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The effect of capping layers, diffusion barriers on TiSi2 phase formation

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dc.contributor.advisor Ndwandwe, O.M.
dc.contributor.advisor Theron, C.C.
dc.contributor.author Nkosi, M.M.
dc.date.accessioned 2011-08-10T13:10:12Z
dc.date.available 2011-08-10T13:10:12Z
dc.date.issued 2002
dc.identifier.other 266040
dc.identifier.uri http://hdl.handle.net/10530/819
dc.description Dissertation presented in partial fulfilment of the requirement for the Degree of Master of Science to the Department of Physics, University of Zululand, 2002 en_US
dc.description.abstract Metal silicides continue to be an important part of the design philosophy in semiconductor technology due to their application as contacts or interconnect. Among these silicides, titanium disilicide is currently the most widely used as it possesses the lowest resistivity (\4\in~cm) of all silicides, a low contact resistance and a good thermal stability. Titanium-silicide formation with and without capping layers, through diffusion barrier layers and on stressed Si (100) substrate was studied. The oxidation of titanium makes accurate kinetics measurements very difficult. Capping layers, namely Al203 and MgO, and sandwich technique were used in attempting to limit the unwanted oxidation. It was found that both capping layers reduced the oxygen concentration in the unreacted Ti film by 30% compared to the uncapped samples. It was also found that the reaction was faster in the MgO capped samples and slower in the Al203 capped samples. In the sandwich technique, the oxygen concentration was found to be less by 35% and the reaction was fast at high temperatures compared to the silicide formation in the unsandwiched samples. In attempting to control the metal concentration at the growth interface diffusion barrier layers were used. Cr and Zr were used as diffusion barrier layers. Both barrier layers were found to react with silicon to form CrSi2 and ZrSi2 respectively. It was found that both barrier layers moved deeper into the samples as more silicide was formed on top, which indicates that Si is the dominant diffusing species during Ti-silicide formation. Both barrier layers delayed the formation of TiSi2. Tensile and compressive stresses were induced by depositing different thicknesses of Si3N4 and Si02 on the backside of Si{100) wafers. The reflection of laser light was used to measure the radius of curvature which was related to stress using Stoney's equation. It was found that the silicide phase formation was faster in samples under tensile stress and slower in samples under compressive stress. The cube root of time gave the best fit to the data for all sample groups. Therefore the TiSi2 formation kinetics was neither diffusion nor reaction limited. en_US
dc.language.iso en en_US
dc.subject Silicides en_US
dc.subject Electronics en_US
dc.subject Semiconductors en_US
dc.title The effect of capping layers, diffusion barriers on TiSi2 phase formation en_US
dc.type Thesis en_US

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