Coating improves plasma etching for next-gen chip transistors
A simple chemical coating could make manufacturing advanced transistors using ultrathin materials more precise by reducing damage during plasma etching.
Researchers are exploring new materials for next-generation transistors as silicon approaches its manufacturing limits. Transition metal dichalcogenides (TMDs), such as molybdenum disulfide, are promising candidates due to their extremely thin nature. Molybdenum disulfide, for instance, is only three atoms thick, consisting of a molybdenum layer sandwiched between two sulfur layers.
The fabrication of transistors using these materials, like silicon and TMDs, requires removing atoms from the uppermost sulfur layer without compromising the underlying layers. A common method for this atomic layer removal involves plasma. However, precisely controlling plasma to remove only the top sulfur atoms without damaging the molybdenum layer beneath presents a significant manufacturing challenge due to the narrow energy margin required.
New research, utilizing computer simulations, suggests that pretreating molybdenum disulfide with oxygen or fluorine can significantly ease this process. This pretreatment lowers the energy required to dislodge sulfur atoms from approximately 30 electron volts (eV) on an untreated surface to around 14 eV with oxygen and about 10 eV with fluorine. This reduction in energy threshold is crucial because plasma ions have a range of energies, and a wider energy window prevents ions from inadvertently damaging the lower molybdenum layer.
Instead of relying solely on the force of plasma particles, the coated surfaces employ a chemical assist. When a plasma ion interacts with an oxygen-coated surface, oxygen and sulfur atoms combine to form sulfur dioxide, a stable gas that easily detaches. Fluorine acts similarly, forming sulfur-fluorine compounds. This chemical interaction makes the removal of the top layer more precise, ensuring the integrity of the underlying material. The researchers plan to further investigate the extent of any residual damage and explore the applicability of this method to related materials.
This development addresses a critical challenge in advanced semiconductor manufacturing, particularly for devices utilizing 2D materials like TMDs. By enabling more precise and less damaging plasma etching, it facilitates the integration of these novel materials into future high-performance transistors, potentially paving the way for smaller, more powerful electronic components and advanced integrated circuits.
Edited by the news editor with AI from the original report — please refer to the original source.