KAIST

<(From Left) Dr. Sukkyung Kang, Professor Sanha Kim from Department of Mechanical Engineering> 

The performance and stability of smartphones and artificial intelligence (AI) services depend on how uniformly and precisely semiconductor surfaces are processed. KAIST researchers have expanded the concept of everyday “sandpaper” into the realm of nanotechnology, developing a new technique capable of processing semiconductor surfaces uniformly down to the atomic level. This technology demonstrates the potential to significantly improve surface quality and processing precision in advanced semiconductor processes such as high-bandwidth memory (HBM).

KAIST (President Kwang Hyung Lee) announced on the 11th of February that a research team led by Professor Sanha Kim of the Department of Mechanical Engineering has developed a “nano sandpaper” that utilizes carbon nanotubes—tens of thousands of times thinner than a human hair—as abrasive materials. This technology enables more precise surface processing than existing semiconductor manufacturing processes, while also reducing environmental burdens generated during fabrication, presenting a new planarization technique.

< Nano Sandpaper AI-Generated Image > 

Although sandpaper is a familiar tool used to smooth surfaces by rubbing, it has been difficult to apply it to fields such as semiconductors, where extremely precise surface processing is required. This limitation arises because conventional sandpaper is manufactured by attaching abrasive particles with adhesives, making it difficult to uniformly secure extremely fine particles.

To overcome such limitations, the semiconductor industry has adopted a planarization process known as chemical mechanical polishing (CMP), which uses a chemical slurry in which abrasive particles are dispersed in liquid. However, this method requires additional cleaning steps and generates large amounts of waste, making the process complex and environmentally burdensome.

To address these issues, the research team extended the concept of sandpaper to the nanoscale. By vertically aligning carbon nanotubes, fixing them inside polyurethane, and partially exposing them on the surface, they implemented a “nano sandpaper.” This structure structurally suppresses abrasive detachment, eliminating concerns about surface damage and maintaining stable performance even after repeated use.

The nano sandpaper developed in this study achieves an abrasive density approximately 500,000 times higher than that of the finest commercially available sandpaper. The precision of sandpaper is expressed in terms of “abrasive density (grit number),” which indicates how densely abrasive particles are arranged on the surface. While everyday sandpaper typically ranges from 40 to 3000 grit, the nano sandpaper exceeds 1,000,000,000 grit. Through this extremely dense structure, surfaces could be processed with precision down to several nanometers—equivalent to the thickness of only a few atoms.

The effectiveness of the nano sandpaper was confirmed through experiments. Rough copper surfaces were polished to a smoothness at the nanometer level, and in semiconductor pattern planarization experiments, the technique reduced dishing defects by up to 67% compared with conventional CMP processes. Dishing defects refer to the phenomenon in which the center of interconnect lines becomes recessed, a major defect affecting the performance and reliability of advanced semiconductors such as HBM.

In particular, because the abrasive materials are fixed on the sandpaper surface, the technology does not require continuous supply of slurry solutions as in conventional processes. This reduces cleaning steps and eliminates waste slurry, presenting the possibility of transitioning semiconductor manufacturing toward more environmentally friendly processes.

< Nano Sandpaper Schematic Diagram > 

< Detailed Image of Nano Sandpaper >

The research team expects that this technology can be applied to advanced semiconductor planarization processes such as HBM used in AI servers, as well as to hybrid bonding processes, which are gaining attention as next-generation semiconductor interconnection technologies. The study is also significant in that it expands the everyday concept of sandpaper into nano-precision processing technology, suggesting the possibility of securing core technologies required for semiconductor manufacturing.

Professor Sanha Kim stated, “This is an original study demonstrating that the everyday concept of sandpaper can be extended to the nanoscale and applied to ultra-fine semiconductor manufacturing,” adding, “We hope this technology will lead not only to improved semiconductor performance but also to environmentally friendly manufacturing processes.”

In this study, Dr. Sukkyung Kang of the Department of Mechanical Engineering participated as the first author. The research was recognized for its excellence by receiving the Gold Prize (1st place) in the Mechanical Engineering Division at the 31st Samsung Human Tech Paper Award, hosted by Samsung Electronics. The findings were published online on January 8, 2026, in the international journal Advanced Composites and Hybrid Materials (IF 21.8).
※ Paper title: “Carbon nanotube sandpaper for atomic-precision surface finishing”
DOI: https://doi.org/10.1007/s42114-025-01608-3

This research was supported by the National Research Foundation of Korea (Mid-Career Researcher Program; Ministry of Science and ICT, NRF, RS-2025-00560856), the Glocal Lab Program (Ministry of Education, NRF, RS-2025-25406725), the InnoCORE Program (Ministry of Science and ICT, NRF, N10250154), and the KAIST Up Program.