Self-Assembling Formation of Ni Nanodots on SiO2 Induced by Remote H2 Plasma Treatment and Their Electrical Charging Characteristics

概要

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We fabricated nanometer-scale Ni dots and NiSi dots on an ultrathin SiO2 layer using remote H2 plasma and demonstrated the feasibility of remote H2 plasma treatment for controlling the areal density of the dots. 1.8-nm-thick-Ni/SiO2 and Ni/Si-quantum dots (QDs)/SiO2 layer were treated with remote H2 plasma generated by the inductive coupling between an external single-turn antenna and a 60 MHz generator. When a Ni/SiO2 was treated with remote H2 plasma at room temperature, Ni nanodot density could be controlled in the range of $10^{9}$ to $10^{12}$ cm-2 by adjusting the plasma conditions. After the remote H2 plasma treatment of the Ni/Si-QDs, the formation of electrically isolated NiSi dots with an areal density of ${\sim}10^{11}$ cm-2 was confirmed. These results imply that hydrogen radicals generated in H2 plasma play an important role in improving surface diffusion caused by energy reduction at the Ni/SiO2 interface. The surface potential of the Ni nanodots changes stepwise with the tip bias. This is due to the multistep electron injection into and extraction of Ni nanodots. The minimum tip biases for electron injection into Ni nanodots, NiSi dots and Si-QDs were $-0.2$, $-0.7$, and $-1.0$ V, respectively. This reflected the difference in electron affinity among Ni, NiSi and Si.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2008-04-25