Fluorinated amorphous carbon films for low permittivity interlevel dielectrics

Abstract

The need to substitute SiO2 with low dielectric constant (κ) materials increases with each complementary metal–oxide–semiconductor process generation as interconnect RC delay, crosstalk, and power dissipation play an ever larger role in high-performance integrated circuits. Fluorinated amorphous carbon films (a-C:F,H) with low-κ properties (κ∼2.0–2.4) deposited by plasma-assisted chemical vapor deposition (CVD) techniques provide several advantages including low temperature processing, good gap fill capabilities, minimal moisture absorption, and simple implementation. Several deposition techniques have been examined, including high-density plasma and parallel-plate plasma-assisted CVD. In each case, it is possible to deposit a-C:F,H films with widely varying properties, such as κ and thermal stability. This has led to a good deal of confusion as to what is required to produce useful material. Results from many different sources are examined to develop a coherent picture of the relationships between deposition techniques, microstructural features, and macroscopic properties, and to summarize the scientific and technical challenges that remain for a-C:F,H implementation. The relationships between film deposition parameters such as applied substrate bias and film properties are presented in the discussion. In addition, x-ray photoelectron spectroscopy and network constraint theory are used to develop connections between microstructural and macroscopic properties, as well as to show how deposition parameters can be used to create a predictive model. This will demonstrate what process parameters are important in film formation. Finally, efforts to incorporate this material into integrated circuits, as well as measurements of the reliability and performance will be reviewed.

Dangling bond energetics in carbon nitride and phosphorus carbide thin films with fullerene-like and amorphous structure

“…were also confirmed by experiments [8]. It is known that the surface of carbon-based films contains dangling bonds that react with hydrogen, oxygen and water molecules and form a chemically bonded surface layer [9][10][11][12]. Taking into account the prospects of FL compounds for, e.g., applications as protective overcoats in computer disk drive systems, etc., the water adsorption on FL carbon-based overcoats (which is directly related to the density of dangling bonds in these materials) represents an important property.…”

Ion beam deposition of fluorinated amorphous carbon

“…The most intense absorption band, between 1050 and 1475 cm Ϫ1 , is related to C-F x groups of various vibrational modes. 1,8,14,35 The band around 1600 cm Ϫ1 belongs to the double bond between two carbon atoms which become IR active due to a F atom bonded to one of the corbon atoms ͑aromatic CvC bond͒. 8,14,35,36 Therefore, we can conclude that this film has a reasonable number of sp 2 bonds.…”

“…[1][2][3][4] The interconnect delay in ULSI circuits caused by parasitic capacitance is expected to be greater than the gate delay and it would dominate device performance with current Cu/SiO 2 or Al/SiO 2 metallization schemes. Therefore, low dielectric materials ͑low ͒ are highly desired as interlayers between conducting lines.…”

Analysis and Kinetics of Transient Species in Electrode Near Plasma and Plasma Boundary Sheath of RF Plasmas in Molecular Gases

“…In particular, the highly reactive species such as atomic oxygen or fluorine are the important reaction partners in surface oxidation/fluorination, modification of polymers or plasma etching [1,2]. On the other hand, small fluorocarbon radicals, such as CF, CF 2 , CF 3 , are important species for formation of compounds with higher molecular weight (oligomers) and precursors in thin film deposition [3,4]. In particular, the fluorocarbon species which are immediately involved in the thin film growth are not clearly defined.…”