An experimentally verified useful new model for reactive sputtering is presented. By considering the total system (target erosion, gas injection, chamber wall deposition, reactive gas gettering at all surfaces, etc.) during deposition it is possible to evaluate quite simple relationships between processing parameters. We have expanded earlier treatments to include these phenomena. The model involves that gettering of the reactive gas takes place at the target and at the walls opposite to the target. Arguments are also presented for how the sputtered materials (elemental target atoms and the formed compound) contribute to the formation of the surface composition of the walls opposite to the sputtering electrode. The mass flow of the reactive gas has been chosen as the independent parameter in this presentation. Results for partial pressure and sputter rate are presented. The theoretical values are compared with experimental results from reactive sputtering of TiN. It is also pointed out that the calculated values agree extremely well with results presented in the literature by several other authors.

The etch rate of silicon, during reactive ion etching (RIE), depends on the total exposed area. This is called the loading effect. However, local variations in the pattern density will, in a similar way, cause local variations in the etch rate. This effect is caused by a local depletion of reactive species and is called the microloading effect. Silicon wafers patterned with silicon dioxide have been etched in order to study the microloading effect. The pattern consists of a large exposed area and narrow lines at different distances from the edge of the large area. This arrangement makes it possible to study how the distance from the large area, which depletes the etchants, influences the etch rate. The influence of different processing parameters like, e.g., pressure, gas flow rate, and flow direction on the microloading effect have been investigated. It has been found that the microloading effect is small (<10%) compared to other pattern dependent nonuniformities. It is also shown that the nonuniformities caused by the microloading effect can be decreased by, e.g., decreasing the pressure or increasing the gas flow rate.

The electrical, optical, and mechanical properties of a compound film depend strongly on the composition of the film. Therefore, it is interesting to study a wide variety of compositions of many new compound materials. Reactive sputtering is a widely used technique to produce compound thin films. With this technique it is possible to fabricate thin films with different compositions. However, it has not yet, to any great extent, been possible to predict the composition of the sputtered film. In this article we will present a model that enables us to predict both sputtering rate and film composition during reactive sputtering. The results point out that there exists a very simple linear relationship between processing parameters for maintaining constant thin-film composition in the reactive sputtering process. Based on these results, it is possible for the first time to combine information of both sputtering rate and film composition into the same graphical representation. Access to this new and simple graphical representation may eliminate much of the ‘‘trial and error’’ work that earlier has been associated with the reactive sputtering process.

The nanostructure and photoluminescence of polycrystalline Er-doped Y2O3 thin films, deposited by radical-enhanced atomic layer deposition (ALD), were investigated in this study. The controlled distribution of erbium separated by layers of Y2O3, with erbium concentrations varied from 6to14at.%, was confirmed by elemental electron energy loss spectroscopy (EELS) mapping of Er M4 and M5. This unique feature is characteristic of the alternating radical-enhanced ALD of Y2O3 and Er2O3. The results are also consistent with the extended x-ray absorption fine structure (EXAFS) modeling of the Er distribution in the Y2O3 thin films, where the EXAFS data were best fitted to a layer-like structure. X-ray diffraction (XRD) and selected-area electron diffraction (SAED) patterns revealed a preferential film growth in the [111] direction, showing a lattice contraction with increasing Er doping concentration, likely due to Er3+ of a smaller ionic radius replacing the slightly larger Y3+. Room-temperature photoluminescence characteristic of the Er3+ intra-4f transition at 1.54μm was observed for the 500Å, 8at.% Er-doped Y2O3 thin film, showing various well-resolved Stark features due to different spectroscopic transitions from the I13∕24→I15∕24 energy manifold. The result indicates the proper substitution of Y3+ by Er3+ in the Y2O3 lattice, consistent with the EXAFS and XRD analyses. Thus, by using radical-enhanced ALD, a high concentration of optically active Er3+ ions can be incorporated in Y2O3 with controlled distribution at a low temperature, 350°C, making it possible to observe room-temperature photoluminescence for fairly thin films (∼500–900Å) without a high temperature annealing.

Articles you may be interested inThree-dimensional simulations of discharge plasma evolution on a dielectric barrier discharge plasma actuator Effective three-dimensional simulation of field emitter array and its optimal design methodology using an evolution strategy J. Vac. Sci. Technol. B 16, 920 (1998); 10.1116/1.589931Monte Carlo numerical analysis of target erosion and film growth in a threedimensional sputtering chamber A concise review of the basic ideas of the generalized kinematic model of surface evolution during growth and erosion is presented. Interpretation of the main results of this model as well as some specific rules and advice as to how this model is applied in practical simulations are also presented. It is concluded that three-dimensional (3D) computer simulation of surface evolution is only possible by the use of adequate, theoretically motivated numerical methods. As a demonstration, 3D topography simulations during broad and focused ion beam bombardment, chemical vapor deposition, and reactive ion etching using the 3D code DINESE are also presented.