The Targets Facing Type of Sputtering (TFTS) system can deposit very dense films on substrates at a high rate without undesirable influences of the plasma. Using this system, Al films 0.7 ∿ 1.5 µm thick were deposited in an argon gas pressure PAr of 9.7 × 10−2 Pa.

The grains with irregular shape grew as PAr became high. However, the number of grains per unit area decreased and their size became small when the bias voltage to the substrate Vb was -40 V. Consequently, the film surfaces became smooth. The Al films became hardest at Vb of about -40 V and were twice as hard as ones prepared without the bias voltage.

The step coverage of these Al films was very satisfactory to the wiring of the integrated circuit (IC) by adjusting Vb and PAr at the proper values.