Joint research teams from South Korea and the United States have discovered a new material to prevent performance degradation in semiconductor fine processes. In existing semiconductors, as the thickness of the metal used decreases, the movement of electrons is hindered. In contrast, the newly found material enhances semiconductor performance as its thickness decreases, allowing electron movement to become more active.
A research team led by Professor Oh Il-gwon of the Department of Intelligent Semiconductor Engineering and the Department of Electronics at Ajou University has developed a 'amorphous semiconductor nanometal ultra-thin film' that has different properties from metals in cooperation with Stanford University. The study results were published on 3rd in the international journal 'Science.'
As information technology (IT) advances rapidly, the performance requirements for semiconductors are also gradually increasing. Semiconductor performance is determined by how many elements and circuits are contained within a single chip. The miniaturization process for incorporating numerous elements and circuits within semiconductor chips has currently advanced to the level of several nanometers (nm), where 1 nm equals one billionth of a meter.
However, there are side effects that arise as semiconductor fine processes develop. If the metal used to draw circuits becomes thinner than a certain thickness, the resistivity increases, hindering the movement of electrons. Electrons play a role in transmitting information as they move between elements. As the metallic path for electron movement narrows, collisions between moving electrons can slow down the transmission of information, acting as a factor that reduces semiconductor performance. Currently, the width of semiconductor circuit lines has become narrower than the distance it takes for electrons to collide, known as the 'mean free path (MFP),' prompting the industrial and scientific communities to seek new materials to replace metals.
The research team has developed an 'amorphous semiconductor thin film' to replace metallic wiring, addressing these issues. The newly developed material is created by stacking niobium (Nb) crystals on a sapphire lattice and overlaying it with amorphous niobium phosphide (NbP). Amorphous structures have an unordered arrangement of elements, in contrast to ordered crystalline arrangements.
The research team analyzed the resistivity differences based on the thickness of metals used in existing semiconductor wiring, such as copper (Cu), tantalum (Ta), and niobium, compared to the amorphous semiconductor thin film. The results showed that while the resistivity of traditional metals increases as thickness decreases, the resistivity of the amorphous semiconductor thin film decreases with reduced thickness. It was also confirmed that when the thickness drops below 10 nm, it performs better than existing metals, enhancing performance when applied to semiconductor miniaturization processes.
The amorphous semiconductor thin film is also noted for its excellent compatibility, allowing it to be applied to existing semiconductor wiring processes. Furthermore, it does not require high-temperature heat treatment processes to create metallic crystals, which can also reduce semiconductor production expenses.
The research team is developing an amorphous semiconductor thin film process based on atomic layer deposition in subsequent studies. Atomic layer deposition allows for control over the thickness of thin films at the atomic level, making it more suitable for semiconductor process miniaturization.
Professor Oh noted, 'This is a significant achievement in proving the performance of a completely new material that has never been attempted before,' and added, 'I expect it to serve as a breakthrough for future semiconductor technology facing limitations and to be utilized as a fundamental technology to seize the leadership in the semiconductor industry.'