Variations of Thin Metallic Zinc Film Resistances With Sputtering Rate

Variations of resistance of evaporated or sputtered films during deposition have been studied for deposition times lower than five minutes and for resistances higher than 100 [2 sq -1 As our main objective is to study the conduction mechanisms in sputtered films over the thickness range from 200 to 1500 A, (i.e. in the 10 to 100 2 sq -1 sheet resistance range), we report in this note our investigations about the electrical resistance R(T) of zinc films for deposition time, T greater than two minutes and for four average deposition rates. Preparation of films has been described in a previous paper; they are deposited by d.c. diode sputtering of a zinc target (99.9% purity) in an atmosphere of U grade argon. As broken sputtering is equivalent to continuous deposition4, sputtering was stopped every minute to measure the resistance R with a multimeter. The average sputtering rate was determined from the deposition time and the film thickness measured by an optical method; this method is adequate for we have observed very slight anisotropic effects, 6 which seem more important for higher sputtering rates; it varied with the intensity Ie of the glow discharge current, the voltage Ue remaining constant (curves 1, 2, 3 on Figure 2). Variations of the deposition rate as a function of the intensity Ie of glow discharge current for a voltage equal to 1500 V are shown in Figure 1. This curve is in good agreement with the results of Laville Saint-Martin who established that sputtering rate v is given by