Plasma cleaning method

Researches are carried out by equipment manufacturers, for example, remote plasma cleaning method was presented by Applied Materials Inc. at the 1997 Semicon West [43]. This method improved the usual decomposition ratio of NF3 ca 50% to more than 99%. Plasma is normally generated in a chamber, however,... 

This method is one of the dry methods in which no chemical reaction is involved. Preparation of ultrafine particles by physical vapor deposition (PVD) dose not require washing and calcination, which are indispensable for chemical preparation such as in CP and DP methods. As waste water and waste gases are not by-produced, the arc plasma (AP) method is expected to grow in popularity as one of the industrial production methods for gold catalysts and as a clean preparation method. 

Rezk et al. [74] developed and validated a reversed-phase HPLC assay method for the simultaneous quantitative determination of omeprazole and its three metabolites in human plasma. The method provides excellent chromatographic resolution and peak shape for the four components and the internal standard within a 17-min run time. The simple extraction method results in a clean baseline and relatively high extraction efficiency. The method was validated over the range of 2-2000 ng/ml. The resolution and analysis for the four analytes omeprazole, hydroxyome-prazole, omeprazole sulfone, and omeprazole sulfide and the internal standard utilized a Zorbax C18 (15 cm x 3 mm, 5 /im) with a Zorbax C18 (12.5 cm x 4.6 mm) guard column. The mobile phase consisted of two components. Mobile phase A was 22 mM phosphate monobasic, adjusted to a pH of 6 with diluted sodium hydroxide. This solution was filtered through a 0.45-/im membrane filter, then mixed as 900 ml buffer to 100 ml methanol. Mobile phase B was composed of 100 ml of the phosphate buffer as mobile phase A, mixed with 800 ml of acetonitrile, 100 ml of methanol, and 100 /A of trifluoroacetic acid with an initial flow-rate of 0.55 ml/min and detection at 302 nm. 

Figures 31.23 and 31.24 show typical scanned images of SO2 and Prohesion salt spray-tested [7B] panels, respectively. Visual observation of these images reveals that the plasma-modified panels of [7B] have outperformed both control panels in the SO2 salt spray test. These plasma film combinations were prepared on deoxidized [7B] surfaces without any plasma cleaning pretreatment. Figure 31.23 also shows an image of a panel that had simply been deoxidized prior to the application of E-coat, which performed excellently in the SO2 salt spray test. Figure 31.25 compares the corrosion width obtained by the two methods. The comparisons shown in Figures 31.19, 31.22, and 31.25 indicates that the results obtained by the two methods do not match, partly due to the different duration of tests, and that samples which show good results in one test do not do as well in the other test.

The in situ plasma cleaning procedure performed after CVD of dielectric thin films is one of the major emitters of PFCs in semiconductor manufacturing it can represent 50-70% of the total PFC emission in a semiconductor fabrication plant. To clean the process chambers of deposited by-products, conventional cleaning methods use CF4 or C2F6 gases activated by RF CCP (usually 13.56 MHz) inside the process chamber. These PFC gases achieve a relatively low degree of dissociation and unreacted molecules are enutted in the process... 

Plasma induced contamination on test silicon substrates using an airlock moimted plasma etching system has proven to be very useful and has been used to develop cleaning methods to remove etchant residue. This system heis also b n used to study plasma-surface interactions in general (46,48,54). 

The shields for suppression of electric field were made in the form of compwsites of polypropylene unwoven fabrics with deposited plasma layers. Additional advantage of the application of the method is the possibility of plasma cleaning of a fabric surface and modifying its surface properties. The unique properties of pulse plasma make possible to obtain metallic and dielectric coatings on polypropylene fabrics, which are not achievable by standard methods. The coatings are characterized by a good adhesion to the substrates. 

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