Fluorinated materials, plasma

In this section the identification of various structural features from the measured binding energies of the core level electrons is discussed. Examples have been chosen in the areas of (a) plasma polymerization of fluorinated materials and (b) surface oxidation of polymers, to encompass both fluorine-containing and oxygen-containing systems. 

Plasma Polymerization of Fluorinated Materials. Figure 8 shows the Cls and FIs binding energies measured for the linear fluoropolymers (.8). While the shifts in binding energy of the FIs levels are relatively small, the shift in the binding energy of the Cls levels induced by fluorine as a substituent is relatively... 

Photoirradiation of this stacked film causes the Ag to diffuse into the Se-Ge film in a process referred to as Ag-photodoping. This diffusion, which is characteristic of amorphous chalcogenide materials, causes the Se-Ge film to become insoluble in alkaline solutions and the resist thus functions as a negative-type photoresist. The photodoped regions also are resistant to fluorine-based plasmas enabling dry development of the resist (7). Dry development has also been achieved using a reactive-ion etching (RIE) technique and is discussed later. 

The part material used is 1.5 mm thick Lucite CP PMMA sheet. This material has a 1.8 MPa heat deflection temperature of 90 °C (manufacturer s data). The tool consists of a 100 mm diameter (100) silicon wafer. The wafer has been etched to a depth of 14 1 pm using a fluorine-based plasma by deep reactive ion etching. The tool is patterned with a set of test features including rectangles, squares, and other shapes. The features widths vary from 3 pm to more than 100 pm, and their spacings vary from 0.1 times to 10 times their widths. An example of e tool features is shown in Figure 2. 

The section on Spectroscopy has been retained but with some revisions and expansion. The section includes ultraviolet-visible spectroscopy, fluorescence, infrared and Raman spectroscopy, and X-ray spectrometry. Detection limits are listed for the elements when using flame emission, flame atomic absorption, electrothermal atomic absorption, argon induction coupled plasma, and flame atomic fluorescence. Nuclear magnetic resonance embraces tables for the nuclear properties of the elements, proton chemical shifts and coupling constants, and similar material for carbon-13, boron-11, nitrogen-15, fluorine-19, silicon-19, and phosphoms-31. 

An important newer use of fluorine is in the preparation of a polymer surface for adhesives (qv) or coatings (qv). In this apphcation the surfaces of a variety of polymers, eg, EPDM mbber, polyethylene—vinyl acetate foams, and mbber tine scrap, that are difficult or impossible to prepare by other methods are easily and quickly treated. Fluorine surface preparation, unlike wet-chemical surface treatment, does not generate large amounts of hazardous wastes and has been demonstrated to be much more effective than plasma or corona surface treatments. Figure 5 details the commercially available equipment for surface treating plastic components. Equipment to continuously treat fabrics, films, sheet foams, and other web materials is also available. 

Chemical removal of surface material is produced through standard bond-breaking reactions. Typically chlorofluorocarbons (CECs) have been used, eg, CECl, CE2CI2, CE Cl, CE4, CHE, C2C1E. Eor example, CE dissociates into E atoms and fluorinated fragments of CE in a plasma ... 

Another field of application of fluorinated biomaterials is connected to lesions or evolving disease pathology of blood vessels. In particular, arteries may become unable to insure an adequate transport of the blood to organs and tissues. Polytetrafluoroethylene (PTFE) and expanded e-PTFE are the preferred materials for vascular prostheses. The interactions of blood cells and blood plasma macromolecules with both natural and artificial vessel walls are discussed in terms of the mechanical properties of the vascular conduit, the morphology, and the physical and chemical characteristics of the blood contacting surface. 

The general structure of this class of materials can, therefore, be summarized as a fine dispersion of metal oxide in a polymer matrix very similar to plasma polytetrafluoroethylene and in principle any metal should be able to be incorporated. Clearly, if the films are protected from the atmosphere, for metals which form involatile fluorides having a relatively weak metal-fluorine bond strength, it should be possible to produce films having metal atoms dispersed in the matrix. It is expected that these films will have many interesting chemical, optical, electrical and magnetic properties., ... 

Reduction in the surface recombination velocity of GaP, from 1.7 x 10s cm/sec to 5xl03 cm/sec, is observed upon exposure to a CF4 plasma in which fluorine is known to be present.20 Again, the product of chemisorption of fluorine on the surface is likely to be a large band gap material such as GaF3, which straddles the edges of the conduction and valence bands of GaP. 

Fluorinated polyurethanes may also be prepared by treating the surface of an unfluorinated material with cold plasma of elemental fluorine37 or carbon tetrafluoride.38... 

---