This work is concerned with the characterization of fluorinated amorphous carbon thin films deposited by Inductively Coupled Plasma Chemical Vapor Deposition (ICP-CVD) for the application as intermetal dielectrics in Ultra Large Scale Integrated (ULSI) devices.
In Part A, the reduction mechanism of dielectric constant of the fluorinated amorphous carbon thin film was investigated by the variation of $CF_4:CH_4$ flow rate ratio, using the Capacitance-Voltage measurement in Metal-Insulator-Semiconductor (Al/a-C:F/Si) structure, the analysis of Elastic Recoil Detection-Time of Flight (ERD-TOF), X-ray Photoelectron Spectroscopy (XPS), Fourier Transformed Infra-Red (FTIR), Auger Electron Spectroscopy (AES). From the ERD-TOF and AES, it was found that F content increased from 12 to 25% and the density of the film is reduced (increase of free volume) with increasing $CF_4$ flow rate, and the $C-F_2$ and $CF_3$ bonding configuration increased from the XPS. The dielectric constant of the film decreased from 3.2 to 2.4 with increasing $CF_4$ flow rate.
From combining the above experimental results, the reduction mechanism of the dielectric constant of the fluorinated amorphous carbon thin film was found out. The reduction mechanism of the dielectric constant is presented as follows ; The reduction of the dielectric constant is divided into two steps in terms of polarization. (1) The dielectric constant decreases by the reduction of the electronic polarization due to an rapid increase of the F content with high electronegativity. (2) The decrease of the dielectric constant is due to the ionic polarization since the $C-F_2 ＆ C-F_3$ bonding configurations increase with little change of the F content. In addition to these factors, the decrease of the density induces the reduction of the dielectric constant. Structure evolution with increasing $CF_4$ flow rate as follows ; increase of $C-F_2$ and $C-F_3$ imply the linear structure with short chain length.
In part B, the the...