Chlorine-containing plasma

Aluminum is used as a metallization material in current microelectronic devices. It can be etched by chlorine containing plasmas, provided that the native aluminum oxide is removed. This is accomplished with oxide scavengers such as BCI3 added to the plasma. Aluminum etching is isotropic in fact a clean aluminum surface reacts with atomic and molecular chlorine even in the absence of a plasma [225]. Anisotropy is achieved by the wall passivation mechanism (Fig. 16d). 

Flamm, D.L. (1990), Mechanisms of Silicon Etching in Fluorine- and Chlorine Containing Plasmas, Report UCB/ERL M90/41, College of Engineering, University of California, Berkley. 

I 1.8.7. Non-Thermal Plasma Control of Diluted Large-Volume Emissions of Chlorine-Containing VOCs... 

Fig. 11-73 shows a comparison between electron-beam, pulsed corona, and DBD processing of 100 ppm CCI4 in dry air at 25°C (Penetrante et al., 1996a,b). The major products of plasma processing of CCU in air are CU, COCU, and HCl. These products can be easily removed from the gas stream they dissolve and/or dissociate in aqueous solutions and combine with NaHCOs in a scrubber solution to form NaCl. Similar approaches can be applied as performed for product removal from air streams during the plasma cleaning of other diluted chlorine-containing VOC exhausts. 

Other methods iaclude hydrogen reduction of TiCl to TiCl and TiCl2 reduction above the melting poiat of titanium metal with sodium, which presents a container problem plasma reduction, ia which titanium is collected as a powder, and ionized and vaporized titanium combine with chlorine gas to reform TiCl2 on cool-down and aluminum reduction, which reduces TiCl to lower chlorides (19,20). 

HOCl is one of the oxidants that activated phagocytes have in their arsenal. Hu et al. (1993) have shown that plasma albumin sulphydryl and ascorbic acid both protect against oxidant injury from HOCl. Neutrophils, interestingly, contain about 25 times more ascorbic acid than plasma. This su ests an endogenous self-protection role. This work is important because of the biological emphasis of reactive chlorine by the neutrophil. 

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