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(a) four-point measurement where a current is passed through the two outer probes and the voltage potential drop in the material is measured over the two inner electrodes. (b) Sketch of a four-point probe based on four individual cantilevers (commercially available from Capres A/S) in contact with a sample surface. The initial point of contact is shown as an arrow. (c) A monocantilever in contact with a sample surface.
Outline of fabrication process. (a) A double polished silicon wafer with and patterned photoresist on top. (b) TiW is deposited. (c) Lift-off and lithography mix-and-match creates the electrode pattern. (d) The support cantilever is etched in bHF. (e) Encapsulation with followed by opening of the backside with reactive ion etching. (f) The chip is defined with KOH and the support cantilever is released. (g) Scanning electron microscopy image of 12–point probe with TiW electrodes placed on cantilever and a probe pitch of 500 mm at the inner probes. They have an uneven spacing to increase the number of possible pitch configurations. Inset: The finished wire bonded 12–point probe mounted on a ceramic substrate.
Four-point measurement performed on at room temperature. curves of four different electrodes in contact with the surface demonstrating a good Ohmic contact. Inset shows four-point measurements made with T-shaped TiW probes with a pitch of , see Fig. 1.
Resistance of three thin films determined by the monocantilever TiW probes and by individual cantilever Au coated probes. All values in . The values are based on ten measurements.
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