Professor Joonki Suh, leading a research team at UNIST in the Department of Materials Science and Engineering and the Graduate School of Semiconductor Materials and Devices Engineering, has achieved a groundbreaking advancement in thin film deposition technology. Utilizing an innovative atomic layer deposition (ALD) technique, Professor Suh has successfully arranged tellurium (Te) atoms with precision at remarkably low temperatures, as low as 50 degrees Celsius.
The ALD method represents a state-of-the-art thin film process that allows for the meticulous layering of semiconductor materials at the atomic level, even on complex three-dimensional structures, all while operating at low process temperatures. Traditionally, applying this method to next-generation semiconductors necessitated high processing temperatures exceeding 250 degrees Celsius, along with additional heat treatment exceeding 450 degrees Celsius.
In this research endeavor, the UNIST team harnessed ALD for monoelemental van der Waals tellurium, a material garnering extensive attention for its potential applications in electronic devices and thermoelectric materials. Impressively, they managed to produce high-quality Te thin films without any subsequent heat treatment, achieving this feat at an unprecedentedly low temperature of only 50 degrees Celsius. These films displayed outstanding uniformity, boasting precise thickness control down to the nanometer scale, resulting in a perfect arrangement of atoms at a rate of one out of every billion atoms.
To boost reactivity at lower temperatures, the research team introduced two precursors with acid-base properties and incorporated co-reactants to enhance surface reactions and stability. They also employed a dosing technique that involved injecting precursors at shorter intervals, thereby facilitating the creation of dense and continuous Te thin films. This stands in stark contrast to conventional methods, which often yield porous or disjointed grain deposits.
The developed manufacturing process allowed for the growth of Te thin films on entire 4-inch (100mm) wafers, enabling precise control of atomic layer-level thickness and uniform deposition. Furthermore, these Te thin films proved to be compatible with vertical three-dimensional structures, a critical requirement for achieving high device integration. This groundbreaking development holds significant promise for a wide range of electronic devices, including transistors, rectifiers, and selection elements.
Professor Suh commented on the significance of this research, stating, “This research fulfills all the essential criteria of low-temperature, large-area, and high-quality synthesis in semiconductor deposition processes.” The results of this research have been published in ACS Nano.