Breakthrough in semiconductor patterning: Latest block copolymer achieves 7.6 nm line width

Miniaturization is certainly one of the basic qualities of recent electronics and is basically accountable for the incredible increments in performance witnessed over the past many years. To maintain this momentum going, it’s needed to attain circuit patterns finer than the prevailing ones on semiconductor chips, that are a vital a part of all electronic devices. Some experts estimate that, by 2037, the smallest distance between features in semiconductor devices, generally known as ‘half-pitch,’ will should be as small as 8 nm to support next-generation electronics, emphasizing the necessity for advancements in lithographic processes (method of making highly complex circuit patterns on semiconductor parts).

As one would expect, creating such finely detailed structures on any form of material is an enormous undertaking. One promising avenue to attain this feat known as directed self-assembly (DSA) with block copolymers (BCPs). Simply put, BCPs are long chain-like molecules produced from two or more distinct sections — or blocks — of polymers. The technique of DSA involves exploiting the interactions between different blocks in BCPs in order that they spontaneously and consistently arrange themselves into ordered structures and patterns. While this strategy is definitely powerful, producing features smaller than 10 nanometers (sub-10 nm) using DSA stays difficult.

In a recent study published on 06 July 2024 in Nature Communications, researchers from Tokyo Institute of Technology (Tokyo Tech) and Tokyo Ohka Kogyo (TOK) managed to push the envelope of the probabilities on this field. Led by Professor Teruaki Hayakawa, the research team developed a novel BCP that was fastidiously adapted to create incredibly small line patterns on a substrate in the shape of lamellar domains (structure composed of fantastic and alternative layers). These tiny patterns could pave the way in which for brand spanking new advanced semiconductor devices.

The newly developed BCP was created from polystyrene-block-poly(methyl methacrylate) (or PS-b-PMMA), a representative and widely studied BCP for DSA. First, the researchers introduced an appropriate amount of poly(glycidyl methacrylate) (PGMA) into PS-b-PMMA, obtaining PS-b-(PGMA-r-PMMA). Afterwards, they modified the PGMA segment with different thiols, aiming to refine the repulsive interactions between the various blocks within the resulting polymer, named PS-b-PG_FM. The PS and PMMA segments also controlled the affinity of the various parts of the molecule for air, which plays a vital role in its self-alignment process during DSA.

The tailored BCP reliably self-assembled into exceptionally small nanometric lamellar structures when applied as a skinny film, as confirmed by atomic force microscopy. Furthermore, this recent compound displayed impressive performance on a substrate with parallel polystyrene chemical guides.

“Thin-film aligned lamellar domains with a vertical orientation might be reliably and reproducibly obtained via directed self-assembly, yielding parallel line patterns that correspond to a half-pitch size of seven.6 nm,” highlights Hayakawa. It’s price mentioning that that is certainly one of the smallest half-pitch sizes reported worldwide for thin-film lamellar structures with no top coating.

Overall, these exciting findings have the potential to advance cutting-edge technologies in semiconductor manufacturing. “PS-b-PG_FM BCPs are promising templates to be used in lithography because they’ll produce fantastic patterns in DSA processes much like those used for conventional PS-b-PMMA, with the potential to outperform them,” concludes Hayakawa. “Studies aimed toward optimizing the pattern-transfer processes using line patterns in PS-b-PG_FM thin movies as templates might be investigated in the longer term,” he adds, sharing their objective for the longer term.

These advancements may bring us closer to a brand new era in electronics and artificial intelligence systems.