A clean semiconductor processing method without residual materials that cause performance degradation—which has been a major obstacle in developing highly integrated next-generation semiconductors—has been developed, with commercialization expected in the future.

The Institute for Basic Science (IBS, Director No Do-young), Nanostructure Physics Research Center, led by Research Director Lee Young-hee (Sungkyunkwan University HCR Chair Professor), announced on the 5th that through collaborative research with Yumin Yoon, Group Leader at Oak Ridge National Laboratory in the United States, they have developed a new process capable of fabricating next-generation semiconductor devices without residual materials causing performance degradation.

To implement next-generation semiconductors with enhanced performance, the development of field effect transistor (FET) devices with superior performance is essential.

Transition metal dichalcogenides (TMD) are attracting attention as ideal FET materials to replace silicon, possessing excellent physical and electrical characteristics as well as semiconductor properties.

However, despite intensive research over the past decade, residual materials used in the process remain on the devices and degrade performance, which has been a major obstacle to commercialization.


In two-dimensional semiconductor device processing, polymethyl methacrylate (PMMA), an insulator, has traditionally been used as a support layer for transferring semiconductor materials.

However, PMMA residue remaining on the TMD semiconductor material has been problematic, degrading device performance. The academic community has been seeking alternative support layers by using various organic materials to replace PMMA, but it has been difficult to avoid electronic and mechanical losses due to residue.

The collaborative research team identified that this problem can be solved by using polypropylene carbonate (PPC) as a support layer instead of PMMA. First, the team synthesized centimeter-scale molybdenum disulfide (MoS2)-based two-dimensional semiconductor materials capable of high integration and transferred the semiconductor material using PPC as the support layer.

In the monolayer MoS2 device fabricated this way, only an extremely small amount of the support layer PPC, less than 0.08%, remained, resulting in minimal performance degradation.

Furthermore, the team also resolved the wrinkle problem in monolayer semiconductor devices, which was another issue with conventional processes.

The research team explained that because the adsorption energy between PPC and molybdenum disulfide is small, PPC easily separates from the semiconductor surface, resulting in minimal residue.

The MoS2 FET device fabricated by the team exhibited superior performance compared to any device developed to date, including a small contact resistance of 78Ω-μm approaching the quantum limit, a large on/off current ratio below 10¹¹, and a maximum current of 1.4mA/μm or less.

Lee Young-hee, the research director leading the study, stated, "The clean two-dimensional device fabrication process we propose is an ideal platform for applying large-area TMD materials as high-performance electronic device components," and added, "The two-dimensional semiconductor material transfer technology using PPC support layers is expected to be widely utilized in various two-dimensional device integration in the future."

The research results were published on September 5th (Korean Standard Time) in the prestigious international journal Nature Nanotechnology (IF 38.3).