Study and optimization of PECVD films containing fluorine and carbon as ultra low dielectric constant interlayer dielectrics in ULSI devices

Abstract

Fluorinated amorphous carbon films that are thermally stable at 400 C have been deposited in a plasma enhanced chemical vapor deposition system using tetrafluorocarbon and disilane (5% by volume in helium) as precursors. The bulk dielectric constant (k) of the film has been optimized from 2.0/2.2 to 1.8/1.91 as-deposited and after heat treatment, by varying process parameters including power density, deposition temperature, and wall temperature. Films, failing shrinkage rate requirements, possessing promising k-values have been salvaged by utilizing a novel extended heat treatment scheme. Film properties including chemical bond structure, F/C ratio, refractive index, surface planarity, contact angle, dielectric constant, flatband voltage shift, breakdown field potential and optical energy gap have been evaluated by varying process pressure, power, substrate temperature, and flow rate ratio of processing gases. Both x-ray photoelectron spectroscopy and FTIR results confirm that the stoichiometry of the ultralow k film is close to that of CF 2 with no oxygen. C-V characteristics indicate the presence of negative charges that are either interface trapped charges or bulk charges. Average breakdown field strength was in the range of 2-8 MV/cm while optical energy gap varied between 2.2 and 3.4 eV.

The Electrical Response of Real Dielectrics: Using the Voltage Ramp Method as a Straightforward Diagnostic Tool for Polymeric Composites

“…Best-fits to the flat current tops (red lines) give a capacitance value C = 7.98 ± 0.01 pF (baseline offset subtracted). This allows us to calculate the static relative permittivity ε r through the formula C = ε 0 ε r S/t, where S is the sample area and t its thickness; it results ε r =1.8, i.e., within 10% from the nominal value of 1.9–2.0 reported in the literature [ 12 , 13 ]. However, as aforementioned, the value obtained with the VRM technique must be considered as a DC or “zero frequency” value.…”

Effect of hydrogen content on dielectric strength of the silicon nitride film deposited by ICP-CVD*

“…[18] However, regarding the relationship between the H content and film breakdown voltage, few experiments have been carried out on ICP-CVD machines, and the conclusions are not perfect, so our experiment uses ICP-CVD machines for film deposition. [19,20] In this article, we changed the gas flow ratio and RF power to deposit silicon nitride films with different hydrogen contents. First, the deposition rate of the silicon nitride film was measured to reflect the growth state of the film.…”