Preparation of MgO doped colloidal SiO2 abrasive and their chemical mechanical polishing performance on c-, r- and a-plane sapphire substrate

• Published in: Ceramics international 2018-08, Vol.44 (12), p.14631-14637
• Main Authors: Yin, Da, Niu, Xinhuan, Zhang, Kai, Wang, Jianchao, Cui, Yaqi
• Format: Article
• Language: English
• Subjects: Chemical mechanical polishing; MgO; Sapphire substrates; Solid-chemical reaction
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2018.05.087

Chemical mechanical polishing (CMP) has been proved to be one of the most important methods to achieve atomic ultra-smooth surface, and it becomes widely used as global planarization techniques. There are some influence factors for CMP processing quality, and abrasive in the slurry is one of the key ones. In order to improve the removal rate and surface quality of sapphire substrate, a new-type MgO doped colloidal silica abrasive was studied Based on the basic principle of chemical thermodynamics, the HSC software was used to analyze the tendency of reactions between MgO doped colloidal silica abrasive and sapphire and between H2O and sapphire to generate solid solutions, compounds and hydrates on the sapphire surface. From the CMP experiment results of a-, r- and c-plane sapphire, it indicated that higher material removal rate (MRR) and lower surface roughness (Sq) were obtained with the slurry containing MgO doped colloidal SiO2 abrasive instead of containing pure SiO2 abrasive under the same conditions. In addition, the action mechanism of MgO doped colloidal SiO2 abrasive on sapphire substrate CMP was studied. From the analyzing result of X-ray photoelectron spectroscopy (XPS), it deduced solid-chemical reaction between sapphire surface and MgO doped colloidal silica abrasive was occurred and Al2Si2O7·2H2O, MgAl2O4 and Al2SiO5 were generated, which can promote chemical effects during CMP and lead to the increase of MRR. Such results have certain guiding significance to practical production.