A domestic research team has succeeded in overcoming the limitations of the heat treatment process, which was a difficult problem in next-generation semiconductor technology, and in developing an innovative technology using lasers, thereby dramatically improving semiconductor performance.

A joint research team from Korea University and Daegu Gyeongbuk Institute of Science and Technology (DGIST) with support from the National Research Foundation of Korea (NRF) of the Ministry of Science and ICT (MSIT) has succeeded in developing a ‘fully laser-based process’ technology that implements high-performance transistors in a ‘monolithic 3D (M3D)’ stacked structure, the latest semiconductor technology.

The results of this study are scheduled to be presented at the 'VLSI Technology Symposium 2025', the most prestigious academic conference in the field of semiconductor devices.

The VLSI Technology Symposium, along with the International Electron Devices and Engineering (IEDM), is considered an authoritative conference where only the highest level of research is presented, as the university paper acceptance rate is very low at less than 25%.

Recently, improving semiconductor performance has become an important task in fields that require high-performance computing, such as artificial intelligence (AI) and big data. Accordingly, M3D technology, which stacks chips in three dimensions to increase integration, is attracting attention, but there was a problem that the high-temperature heat treatment process essential in the existing process caused damage to the semiconductor elements in the lower layer.

To solve this problem, the research team introduced an innovative approach that replaces all processes in the semiconductor manufacturing process with lasers. They experimentally demonstrated that by implementing high-quality silicon channels using lasers without the conventional heat treatment method, the performance of the device can be significantly improved.

The research team succeeded in forming high-quality silicon channels without using single-crystal seeds by applying pattern-based seedless laser crystallization (PSLC) technology. Through this, a large crystal grain size of 25 micrometers (μm) or larger was secured, maximizing the electron transfer speed.

In addition, by applying a laser to the source/drain (S/D) activation process of the transistor, impurities were effectively activated even at low temperatures below 400℃.

This technology has resulted in maximizing the power efficiency of the device by implementing an ‘ultra-shallow junction’ that is more precise than conventional methods.

Experimental results showed that the M3D transistors fabricated using the fully laser-based process developed by the research team outperformed previous research results.

In particular, it achieved performance that was far higher than that of existing technologies, recording a current on/off ratio (ION/IOFF) of over 100 million to 1, electron mobility (NMOS) of 521 cm²/Vs, and hole mobility (PMOS) of 163 cm²/Vs.

Professor Hyun-Yong Yoo of Korea University and Professor Hyuk-Jun Kwon of DGIST, who led this research, said, “Fully laser-based process technology will be a key driving force for advancing the commercialization of M3D technology,” and “It is expected to greatly contribute to the development of various next-generation semiconductors, such as 6G mobile communications and high-performance artificial intelligence chips.”

Meanwhile, this study was conducted with the support of the Next Generation Intelligent Semiconductor Technology Development (Device) Project. The Next Generation Intelligent Semiconductor Technology Development Project is a multi-ministerial R&D project of the Ministry of Science and ICT and the Ministry of Trade, Industry and Energy, and is a mid- to long-term project with an investment of KRW 1.096 trillion over 10 years from 2020, with the goal of developing artificial intelligence semiconductor design and devices and equipment.