IVB-7 the sidewall resistor—A novel test structure to reliably extract specific contact resistivity

Abstract

Abstract : Conventional contact resistance exsistance extraction structures suffer inaccuracies when measuring small values of contact resistivity which are sensitive to small perturbations in device fabrication. This is because two- dimensional current crowding around the perphery of the contact window introduces parasitic resistance components which are not accounted for by the one-dimensional model and which can be much larger than the contact resistance component for low values of specific contact resisivity rho sub c. Unfortunately, there is no direct method to isolate these parastics, which makes the extraction of rho sub c using the conventional test structures difficult. In this paper, a novel test device, the sidewall resistor, which utilizes the vertical sidewall dimensions, is demonstrated to circumvent these difficulties. The proposed structure has the advantage that a simple one dimensional (1 D) extraction technique can still be used. The specific contact resistivity between pure Al and N+ polycrystalline Si is accurately extracted with the value of 7.4 x 10 to the -8th power ohm cm. The sidewall resistor is then used to extract the contact resistivity between pure A1 and WSi2 which turns out to be less than 5 x 10 to the -9th power ohm cm. Reprints.