Super fine cerium hydroxide abrasives for SiO2 film chemical mechanical planarization performing scratch free

Abstract

Face-centered-cubic crystallized super-fine (~ 2 nm in size) wet-ceria-abrasives are synthesized using a novel wet precipitation process that comprises a Ce4+ precursor, C3H4N2 catalyst, and NaOH titrant for a synthesized termination process at temperature of at temperature of 25 °C. This process overcomes the limitations of chemical–mechanical-planarization (CMP)-induced scratches from conventional dry ceria abrasives with irregular surfaces or wet ceria abrasives with crystalline facets in nanoscale semiconductor devices. The chemical composition of super-fine wet ceria abrasives depends on the synthesis termination pH, that is, Ce(OH)4 abrasives at a pH of 4.0–5.0 and a mixture of CeO2 and Ce(OH)4 abrasives at a pH of 5.5–6.5. The Ce(OH)4 abrasives demonstrate better abrasive stability in the SiO2-film CMP slurry than the CeO2 abrasives and produce a minimum abrasive zeta potential (~ 12 mV) and a minimum secondary abrasive size (~ 130 nm) at the synthesis termination pH of 5.0. Additionally, the abrasive stability of the SiO2-film CMP slurry that includes super-fine wet ceria abrasives is notably sensitive to the CMP slurry pH; the best abrasive stability (i.e., a minimum secondary abrasive size of ~ 130 nm) is observed at a specific pH (6.0). As a result, a maximum SiO2-film polishing rate (~ 524 nm/min) is achieved at pH 6.0, and the surface is free of stick-and-slip type scratches.

Minimizing Recess of Cu Pad on Hybrid Bonding with SiCN via Non-selective Chemical Mechanical Polishing and Post-cleaning Steps

“…Hence, the removal rate of SiCN under the alkaline condition could be more easily adjusted than that of SiO 2 . 27,29,30 Removal rate.-Given the zeta-potential results, we conducted CMP using the alkaline slurry. Figure 8 shows the removal rate (RR) of the Cu, Ta, and SiCN.…”

Surface Transformation of Spin-on-Carbon Film via Forming Carbon Iron Complex for Remarkably Enhanced Polishing Rate

“…It is important to remember that, generally, the polishing rate of the SOC film surface increases with a decreasing repulsive force between the ZrO 2 abrasives and the SOC film surface. [ 26 , 27 , 28 , 29 ]. Otherwise, for Region 2, with a ferric catalyst concentration of 0.04~0.20 wt%, the attractive force between the negatively charged ZrO 2 abrasives and positively charged SOC film surface increased notably, from 0 to 32.67 abs.…”

“…In general, the polishing rate of the SOC film surface increases with the attractive force between the ZrO 2 abrasives and the SOC film surface. [ 26 , 27 , 28 , 29 ]. Therefore, for Region 2, the increase in the SOC film surface polishing rate with the ferric catalyst concentration could not be understood from the increase in both the chemical property (i.e., C-C bonds breakage) and the mechanical property (i.e., electrostatic force between the ZrO 2 abrasive and the SOC film surface).…”

Fused silica with sub‐angstrom roughness and minimal surface defects polished by ultrafine nano‐CeO2

“…Based on the previous reasons, we can explore the key factor affecting the generation of submicron defect by the disparity in the number of submicron defect after CMP through using different CeO 2 . As the presence of coarser particles in polishing slurry tends to create critical defects on the surface, 21,36,41 secondary particles can be considered “coarser contamination particles” compared with primary particles in ultrafine nano‐CeO 2 , which taking UF‐1, for example, its primary particle size is 4.0 nm, whereas the length of the secondary particle is 56 nm. In addition, the agglomeration of CeO 2 has been regarded as a vital reason in the generation of surface scratches 30,42 .…”