Mechanisms of colloidal ceria contamination and cleaning during oxide post CMP cleaning

Ceria removal during the STI post-CMP cleaning process has recently become a serious concern in the semiconductor industry. Understanding ceria adhesion and its removal mechanism is necessary for designing a suitable post CMP cleaning methodology. Recently, colloidal ceria slurries have been heavily...

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Bibliographic Details
Published in:Microelectronic engineering 2021-03, Vol.241, p.111544, Article 111544
Main Authors: Sahir, Samrina, Yerriboina, Nagendra Prasad, Han, So-Young, Kim, Tae-Gon, Mahadev, Niraj, Park, Jin-Goo
Format: Article
Language:English
Subjects:
Adhesion
Adhesive bonding
Adhesive strength
Brush scrubbing
Ce-O-Si bonding, Colloidal Ceria
Cerium oxides
Chemical bonds
Cleaning
Colloids
Contamination
Hydrofluoric acid
Hydrogen peroxide
Particle size
Post CMP cleaning
Semiconductors
Slurries
STI CMP
Sulfuric acid
Washing
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Summary:Ceria removal during the STI post-CMP cleaning process has recently become a serious concern in the semiconductor industry. Understanding ceria adhesion and its removal mechanism is necessary for designing a suitable post CMP cleaning methodology. Recently, colloidal ceria slurries have been heavily used due to the low defectivity factor. In this work, colloidal ceria adhesion and removal behaviors were studied as a function of particle sizes. It was found that polishing produces more contamination of ceria to oxide surface than dipping conditions and the strength of adhesion is increased with decreasing ceria size due to a higher Ce3+ concentration for smaller size particles resulting in more Ce-O-Si bonding. Ceria adhesion is mainly attributed to Ce-O-Si bond formation. Different cleaning methods (megasonic, brush scrubbing, SC1 (standard cleaning solution 1), DHF (diluted hydrofluoric acid) and SPM (sulfuric acid and hydrogen peroxide solution) were employed in removing these ceria particles. It was found that larger particles could be removed effectively with physical force, and smaller particles could be removed using chemicals such as DHF or SPM. Hence, it is concluded that an appropriate cleaning method should be chosen based on the size of the ceria. [Display omitted] •Characterization of different particle size ceria slurries.•Smaller size cerai resulted in higher Ce-O-Si bonding.•Polishing with ceria resulted in higher Ce-O-Si bonding than contamination by dipping.•Megasonic and brush scrubbing could effectively remove large size particles.•DHF and SPM could effectively remove chemically bonded (Ce-O-Si) smaller ceria particles.
ISSN:0167-9317
1873-5568
DOI:10.1016/j.mee.2021.111544