Thickness Uniformity Of Thin Films Research Articles

Effect of magnetic field on the thickness uniformity of thin film deposited on inner surface

In order to improve the thickness uniformity of thin film deposited on inner surface, an auxiliary magnetic field was set inside the arc ion plating device and applied during thin film deposition. Effect of magnetic field on the film thickness uniformity was studied through simulation and experiments. Simulation results revealed that magnetic field significantly increased the amount of ions deposited in the pipe. Along the axis of the pipe, the number of deposited ions first decreased and then increased. Experiment results proved that magnetic field changed the trend of the film thickness along the axis of the pipe and raised the ratio of the minimum to the maximum of the film thickness, thereby improving the film thickness uniformity. When magnetic field was applied together with bias, both the film thickness and thickness uniformity increased with the magnetic field intensity. • An auxiliary magnetic field was set inside the arc ion plating device and applied to assist the deposition. • Thin films were prepared onto the inner surface of a pipe. • Magnetic field significantly increased the amount of ions deposited in the pipe. • Magnetic field changed the trend of the film thickness along the axis of the pipe and improved the film thickness uniformity.

Monte Carlo Simulation Model for Magnetron Sputtering Deposition

Thin Film layers of metal are often prepared by magnetron sputtering technique for electronic, optical and micro/nanoelectromechanical systems. Usually, experimental work is a common way to find out the optimum deposition conditions and correlate between the thin film properties and the deposition parameters. However, experimental methods are very exhaustive, time and cost-consuming. A good simulation model which can provide the optimum operating conditions to avoid exhaustive experiments and reduce time and cost is highly recommended. Therefore, the present paper is focusing on the development of a computer simulation model of the deposition process in the magnetron sputtering system since such type of models is not well established yet. Monte Carlo (MC) simulation model has been developed to study the effects of deposition parameters on the deposition rate and thin film thickness uniformity. Titanium (Ti) samples were used as the target whereas argon (Ar) was the ambient inert gas. MC simulation has successfully predicted the optimum deposition rate and thickness of Ti thin films on the plastic substrate. The model also depicted the performance of magnetron deposition due to change of processing parameters. Comparison between the simulation and experimental results proved the validity of the proposed model.

Research on Thin Film Thickness Uniformity for Deposition of Rectangular Planar Sputtering Target

Abstract Magnetron sputtering coating is widely applied in the large area deposition, and thin film thickness uniformity, deposition ratio, utilization ratio of target material and other problems in coating industry are paid great attention. As one of the most important parameters for testing sputtering process, the study on the related issues of thin film uniformity is of great theoretical and practical value. The fundamental theory on deposition of sputtering coating is analyzed based on existing theories, and the modelof deposition flux that is composed of fast- and slow-moving particles is applied to the rectangular planar magnetron sputtering target. Through the application of Matlab software and the numerical calculation of thin film deposition uniformity of a rectangular planar magnetron sputtering target, it is easy to come to the following conclusions: the thickness uniformity will reduce with the increase of target-substrate distance and with the decrease of erosion zone of the target ends. When the erosion zone of the target ends increases to some extend, the thin film thickness uniformity will become higher with the increase of target-substrate distance and then become lower. There are two tendencies for thin film thickness uniformity with the increase of length-width ratio of target erosion zone, that is, it will become a little lower when the length is a constant, or become higher when the width is a constant. And the thin film thickness uniformity will become lower with the decrease of po wer and the increase of gas temperature. The deposition rate will become higher with the decrease of target-substrate distance, or the increase of power and gas temperature.

Simulation Study on the Thickness Uniformity of Thin Film Deposited on a Large-Size Substrate in Multi-Source Evaporation System

Multi-source evaporation is one of the methods to improve the thickness uniformity of thin films deposited by evaporation. In this study, a simulator for the relative thickness profile of a thin film deposited by a multi-source evaporation system was developed. Using this simulator, the relative thickness profiles of the evaporated thin films were simulated under various conditions, such as the number and arrangements of sources and source-to-substrate distance. The optimum conditions, in which the thickness uniformity is minimized, and the corresponding efficiency, were obtained. The substrate was a 5th generation substrate (dimensions of 1300 mm <TEX>${\times}$</TEX> 1100 mm). The number of sources and source-to-substrate distance were varied from 1 to 6 and 0 to the length of the major axis of the substrate (1300 mm), respectively. When the source plane, the area on which sources can be located, is limited to the substrate dimension, the minimum thickness uniformity, obtained when the number of sources is 6, was 3.3%; the corresponding efficiency was 16.6%. When the dimension of the source plane is enlarged two times, the thickness uniformity is remarkably improved while the efficiency is decreased. The minimum thickness uniformity, obtained when the number of sources is 6, was 0.5%; the corresponding efficiency was decreased to 9.1%. The expansion of the source plane brings about not only the improvement of the thickness uniformity, but also a decrement of the efficiency and an enlargement of equipment.

