Characterization of confocal sputtered molybdenum thin films for aluminum nitride growth

Molybdenum is commonly deposited as a seed layer for piezoelectric Aluminum Nitride (AlN) growth, whose properties are dependent on the quality of the Mo thin film, which includes the crystal orientation and stress. This paper investigates the morphology effects of varying sputtering parameters using confocal sputtering of Mo thin films. DC and pulsed DC sputtered Mo and bilayers of AlN/Mo on Si were deposited using confocal sputtering techniques by varying power and temperature. Films were characterized by measuring crystallinity properties of the film, electrical resistivity, and stresses. Results demonstrated that controlling parameters of pulsed DC deposition produced lower compressive film stress (-0.13 GPa) compared to DC sputtered film (- 1.6 GPa). The crystal structure of the films was analyzed by measuring the full-width-half-maximum values on the 2. X-ray diffraction scans. Increasing surface mobility by increasing power and temperature resulted in an increased crystallinity of (110) Mo with increased crystallite size and lower electrical resistivity and stress. Pulsed DC sputtered Mo further enhanced the crystallinity of the film. It was determined that depositing pulsed DC AlN as an interlayer for Mo growth resulted in an increase in crystallinity and lower stress compared to DC sputtered Mo.