Electrical and Physical Properties of HfO[sub 2] Deposited via ALD Using Hf(OtBu)[sub 4] and Ozone atop Al[sub 2]O[sub 3]

Abstract

HfO 2 films were deposited via Hf(OtBu) 4 precursor and ozone oxidant using atomic layer deposition ͑ALD͒ atop Al 2 O 3 . We report the impact of annealing conditions on the physical and electrical properties of a HfO 2 on Al 2 O 3 /SiN/Si substrate using medium-energy ion scattering spectroscopy, high-resolution transmission electron microscopy, thermal desorption spectra, and electrical measurements. Annealing temperatures influence the microstructure and impurity levels of Hf(OtBu) 4 HfO 2 /Al 2 O 3 /SiN films. The leakage currents of Al 2 O 3 -HfO 2 bilayer were decreased with the increase of annealing temperature and the structures of the bilayer did not break until 850°C. This change was closely related to the reduction of carbon and organic contamination during annealing. However, annealing at 950°C drastically degraded electrical properties due to the intermixing of the HfO 2 -Al 2 O 3 bilayer structure.As device dimensions are scaled down to the sub-0.1 m generation, metal-oxide-semiconductor field-effect-transistor ͑MOS-FET͒ devices require high quality ultrathin dielectric films to satisfy the requirements of the reliability characteristics. However, in this region of dielectric thickness the large leakage current due to direct tunneling will increase power consumption. Recently, several high-k dielectrics have been widely studied to prevent the problems caused by large leakage current. Among them, both HfO 2 and Al 2 O 3 structures have attracted attention for MOS device applications such as storage capacitors and gate insulators because of their high permittivity and low leakage current. 1-6 Especially, HfO 2 -Al 2 O 3 layered structures using both advantages of a nanolaminate structure and combinations of their properties are the most promising. 5,7 A number of studies on HfO 2 films and HfO 2 -Al 2 O 3 composite films using HfCl 4 precursor have been reported. 4-6 However, correlation of the physical film properties with electrical behavior of the HfO 2 -Al 2 O 3 films deposited via Hf(OtBu) 4 precursor was not studied.In this article, we report the impact of postannealing temperature on the physical and electrical properties of Hf(OtBu) 4 HfO 2 / Al 2 O 3 /SiN films and the structure stability. Particularly, we focused on the characteristics of the Hf(OtBu) 4 HfO 2 film grown on Al 2 O 3 /SiN/Si substrate. 1 nm thick HfO 2 and 3 nm thick Al 2 O 3 films are deposited on SiN layer by atomic layer chemical vapor deposition ͑ALCVD͒. p-type Si͑001͒ wafers were cleaned by the RCA cleaning method and dipped in dilute HF to remove the metallic contamination and native oxide. An ultrathin SiN layer with the order of 1 nm was grown by plasma nitridation prior to the Al 2 O 3 dielectric layers to prevent interface reaction. The precursors used for Hf source and Al source were Hf(OtBu) 4 and ozone and trimethylaluminum and ozone, respectively. The substrate temperature was fixed at 450°C during the HfO 2 film growth.To investigate interfacial reaction and structural characteristics of HfO 2 /Al 2 O 3 /SiN/Si ...

Graphene functionalization and seeding for dielectric deposition and device integration

“…61 This image shows an almost ideal 2D growth mode with very little surface roughness, rms $0.2 nm and enhanced coverage on both step edges as well as basal planes. [65][66][67] Using an O 3 -based ALD process, Lee et al 68 realized dual-gated exfoliated graphene devices with a Al 2 O 3 top gate dielectric. 10(b) shows that neither the ozone pretreatment nor the Al 2 O 3 deposition damaged the top graphene layer.…”

Improvement of the high- κ /Ge interface thermal stability using an in-situ ozone treatment characterized by conductive atomic force microscopy

“…It can be explained by the fact that the impurity concentration and defects decrease due to the thermal annealing supplying enough thermal energy for the by-products residing and dangling bonds decomposition and re-composition, leading to the HfO 2 /Al 2 O 3 gate stack becoming a good gate dielectric insulator. [18,19] However, as shown in Figs. 2(c) and 2(d), the density of leakage spots in sample B increases significantly after annealing, which indicates that the 087701-2 conductive paths increase significantly.…”