Beta 1

Title Nanocrystalline Silver
Author Hansen, Karsten
Supervisor Horsewell, Andy (Materials Science and Engineering, Department of Mechanical Engineering, Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark)
Pantleon, Karen (Materials Science and Engineering, Department of Mechanical Engineering, Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark)
Institution Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark
Thesis level Master's thesis
Year 2006
Abstract In situ X-ray diffraction (XRD) measurements during annealing were applied to study the influence of room temperature annealing on the microstructure of electrodeposited silver. Silver were electrodeposited on copper, ITO-glass and silicium/gold substrates with various thicknesses; 2.4 µm to 8.4 µm. Silver electrodeposits were manufactured with current densities from 0.5 A/dm2 to 3.77 A/dm2 at room temperature. The obtained silver thin films were nanocrystalline; as-deposited crystallite size was around 25 nm for line profile 111 and around 12 nm for line profile 200. Silver electrodeposits obtained from cyanide bath with brighteners (165 g/L KCN, 36 g/L AgCN and 15 g/L K2CO3 and 10 ml/L brighteners) have <100> texture as-deposited, and samples obtained from cyanide bath without brighteners have <111> texture as-deposited. During room temperature annealing samples with <100> as-deposited texture change to <111> with minor components <112> and <118>. Observations on <111>-textured substrates reveal that <111> can be obtained in a cyanide bath with brighteners. Integral intensities from XRD investigations were consistent with the texture analysis. Current density and deposited silver layer thickness were observed to have a strong effect on the room temperature annealing kinetics. Moreover, the current density and the brightness could not be correlated. Comprehensive in situ XRD studies on widths of line profiles 111, 200 and 222 were correlated with the grain growth occurring during recrystallization. Microhardness was found to decrease during room temperature annealing and it was linked to the microstructural evolution. As-deposited Vickers microhardness was around 108 kg/mm2, and decreased to 61 kg/mm2 after 212 hours. This study also investigated the electrical resistivity on silver electrodeposits on silicium wafers. The dependence of electrical resistivity and silver layer thickness was revealed by in situ four-point probe geometry analysis. The silver layer thicknesses were investigated applying X-ray fluorescence (XRF) measurements by means of a Fischerscope X-ray XDVM-W with WinFTM software. Microstrain was determined by Williamson-Hall plots; as-deposited microstrains were found to be around 0.006 and annealed microstrains were around 0.0005. During annealing, some samples were heat treated at various temperatures, 67 oC, 160 oC and 390 oC in various time periods respectively 3 minutes, 5 minutes and 105 seconds. Heat treatment enhances the recrystallization kinetics. The presented XRD analysis demonstrates the applicability of X-ray diffraction for complex and qualitative in situ investigations of microstructural changes in silver electrodeposits during self-annealing.
Pages 112
Original word document Nanocrystalline_Silver.doc (14.63 MB)
Derived PDF Nanocrystalline_Silver.pdf (7.07 MB)
Admin Creation date: 2009-02-13    Update date: 2011-09-27    Source: dtu    ID: 238649    Original MXD