Fluorinated amorphous carbon thin films grown by helicon plasma enhanced chemical vapor deposition for low dielectric constant interlayer dielectrics

Abstract

Fluorinated amorphous carbon thin films (a-C:F) for interlayer dielectrics are grown by helicon plasma enhanced chemical vapor deposition. The source gases are CH4, CF4, C2F 6 and their H2mixtures. a-C:F films can be fabricated without adding hydrogen using the helicon reactor, while in the previously reported parallel-plate reactor, no film grows unless a hydrogen source is added. The films grown in the helicon reactor have no hydrogen content. The growth rate of the films reaches 0.3 μm/min (C2F 6) and 0.15 μm/min (CF4). The thickness of the films deposited with C2F6 does not decrease on heating to 300 °C, while the films with CF4 shrink. The dielectric constants of the films deposited from C2F6 and CF4 are 2.4 and 2.3 respectively at 1 MHz. The dielectric loss tangent of these films is 0.01 at 1 MHz.