Comparison of plasma chemistries and structure-property relationships of fluorocarbon films deposited from octafluorocyclobutane and pentafluoroethane monomers

Abstract

Effect of plasma interactions with low-κ films as a function of porosity, plasma chemistry, and temperature J. Synthesis of organically modified mesoporous silica as a low dielectric constant intermetal dielectricFluorocarbon films are deposited from mixtures of pentafluoroethane ͑PFE͒/argon and octafluorocyclobutane/argon in a parallel plate reactor at pressures of 0.75 and 1 Torr and substrate temperatures between 120 and 240°C. These monomers are compared in terms of plasma dissociation chemistries as well as chemical structure and properties ͑electrical, thermal, chemical, and optical͒ of the resulting films. Deposition rates with C 4 F 8 are significantly higher than CF 3 CHF 2 . With both monomers, the deposition rate decreases with an increase in substrate temperature, indicative of an adsorption limited process. Films deposited from both monomers are analyzed using Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy ͑XPS͒, thermogravimetric analysis ͑TGA͒, and capacitance measurements. XPS analyses indicate a higher flourine to carbon ratio for films deposited from C 4 F 8 . Likewise, these films have lower refractive indices (nϳ1.38-1.39) and lower dielectric constants (kϳ2.18-2.33) than PFE films (nϭ1.41, kϭ2.23-2.55). Films deposited from both monomers exhibit high dielectric losses (ϳ10 Ϫ2 -10 Ϫ3 ) at deposition temperatures Ͼ200°C. TGA analyses of films deposited from both monomers indicate comparable thermal stabilities up to a temperature of 300°C. However, the decomposition rate is much higher for C 4 F 8 films in the temperature range between 300 and 425°C. Thermal stability of films deposited from both monomers is enhanced at higher deposition temperatures. However, the sensitivity of thermal stability to deposition temperature is lower for films deposited from C 4 F 8 . A tradeoff exists between the electrical properties and thermal stability of films deposited from both monomers.

Increased negatively charged nitrogen-vacancy centers in fluorinated diamond

“…The main peak at 286.9 eV mostly likely reflects a C-CF bond, 13,17 and the peaks at 288.5 eV and 290.3 eV (better seen in inset) correspond well to C-F and C-F 2 literature values. 17,18 The high concentration of C-CF bonds and the presence of C-F 2 suggest some fluorocarbon deposition from the CF 4 plasma, which also has been reported previously in the literature. 13 We estimate the polymerized fluorocarbon layer to be about 3 nm thick, given that the C-C bond signal disappears at a 60 stage tilt, which reduces the analysis depth by half.…”

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

“…Fluorinated carbon-based (CF x ) thin films have been synthesized by different variants of chemical vapor deposition [17][18][19][20][21] as well as by physical vapor deposition. [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.…”

“…In order to tailor the properties of nanostructured carbon-based thin films for desired technological applications, other elements such as nitrogen, 4,[8][9][10] phosphorus, [11][12][13] sulfur 8,[14][15][16] and fluorine [17][18][19][20][21][22][23][24][25] are often incorporated in the carbon matrix at concentrations between 0-30 at.%.…”

“…[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.…”

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].…”