Hyoungkyun Kim

Robust TaNx diffusion barrier for Cu-interconnect technology with subnanometer thickness by metal-organic plasma-enhanced atomic layer deposition

TaNx diffusion barriers with good barrier properties at subnanometer thickness were deposited by plasma-enhanced atomic layer deposition (PE-ALD) from pentakis(dimethylamino)Ta. Hydrogen and/or nitrogen plasma was used as reactants to produce TaNx thin films with a different nitrogen content. The film properties including the carbon and oxygen impurity content were affected by the nitrogen flow during the process. The deposited film has nanocrystalline grains with hydrogen-only plasma, while the amorphous structure was obtained for nitrogen plasma. The diffusion barrier properties of deposited TaN films for Cu interconnects have been studied by thermal stress test based on synchrotron x-ray diffraction. The results indicate that the PE-ALD TaN films are good diffusion barriers even at a small thickness as 0.6nm. Better diffusion barrier properties were obtained for higher nitrogen content. Based on a diffusion kinetics analysis, the nanocrystalline microstructure of the films was responsible for the bette...

Analytic model for a dual frequency capacitive discharge

A homogeneous plasma model for dual radio-frequency (rf) discharges driven by two sinusoidal current sources has been analyzed. Under the assumptions of time-independent and collisionless ion motion and inertialess electrons, the analytic expressions for discharge parameters are obtained as a function of the effective parameters such as effective frequency, effective current, and effective voltage. Effective parameters are determined by the ratio of two currents or voltages. Two rf sources are generally coupled to each other through the plasma medium. It is also shown that the reduction of the bulk plasma length due to the sheath size has to be considered for calculating the discharge parameters since the sheath length is not always negligible compared to the bulk plasma length. Furthermore, the dependence of discharge parameters on the low frequency is presented.

Simulations of capacitively coupled single- and dual-frequency RF discharges

For a single-frequency capacitively coupled radio-frequency discharge, the detailed examination has been carried out of plasma density and sheath width, average potential profiles, ion-energy distribution at the electrodes and electron-energy distribution in the bulk plasma as a function of pressure, voltage, and frequency using particle-in-cell/Monte Carlo simulation. The results for Ar gas are presented. Scaling of plasma parameters with external parameters is determined. The characteristics of dual-frequency argon discharge are studied for different ratio of high/low frequencies. Nonmonotonous behavior of plasma density versus low-frequency voltages is attributed to the increase of sheath width and, as a consequence, to the increase of energy absorbed by ions in the sheath region. Subsequent decrease of energy absorbed by electrons results in the decrease of plasma density. For certain frequency ratio with the further increase of power, the plasma density increases again until the collapse of the bulk occurs.

Dual-frequency capacitive discharges: Effect of low-frequency current on electron distribution function

In low-pressure dual-frequency capacitive discharges, the effect of the low-frequency current on the electron distribution function (EDF) was investigated through the particle-in-cell simulation with Monte Carlo collision model. As the low-frequency (2MHz) current increases for the fixed high-frequency (27MHz) current, the EDF changes from Druyvesteyn to bi-Maxwellian (in the absence of secondary electron emission) or Maxwellian type (in case with secondary electron emission), along with the significant drop in the effective electron temperature. When the role of secondary electron emission is negligible, the EDF transition is attributed to the transition from collisional to collisionless property (but not stochastic heating) of the low-energy electrons. The Ramsauer minimum which makes low-energy electrons less collisional plays an important role in making this transition as well as in determining the spatial electric field structure. When the role of secondary electron emission is significant, the trans...

The mechanism of striation formation in plasma display panels

Despite the high pressure employed in plasma display panels, the energy balance of low-energy electrons is found to be dominated by inelastic collisions, and the resulting nonlocal electron kinetics plays a key role in the striation formation. Surface charge accumulation on the anode dielectric, however, is also needed for striations to form. It is the combined effect of surface charges and nonlocal electron kinetics that results in the striation formation in plasma display panel cells. Two-dimensional fluid simulations, which assume local electron kinetics, and two-dimensional particle-in-cell Monte Carlo collision simulations with a bare conducting anode show that striations do not form if either the nonlocal electron kinetics or the surface charge accumulation is not considered.

