S.J. Suh

High aspect ratio via etching conditions for deep trench of silicon

Abstract Deep trench etching of silicon was investigated as a function of platen power, operational pressure and the SF6:C4F8 gas flow rate. Their effects on the etch rate, etch profile and scallops were also studied. As the platen power was increased from 5 to 30 W, the etch rate was increased from 0.54 to 2.51 μm/min. However, the etch rate was decreased at platen power higher than 30 W. As the pressure was increased from 10 to 25 mTorr, the etch rate was increased from 1.93 to 2.69 μm/min but the etch rate was decreased at the pressure higher than 35 mTorr. As the SF6:C4F8 gas flow rate was increased from 50:50 to 200:160 sccm, the etch rate was increased from 1.91 to 2.31 μm/min and at the SF6:C4F8 gas flow rate of 260:220 sccm, it was decreased to 2.21 μm/min.

Fabrication condition effects on the magnetic and magnetostrictive properties of sputtered Tb-Fe thin films

Magnetic and magnetostrictive properties of amorphous Tb-Fe thin films are investigated as functions of sputtering conditions such as the substrate thickness, input power, sputtering time, and coverage area ratio of coated thin film to substrate. The observed magnetic and magnetostrictive properties are well explained in terms of the macroscopic tensile stress, which is formed due to the difference of the thermal expansion coefficients between the thin film and substrate, and an annealing effect. The macroscopic tensile stress enhances in-plane anisotropy, and the annealing effect mainly reduces local residual stress introduced during sputtering. At sputtering conditions corresponding to a high thin-film/substrate temperature, the macroscopic tensile and an annealing effect are high, causing the magnetostriction sensitivity to increase at low magnetic fields, coercivity, and remanence ratio.Magnetic and magnetostrictive properties of amorphous Tb-Fe thin films are investigated as functions of sputtering conditions such as the substrate thickness, input power, sputtering time, and coverage area ratio of coated thin film to substrate. The observed magnetic and magnetostrictive properties are well explained in terms of the macroscopic tensile stress, which is formed due to the difference of the thermal expansion coefficients between the thin film and substrate, and an annealing effect. The macroscopic tensile stress enhances in-plane anisotropy, and the annealing effect mainly reduces local residual stress introduced during sputtering. At sputtering conditions corresponding to a high thin-film/substrate temperature, the macroscopic tensile and an annealing effect are high, causing the magnetostriction sensitivity to increase at low magnetic fields, coercivity, and remanence ratio.

Electrochemical characteristics of alumina dielectric layers

Abstract The electrochemical characteristics of alumina dielectric layers were studied using a surface roughness factor and an impedance spectroscopy. From the limiting diffusion current method, the surface area factor of the dielectric anodic layer with low electrical conductivity was estimated to be 1.03. As alumina dielectric films on Al have a variable stoichiometry, the electrochemical behavior of Al 2 O 3 layer can be monitored by evaluating an equivalent circuit with Young impedance of dielectric constant with a vertical decay of conductivity.

Application-related properties of giant magnetostrictive thin films

In an effort to facilitate the utilization of giant magnetostrictive thin films in microdevices, application-related properties of these thin films, which include induced anisotropy, residual stress and corrosion properties, are investigated. A large induced anisotropy withan energy of 6 � 10 4 J/m 3 is formed in field-sputtered amorphous Sm–Fe– B thin films, resulting in a large magnetostriction anisotropy. Two components of residual stress, intrinsic compressive stress and tensile stress due to the difference of the thermal expansion coefficients between the substrate and thin film, are identified. The variation of residual stress with fabrication parameter and annealing temperature, and its influence on mechanical bending and magnetic properties are examined. Better corrosion properties are observed in Sm–Fe thin films than in Tb–Fe. Corrosion properties of Tb–Fe thin films, however, are much improved with the introduction of nitrogen to the thin films without deteriorating magnetostrictive properties. r 2002 Elsevier Science B.V. All rights reserved.

