Measurements of secondary electron emission in reactive sputtering of aluminum and titanium nitride

Abstract

Measurements have been made of the secondary electron emission coefficients (γ) of several target materials. An ion beam sputtering technique was used with Ar, N2, and mixtures of Ar and N2 in the typical magnetron sputtering energy range of 400 to 700 eV. The accuracy of the technique was determined by measuring γ of two previously characterized materials: Mo and Al. The results are in good agreement with published experimental data. The secondary electron yields of Ti and Al have been measured as a function of N2 content in the ion beam. In both cases, γ was observed to increase with N2 content of the beam. At 700 eV, γ for Ti increased from 0.102 to 0.172 as the sputter gas was varied from pure Ar to pure N2. Similarly, at 700 eV, γ for Al increased from 0.086 to 0.661 as the gas was varied from pure Ar to pure N2. The implications of these data to the interpretation of current–voltage relationships in reactive dc magnetron sputtering will be presented for TiN and AlN. Estimations of the sputter yield for TiN are proposed based on dc magnetron sputtering data and on the secondary electron yield data generated in this study.