Abstract-Two methods are described to obtain the value of the eeries resistance (R) of a Schottky diode from its forward I-V character ~stic. The value of R is then used to plot the curve In ( I ) versus VD (=V .. IR) which becomes a straight line even if In ( I ) versus V does not. The ideality factor n and the Schottky-barrier height @BO of the diode then follow from the standard procedure. The main advantages of the methods are: 1) a linear regression can be used to calculate the vah &: of R , 2) many data points are used over the whole data range which I:llses the accuracy of the results, and 3) the validity of constant R assumption can be checked by the linearity of the In (I) versus VD curve. The methods are illustrated on the experimental data of a real diode.

The thermal stability of reactively sputtered RuO2 films is investigated from the point of view of their application as diffusion barriers in silicon contact metallizations with an Al overlayer. Backscattering spectra of Si/RuO2/Al samples and electrical measurements on shallow junction diodes with 〈Si〉/TiSi2.3/RuO2/Al contacts both show that RuO2 films are effective diffusion barriers between Al and Si for 30-min annealing at temperatures as high as 600 °C.

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Reactively sputtered tungsten nitride (WxN1−x) layers are investigated as diffusion barriers between Al overlayers and Si shallow n+ -p junctions. Both amorphous W80 N20 and polycrystalline W60 N40 films were found to be very effective in preserving the integrity of the n+ -p diodes for 30-min vacuum annealing up to 575 °C. Diode failure at higher temperatures is caused by localized penetration of Al into 〈Si〉 through the WxN1−x barriers. The effectiveness of the barrier decreases for polycrystalline W90 N10 and is worse for pure W.

Reactions of Ti/Al couples induced by furnace annealing were investigated (at elevated temperature) using large-grained Al substrates and vacuum-evaporated bilayers of both sequences. 4 He MeV backscattering spectrometry was principally used to monitor the reactions. Profiles of oxygen impurity were obtained by elastic 16 O(α,α)16 O resonant scattering. In the range of 460–515 °C, TiAl3 forms as a laterally uniform layer at the Ti/Al interface. The thickness of this compound layer increases as (annealing time)1/2. The activation energy is 1.9–2.0±0.1 eV. For evaporated bilayers on an oxidized Si substrate, the sequence of the bilayers does not effect the growth mechanism of TiAl3 , but the growth rate of samples with the Ti on top is lower than that of samples with Al on top, that is, oxygen in Ti/Al samples can reduce the reaction rate by decreasing the pre-exponential factor. Oxygen already contained in the Ti film and oxygen from the annealing ambient are incorporated in the growing TiAl3 compound during thermal annealing. In addition, a TiAl3 layer also forms at the free Ti surface during vacuum annealing when the oxygen-containing contaminants in the ambient are minimized. So far, we succeeded in accomplishing this only for large-grained Al substrates. We conclude that the formation of the TiAl3 compound at the surface is controlled by nucleation and depends sensitively on the condition of the surface layer of the Ti film.