Liu, Zhi Tang Song, and Ji Yan Dai "Ge nanocrystals embedded in Hf-aluminate high-k gate dielectric for floating gate memory application", Proc. SPIE 5650, Micro- and Nanotechnology: Materials, Processes, Packaging, and Systems II, (23 February 2005); https://doi.org/10.1117/12.582062

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KEYWORDS

Germanium

Nanocrystals

Dielectrics

Capacitors

Oxygen

Silicon

Annealing

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