Schematic Diagram of a Typical R-F Sputtering System

Further control of the ion paths can be obtained by introducing a positively charged screen or ring either between the target and the substrate or below the substrate . This can be used to apply a positive DC bias in the region of the substrate, and provides further control of the plasma and sputtering conditions. 

The introduction of unbalanced magnetron sputtering, in which part of the argon plasma can impinge on the substrate, allows ion bombardment of the coating as it forms. The use of ion-beam assisted deposition can be used concurrently or sequentially. This technique is described separately later in the chapter. 

Because of the complex interaction of many of the variables, and the influence of the shape and size of the vacuum chamber and the sputtering module, no attempt will be made here to analyse or define all the effects of the variables. In practice it seems that different operators have established their own optimum operating conditions, and that these differ considerably between different operators, even after thirty years of experience. 

The influence of the substrate will be discussed later, but in general substrates for sputtered molybdenum disulphide films are very smooth, with surface textures of the order of 0.1 //m. The gross keying effect which has been found important for adhesion of bonded or burnished films is therefore not normally available. It has been 

Lavik and Campbell studied coatings sputtered at temperatures between 150°C and 427°C, and found a high degree of crystallinity. They estimated that about 30 per cent of the crystais were oriented with their basal planes parallel to the substrate surface, and 70 per cent perpendicular to the surface. Most workers now appear to assume that above 70°C an even higher proportion of the crystals have the perpendicular orientation and this is discussed later. 

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Figure 10.2 Schematic Diagram of a Typical R-F Sputtering System (Ref.559)...

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