With strong alkaline anion-exchange resin 717 as the sorbent and NaOH solution as the eluent, a study on the sorption from alkaline solution and elution of vanadium(V), silicon(IV), and aluminium(III) was carried out. Different parameters affecting the sorption and elution process, including temperature, pH values as well as the ratio of resin to solution, were investigated. The results show that sorption degree of vanadium(V) increases with a decrease of pH values, and V(V) ions are easier sorbed than Si(IV) and Al(III) ions under the same conditions. The sorption degree of V(V), Si(IV), and Al(III) at pH 9.14 for 15 min are 90.6%, 33.5%, and 21.6%, respectively. Si(IV), Al(III), and V(V) ions sorbed on 717 resin were eluted by use of 2 mol⋅L −1 NaOH solution; the desorption degree of V(V), Si(IV), and Al(III) for 5 min are 81.7%, 99.1%, and 99.3%, respectively.
The laser-generated surface acoustic wave (SAW) technique is a promising method to measure the mechanical properties of thin films quickly and nondestructively. Residual stress is inevitable during the processing and manufacturing of integrated circuits, which will have a major impact on the physical and mechanical properties of the thin film materials and cause deterioration to the structural strength. In this study, the SAW technique based method is proposed for quantitative and nondestructive measuring the residual stress in the nanostructured films. The method is verified by the experiment measuring the SiO2 films in the thickness range of 100 to 2000 nm. The experimental procedures, including signal excitation, reception and processing, are described in detail. By matching the SAW experimental dispersion curve with the calculated theoretical dispersion curve containing the residual stress, the residual stress of the SiO2 films along [110] and [100] crystallographic orientation of the Si wafer is successfully quantified. The determination results are ranged from -65.5 to 421.1 MPa and the stress value increases as the film thickness decreases, revealing the residual stress of the SiO2 film is compressive. Meanwhile, the conventional substrate curvature method as a comparison is used to verify the correctness and feasibility of the proposed SAW method for the residual stress determination.
The surface acoustic wave (SAW) technique is attractive for nondestructive mechanical determination of thin films. In this paper, the influence of residual stress on the Young's modulus determination for SiO 2 thin film is discussed. The residual stress model is established by introducing the E eff (effective elastic constants) into the ideal model. When SAWs propagate along the Si[110] and [100] direction, the dispersion curves obtained from ideal SAW model and residual stress model are compared, respectively. The ratio (D / E E f f ) is used to judge the impact. The modified formula for the Young's modulus value determined by the ideal model is calculated. The scope of the application of the ideal SAW model is obtained, where the influence of residual stress could be safely ignored. This study indicates that the influence of residual stress on the determination of Young's modulus for SiO 2 thin film by SAWs are small, and it can be ignored or revised.
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