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Electrical conductivity effects in ultra-thin Tungsten films

Klein Essink, Jeroen (2018) Electrical conductivity effects in ultra-thin Tungsten films.

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Abstract:In this work, an attempt is made to characterize the electrical conductivity of ultrathin films of tungsten(W). This is done by measuring on wafers that have films of W with a thickness between 0.57 and 8.5nm. A method for characterizing ultra-thin films is by measuring their I-V relationship on circular transfer length method structures. This can give information about the film’s resistivity, contact resistance and transfer length. By looking at how non-linear the I-V relationship is, information can be obtained regarding the thickness at which the film goes from discontinuous to continuous. By measuring at various temperatures, the temperature coefficient of resistance (TCR) can be obtained. It was found that the W layers on the tested wafers are highly non-homogeneous. As such, any characterizations from these tests are tentative. Nevertheless, some conclusions could still be drawn. The thickness at which W films transition from semi-continuous to continuous is around 1.6nm. W films with a thickness up to at least 0.9nm have a highly nonlinear I-V relationship, a negative TCR and a contact resistance that decreases with an increased temperature. In order to better characterize ultra-thinWfilms, new wafers will have to be made. If these are made with W films with thicknesses around 1.6nm, the thickness at which the transition to continuous occurs can be characterized more precisely.
Item Type:Essay (Bachelor)
Faculty:EEMCS: Electrical Engineering, Mathematics and Computer Science
Subject:51 materials science, 53 electrotechnology
Programme:Electrical Engineering BSc (56953)
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