Influence of gas flow dynamics on discharge stability and on the uniformity of atmospheric pressure PECVD thin film

The aim of this paper is to improve the understanding of the mechanisms controlling the uniformity of thin films made by atmospheric pressure plasma enhanced chemical vapour deposition (AP-PECVD). To reach this goal, the influence of the gas flow-rate and injection design on the thin film thickness uniformity is studied through experiments and numerical simulation in the case of silica-like layers deposited from silane and nitrous oxide using a nitrogen Townsend dielectric barrier discharge. Results show that whatever the gas flow-rate, when the gas is injected uniformly parallel to the substrate, the obtained layer is always uniform along the substrate width, while when the gas is injected perpendicularly to the substrate, the width-uniformity of the layers decreases when the gas flow-rate increases. The layer non-uniformity is related to the penetration of gas recirculation into the discharge zone, which was confirmed by computational fluid dynamics. This link is corroborated experimentally by a clear improvement of the deposit uniformity when the discharge cell dimensions are modified in order to reduce the recirculation influence on the discharge. A plausible hypothesis for the layer uniformity dependence on the recirculation is the possible enhancement of powder formation and growth in the recirculation zone: when the particle size is large enough, electrons may attach on the powder inducing electron depletion at the origin of the discharge instabilities.

Structural Characteristics of KTa0.5Nb0.5O3 Ferroelectric Thin Films and Applications to Planar Transmission Lines

Firstly, we describe a method to improve the thickness uniformity of thin films. Then epitaxial KT 0.5 Nb 0.5 O 3 films were obtained on MgO and LaAlO 3 substrates, whereas films on sapphire are textured. Secondly, we determine numerically the tunability at 10 GHz of different transmission lines printed on a ferroelectric film deposited on sapphire. The ferroelectric film permittivity was varied from 700 to 500. Uniplanar lines (coplanar waveguide and coplanar strips) have a higher tunability (16%) than microstrip lines (2%). Moreover, the definition of a figure of merit, compromise in terms of tunability and insertion loss, shows that the coplanar strips exhibit the best performance.

Effect of the Pd–Au thin film thickness uniformity on the performance of an optical fiber hydrogen sensor

Thin alloy film of Pd and Au, formed by simultaneous electron-beam and thermal evaporation techniques, respectively, is used in the design of an optical fiber hydrogen sensor. The sensor consists of a multimode fiber (MMF) in which a short section of single mode fiber (SMF), coated with the Pd–Au thin film, is inserted. Due to core diameter mismatch, the SMF cladding guides light, allowing the interaction between the sensing layer and the guided light. When the sensor is exposed to hydrogen, the Pd–Au layer refractive index diminishes and causes attenuation changes on the transmitted light. Several samples with different layer thickness uniformity were fabricated and tested in a very simple experimental set-up. We have observed that the sensor signal change is dependant on layer thickness uniformity, since the effective interaction length between the evanescent field and the sensing layer is increased. By contrast, such uniformity practically has no influence on the time response of the sensor. The resulting Pd–Au film can detect 4% hydrogen with a response time of 15 s.

121 蒸着装置の面内均一性を改善するマスク形状・配置の最適化(計算力学と最適化(4),OS19 計算力学と最適化)

121 蒸着装置の面内均一性を改善するマスク形状・配置の最適化(計算力学と最適化(4),OS19 計算力学と最適化)

Deposition rate and thickness uniformity of thin films deposited by a pulsed cathodic arc process

The deposition rate and the film thickness uniformity in a vacuum arc deposition process were investigated with respect to dependence on static and dynamic arc current parameters. Measurements were based on the ion current density. The known relations between the investigated process parameters were verified for the d.c. arc process and served as a reference. In the modified pulsed arc process a considerably increased ion current density was measured (up to 1.2 mA A −1 cm −2 during a 500-A pulse). The angular distribution changed in dependence on maximum pulse current especially and could be measured to be cos 3ϕ for I p=150 A to cos 7ϕ for I p=500 A. This results in very high deposition rates in the central region of the substrate and in changes of the film thickness uniformity. A maximum increase of the deposition rate by a factor 3 (perpendicular to the cathode) was measured. Only in a smaller sector the distribution of the film thickness can be approximated by a cosine function (with exponent n up to 27).

