Abstract
Fluorinated amorphous carbon (a–C:F) films have been deposited by electron cyclotron resonance chemical vapor deposition (ECR–CVD) at room temperature using C 4F 8 and CH 4 as precursor gases. The chemical compositions and electrical properties of a–C:F films have been studied by X-ray photoelectron spectroscopy (XPS), capacitance–voltage (C–V) and current-voltage ( I– V) measurements. The results show that C–CF x and C–C species of a–C:F films increase and fluorine content decreases after annealing. The dielectric constant of the annealed a–C:F films increases as a result of enhancement of film density and reduction of electronic polarization. The densities of fixed charges and interface states decrease from 1.6 × 10 10 cm − 2 and (5–9) × 10 11 eV − 1 cm − 2 to 3.2 × 10 9 cm − 2 and (4–6) × 10 11 eV − 1 cm − 2 respectively when a–C:F films are annealed at 300 °C. The magnitude of C– V hysteresis decreases due to reduced dangling bonds at the a–C:F/Si interfaces after heat treatment. The conduction of a–C:F films shows ohmic behavior at lower electric fields and is explained by Poole–Frankel (PF) mechanism at higher electric fields. The PF current increases indicative of reduced trap energy when a–C:F films are subjected to higher annealing temperatures.
Published Version
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