Optical Properties of Er Doped Congruent and Stoichiometric LiNbO3 Single Crystals

Erbium doped LiNbO 3 (Er:LiNbO 3 ) single crystal fibers were grown free of cracks along c-axis by the micro-pulling down (μ-PD) method. We have investigated the up-conversion property with the change of doped Er 2 O 3 concentration and the starting melt composition. An enhancement of green up-conversion according host matrix is also observed the stoichiometric LiNbO 3 . And, the dependence of the green emission according to Er 3+ concentration is analyzed. The possible application of the Er 3+ doped stoichiometric LiNbO 3 single crystal fiber for up-conversion based optical devices is discussed.

Refractive index control of core layer using PECVD and FHD for silica optical waveguide

Abstract Silicon oxynitride (SiON) and GeO 2 –SiO 2 layers as core layers deposited using the plasma-enhanced chemical vapor deposition (PECVD) and flame hydrolysis deposition (FHD), respectively. For PECVD technique, the deposition rate monotonically rises with increasing r.f. power from approximately 4.5 μm/h at the power of 60 W to 5.9 μm/h at the power of 180 W. As r.f. power increased from 60 to 180 W, refractive index (RI) of SiON films decreased from 1.5312 to 1.4620. For FHD technique, the RI increases from 1.4615 to 1.4809 with the increase in the GeCl 4 flow rate from 30 to 100 sccm. Material grown by two processes, FHD and PECVD, exhibited the similar etching characteristics by inductively coupled plasma etching.

Magnetostrictive properties of polymer-bonded Fe-Co based alloy composites

Polymer-bonded composites of a Fe–Co based alloy are fabricated and their magnetic and mechanical properties are characterized. The use of flake-type powders with a thickness of 3–5 μm, instead of conventional spherical powders, is the key to good magnetostrictive properties and this is made possible by suitable design of the alloy (Fe36Co62Ge2) and the development of a pulverization process. The composites exhibit high magnetostriction of 105 ppm measured at an applied field of 4.3 kOe (70 ppm at 1 kOe). Large compressive strength of 42 MPa is also obtained for the composites, indicating solid bonding of flake-type powders by the polymer.

Growth and characterization of Er-doped stoichiometric LiNbO3 single crystal fibers by the micro-pulling down method

Er-doped stoichiometric LiNbO 3 single crystal fibers were grown by a micro-pulling down (μ-PD) method along the c-axis. The crystals were grown free of cracks and had a uniform shape. We evaluated the homogeneity of the distribution of Er 2 O 3 concentration by electron probe micro analysis (EPMA). We investigated the photoluminescence (PL) properties of the crystal using the 514nm line of an Ar-ion laser by changing the concentration of Er 2 O 3 in the dopant. Result of optical determination, the strong peak of intensity was observed in the green wavelength range around 550 nm. Also, the intensity of PL increased with an increase of Er 2 O 3 concentration and with the power of the laser as excitation source.

The distribution of Cu and resultant resistivity change in sputter deposited Al–Cu film as a conductive layer

Abstract As a conductive layer, sputter-deposited Al–Cu 1 at.% thin film was investigated, with particular focus on the effect of Cu precipitates and film strain on the electric conductivity. The 400-nm-thick film was deposited on Si wafer and heat-treated at 200 and 480 °C. Cu precipitation was investigated using electron microscopy and film strain using XRD. As a result of heat treatment, changes in the electric resistivity showed the same trend as the film strain. This study concluded that the trends in resistivity and film stress could be related to Cu precipitation to some extent. In other words, the resistivity changes depending on whether the precipitates are coherent with the Al matrix and on the distribution of the precipitates.

Characterization of a‐SiC:H Films Deposited by RF Plasma CVD

The effects of annealing temperature on the structure of hydrogenated amorphous silicon carbide (a-SiC:H) films prepared by RF plasma CVD were investigated by using X-ray diffraction, UV-VIS spectrophotometer and atomic force microscopy techniques. It was found that an annealing process results in structural rearrangement. The amorphous phase transforms into the crystalline β-SiC phase at an annealing temperature of approximately 900°C.