The electrical characteristics were evaluated for the metal-oxide-semiconductor (MOS) devices with Ti and Pt gates on the atomic-layer-deposited (ALD) HfO2. The equivalent oxide thickness (EOT) of the Ti gate is shown to be nearly the same as that of the Pt gate, which means that a negligible chemical reaction occurs between the gate and dielectric. The values of the effective metal work function (Φm,eff), extracted from the conventional relations of flatband voltage versus EOT, were ∼4.2eV for Ti and ∼5.4eV for Pt, respectively. However, somewhat higher values of Φm,eff were extracted by considering the existence of an interfacial layer and the high negative charge at an interface between HfO2 and interfacial layer. The exact values of Φm,eff were ∼4.37eV for Ti and ∼5.51eV for Pt, respectively. Therefore, the Ti gate is compatible with ALD-HfO2 and can be a candidate for n-type MOS devices.

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 ...

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We have investigated the effect of a Mo interlayer on the electrical properties of Ni-silicided normaln+∕p diodes and n+ poly-Si gate electrodes. It is shown that the use of the Mo interlayer results in reduction of the reverse leakage current of the Ni-silicided normaln+∕p diodes. It is also shown that the interlayer effectively serves as a barrier to the in-diffusion of interconnection Al, leading to the formation of the uniform silicide layer. It is further shown that the Ni-silicided poly-Si gate electrodes with the interlayers produce similar equivalent oxide thickness and a positive shift of flatband voltage ( VFB ), compared to the samples without the interlayers. Secondary ion mass spectroscopy results show that Ni is segregated at the poly- Si∕SiO2 interface and the Mo interlayer affects the redistribution of phosphorus.