Three-dimensional self-consistent radiation transport model for the fluid simulation of plasma display panel cell

In plasma display panels (PDPs), the resonance radiation trapping is one of the important processes. In order to incorporate this effect in a PDP cell, a three-dimensional radiation transport model is self-consistently coupled with a fluid simulation. This model is compared with the conventional trapping factor method in gas mixtures of neon and xenon. It shows the differences in the time evolutions of spatial profile and the total number of resonant excited states, especially in the afterglow. The generation rates of UV light are also compared for the two methods. The visible photon flux reaching the output window from the phosphor layers as well as the total UV photon flux arriving at the phosphor layer from the plasma region are calculated for resonant and nonresonant excited species. From these calculations, the time-averaged spatial profiles of the UV flux on the phosphor layers and the visible photon flux through the output window are obtained. Finally, the diagram of the energy efficiency and the c...

Contact force decomposition using tactile information for haptic augmented reality

This paper proposes a contact force decomposition method using tactile information for haptic augmented reality (AR). Haptic AR modulates real haptic interaction to desired interaction by adding virtual haptic feedback. For haptic AR rendering, the measurement of real haptic interaction including deformation and friction force is important for accurate rendering, but the current haptic AR algorithms do not support it properly. The proposed method, derived from a simple model of rigid-deformable body contact, decomposes contact force into deformation force and friction force using force and tactile information. A finite element method (FEM) based simulation of contact between two objects was performed for the performance verification of the proposed method. The results showed the proposed method can decompose contact force more exactly than the conventional decomposition methods in haptic AR.

P‐57: Striation Phenomenon of Plasma Display Panel (PDP) Cell and Its Application to Efficiency Improvement

The first observation of striation in plasma display panel (PDP) cell by kinetic and fluid simulations is presented. The striation phenomenon in the kinetic simulation is clearer than that in fluid simulation. The striation is due to the self-consistent interaction of plasma, dielectric wall, and applied voltages. Simulation results indicate that the phenomenon occurs due to the non-uniform accumulation of surface charges on the sustain electrodes, which consequently deform the local potential profile. The surface and space charges locally create multiple-tier potential distribution near anode region that makes plasma bunches. The discharge in this region is governed by ionization process, but the cathode discharge depends on the secondary-electron emission process on the dielectric surface. Based on these discharge characteristics, 80 % efficiency increase of PDP cell is obtained due to triggered striation by the modification of front dielectric material and MgO protective-layer.

Nonlocal electron electrodynamics in high-frequency capacitive discharges

Several nonlocal electron behaviors in low-pressure high-frequency capacitive discharges were found through particle-in-cell/Monte Carlo simulations. First, a negative power deposition region becomes wider as the rf frequency decreases. Second, in the spatial profile of the amplitude of the rf electric field, a nonmonotonic structure appears at the bulk-sheath boundary along with an abrupt change in the phase of the rf electric field. Third, in the spatial profile of the amplitude of the rf electron current, the second peak appears in the bulk.

A parameter estimation method for the bilateral teleoperation framework for an O 2 lance manipulator

The O2 lance manipulator is used in the electric arc furnace (EAF) process to supply oxygen in order to remove impurities in molten metal. However, since it is controlled by the human operator who can get only visual information about the EAF, the collision between the lance and the EAF can happen which must be avoided in the process. The bilateral teleoperation can be a solution for this problem, but due to the extreme environment of the EAF environment, the feedback force should be generated based on the virtual environment. Since the parameters of the EAF and O2 lance is time-varying, there exist some errors between VE and real environment which lead to the incorrect force feedback. In this paper the estimation method for parameters of the lance and EAF used in this framework is developed. The proposed method can update the parameters of the EAF and O2 lance manipulator in on-line process, so the bilateral teleoperation can generate more accurate feedback force. The functionality of the proposed method is validated by experiment.