Processing methods sputtering

The atom flux sputtered from a solid surface under energetic ion bombardment provides a representative sampling of the solid. Sputtered neutral mass spectrometry has been developed as method to quantitatively measure the composition of this atom flux and thus the composition of the sputtered material. The measurement of ionized sputtered neutrals has been a significant improvement over the use of sputtered ions as a measure of flux composition (the process called SIMS), since sputtered ion yields are seriously affected by matrix composition. Neutral panicles are ionized by a separate process after sputter atomization, and SNMS quantitation is thus independent of the matrix. Also, since the sputtering and ionization processes are separate, an ionization process can be selected that provides relatively uniform yields for essentially all elements. 

These are produced by several conversion processes (evaporation, sputtering, chemical plasma deposition). Evaporation is the same method as that used to create metallisation using aluminium. A material is heated in a crucible by either a resistive heat or an electron beam gun (hence the name electron beam deposition), whereby the material evaporates and subsequently condenses on a chilled film in a vacuum chamber. In the case of Sit), coatings, the aluminium used in metallisation is replaced by SiO/Si02. 

Anodization is an intriguing approach to generating controlled thickness dielectric films. Sputtering the metals onto flexible substrates opens up the possibility of flexible devices. Anodization is a low-temperature process that occurs in aqueous solution, which suggests potentially easy processing methods. 

Several processing methods, including sputtering, sol-gel processes, vapour deposition and thermal spraying, have been developed to deposit nanocrystalline and microcrystalline Ti02 powders. 

Another way to achieve a wide variety of the metallic compositions is sputtering deposition, where a set of ion beams hits a target surface. Each sputter gun holds targets of a specific element of interest. This process, called sputter deposition, is the primary method for the production of thin films [129]. Details of the preparation can be obtained elsewhere [130]. 

Ion implantation (qv) has a large (10 K/s) effective quench rate (64). This surface treatment technique allows a wide variety of atomic species to be introduced into the surface. Sputtering and evaporation methods are other very slow approaches to making amorphous films, atom by atom. The processes involve deposition of a vapor onto a cold substrate. The buildup rate (20 p.m/h) is also sensitive to deposition conditions, including the presence of impurity atoms which can faciUtate the formation of an amorphous stmcture. An approach used for metal—metalloid amorphous alloys is chemical deposition and electro deposition. 

Metallization layers are generally deposited either by CVD or by physical vapor deposition methods such as evaporation (qv) or sputtering. In recent years sputter deposition has become the predominant technique for aluminum metallization. Energetic ions are used to bombard a target such as soHd aluminum to release atoms that subsequentiy condense on the desired substrate surface. The quaUty of the deposited layers depends on the cleanliness and efficiency of the vacuum systems used in the process. The mass deposited per unit area can be calculated using the cosine law of deposition ... 

Up to the present, a number of conventional film preparation methods like PVD, CVD, electro-chemical deposition, etc., have been reported to be used in synthesis of CNx films. Muhl et al. [57] reviewed the works performed worldwide, before the year 1998, on the methods and results of preparing carbon nitride hlms. They divided the preparation techniques into several sections including atmospheric-pressure chemical processes, ion-beam deposition, laser techniques, chemical vapor deposition, and reactive sputtering [57]. The methods used in succeeding research work basically did not... 

Susac et al. [33] showed that the cobalt-selenium (Co-Se) system prepared by sputtering and chemical methods was catalytically active toward the ORR in an acidic medium. Lee et al. [34] synthesized ternary non-noble selenides based on W and Co by the reaction of the metal carbonyls and elemental Se in xylenes. These W-Co-Se systems showed catalytic activity toward ORR in acidic media, albeit lower than with Pt/C and seemingly proceeding as a two-electron process. It was pointed out that non-noble metals too can serve as active sites for catalysis, in fact generating sufficient activity to be comparable to that of a noble metal, provided that electronic effects have been induced by the chalcogen modification. 

Modem trace analysis is interested in detailed information about the distribution of elements in microareas and their chemical binding forms (specia-tion). The limited sample mass implies methods with absolute detection limits as high as possible. Use of the sputtering process as a sampling technique localises the analytical zone at the outer layers of a solid, and allows analysis to progress into the interior. 

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