Oxide deglazing step

As observed in the scanning electron microscope (SEM) image, any macro-scratch can be observed right after the STI CMP step, but most of the polishing scratches can be seen after the oxide deglazing step since the wet etch step can make any tiny microscratch more visible by isotropic etching (Figure 1.13). A very tiny micro-scratch can be observed on the nitride surface, but the scratch on the oxide surface is expanded due to the additional wet etch step. 

Figure 1.19 Side view of polishing scratch after oxide deglazing step at post-STI CMP [10].

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