Enhancement of thickness uniformity of thin films grown by pulsed laser deposition

A peculiarity of the pulsed laser deposition technique of thin-film growth which limits its applicability is the very rapid drop of resulting film thickness as a function of distance from the deposition axis. This is due to the narrow forward peaking of the emission plume characteristic of the laser ablation process. The plume is usually modeled by a cosn θ function with n greater, and in some cases much higher, than 1. Based on this behavior, a method is presented to substantially enhance coverage uniformity in substrate zones of the order of the target-substrate distance h, and to within a specified thickness tolerance. Essentially, target irradiation is caused to form an annular emission source instead of the usual spot. By calculating the resulting thickness profiles, an optimum radius s is found for the annular source, corresponding to a given power in the emission characteristic and a given value of h. The radius of this annulus scales with h. Calculated numerical results for optimal s/h ratios corresponding to a wide range of values for n are provided for the case of ±1% tolerance in deviation from the thickness at deposition axis. Manners of producing annular illumination of the target by means of conic optics are presented for the case of a laser beam with radially symmetric profile. The region of uniform coverage at the substrate can be further augmented by extension of the method to multiple concentric annular sources. By using a conic optic of novel design, it is shown also how a single-laser beam can be focused onto a target in the required manner. Applicability of the method would be limited in practice by the available laser power. On the other hand, the effective emitting area can be large, which favors extremely high growth rates, and since growth can occur uniformly over the whole substrate for each laser pulse, single-shot depositions with substantial thicknesses are possible. In addition, the simultaneity of growth over the complete substrate is desirable when monitoring the growth in situ.

New rotating target holder for laser ablation and ion beam sputter deposition of multicomponent and multilayered thin films

A versatile ultrahigh vacuum rotating target holder has been designed and constructed for use in ion beam sputter and laser ablation deposition systems for producing multicomponent and/or multilayered thin films. The device features a capability for rotating the targets continuously during exposure to the beams to minimize the development of an undesirable surface topography that otherwise would occur if the targets were still during irradiation. In addition, each individual target holder can be tilted at a predetermined angle. The combined tilting and rotation produces a wobbling movement of the target surface that can be used advantageously to achieve a more uniform distribution of the materials ejected from the targets, which in turn can result in better composition and thickness uniformity of thin films over large area substrates. The device can be baked up to 150 °C depending on the choice of driving motor.

Thickness uniformity of thin films deposited on a flat substrate by sputtering of a target with rotational symmetry

A generalized model has been developed for the calculation of the thickness uniformity of vacuum deposited films when the atom emission takes place from a surface with rotational symmetry. In the general case this surface can be composed of several simple rotational surfaces described with well-known analytical expressions. The Monte Carlo method has been used for the numerical calculations of the integrals included in the expressions for the thickness uniformity.

Theoretical Aspects on Spatial Thickness Variations in Laser-Deposited Thin Films.

AbstractWe have studied predicted thickness uniformity of thin films deposited by the pulsed laser ablation technique. Unlike a conventional evaporation process, the spatial thickness characteristics of laser-deposited films is controlled by a number of laser and other deposition variables including laser wavelength, pulse energy density, substrate-target distance, area and shape of the laser irradiated spot, etc. The effect of these parameters on the spatial thickness variations have been analyzed by using a model proposed by Singh et. al. [1]. This model is based on the anisotropic expansion of the laser-generated high-temperature and high-pressure plasma, which is initially confined to small dimensions and then expands anisotropically in vacuum. The results show that spatial film uniformity can be improved by decreasing plasma temperature and specific heat capacity ratio of the plasma gas. For large laser irradiated spot diameters (&gt; 8 mm), the film uniformity was found to decrease with decreasing spot diameters, but this trend reversed at smaller: irradiated spot sizes. Depending on the laser irradiated conditions and substrate-target geometry, the thickness variations have been found to vary from (cos θ)2.5 to (cos θ)12. Optimization of various parameters to decrease the spatial-thickness inhomogeneities across the film are also discussed.