Effect of La Doping of Ceria Abrasives for STI CMP
In the present study, ceria is synthesized using sol gel and liquid phase synthesis (LPS). Polishing experiments are done on different ceria abrasives with same additives. To study the effect of impurity on polishing, lanthanum is added to ceria during the synthesis stage. The polishing results show that ceria without any impurity give high selectivity with L-proline while ceria with lanthanum as impurity does not give high selectivity.
To compare the results of polishing, commercial ceria with high and low purity obtained from sigma aldrich (ceria-SA) are considered for polishing experiments. Polishing with commercial ceria show similar results obtained with synthesized ceria. The ceria particles both commercial and synthesized were characterized by x-ray diffraction, energy dispersive spectra and scanning electron microscopy techniques. Polishing experiments were also conducted with milling the commercial ceria to evaluate if the size of ceria abrasive plays a role in modifying the selectivity.
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