Clarkson University
Department of Chemical and Biomolecular Engineering
SEMINAR
Surfactant-Mediated Non-Contact Dual Jet Cleaning for Post-CMP Wafer Surface
Wafi Aziz
MS Student, Chemical and Biomolecular Engineering
Clarkson University
The semiconductor industry relies on the process of chemical mechanical planarization (CMP), which can leave a variety of contaminants like particulates, residue, pad debris, and various impurities on the wafer surface. Such defects need to be removed during post-CMP cleaning while minimizing the formation of surface scratches. Traditional cleaning methods such as cleaning solutions along with brush cleaning are efficient but face challenges like cross-contamination, surface scratching, and particle residues.
Cleaning solutions used after CMP, especially for ceria particles, typically include a bond-breaking reagent, a complexing reagent, a cleaning additive, and a pH adjuster. Surfactants are commonly employed as cleaning additives, interacting with films and particles to prevent the redeposition of particles during polishing. Therefore, the concentration, charge, and micelle formation properties of surfactants play a key role in forming complexing agents around ceria particles.
In our research, we investigated how the charge of surfactants and the critical micelle concentration (CMC) affect particle removal during the cleaning process. We used non-contact dual jet cleaning to avoid cross-contamination and surface scratching issues. Our findings showed that cleaning solutions containing anionic surfactants performed well across an 8-inch wafer. Anionic surfactants, with comprehensive attachment of micelles to ceria particles from all sides, outperformed cationic surfactants. We observed that cleaning efficiency improved when surfactant concentrations approached the CMC value, as more micelles were available to saturate the substrate. However, cleaning efficiency decreased when concentrations exceeded the CMC value due to reduced micelle formation in the supersaturated cleaning solution. Additionally, non-contact dual jet cleaning proved effective in reducing cross-contamination, minimizing the risk of wafer surface damage, and enhancing overall cleaning performance by avoiding direct contact with the wafer. These insights provide a better understanding of the cleaning process and can contribute to an improved cleaning protocol in the semiconductor industry.
Monday, October 02, 2023, at 3:00 pm
Science Center 160
Wafi Aziz is a MS student in Chemical and Biomolecular Engineering at Clarkson University under the supervision of Dr. Jihoon Seo. Prior to joining Clarkson University, he received his Bachelor of Science in Chemical Engineering from Bangladesh University of Engineering and Technology. His research focuses on Chemical Mechanical Planarization (CMP) and Post-CMP cleaning techniques of Semiconductor wafers.
