On a single semiconductor wafer, billions of ultraminiature electronic components such as transistors and wiring are densely implemented at a scale of thousandths of the thickness of a hair. Among them, the process that precisely removes unnecessary parts to create paths for electricity to flow is etching. The precision of this process determines semiconductor performance and Production yield.
On the 19th at the headquarters in Yongin, Gyeonggi Province, Process Engineer Lee Min-jae (41) of Lam Research Korea Technology Center (KTC) likened an etch engineer to a sculptor working at the nanometer scale. Lee said, "Etch engineers develop processes that remove unnecessary material in nanometers so that the circuit on the wafer is actually implemented," and noted, "Not only nanometer-level precision but also the need to repeatedly produce the same result makes the process very challenging." Even a slight deviation in circuit geometry can disrupt current flow and lead to a defective chip, so the etch process is considered a key stage that determines Production yield.
Lam Research, headquartered in the United States, is the world's No. 1 company in deposition and etch equipment, supplying tools to major semiconductor corporations such as Samsung Electronics and SK hynix. Lam Research recorded $5.84 billion in sales this year (about 8 trillion won), up 24% from a year earlier.
Since entering Korea in 1989, Lam Research has built hubs spanning manufacturing and logistics, training, and research and development (R&D). The Korea Technology Center (KTC), established in Yongin in 2022, is used as a core R&D hub to co-develop and validate processes with customers. This has increased process development speed by 2 to 2.5 times compared with before.
As NAND flash stacking has risen to several hundred layers recently, the difficulty of the etch process has surged sharply. In the process of drilling a deep and narrow structure vertically to the end, reactants struggle to reach the bottom, and byproducts are hard to be expelled, creating a "transport limit." Ultimately, process performance depends on how precisely gas injection, reactions, and byproduct removal are controlled, and the equipment's control capability determines Production yield. In this high-difficulty environment, Lee is responsible for developing and optimizing processes that precisely etch NAND stack structures.
Lee said, "We must control plasma, gas reactions, temperature, and time in milliseconds, and equipment stability that can repeatedly deliver the same results is the core competitive edge."
After graduating from the Department of Chemical and Biomolecular Engineering at Sogang University, Lee earned a Ph.D. from the Department of Nuclear and Quantum Engineering at Korea Advanced Institute of Science and Technology (KAIST). At KAIST, Lee conducted research on nanomaterial synthesis and structural analysis, and later worked at Samsung Electronics as a semiconductor process engineer, gaining mass-production experience. Lee now handles NAND etch process development and Production yield optimization at Lam Research.
Having worked at both a chipmaker and an equipment company, Lee said, "I understand the metrics customers value and the process risks, so problem definition and experimental design are far more efficient," adding, "As process difficulty increases, equipment companies expand their role from simple suppliers to co-development partners."
As semiconductor processes become more miniaturized and stacked, reliance on equipment is increasing. As the structure shifts so that process difficulty directly depends on equipment performance, the technology of equipment companies is translating directly into Production yield competitiveness. Lee explained, "The more complex the process becomes, the greater the inevitable dependence on equipment," and added, "The same goes for the influence of equipment companies."
Regarding Lam Research's organizational culture, Lee said, "Engineers have high autonomy to focus on process development, and decisions are made quickly in a horizontal atmosphere," adding, "With various reward systems such as stock compensation, it's a motivating environment." The following is a Q&A with Lee.
— What role does an etch engineer perform?
"Etch engineers develop processes that precisely remove unnecessary material in nanometers so that circuit patterns formed on a wafer can be realized as actual devices. The key is not simply creating a particular structure, but repeatedly producing tens of billions of microstructures with the same geometry and quality. To that end, we secure process reproducibility and stability by precisely controlling equipment conditions, gas composition, and plasma parameters based on metrology data and defect analysis results."
— Why is etching called a "process of terror" as NAND stacking increases?
"In high-stack structures, the 'transport limit,' which restricts the movement of reactants and byproducts, acts as the biggest variable. Reactants find it harder to reach the bottom of the structure, and byproducts generated during etching struggle to be expelled. In addition, if tiny angular errors accumulate, significant shape distortion can appear in the bottom structures. Ultimately, deep and narrow structures simultaneously require maintaining verticality and shape to the end, and these combined physical constraints make etching even more difficult."
— Where does Lam Research's equipment competitiveness come from?
"The core is precision control that can maintain profile and uniformity even under extreme process conditions. In environments with a very narrow process window, the difference in results comes from how precisely and independently plasma, gas reactions, temperature, and time can be controlled. Moreover, stability that can repeatedly deliver the same results not only on a single wafer but also across multiple wafers and lots serves as an important competitive factor."
— Describe an experience when you succeeded in improving Production yield.
"In improving a process that failed to secure Production yield, continuous checks of variables and condition optimization are repeated. After going through these steps and securing results at the target level, you feel a strong sense of accomplishment for resolving a long-accumulated problem. In particular, the experience of stabilizing a process within the delivery schedule serves as an important turning point as an engineer."
— What is your goal as an engineer in your 30s and 40s?
"Semiconductor processes have a structure in which individual unit technologies consolidate into overall Production yield and industrial competitiveness. In this environment, it is important to stabilize the assigned process for mass production and secure expertise to solve problems when they arise. Personally, my goal is to grow into an engineer trusted by both colleagues and the organization."
— What advice would you give to juniors who are challenging themselves beyond their majors?
"Differences in majors are only differences in starting lines; what matters is the mindset to define problems logically and solve them based on data. When entering a new field, you need to relearn the basic principles and resolve on-site issues step by step. Rather than waiting for a perfect state of readiness, it is important to grow by combining learning with experience."