CHEMOMECHANICAL SILICON POLISHING - ELECTROCHEMICAL INSITU MEASUREMENTS

Silicon polishing in aqueous silica suspensions with a pH of about 10 was studied by electrochemical in situ measurements and defect sensitive etching. It was found that the anodic dissolution current at both p- and n-type Si can be greatly enhanced by mechanical removal of oxide layers. When polishing is performed with a soft polishing pad that can absorb large amounts of polishing fluid, the main mechanism of material removal is chemical etching, which results in defect-free Si surfaces. When a relatively hard, abrasive polishing pad is used, the material is removed by both chemical etching and mechanical abrasion. The latter process yields Si surfaces which show many imperfections after defect sensitive etching.