Development of “Soft” Cleaning Chemistries for Enhanced STI Post-CMP Cleaning

Abstract

With the rapid miniaturization of advanced technologies, limiting device defects has become of utmost importance in maintaining high performing integrated circuits. Shallow trench isolation (STI) chemical mechanical planarization (CMP) uses a synergistic balance of ceria (CeO2) nanoparticles and functional chemistry to modulate surface adsorption interactions necessary to remove excess topography. This work aims to develop a post-CMP cleaning chemistry that enhances nanoparticle removal via “soft” encapsulation by employing a polyelectrolyte/surfactant (PES) matrix. A surface adsorbing/charge flipping encapsulation process is proposed as a vehicle to remove slurry contamination at low friction. Investigation into the synergy between slurry chemistry and PES cleaning chemistry, with respect to defect aggregate formation, was correlated to the cleaning efficiency as well as friction. Using a suite of techniques to study the real-time defect aggregate formation mechanism it was determined that the supramolecular structure is critical to balance defect forming events with enhanced cleaning efficiency.

Effects of Gas-Dissolved Water for Ceria Nanoparticles on the SiO2 Film Surface in Post-CMP Cleaning

“…Re-adhesion can be migrated through zeta potential adjustments 79 or use of surfactants. [80][81][82][83] Mechanisms of CNP removal with GDWs under megasonic conditions.-The mechanisms underlying the removal of CNPs from the SiO 2 film surface by GDW supply and under megasonic conditions are depicted in Fig. 13.…”

Review—Post-Chemical Mechanical Planarization Cleaning Technology

“…Ascorbic acid, ammonium carbonate, Triton X-100 (used for cleaning Si 3 N 4 and Si 3 N 4 surfaces). 119 Graverson et al 120 developed post-CMP chemistry using a polyelectrolyte/surfactants (POS) matrix to clean the ceria nanoparticle contaminants at very low friction. 120 For the removal of contaminants, they employed the concept of charge flipping/surface adsorbing "soft" encapsulated process.…”

“…119 Graverson et al 120 developed post-CMP chemistry using a polyelectrolyte/surfactants (POS) matrix to clean the ceria nanoparticle contaminants at very low friction. 120 For the removal of contaminants, they employed the concept of charge flipping/surface adsorbing "soft" encapsulated process. The other commonly noticed defect after oxide CMP is scratch.…”

Coupling Supramolecular Assemblies and Reactive Oxygen Species (ROS) with Megasonic Action for Applications in Shallow Trench Isolation (STI) Post-Chemical Mechanical Planarization (p-CMP) Cleaning

“…While this has shown to be an effective mode of particle removal, there is an increase in the process shear force (mechanical component), which results in secondary defect formation (i.e., increased scratching/surface roughness). , More recently attention has shifted to developing p-CMP cleaning formulations that employ encapsulation of the CeO 2 nanoparticle using supramolecular chemistries (i.e., surfactants, polyelectrolytes, liposomes, etc.). Previous work has shown that the shape and charge of the supramolecular structure play a crucial role in effective CeO 2 nanoparticle removal. − More specifically, upon delivery to the wafer surface, micelles recover at a slower rate than polyelectrolytes. Though these additives do reduce the overall shear force and help to minimize defectivity induced during the cleaning process, it is not perfect and can cause p-CMP defects from the contact modality.…”