Investigation On The Thermal Stability And Influence Of Thermal Annealing In N₂ Ambience On The Structures And Properties Of Fluorinated Amorphous Carbon Films

Fluorinated amorphous carbon films were deposited using Microwave electron cyclotron resonance chemical vapor deposition (ECR-CVD) reactor with CF4 and C6H6 as source gas and were annealed in nitrogen ambience in order to investigate their thermal stability. The thickness of a-C:F films was measured by a profilometer (ET300,Japan)before and after annealing and the optical transmission spectrum was obtained by a Ultraviolet-Visible(UV-VIS) spectrophotometer(X-17,PklinElmer)and optical bandgap was calculated . The bonding configurations of a-C:F films were analyzed by a Nicolet 550 Fourier-transformed infrared spectrometer(FTIR)as well as X-ray photoelectron spectroscopy(XPS).The dielectric properties and phase information were examined by capacitance-voltage (C-V)characterization and XRD , respectively. We mainly discussed the influence of Microwave power on the thermal stability and annealing temperature in N2 ambience on the structural modifications and properties evolutions of a-C:F films.It indicated that a-C: F films deposited at higher microwave power have a better thermal stability. And the films deposited at R.T (Room Temperature) were mainly composed by CF2 and CF as well as C=C bonding. F is desorbed with C with the form of CFx at lower annealing temperature and the transformation of the band state of C atom from SP* to SP2 occurs at higher annealing temperature which enhances the C=C bonding of a-C:F film. Thefilms take on amorphous structure even after 400C annealing .There is a close relationship between relative concentration of C=C bond and optical band gap and a lower optical band gap corresponds to a better thermal stability. Both dielectric constant and dielectric loss increased after annealing due to the loss of F and enhanced orientation polarization, respectively.