On a single semiconductor wafer, billions of ultrafine electronic components such as transistors and wiring are densely formed at a scale of a few-thousandths the thickness of a human hair. Among these, the process of precisely removing unnecessary parts to create pathways for electric current is "etching." The precision of this process determines semiconductor performance and Production yield.
Meeting on the 19th at the company's headquarters in Yongin, Gyeonggi Province, process engineer Lee Min-jae, 41, at Korea Technology Center (KTC) of Lam Research likened etch engineers to "nanometer-scale sculptors." Lee said, "Etch engineers develop processes that remove unnecessary material at the nanometer scale so that the circuits on the wafer are actually realized," and added, "Not only nanometer-scale precision but also the need to repeatedly produce the same results makes the process extremely challenging." Because even a slight deviation in circuit geometry can disrupt current flow and lead to defects across the entire chip, etching is considered a key step that determines Production yield.
Lam Research, headquartered in the United States, is the world's No. 1 company in etch equipment and supplies equipment to major semiconductor corporations such as Samsung Electronics and SK hynix. In the first quarter of this year, Lam Research posted sales of $5.84 billion (about 8 trillion won), up 24% from a year earlier.
Since entering Korea in 1989, Lam Research has built a base covering manufacturing and logistics, training, and research and development (R&D). The Korea Technology Center (KTC) established in Yongin in 2022 is being used as a core research and development (R&D) hub for co-developing and validating processes with customers. This has increased process development speed by 2 to 2.5 times compared with before.
As NAND flash stacking has recently grown to hundreds of layers and more, the difficulty of etching has risen sharply. In the process of drilling deep, narrow structures vertically to the end, reactive species struggle to reach the bottom and byproducts are hard to evacuate, causing "transport limitations." Ultimately, process performance depends on how precisely gas injection, reactions, and byproduct removal are controlled, and equipment controllability determines Production yield. In this high-difficulty environment, Lee is responsible for developing and optimizing processes to precisely etch NAND stacked structures.
Lee said, "Plasma, gas reactions, temperature, and time must be controlled in millisecond units, 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 doctorate 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, then worked at Samsung Electronics as a semiconductor process engineer, gaining mass production experience. Lee currently oversees 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 care about and the process risks, so problem definition and experimental design are much more efficient," adding, "As process difficulty rises, equipment makers expand their role from simple suppliers to co-development partners."
As semiconductor processes become finer and more stacked, reliance on equipment is increasing. With process difficulty shifting to a structure directly determined by equipment performance, the technology of equipment makers is directly translating into Production yield competitiveness. Lee explained, "The more complex the process, the more unavoidable the dependence on equipment," and added, "The same goes for the influence of equipment makers."
Lee went on to describe Lam Research's organizational culture, saying, "Engineers have a high degree of autonomy to focus on process development, and decisions are made quickly in a horizontal atmosphere," and added, "There is a range of reward systems, including stock compensation, that make it a motivating environment." The following is a Q&A with Lee.
― What does an etch engineer do?
"Etch engineers develop processes that precisely remove unnecessary materials at the nanometer scale so that circuit patterns formed on a wafer can be realized as actual devices. The core is not simply to create a specific structure but to repeatedly produce tens of billions of microstructures with the same shape and quality. To that end, we secure process reproducibility and stability by precisely controlling equipment conditions, gas compositions, and plasma parameters based on metrology data and defect analysis results."
― Why is etching called the "process of dread" as NAND stacking increases?
"In high-stack structures, 'transport limitations' that restrict the movement of reactants and byproducts act as the biggest variable. Reactants have a hard time reaching the bottom of the structure, and byproducts generated during etching have difficulty being discharged. If minute angular errors accumulate, significant shape distortion can appear in the bottom structures. In the end, deep and narrow structures simultaneously demand maintaining verticality and shape to the very end, and these compounded physical constraints make the etch process 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 we can control plasma, gas reactions, temperature, and time. In addition to performance on a single wafer, stability that can repeatedly deliver the same results across multiple wafers and lots is an important competitive factor."
― Describe a time when you succeeded in improving Production yield.
"When improving a process that had not secured Production yield, we repeatedly checked variables and optimized conditions. After going through this, achieving target-level results brings a strong sense of accomplishment for resolving a long-standing problem. In particular, the experience of stabilizing a process within the delivery deadline serves as an important turning point as an engineer."
― What are your goals as a 30s–40s engineer?
"Semiconductor processes have a structure in which individual unit technologies connect to overall Production yield and industrial competitiveness. In this environment, it is important to stably bring assigned processes into 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."
― Any advice for juniors taking on challenges beyond their major?
"Differences in majors are only differences at the starting line; 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 fundamentals and work through field issues step by step. Rather than waiting for a perfectly prepared state, it is important to grow by learning and gaining experience in parallel."