HEAT & MASS TRANSFER ANALYSIS OF GOLD, TIN & INDIUM THIN LAYER DEPOSITION ON SURFACE

Abstract

The surface temperature is required to specifying the temperature of the evaporating Gold, Tin and Indium source using constant elements for turn off the refinement in the post-processing settings. The present work represents the modeling of nanoscale Gold, Tin & Indium films by computing the film thickness, mass deposited on the substrate and mass transfer rate on silicon substrates with time dependent model using BDF solver. Gold is deposited by thermal evaporation process 34-38 nm by evaporating at temperature of 2000 °K in the vacuum of 50 Pa. Mass of gold deposited for 60 sec is 5.8 x 10-6 kg with mass transfer rate of 9.9 x 10-8 kg/sec. The SEM micrographs shows the smooth and uniformly distributed nanoscale gold film on silicon and the average grain size of gold is 12-30 nm. The XRD analysis shows the polycrystalline face centered cubic (fcc) structure in preferential (111) plane. Tin and Indium is evaporated from a resistively heated evaporator source at a temperature of 1855 °K and 1485 °K respectively in a pressure (vacuum) of 100 Pa onto silicon surface held on a fixed surface. The film thickness varies between 144 nm to 165 nm for Tin and 160 nm to 183 nm for Indium across the sample after 60 sec of deposition, with radial symmetry about the midpoint of the source. The film thickness as well as mass deposited at a point increases linearly with time. Like gold mass deposited & mass transfer rate for tin and indium also computed from the flux arriving on the substrate. Since the angular distribution is of particular interest in this model, by increasing the integration resolution to a maximum value for ensuring the most accurate angular resolution when computing the flux. The SEM micrographs of Tin and Indium at different magnifications shows the 100nm to 1microns grain size along the grain boundaries. Similarly, XRD analysis with Kα (wavelength 1.541874) shows the peaks of intensity at different 2θ angles for different orientations of planes with polycrystalline structure. The XRD of tin shows tetragonal polycrystalline structure in preferential (101) plane while XRD for indium shows tetragonal bcc structure in preferential (103) plane for tin & indium thickness of 164 nm, 183 nm respectively. Deposited gold, tin & indium film thickness measured from Dektek surface profiler at different points on the substrate surface.