Dielectric properties of composition spread SiO2–Al2O3 mixed phase thin films deposited at room temperature by off-axis RF magnetron sputtering

The dielectric properties of composition spread SiO2–Al2O3 thin films deposited by off-axis radio-frequency magnetron sputtering at room temperature were explored to obtain optimized compositions, which have low dielectric constants and losses. The specific points (compositions) showing superior dielectric properties of low dielectric constants (8.13 and 9.12) and losses (tanδ ∼0.02) at 1 MHz were found in area of the distance of 25.0 mm (Al2Si3O8) and 42 mm (Al2.4Si3O8) apart from SiO2 target side in 75 mm × 25 mm sized Pt/Ti/SiO2/Si(1 0 0) substrates, respectively. The specific thin films were amorphous phase and the compositions were Al2Si3O8 (k ∼8.13) and Al2.4Si3O8 (k ∼9.12).