Titanium underlayer

In our ILIT application, a thin gold film (e.g., 10 " cm) is deposited on a quartz substrate with a thinner underlayer ( 5 x 10 cm) of titanium. The titanium underlayer serves three purposes ... 

Figure 1 shows AES data for the oxidized titanium surface before and after deposition of 30 X of platinum with the substrate held at 130 K. The platinum thickness was calculated from the attenuation of the oxygen AES signal assuming layered growth of the metal. From the spectra It Is clear that the platinum was sufficient to completely attenuate the underlaying features of the titanium oxide. 

Recently Evans et al have reported an extreme pattern dependence in the copper polish rate over a tantalum overlayer. Features with large perimeter to area ratios were completely removed while features with lower ratios remained. This behavior was not observed when TiN was used as the underlayer. The behavior, which is attributed to electrochemically induced interaction caused by the difference in the electrochemical potentials of tantalum and copper, is similar to the case of interaction seen between titanium and copper. 

Calcium carbonate is used as a low-cost filler in rubber products for static applications such as carpet underlay. Titanium dioxide finds extensive use in white products such as white tire sidewalls where appearance is important. 

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