EFFECT OF NEAR-SURFACE DAMAGE ON C-V MEASUREMENTS OF SCHOTTKY-BARRIER DIODES

During a number of current silicon technological processes used for the realization of Schottky barrier diodes, the silicon surface is bombarded by energetic particles so that deep traps are being detected in the device up to a fraction of a micron from the metal-silicon interface. The effect of such traps on the parameters, usually extracted from capacitance-voltage measurements under the form 1/C2-V is studied. It is shown that the traps modify the extracted doping profile at a low reverse bias and that they have a strong effect on the extracted barrier height which can be larger or lower than the value obtained in the absence of traps, depending upon the trap characteristics. Experimental results obtained on Ti-W/nSi Schottky barrier diodes confirm these considerations.