Electron stimulated decomposition of fluorocarbons on amorphous hydrogenated carbon (a-CHx) overcoats used in data storage media

Yun, Yang; Broitman, Esteban; Gellman, Andrew J.

doi:10.1007/s11249-006-9181-x

Cited by 2 publications

(3 citation statements)

References 35 publications

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“…The net observation is that the changes in the C 1s feature of the a -CF x film are consistent with a net increase in the oxidation state of the surface atoms. This is consistent with XPS studies of the oxidation of a -CH x films which reveal the appearance of high binding energy features during the course of oxidation. − , In the case of the a -CF x film, the changes can be resolved into the changes in the concentrations of the different components of the film.…”

Section: Resultssupporting

confidence: 85%

“…An ion gauge was used to determine the pressure as O 2 was being introduced into the chamber but was then turned off immediately afterward to avoid the influence of electrons, ions, or excited state neutrals emitted from the ion gauge. In prior work studying the oxidation of a -CH x films, it was discovered and reported that the oxidation kinetics are sensitive to the ions and free electrons that are generated by the ion gauge used to measure O 2 pressure. − The same effect was observed when using a -CF x films, and so the uptake curves reported in Figure were all obtained with the ion gauge on for only 30 s every 30 min. This was determined to be sufficiently short that it did not influence the oxidation of the surface.…”

Section: Resultsmentioning

confidence: 83%

“…The conditions for deposition of the a -CF x film were chosen to be similar to those used to deposit the a -CH x films used as overcoats on magnetic data storage media. The a -CH x films generated under these conditions exhibited Raman spectra similar to those of a -CH x films used in commercial hard disk drives. − The dc power of the magnetron sputter source was set to be 75 W. a -CF x films were then deposited under various conditions: substrate temperatures in the range 443−843 K, total CF 4 and Ar gas pressure of 5−12 mTorr, and 10−30% CF 4 /(Ar + CF 4 ). The optimal a -CF x film deposition condition was determined to be the one which generated an a -CF x film having the highest F:C ratio.…”

Section: Methodsmentioning

confidence: 99%

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Oxidation of Fluorinated Amorphous Carbon (a-CF_x) Films

2009

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Amorphous fluorinated carbon (a-CF(x)) films have a variety of potential technological applications. In most such applications these films are exposed to air and undergo partial surface oxidation. X-ray photoemission spectroscopy has been used to study the oxidation of fresh a-CF(x) films deposited by magnetron sputtering. The oxygen sticking coefficient measured by exposure to low pressures (<10(-3) Torr) of oxygen at room temperature is on the order of S approximately 10(-6), indicating that the surfaces of these films are relatively inert to oxidation when compared with most metals. The X-ray photoemission spectra indicate that the initial stages of oxygen exposure (<10(7) langmuirs) result in the preferential oxidation of the carbon atoms with zero or one fluorine atom, perhaps because these carbon atoms are more likely to be found in configurations with unsaturated double bonds and radicals than carbon atoms with two or three fluorine atoms. Exposure of the a-CF(x) film to atmospheric pressures of air (effective exposure of 10(12) langmuirs to O(2)) results in lower levels of oxygen uptake than the low pressure exposures (<10(7) langmuirs). It is suggested that this is the result of oxidative etching of the most reactive carbon atoms, leaving a relatively inert surface. Finally, low pressure exposures to air result in the adsorption of both nitrogen and oxygen onto the surface. Some of the nitrogen adsorbed on the surface at low pressures is in a reversibly adsorbed state in the sense that subsequent exposure to low pressures of O(2) results in the displacement of nitrogen by oxygen. Similarly, when an a-CF(x) film oxidized in pure O(2) is exposed to low pressures of air, some of the adsorbed oxygen is displaced by nitrogen. It is suggested that these forms of nitrogen and oxygen are bound to free radical sites in the film.

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