[2025 The CEO of Sunchon National University Early-Stage Startup Package] Kyong Moo Lee, CEO of Letechnus

‘Letechnus’, a company that developed ‘diamond wires made of carbon fiber’ using technology unique in Korea

Supplying core materials and components for semiconductors, secondary batteries, and solar power
The world’s first company to replace the core material with ‘carbon fiber’ instead of steel

Letechnus supplies core materials and components for semiconductors, secondary batteries, and solar power. It is the only Korean company to develop ‘diamond wires made of carbon fiber’, which can significantly improve the yield of next-generation power semiconductors. The company was founded in June 2022 by CEO Kyong Moo Lee (52).

Its flagship product is a high-tensile-strength diamond wire made of carbon fiber used in the manufacturing of power semiconductor wafers. This wire is a thread-like cutting tool that is used to slice silicon ingots (cylindrical, single-crystal silicon blocks) into thin wafers. The rise of advanced industries like electric vehicles, 5G communications, and data centers is increasing the need for compound power semiconductors like silicon carbide (SiC) and gallium nitride (GaN). These compound power semiconductors are significantly harder than conventional silicon, which makes them difficult to process.

“Previously, wires coated with diamond particles around a steel core were used. However, these wires frequently broke during the process due to the high loads applied when cutting tough materials. This resulted in the complete disposal of expensive semiconductor materials, causing a critical problem of reduced production yield.”

To solve this problem, Letechnus pioneered replacing the core material with ‘carbon fiber’ for the first time in the world. Carbon fiber offers significantly superior tensile strength and impact resistance compared to steel, effectively withstanding the loads generated during the cutting process and minimizing wire breakage. This enables customers to maximize the processing yield of costly compound semiconductor wafers, enhancing productivity and efficiency.

Furthermore, in collaboration with Jeonbuk National University, Letechnus is researching a pellicle frame material for photomasks used in semiconductor lithography processes, based on an industry-academic cooperation foundation. The pellicle is a critical component that protects expensive photomasks from contamination during the lithography process. Recently, thermal deformation and contamination issues have arisen with existing aluminum frames in high-power extreme ultraviolet lithography (EUVL) environments. To address these issues, Letechnus is developing frames made from silicon (Si), which has a low thermal expansion coefficient, to minimize deformation. This effort aims to contribute to the localization of EUV pellicle frames, which were previously reliant on imports.

Letechnus’s greatest competitive advantage lies in the superior mechanical properties and technological differentiation of its products. While conventional steel wires have a tensile strength of approximately 3,200 N/mm², Letechnus’s diamond wires made of carbon fiber are being developed to achieve a tensile strength of over 3,600 N/mm² and a breaking strength of over 60 N, which are significantly higher than competing products. This ensures stable performance without breakage, even during high-load cutting processes. By drastically reducing wire breakage, Letechnus minimizes wafer scrap losses for customers and directly contributes to yield improvement. This directly translates to an enhanced cost-competitive advantage for our customers.

“Letechnus’s core competency is replacing conventional steel wire with carbon fiber and uniformly coating it with diamond particles. We have already filed three patent applications related to this technology, creating a technological barrier. Letechnus’s product can be utilized in the processing of various high-hardness materials that are difficult to cut, including sapphire wafers and ceramics used in high-luminance LEDs, as well as power semiconductors. This offers significant potential for market expansion.”

Lee is pioneering the market with a clear target market and phased entry strategy. Domestic and international power semiconductor and wafer manufacturers are the core target customers. Specifically, potential customers with whom to build cooperative relationships have been secured, including Luminus, GSN, SK siltron, and MEMC Korea. The company provides customers with prototypes for qualification purposes, which verifies their superior performance directly. This approach is intended to build trust in the product and achieve rapid initial market penetration.

Regarding future plans, Lee stated, “In the short term, our goal is to complete prototype development by early 2026, obtain quality certification from major Korean customers, and successfully enter the initial market.”

Founded: June 2022
Main business: development and manufacturing of diamond wires made of carbon fiber and processing of silicon components (Si-Parts) for semiconductor processes
Achievements: Achieved sales of 571 million won by 2024; Selected for multiple government R&D projects, including the Korea Institute of Startup & Entrepreneurship Development’s ‘Early-Stage Startup Package’; Filed three patents related to diamond wires made of carbon fiber; Secured funding from the Korea Credit Guarantee Fund; Established a dedicated corporate R&D department and received certification in June 2023; Registered a new factory in Gunsan in July 2025

reporter jinho lee
jinho2323@hankyung.com