Plasma deposition of low-dielectric-constant fluorinated amorphous carbon

Abstract

Fluorinated amorphous carbon thin films (a-C:F) for use as low-dielectric-constant interlayer dielectrics are deposited by helicon-wave plasma enhanced chemical vapor deposition. To improve their thermal stability, the feasibility of adjusting the fluorine-to-carbon (F/C) ratio by changing the deposition pressure was investigated. Decreasing the pressure increased the dissociation of a source fluorocarbon material in the plasma and decreased the F/C ratio of the deposited film. Both the thermal stability and the dielectric constant of the a-C:F films were increased as the F/C ratio was decreased. Thus, there is a tradeoff relationship between a low dielectric constant and high thermal stability and the tradeoff could be optimized by the pressure during deposition. The mechanism of the pressure dependency of the dielectric constant of a-C:F films was investigated by quantifying the contribution of each polarization and found that a decrease in the dielectric constant of a-C:F films can be attributed to decreases in the orientational and electronic polarizations.

Carbon Fluoride, CFx: Structural Diversity as Predicted by First Principles

“…[22][23][24][25][26][27] CF x films display a low dielectric constant and a low refractive index, 17,19,20 moderate hardness 21,23,25 as well as low friction coefficients, high wear resistance, 23 and biocompatibility. 21 These properties make them suitable for electrical, tribological, and biomedical applications.…”

Elemental distribution in fluorinated amorphous carbon thin films

“…The physical properties of the ϪCF x groups, which are a film constituent, permit a considerable reduction in friction and a substantial improvement in wear resistance, and confer a hydrophobic behavior to the film surface. Electronic applications of such a material are also foreseen because of the low value of the dielectric constant k [5][6][7][8][9][10][11][12][13][14].Several material properties (structural, chemical, mechanical, electrical, optical, etc.) have been studied as functions of process parameters [4, 12, 14 -20], but a direct visualization of the surface element distribution is still lacking.…”

Nanostructured carbon-based thin films : prediction and design

“…Fluorinated carbon-based thin films 5 have been largely studied in the last fifteen years due to their low dielectric constant and low refractive index [104][105][106], moderate hardness [55,56,107], low surface energy, high wear resistance and low friction coefficient [107,108], chemical inertness, and biocompatibility [55]. These films have been synthesized by different vapor phase deposition methods with resulting structures of amorphous nature (e.g., DLC and polymer-like) [54][55][56][57][104][105][106][107][109][110][111].…”

“…These films have been synthesized by different vapor phase deposition methods with resulting structures of amorphous nature (e.g., DLC and polymer-like) [54][55][56][57][104][105][106][107][109][110][111]. Another line of research dedicated to CF x compounds is related to the substantial interest in Teflon R -like materials with improved thermal resistance [112,113].…”