The impact of sputter conditions on the microstructure and on the resistivity of tantalum thin films

In this work, the influence of sputter conditions and film thickness on both the morphology and the resistivity of tantalum (Ta) thin films will be investigated. Glass wafers were used as substrates. With increasing back pressure level ranging from 0.3 to 6 Pa at a fixed plasma power of 100 W, the microstructure changes from a dense to an open porous characteristics. At a moderate back pressure level of 0.9 Pa, the stable α-phase is detected when the film thickness exceeds a value of about 1.3 µm. Besides the impact of phase composition, the microstructure influences in addition the electrical performance of the Ta films. Therefore, the room-temperature resistivity can be varied within two orders of magnitude by applying different parameters for film deposition.