Annealing effects on the film stress and adhesion of tungsten titanium barrier layers

Tungsten titanium WTi alloys are important barrier materials in microelectronic devices. Thus the adhesion of WTi to silicate glass substrates influences the reliability of these devices. One factor that affects the adhesion of barrier layers are thermal treatments during and after fabrication. To address the impact of annealing, WTi films deposited on silicate glass substrates were subjected to different annealing treatments. The stress development in the WTi film has been monitored with wafer curvature and X ray diffraction. Quantitative measurements of the adhesion energies were performed using scratch testing to induce interface delamination. Imaging with atomic force microscopy provided the dimensions of the buckles to quantify adhesion energies. Focused ion beam crosssections were used to verify the failing interfaces and to inspect any deformation in the film and the substrate caused by scratch testing. It was found that as the annealing duration increased, the residual compressive stresses in the film and the adhesion energy increase

The bacterial dicarboxylate transporter VcINDY uses a two-domain elevator-type mechanism

Secondary transporters use alternating-access mechanisms to couple uphill substrate movement to downhill ion flux. Most known transporters use a 'rocking bundle' motion, wherein the protein moves around an immobile substrate-binding site. However, the glutamate-transporter homolog GltPh translocates its substrate-binding site vertically across the membrane, through an 'elevator' mechanism. Here, we used the 'repeat swap' approach to computationally predict the outward-facing state of the Na(+)/succinate transporter VcINDY, from Vibrio cholerae. Our model predicts a substantial elevator-like movement of VcINDY's substrate-binding site, with a vertical translation of ~15 Å and a rotation of ~43°. Our observation that multiple disulfide cross-links completely inhibit transport provides experimental confirmation of the model and demonstrates that such movement is essential. In contrast, cross-links across the VcINDY dimer interface preserve transport, thus revealing an absence of large-scale coupling between protomers