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

Abstract

We fabricated nanometer-scale Ni dots and NiSi dots on an ultrathin SiO 2 layer using remote H 2 plasma and demonstrated the feasibility of remote H 2 plasma treatment for controlling the areal density of the dots. 1.8-nm-thick-Ni/SiO 2 and Ni/Siquantum dots (QDs)/SiO 2 layer were treated with remote H 2 plasma generated by the inductive coupling between an external single-turn antenna and a 60 MHz generator. When a Ni/SiO 2 was treated with remote H 2 plasma at room temperature, Ni nanodot density could be controlled in the range of 10 9 to 10 12 cm À2 by adjusting the plasma conditions. After the remote H 2 plasma treatment of the Ni/Si-QDs, the formation of electrically isolated NiSi dots with an areal density of $10 11 cm À2 was confirmed. These results imply that hydrogen radicals generated in H 2 plasma play an important role in improving surface diffusion caused by energy reduction at the Ni/SiO 2 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 À0:2, À0:7, and À1:0 V, respectively. This reflected the difference in electron affinity among Ni, NiSi and Si.

Comparison of Nonvolatile Memory Effects in Ni-Based Layered and Dotted Nanostructures Prepared through Atomic Layer Deposition

“…In particular, Ni-based nanocrystals were attempted in the combined form of physical deposition and post thermal treatments. [18][19][20][21][22][23] The formation of charge-trapping nanocrystals has been shown through physical and chemical deposition of metallic or semiconducting layers followed by thermal or optical annealing or chemical dispersion of nanocrystals onto the dielectric thin films. Those approaches suffer from the disadvantage that processing is discontinuous, while facile continuous processing would be preferred.…”

“…Unlike previous approaches, [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] the current layered nanolaminate was fabricated using ALD according to the schematic diagram shown in Fig. 1a and the corresponding energy band diagram of Fig.…”

Charge Storage and Optical Response of Hybrid Nanodots Floating Gate For Functional Memories

“…Also, from the cut-off energy for electron emission in high-resolution photoemission measurements, the work function (WF) value of NiSi nanodots was determined to be 4.53± 0.05eV, being close to the WF value of Ni-monosilicide, namely around the energy position of the Si midgap. It is interesting to note that, in the case of remote H 2 plasma exposure to ~1.4nm thick Ni layer formed on SiO 2 under the same condition [9], pure Ni nanodots with an areal density of ~3x10 10 cm -2 are formed as a result that surface migration of Ni atoms and their agglomeration is promoted by exothermal recombination of hydrogen radicals on the metal surface. As-prepared sample, in which NiSi nanodots were formed on thermally-grown SiO 2 , shows a uniform surface potential image initially.…”

Light Induced Carrier Transfer in NiSi-Nanodots/Si-Quantum-Dots Hybrid FG in MOS Structures

“…To form NiSi-nanodots, the second Si-QDs layer was deposited under the same conditions with the formation of the first Si-QDs layer and a ~3nm-thick Ni film was evaporated on the second Si-QDs layer by electron beam. Subsequently, the sample surface was exposed to remote plasma of pure H 2 for 5min without any external heating [4]. After that, a ~3-nm-thick SiO 2 layer was formed at 350°C by inductively-coupled remote plasma CVD with SiH 4 and excited O 2 /Ar.…”