Contamination Mechanism of Ceria Particles on the Oxide Surface after the CMP Process

Abstract

The contamination behavior of ceria particles (50 and 100 nm) with oxide surfaces at pH 4 and 8 was studied using dipping and polishing conditions. Higher contamination at pH 4 than pH 8 was observed for dipping cases. In contrast, pH 8 conditions produced higher contamination than pH 4 for polishing cases. The difference in the contamination between dipping and polishing could be attributed to electrostatic attraction and chemical bonding. During polishing, weak or no chemical bonding may occur at pH 4, whereas the Ce–O–Si bond may form due to the surface charges of ceria and silica at pH 8. XPS analysis revealed that strong additional peaks related to Ce–O–Si bonding were detected for O 1s spectra at a binding energy of around 532 eV for surfaces polished at pH 8. Similar results were observed for 50 nm as well as 100 nm ceria particles. Based on the results, we concluded that ceria particles would have different adhesion behaviors for dipping and polishing at the same pH value. Also, higher ceria adhesion was observed at higher pH compared to lower pH during the CMP process, which was correlated to strong Ce–O–Si chemical bond formation due to the CMP conditions.

Changing the calcination temperature to tune the microstructure and polishing properties of ceria octahedrons

“…Considering that K9 glass has an electronegative surface charge (negative zeta potential), opposite surface charge will lead to the adhesion of calcined particles to the K9 surface by electrostatic attraction, which is helpful to improve the removal rate. 29,30 The particle size distribution measurement showed that D 90 of the calcined products was remarkably increased with the rising of calcination temperature, resulting in the broadening of the particle size distribution (R values). This may be because with the increase of calcination temperature, fusion occurred not only between primary nanocrystals, but also between octahedrons, forming particle agglomerates.…”

Selective Leaching of Rare Earth Elements from Ion-Adsorption Rare Earth Tailings: A Synergy between CeO2 Reduction and Fe/Mn Stabilization

“…Both pseudoternary phase equilibria diagrams of the CeO 2 –MnO 2 –Fe 2 O 3 –S and FeS–MnSO 4 –Fe 2 O 3 –CeO 2 system (Figures S7) suggested that Ce 2 (SO 4 ) 3 was found to be a favorable stable phase in the synergistic process. Binding energy at 886.5, 890.2, 893.9, and 897.9 eV in the XPS spectra (Figures S6D) and the characteristic peaks at 1120.8 cm –1 in the Raman spectrum (Figure S8) were assigned to Ce­(III) 3d 5/2 and SO 4 2– , respectively, ,− which further confirmed the transformation of CeO 2 as Ce 2 (SO 4 ) 3 . However, the orthogonal experimental results revealed that when the calcinating temperature was over 400 °C, lower leaching efficiency of Ce was obtained, indicating the further transformation of Ce 2 (SO 4 ) 3 with the raised temperature.…”

Study on PVA Brush Loading and Conditioning during Shallow Trench Isolation Post-CMP Cleaning Process

“…Different removal mechanisms such as undercut/etching, dissolution, bond rupture, and electrostatic interactions have been reported for ceria removal from oxide wafers. 9,20,[25][26][27][28] To investigate the mechanism of ceria removal from oxide wafers during scrubbing, we focused on undercut/etching and electrostatic interaction phenomena. No significant etching of the oxide was observed with different pH cleaning solutions (results are not reported here), which indicates that undercutting is not a major factor during brush scrubbing at any pH condition.…”