UNIST Develops Atomic-Level Semiconductor Customized Process Technology by Material Type

Professor Seo Jung-gi's Team Develops Thin Film Deposition Process Based on Organometallic Chemical Vapor Deposition Method

Enables Deposition of Several Nanometers Thickness per Wafer Unit … Published in Advanced Materials

A process technology has been developed that can uniformly and stably deposit atomically thin films at low temperatures.

From the top row, left to right: Researcher Gyo Kyung-min, co-first author Researcher Lee Wook-hee, Researcher Cho Han-bin; from the bottom row, left to right: Professor Seo Joon-gi, first author Researcher Kim Sung-yeon.

The research team led by Professor Junki Seo from the Graduate School of Semiconductor Materials and Components and the Department of Materials Science and Engineering at UNIST (President Yong-Hoon Lee), in collaboration with Professor Feng Ding from the Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Professor Sungkyu Kim from Sejong University, and Professor Changwook Jung’s team at UNIST, developed a thin film deposition process that can deposit thin films over wafer-scale large areas using metal-organic chemical vapor deposition (MOCVD) at a low temperature of 200 degrees Celsius with a customized process for each tin selenide-based material.

Metal-organic chemical vapor deposition is a next-generation process that uses gaseous precursors involved in chemical reactions, offering excellent precision. It can deposit thin films over large areas such as semiconductor wafers. However, to synthesize reactants, ligands had to be decomposed at high temperatures above 650 degrees Celsius.

The research team applied MOCVD to two types of tin selenide materials (SnSe2, SnSe), which are being studied in various fields such as electronic devices, optical devices, and thermoelectric devices. Both types of tin selenide thin films were uniformly deposited at wafer scale with thicknesses of a few nanometers.

To enable deposition at low temperatures, the team physically separated the temperature ranges where ligands decompose and where thin films deposit. They adjusted the ratio of tin and selenium precursors used in the deposition method and precisely controlled the flow rate of argon gas carrying the precursors.

The thin films produced in this way exhibit high crystallinity, meaning they are regularly arranged. The phase and thickness of the material can also be controlled during the deposition process. Despite using MOCVD, the films were uniformly deposited at a low temperature of about 200 degrees Celsius regardless of the substrate type.

The research team applied the developed process to the entire wafer. Both types of thin films maintained chemical stability and high crystallinity. Atomic-level thickness control and uniform deposition were also possible. This demonstrates that the developed process can be widely applied to various electronic devices.

First author Researcher Sungyeon Kim stated, “This study overcame the limitations of conventional MOCVD and enabled large-area deposition of multiphase materials without changing their chemical composition. In the future, it will be applicable not only to material research on tin selenide thin films but also to various electronic devices.”

Professor Junki Seo said, “This research presents a process strategy based on the intrinsic thermodynamic and kinetic behaviors according to the phase of semiconductor thin film materials. It is significant in that it succeeded in developing a customized process for next-generation semiconductor materials, which will accelerate research on electronic device applications.”

Proposed cover image for the Advanced Materials journal depicting the research.

This research was published online on April 10 in the international nanoscience journal Advanced Materials. The study was supported by the Ministry of Science and ICT’s National Research Foundation of Korea through the Excellent New Researcher Program, the Next-Generation Intelligent Semiconductor Technology Development (Device) Project, and Ulsan National Institute of Science and Technology.

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