The performance and reliability of smartphones and artificial intelligence services depend on how evenly and precisely semiconductor surfaces can be processed. KAIST researchers have developed a new technology that extends the concept of everyday sandpaper to the nano level, enabling semiconductor surfaces to be processed uniformly down to the atomic scale. This technology demonstrates the potential to significantly improve surface quality and processing precision in advanced semiconductor processes such as high-bandwidth memory (HBM).
KAIST announced on the 11th that a research team led by Professor Kim San-ha of the Department of Mechanical Engineering has developed "nano sandpaper" using carbon nanotubes—tens of thousands of times thinner than a human hair—as an abrasive material.
This technology is a new planarization method that can process surfaces more precisely than existing semiconductor manufacturing processes while reducing environmental impact during production.
Sandpaper is a familiar tool for smoothing surfaces by rubbing, but it has been difficult to apply in fields requiring extremely precise surface processing, such as semiconductors. This is because conventional sandpaper is made by attaching abrasive particles with adhesive, which limits the ability to fix fine particles evenly.
The semiconductor industry has used Chemical Mechanical Polishing (CMP), a planarization process using slurry—a chemical liquid with abrasive particles dispersed in it—to overcome these limitations. However, this method requires additional cleaning processes and generates significant waste, making the process complex and environmentally burdensome.
To solve these problems, the research team extended the sandpaper concept to the nano level. They created nano sandpaper by vertically aligning carbon nanotubes, fixing them inside polyurethane, and exposing only a portion on the surface. This structure structurally prevents abrasive detachment, eliminating surface damage concerns while maintaining stable performance through repeated use.
The newly developed nano sandpaper achieves an abrasive density approximately 500,000 times higher than the finest commercial sandpaper products. Sandpaper precision is expressed as "abrasive density (grit number)," indicating how densely abrasive particles are arranged on the surface.
This figure represents the number of abrasive particles per unit area of sandpaper. While everyday sandpaper typically has a grit number of 40 to 3,000, nano sandpaper has a grit number exceeding 1 billion. Through this extremely dense structure, surfaces could be precisely processed to a few nanometers—equivalent to the thickness of just a few atoms.
Experiments confirmed nano sandpaper's effectiveness. Rough copper surfaces could be smoothed to within a few nanometers. In semiconductor pattern planarization experiments, dishing defects were reduced by up to 67% compared to conventional CMP processes. Dishing defects, where the center of wiring becomes depressed, are major flaws affecting the performance and reliability of advanced semiconductors such as HBM.
Notably, because the abrasive is fixed to the sandpaper surface, there is no need for continuous slurry solution supply as in existing processes. This could reduce cleaning processes and eliminate waste slurry, offering the potential to make semiconductor manufacturing more environmentally friendly.
The research team expects this technology could be applied to advanced semiconductor planarization processes such as HBM used in AI servers and hybrid bonding processes, which are attracting attention as next-generation semiconductor connection technology. The significance lies in expanding the everyday concept of sandpaper into nano-precision processing technology, demonstrating the possibility of securing fundamental technology needed for semiconductor manufacturing.
"This is original research showing that the concept of everyday sandpaper can be extended to the nano level and applied to ultra-fine semiconductor manufacturing," said Professor Kim San-ha. "I hope this technology will lead not only to improved semiconductor performance but also to eco-friendly manufacturing processes."
This research, with Dr. Kang Seok-kyung of the Department of Mechanical Engineering as first author, received the Gold Award (first place) in the Mechanical Engineering category at the 31st Samsung Humantech Paper Award hosted by Samsung Electronics. The results were published online on January 8, 2026, in the international journal Advanced Composites and Hybrid Materials (IF 21.8), covering composite materials and nano-engineering.