Effect of ZnO-SiO₂ Composite Abrasive on Sapphire Polishing Performance and Mechanism Analysis

Abstract

Sapphire is widely used because of its excellent physical and chemical properties, and the requirements for its surface quality and processing efficiency are becoming more stringent. Chemical mechanical polishing (CMP) has been widely used to achieve nondamaged and atomically smooth surfaces on sapphire wafers. To promote the removal rate and surface quality, the effect of ZnO-SiO 2 composite abrasive on sapphire CMP performance was studied. A higher material removal rate and lower Root mean squared surface roughness (Sq) (less than 0.3 nm) were obtained with the ZnO nano-particle slurry. HSC chemistry software was used to calculate the Gibbs free energy of possible chemical reactions between sapphire, SiO 2 , H 2 O, and ZnO to determine whether new reactions can occur. At the same time, the action and removal mechanism of sapphire using the ZnO-SiO 2 composite slurry were investigated. X-ray photoelectron spectroscopy showed that the new reaction was produced and the product of the solid-state reaction was ZnAl 2 O 4 . In addition, only a hydration layer was observed on the surface of soaked sapphire in ZnO-based slurry, while the solid-state reaction products of Al 2 SiO 5 /Al 2 SiO 5 (OH) 4 and ZnAl 2 O 4 existed on the surface of polished sapphire. This indicates that mechanical processing provides energy or conditions which can promote chemical effects during CMP and lead to solid-phase reactions. Finally, a mechanochemical effect is introduced to explain the mechanism of solid state reaction in sapphire CMP process, which has a certain guiding significance to the mechanism analysis of CMP for different materials.

A Novel Circulating Abrasive Flow Strategy Using Circular Halbach Array for Magneto-Rheological Finishing of Ti-6Al-4V

“…In the context of polishing sapphire wafers, SiO2 emerges as a more favourable material than CeO2 and ZrO2. The abrasive SiO2 exhibits preference due to its capacity to react with the sapphire surface, creating a soft layer easily removable through mechanical action, as observed in previous studies [13][14][15]. Pan et al [16] innovatively developed SiO2-CI composite particles using the sol-gel method for MRF of sapphire materials.…”

Preparation of the Nanodiamond@SiO2 Abrasive and its Effect on the Polishing Performance of Zirconia Ceramics

“…[9][10][11] The polishing slurry is a crucial part of CMP, containing abrasives, chemicals, and so on. 12,13 Among them, nanodiamond (ND) abrasives are characterized by ultra-hardness and large specific surface area, which brings to outstanding mechanical polishing effect and high material removal rate. 14,15 However, the presence of active hydroxyl groups on the surface of nanodiamond makes nanodiamond particles easily agglomerate together to form micron agglomerates, causing mechanical damage to the surface of the polished workpiece.…”