1,721,016 research outputs found
Thermodynamic equilibrium calculation of CU(s)-Cl-2(g) reaction
No full textThermodynamic calculations of the equilibrium compositions of condensed- and gaseous-reaction products from the reaction between Cu(s) and Cl-2(g) has been performed to understand the fundamental reactions during the Cl-based dry etching of Cu thin film. Total pressure was fixed at 5 mTorr, which is typical for high-density plasma etching. The final phase equilibrium state of Cu(s)-Cl-2(g) system was determined by using the minimization of the total free energy of the system as a function of temperature and initial Cl-2(g)/Cu(s) molar ratio, and the calculated phase equilibrium results were discussed in relation to the Cl-based Cu dry etch reaction. (C) 2002 Elsevier Science B.V. All rights reserved
Reaction mechanism of low-temperature Cu dry etching using an inductively coupled Cl-2/N-2 plasma with ultraviolet light irradiation
No full textTo understand the mechanism of recently reported low-temperature Cu dry etching using an inductively coupled Cl-2/N-2 plasma with ultraviolet light irradiation, we have studied the reaction characteristics between Cu thin film and an inductively coupled Cl-2/N-2 plasma at room temperature without/with ultraviolet irradiation, Light absorption characteristics of solid etch products in ultraviolet/visible region, and mass spectrometry of gaseous desorption products during ultraviolet photon irradiation on solid etch product CuClx(s) surface. Ultraviolet irradiation increased the Cu consumption rate for the total etch reaction by approximately five times and the Cl stoichiometry x of CuClx(s) was always above 1.0 (1.2-1.3) regardless of reaction time in contrast to results without ultraviolet light irradiation. The mechanism of low-temperature Cu dry etching induced by ultraviolet light irradiation consists of selective absorption of ultraviolet radiation (300-400 nm) by the solid etch product CuClx(s) depending on the Cl stoichiometry x due to the electronic transitions of bonding electrons of CuCl (bandgap transition) or CuCl2 (charge transfer), weakening of CuClx(s) bonding, and nonthermal desorption of gaseous products. The dominant desorbed species were CuCl2 and Cu2Cl3 during the ultraviolet irradiation on CuClx(s), which is different from the Cu3Cl3 for the pure thermal desorption. Also, the distribution of gaseous products from the CuClx(s) by ultraviolet irradiation depends on the Cl stoichiometry x of CuClx(s), especially whether x < 1.0 or x > 1.0. (C) 1999 The Electrochemical Society. S0013-4651(99)01-002-2. All rights reserved
Formation of CuPt-type ordered (Cd, Zn)Te at CdTe/ZnTe interface
No full textA CuPt-type ordered CdZnTe has been observed at CdTe/ZnTe interface sequentially grown by organometallic vapor-phase epitaxy on (001)GaAs at 400 degrees C. Selected area electron diffraction, cross-sectional high-resolution electron microscopy, and computer image simulation have been employed to characterize the ordered structure in CdZnTe. Between CdTe and ZnTe, we observed a relatively uniform layer with dark contrast band image by conventional transmission electron microscopy. Through [110] projection, selected area electron diffraction pattern showed two sets of (1/2 1/2 1/2) extra spots with symmetrical intensity and corresponding high-resolution images showed doubling periodicity in contrast on {111} lattice planes. The ordered structure has been identified as CuPt-type ordered CdZnTe from electron diffraction, high-resolution images, and computer image calculations. Through [110] projection, it was observed that there were two variants for ordering according to each direction of doubling periodicity on {111} lattices planes, i.e., on (1(1) over bar 1) and on (<(1)over bar 11>). Each variant was observed to have its own domain structure of which size ranged from 10 to 20 nm and the two variants were observed with equal probability. (C) 1998 Elsevier Science B.V. All rights reserved
O-2 plasma oxidation of sputter-deposited Cu thin film during photo resist ashing
No full textO-2 plasma oxidation of sputter-deposited copper thin film during photoresist ashing has been investigated by X-ray diffraction (XRD), Auger electron spectroscopy (AES), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The copper thin film was oxidized by O-2 plasma under a typical condition to remove photoresist. O-2 pressure was 700 mTorr and 500 W radio frequency power was supplied. Substrate was held at room temperature before plasma generation and it was not heated additionally during plasma treatment. After O-2, plasma treatment, a new surface oxide layer was formed on copper film. It was found from electron diffraction and Auger electron depth profiling that the plasma-induced oxide had an oxygen deficient Cu2O1-x structure compared to the conventional thermal oxide. The oxide layer was composed of very small and relatively tightly packed grains typically 25 nm in diameter and with random orientation on large grains of copper. The topography of plasma-induced oxide layer was close to that of thermal oxide formed at a low temperature, but the oxidation rate of plasma oxidation was relatively high and seemed to follow an oxidation law at relatively high temperature. (C) 1998 Elsevier Science B.V. All rights reserved
Characteristics of polymer waveguide notch filters using thermooptic long-period gratings
No full textWe demonstrate experimentally the feasibility of a polymer waveguide notch filter using a thermooptic long-period grating. This notch filter consists of a channel waveguide, a cladding surrounding the channel, and buffer layers sandwiching the cladding. Periodic heaters formed on the upper buffer layer induce a long-period grating thermooptically. Thus, they generate temporarily a resonance band of notch type in the transmission spectrum of the filter. Using thermocurable polymers, we have fabricated notch filters 1 and 2 that have different cladding thicknesses. Experimental results demonstrate two features of the notch filters. One feature is dynamical controllability of the attenuation of a resonance band. For TE mode, the maximum attenuation of notch filters 1 and 2 increases from 0 to 27 dB as the power applied to notch filters 1 and 2 increases from 0 to 851 and 1170 mW, respectively. The other feature is controllability of the direction and magnitude of the center wavelength shift occurring when the attenuation is tuned. The shift property depends on the cladding thickness. The measured characteristics of notch filters 1 and 2 are qualitatively in good agreement with our theoretical analysis. Using this feature, we may implement the notch filter whose attenuation is. adjustable without center wavelength shift. This polymer waveguide notch filter may be used to implement a compact filter whose spectrum is dynamically tailored
Tunable notch filter using a thermooptic long-period grating
No full textThis paper proposes a tunable notch filter using a thermooptic long-period grating and investigates it theoretically. This notch filter is in the form of an integrated optical device and is based, on a simple structure as compared with existing integrated optical notch filters. The thermooptic grating denotes a thermooptic index perturbation induced by. periodic heaters. The attenuation of a resonance band in the transmission spectrum of the proposed notch filter can be controlled by adjusting the electric power applied to the periodic heaters. Employing the heat transfer theory and the coupled-mode theory, the proposed filter is designed and analyzed. The paper also presents analytic expressions for the temperature change due to a heater and the coupling coefficients due to the thermooptic grating. This filter may have potential as a compact dynamically controllable device like a tunable gain flattening filter
Spectral tailoring of uniform long-period waveguide grating by the cladding thickness control
No full textWe propose a new spectral tailoring method applicable to long-period waveguide gratings. It is based on the cladding thickness control along the direction of light propagation. Partially changing the cladding thickness with only a single uniform grating, we can make the core mode coupled to different cladding modes. Hence, almost independent resonance bands are formed in the transmission spectrum. The overall transmission spectrum is tailored by controlling each resonance band. Theoretically, the proposed spectral tailoring method is investigated. (C) 2005 Elsevier B.V. All rights reserved
Refractive Index Sensitivity and Post-Fabrication Tuning in a Long-Period Waveguide Grating
No full textFilter using vertical coupling between a single-mode waveguide and a multimode waveguide
No full text- …
