Tungsten nanocrystals embedded in high-k materials for memory application

Abstract

Low temperature crystallization of high permittivity Ta oxide using an Nb oxide thin film for metal/insulator/metal capacitors in dynamic random access memory applications J. Vac. Sci. Technol. B 23, 80 (2005); 10.1116/1.1829060Effect of growth temperature and postmetallization annealing on the interface and dielectric quality of atomic layer deposited HfO 2 on p and n siliconThe formation of tungsten nanocrystals ͑W-NCs͒ on atomic-layer-deposited HfAlO/ Al 2 O 3 tunnel oxide was demonstrated for application in a memory device. It was found that the density and size distribution of W-NCs are not only controlled by the initial film thickness, annealing temperature, and time, but also by the metal/tunnel oxide interface structure. Well-isolated W-NCs with an average diameter of 5 nm and a surface density of 5 ϫ 10 11 cm −2 were obtained by applying a thin Al 2 O 3 wetting layer onto HfAlO tunneling oxide. A large flatband voltage shift of 5.7 V was observed from capacitance-voltage measurement when a bias voltage up to ±4 V was applied.

Growth of high-density Ru- and RuO2-composite nanodots on atomic-layer-deposited Al2O3 film

“…During the last few years, Ru nanodots have been prepared by colloidal suspension, aerosol deposition, ion implantation and direct-deposit methods mainly for catalyzer application. From the viewpoint of memory application, the sputtering method offers good compatibility with metal-oxide-semiconductor (MOS) fabrication process [10], and has been demonstrated to have the capability to achieve high density metal nanodots with uniform space and size distributions [3,11]. On the other hand, amongst high-k materials used as the potential tunnel layers, Al 2 O 3 has a large band gap and amorphous texture in the process temperature range of memory device.…”

Robust low-voltage program-erasable capacitors of Pd-Al<inf>2</inf>O<inf>3</inf>-Si with high density Ru-based nanocrystals embedded

“…Driven by down-scaling of memory devices, nonvolatile memory devices based on discrete nanocrystal charge storage are attracting more and more attention due to low programming/erasing voltage, fast operating speed, good scalability and endurance characteristics [1][2][3]. Regarding nanocrystal materials, it is considered that metallic nanocrystals are more advantageous than semiconducting ones [4].…”

Preparation of BST nanocrystals embedded in SiO2 film by magnetron sputtering for nonvolatile memory applications

“…A variety of nanocrystal floating gates have been fabricated and significant improvements in charge storage capability have been verified. However, to date the selection of nanocrystal materials consists mainly of semiconductors and metals such as Si, Ge, Ag, Ni, W and Pt [4][5][6][7][8][9]. Only a few studies deal with the fabrication of nanocrystal floating gates from other types of nanocrystals.…”