Effect of argon ion beam voltages on the microstructure of aluminum nitride films prepared at room temperature by a dual ion beam sputtering system

Abstract

Aluminum nitride (AlN) films were successfully deposited at room temperature onto p-type (1 0 0) silicon wafers by manipulating argon ion beam voltages in a dual ion beam sputtering (DIBS). X-ray diffraction spectra showed that aluminum nitride films could be synthesized above 800 V. The (0 0 2) orientation was dominant at 800 V, above which the orientation was random. The atomic force microscope (AFM) images displayed a relatively smooth surface with the root-mean-square roughness of 2–3 nm, where this roughness decreased with argon ion beam voltage. The Al 2p 3/2 and N 1s spectra indicated that both the aluminum-aluminum bond and aluminumnitrogen bond appeared at 600 V, above which only the aluminumnitrogen bond was detected. Moreover, the atomic concentration in aluminum nitride films was concentrated in aluminum-rich phases in all cases. Nevertheless, the aluminum concentration markedly increased with argon ion beam voltages below 1000 V, above which the concentration decreased slightly. The correlation between the microstructure of aluminum nitride films and argon ion beam voltages is also discussed.