Chemistry Reference
In-Depth Information
The etch rates of as-deposited oxides can be greatly reduced by annealing which
results in densification of the oxides.
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As shown in Table 4.1, annealing can
result in two- to sixfold reduction in etch rate depending on the oxide and etching solu-
tion. For example, after annealing in steam at about 900 °C for 15min, which results
in a 5% increase in the density of the oxide, the etch rate is reduced by a factor of 6.
232
The effect of annealing depends on solution composition as
Figure 4.25 shows the effect of annealing temperature on the etch rate of CVD
For fluorinated oxides, annealing results in the reduction of fluorine concentration as
well as the etch rate.
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452
shown in Fig. 4.24.
4.6. ANODIC OXIDES
There is very little systematic information on the etch rates of anodic oxides in
the literature. Some of the etch rate data are listed in Table 4.1. In relative terms, the
