Papers by Author: Hi Deok Lee

Abstract: In this paper, Ni-silicide formed by co-sputtering of Ni and Ti on a boron cluster (BF₂, B₁₈H₂₂) implanted ultra-shallow source/drain for MOSFET (metal oxide semiconductor field effect transistor) is proposed. Ni and Ti with a TiN capping layer were deposited by co-sputtering on boron cluster implanted wafer. By analysis of its sheet resistance, interfacial structures, surface morphological stability, and phase formation after post-silicidation annealing, thermal stability of Ni-silicide was found to be improved a lot.

Abstract: . In this paper, dielectric relaxation and reliability of high capacitance density metal-insulator-metal (MIM) capacitor using Al2O3-HfO2-Al2O3 sandwiched structure were analyzed. It is shown that multilayer MIM capacitor provides high capacitance density and low dissipation factor at room temperature. The dielectric relaxation voltage shows little dependence on the capacitor area. The capacitance density (C0) increases and quadratic voltage coefficient (α) decreases as a function of stress time under constant voltage stress (CVS) because of the charge trapping effect in the high-k dielectric.

Abstract: RF characteristics of metal-insulator-metal (MIM) capacitors with SiO2/HfO2/SiO2 (SHS) were investigated using an equivalent circuit model that is associated with the main impedance ZMIM.cap and the substrate-related conductance Ysub. However, the parasitic capacitance in Ysub was lower than that of another element component in ZMIM.cap, which makes difficult for accurate RF modeling because the parasitic component was dominant at high frequency regions. As low parasitic component is eliminated from the modeling, the extracted capacitance for SHS MIM capacitor was stable up to 20 GHz. The Q-factor and resonant frequency (fr) point of SHS structure are 23.9 at 1 GHz and 9.76 GHz, respectively.

Abstract: In this paper, novel Ni Germanosilicide technology using the 1%-nitrogen doped Ni and pure Ni stack structure has been proposed for nano-scale CMOS technology. The Ni Germanosilicide is formed on the Si0.8Ge0.2 layer which is known as an optimal composition for strained silicon application. Proposed structure showed much better thermal stability than pure Ni case. Silicide characteristics such as the sheet resistance, the interface uniformity of silicide/SiGe, surface roughness, and depth profile of the Ni, Si, and Ge showed little degradation even with the high temperature post-silicidation annealing at 600
for 30 min. Therefore, the proposed method is highly promising for nano-scale CMOS technology.

Abstract: In this paper, it is presented that flicker (1/f) noise of ultra thin gate oxide can be improved by initial oxidation and subsequent plasma nitridation(PN). PN which raises Nitrogen peak upward from the Si/Oxide interface to gate polysilicon/Oxide interface is adopted mainly to improve the life time such as Negative-Bias Temperature Instability (NBTI) and hot carrier in Nano CMOS technology. Three different types of initial oxidation prior to plasma nitridation are investigated. One is slow thermally grown oxide(STO) in very small Oxygen ambient, another is rapid thermally grown oxide(RTO) and the other is grown in Nitrous oxygen ambient (NO). Oxide thickness of all splits is about 14.5< Then, it is shown that STO has the lowest drain current noise power (Sid) among the splits. The interface trap densitie (Dit) of each oxide is characterized using charge pumping method. Finally, we reached a conclusion that the 1/f noise can be significantly reduced by initial STO and Plasma Nitridation in Nano CMOS technology.

Abstract: In this paper, the electrical properties of NiSi have been characterized using multi capping layer structure for nano CMOS application. We have investigated the formation and thermal stability of Ni silicide using Ni, Ti and TiN capping layers (Ti/Ni/TiN) as a function of Rapid Thermal Processing (RTP) temperature. It was shown that the NiSi with multi capping layer has lower sheet resistances than that with single capping (TiN) layer. NiSi with multi capping layer also showed much better thermal stability. It was verified that the formation Ni-Ti-Si ternary like layer at the top region of thhe NiSi results in improvement of thermal stability.

Abstract: We investigated the effect of SiO
cap layer on the thermal stability of nickel and nickel-cobalt silicide by measuring its sheet resistance. The stability of nickel silicide was deteriorated as a function of annealing temperature, while that of nickel-cobalt silicide was not. In case of both silicides, the SiO
cap layer improved the stability. Tensile stress from the difference of thermal expansion coefficients between SiO2 and nickel silicide may suppress the agglomeration of nickel silicide.