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Rf plasma-enhanced deposition of fluorinated filmsRelated Patent Categories: Stock Material Or Miscellaneous Articles, Composite (nonstructural Laminate), Of Fluorinated Addition Polymer From Unsaturated MonomersRf plasma-enhanced deposition of fluorinated films description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070172666, Rf plasma-enhanced deposition of fluorinated films. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0002] This invention pertains generally to the radiofrequency (RF) plasma enhanced deposition of fluorinated thin films. BACKGROUND OF THE INVENTION [0003] Use of low fluorescence background (LFB) substrates for Raman Spectroscopy investigations is crucial for the generation of high-resolution Raman spectra. Equally significant is the fact that the LFB substrates should exhibit an advanced hydrophobic character that eliminates the spread of the deposited analyte-spots and renders as a result small (concentrated) analyte surface areas. LFB is also a concern for biosensor and large surface area bio-array applications where the desired molecular recognition sites, the ordered spots of the network, should not "communicate" and should retain their individual reactive specificities. [0004] Hydrophobic, low-friction substrates are also crucial for certain applications. For example, catheter guiding wires have to exhibit inert surface characteristics and should have a low surface energy in order to avoid the development of friction forces between the inner surfaces of the catheters and the surfaces of the metal guiding wire during the insertion of the catheter in a living tissue environment, positioning of stents, etc. Current guiding wire surfaces often exhibit rough and non-lubricious surface characteristics. Coating wire surfaces with an inert, highly fluorinated (Teflon-like) thin layer could significantly enhance all operations and safety issues related to the insertion of bioactive devices into "in vivo" environments. [0005] It is known that LFB and very hydrophobic substrates can be produced by the deposition of Teflon or Teflon-like layers using conventional, immersion, spin-coating and spraying technologies. However, Teflon is not soluble in any solvents and modified poly-tetrafluoroethylene macromolecular chains are shy on certain including thermal stability and hydrophobic character. Adhesion of Teflon particles suspended in organic and inorganic media and Teflon-like materials dissolved in organic solvents is often not satisfactory due to the inert nature of the perfluorinated macromolecular chains that create poor adhesion characteristics of the deposited layers. [0006] An alternative approach for the deposition of highly fluorinated organic macromolecular thin layers onto inorganic and organic substrate surfaces is offered by cold-plasma reaction mechanisms. By starting from various fluorinated olefin and paraffin volatile derivatives Teflon-like thin layers may be deposited onto various substrates using plasma deposition techniques. However, the presence of plasma-generated, omnipresent, free radical sites located on the plasma-coated surfaces and generated as a result of the interaction of plasma species with the "nascent" macromolecular thin-layers induce, under open laboratory conditions, oxidation reactions with the formation of polar functionalities. These oxygen containing groups increase the surface energy of the deposited layers and generate reactive surfaces, which significantly reduce the efficiency of the molecular recognition process. SUMMARY OF THE INVENTION [0007] Low- or atmospheric pressure RF plasma-enhanced thin film deposition methods are provided for the deposition of hydrophobic fluorinated thin films onto various substrates. The methods include at least two steps. In the first step, RF plasma-mediated deposition is used to deposit a fluorinated film onto a substrate surface. In a second step, plasma-generated active sites on the fluorinated film are quenched by reacting them with stable fluorinated gas-phase molecules in situ, in the absence of plasma, to provide a hydrophobic fluorinated thin film having very low oxygen content. In some instances the hydrophobic fluorinated thin films have an atomic oxygen concentration of no more than about 3%. [0008] The fluorinated films deposited using the methods provided herein may be fabricated with lower oxygen content than similar surfaces fabricated using other plasma-mediated deposition techniques that lack an in situ active site quenching step. In addition, unlike similar surfaces made using spin coating techniques, the fluorinated films are strongly bound to the surface. The fluorinated films are hydrophobic and provide very low fluorescence background. [0009] The fluorinated films provided herein are well suited for use as coatings in chemical and biochemical sensors where low fluorescence background is important. Such sensors include biochips and biosensors, including flexible, thin-film biosensors that can be integrated into traditional microelectronics and used in fluorescence assays. The fluorinated films are also well suited for use as coatings on implantable medical devices where low friction, hydrophobic surfaces are important. For example, the coatings may be applied to catheter guide wires to prevent sticking of the guide wires to the catheter surface. [0010] In a first step of the methods provided herein, the surface of a substrate is exposed to a plasma of fluorine-containing fragment molecules generated from fluorinated precursor molecules under conditions that promote the deposition of a crosslinked fluorinated film on the surface of the substrate. In a subsequent step, plasma generated active sites (e.g., ion and free radicals) on the surface are reacted with molecules of a fluorinated quenching molecule (which may or may not be same as the fluorinated precursor molecule used to generate the fluorine-containing fragment molecules) in situ, in the absence of plasma, to quench the surface active sites and prevent or minimize surface oxidation. [0011] The methods provided herein may be used to coat the surfaces of a broad range of organic and inorganic substrates. The methods are particularly well-suited for use with inorganic substrates, including, but not limited to, metal substrates (e.g., stainless steel), silica, quartz, glass, and metal-coated substrates (e.g., gold-coated substrates). [0012] Further objects, features and advantages of the invention will be apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0013] FIG. 1 shows the electron-impact fragmentation pattern for hexafluoropropylene oxide. [0014] FIG. 2 shows the electron-impact fragmentation pattern for hexafluoropropene. [0015] FIG. 3 is a schematic diagram of a parallel plate plasma reactor that may be used to carry out the present methods. [0016] FIG. 4 is a schematic diagram the gas reservoir, valve and tubing of the plasma reactor of FIG. 3. [0017] FIG. 5 is a schematic diagram of a rotary plasma reactor that maybe used to carry out the present methods. [0018] FIG. 6 shows the fluorescence Raman spectra for lysozymes on a HFPO-based fluorinated thin film made in accordance with the present methods and a fluorinated film made by spin-coating. [0019] FIG. 7 shows the fluorescence Raman spectra for lysozymes on a HFPO-based fluorinated thin film made in accordance with the present methods and a fluorinated film made by spin-coating. [0020] FIG. 8 shows the fluorescence Raman spectra for lysozymes on a HFPP-based fluorinated thin film made in accordance with the present methods and a fluorinated film made by spin-coating. DETAILED DESCRIPTION Continue reading about Rf plasma-enhanced deposition of fluorinated films... Full patent description for Rf plasma-enhanced deposition of fluorinated films Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Rf plasma-enhanced deposition of fluorinated films patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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