Contact Characterizations of ZrN Thin Films Obtained by Reactive Sputtering
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1040-Q09-04
Contact Characterizations of ZrN Thin Films Obtained by Reactive Sputtering Joshua Pelleg, Asaf Bibi, and Michael Sinder Materials Engineering, Ben Gurion University of the Negev, Beer Sheva, 84105, Israel ABSTRACT The contact properties of ZrN on p-type Si obtained by magnetron reactive sputtering were investigated. Schottky diodes characteristics were evaluated by current-voltage (I-V) and capacitance voltage (C-V) measurements. The barrier heights obtained by I-V and C-V are in the range of 0.55-0.63V and 0.88-0.91V, respectively. Due to the possible presence of interfacial layer and interface states which are located at the ZrN-semiconductor interface the I-V curves are not ideal. It is likely that n, the ideality factor is controlled by the interface state density. For each diode investigated in the ZrN/Si system, the barrier heights measured by the C-V method are considerably higher than those evaluated by I-V technique. At this stage we cannot present a theoretical explanation for the difference between the values of φBp beyond the speculations that the presence of interface states might be responsible for the difference. Since IV measurements tend to emphasize the lower value of φBp while C-V measurements would give a value of φBp averaged over the entire interface the more probable magnitude of the barrier height can be assumed to be those measured by I-V technique. INSTRUCTION In the search for good diffusion barrier in Cu metallization in silicon semiconductor technology, ZrN is expected to be a good candidate, due to its low electrical resistivity, chemical and metallurgical stability. Thermally stable ZrN film was reported to act as a good diffusion barrier in Cu/ZrN/Si contact systems up to 1023 K for 1 h without any Cu penetration through it into the silicon [1]. In the current processing technique of device size miniaturization, electrical properties, in particularly for contact purposes become of utmost importance. The resistivity of ZrN films varies from 200 µΩcm up to 15Ωcm [2] depending on the N2 content in the working gas and it has been considered advantageous to incorporate this nitride as a thin film in integrated circuits. Given the characteristics of ZrN films, it is of interest to explore its contact properties also. Based on the promising results of TiN/p-type Si (100) contacts, which show Schottky diode behavior [3], it was of interest to evaluate the characteristics of ZrN films and determine whether it is rectifying or Ohmic. To the best of the authors' knowledge, no information on ZrN/p-type Si (100) contacts is available in the open literature except by the authors of this communication [4]. EXPERIMENT Thin ZrN films were obtained by DC magnetron reactive sputtering of Zr on p-type Si (100) substrates. The base pressure in the system before deposition was ~ 6.7x10-5Pa. Pre-sputtering of the Zr target in Ar and subsequent reactive sputtering in Ar + 15 % N2 were performed at a pressure 0.67 Pa. A typical DC power input to the Zr target was 150 W. The composition of the fi
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