A joint research team from Ajou University and Stanford University creates a semiconductor using 'amorphous semimetallic materials.' This material shows the characteristic that as its thickness decreases, its resistivity decreases. It appears to solve the issue of increased resistivity due to semiconductor miniaturization./Courtesy of Stanford University
A joint research team from Ajou University and Stanford University creates a semiconductor using 'amorphous semimetallic materials.' This material shows the characteristic that as its thickness decreases, its resistivity decreases. It appears to solve the issue of increased resistivity due to semiconductor miniaturization./Courtesy of Stanford University

A joint research team from South Korea and the United States has discovered a new material that can prevent performance degradation in semiconductor fine processes. The metal previously used in semiconductors hinders the movement of electrons as its thickness decreases. In contrast, the newly found material enables the movement of electrons to become more active as the thickness decreases, thereby enhancing semiconductor performance.

The research team led by Professor Oil Kwon of the Department of Intelligent Semiconductor Engineering and the Department of Electrical Engineering at Ajou University developed a material known as "amorphous semimetallic nano ultrathin film" with different properties from metals in collaboration with Stanford University. The research results were published in the international journal "Science" on the 3rd.

As information communication (IT) technology has rapidly advanced recently, the performance requirements for semiconductors have also gradually increased. Semiconductor performance is determined by how many devices and circuits are contained within a single chip. The miniaturization process that allows a large number of devices and circuits to be placed inside a semiconductor chip has currently progressed to the level of several nanometers (1 nm is 1 billionth of a meter).

However, as semiconductor fine processes advance, there are also side effects. When the metal used to draw circuits becomes thinner than a certain thickness, its resistivity increases, hindering the movement of electrons. Electrons play a role in transmitting information as they move between devices. When the metal, which serves as the channel for electron movement, narrows and the moving electrons collide, the speed of information transmission decreases, which acts as a factor that lowers semiconductor performance. Currently, the line width of semiconductor circuits has become narrower than the distance it takes for electrons to collide, known as the "mean free path (EMFP)," leading the industry and scientific community to seek new materials to replace metals.

The research team addressed this issue by developing an "amorphous semimetallic thin film" to replace metal wiring. The newly developed material was created by stacking niobium (Nb) crystals on a sapphire crystal layer and placing amorphous niobium phosphide (NbP) on top. Amorphous materials refer to structures where the arrangement of elements is disordered, unlike crystals that have a regular arrangement pattern.

The research team analyzed the resistivity differences with varying thicknesses among metals previously used for semiconductor wiring, such as copper (Cu), tantalum (Ta), and niobium, compared to amorphous semimetallic thin films. The results showed that while the resistivity of existing metals increases as they become thinner, amorphous semimetallic thin films decrease in resistivity as their thickness reduces. It was also confirmed that when the thickness drops below 10 nm, the new material exhibits superior performance compared to existing metals, thereby enhancing performance when applied to the semiconductor miniaturization process.

The amorphous semimetallic thin films are noted for their excellent compatibility, making them advantageous for use in existing semiconductor wiring processes. Additionally, they do not require high-temperature heat treatment processes for creating metal crystals, which can reduce the expense of semiconductor production.

The research team is developing an atomic layer deposition-based process for amorphous semimetallic thin films through follow-up studies. Atomic layer deposition allows for adjusting the thickness of the thin film on an atomic scale, making it more suitable for the miniaturization of semiconductor processes.

Professor O said, "This is a significant achievement, proving the performance of a completely new material that has never been attempted before," and added, "I expect that this could be utilized as a breakthrough for semiconductor technology facing limitations and as a fundamental technology to seize leadership in the semiconductor industry."