A trace gas impurity can ruin a chip. KRISS now has a way to catch it

The Korea Research Institute of Standards and Science (KRISS, President Dr. Lee Ho Seong) has established purity analysis techniques and testing procedures for 15 high-purity gases used in semiconductor processes, and has developed six certified reference materials (CRMs) that verify measurement accuracy. This provides a foundation for objectively evaluating the quality of semiconductor gases domestically, moving beyond a reliance on the certificates of analysis provided by suppliers themselves.

* The table on the right shows the measured levels of gaseous, moisture, and metallic impurities, each with its unit, relative expanded uncertainty, and analytical method. The product's final purity is determined from these impurity values.

The need to localize semiconductor materials and diversify supply chains grew significantly through the 2019 Japanese export restrictions and instability in global supply chains. However, given the nature of semiconductor manufacturing, where numerous materials are used across hundreds of demanding process steps, even trace impurities or slight quality variations in a particular gas can lead to reduced yields or product defects months later. For this reason, introducing a new material requires lengthy process validation and considerable cost, making it difficult to switch suppliers.

Until now, the industry has effectively relied on the certificates of analysis issued by existing suppliers and their long track record of use as a form of quality assurance. However, as supply chain realignment has increasingly led companies to consider adopting domestic products or products from new suppliers, independent test results that can objectively verify the quality of these products have become necessary.

* A gas mixture reference material with helium as the balance gas and a certified value assigned to the iron pentacarbonyl concentration. When analyzing iron impurities in carbon monoxide, it serves as a reference for verifying the accuracy of instruments and testing methods and ensuring reliable results.

In response, since launching its hydrogen fluoride quality evaluation service in 2020, KRISS has gradually expanded its scope to build a purity analysis infrastructure for 15 high-purity gases used in etching, cleaning, and deposition. By establishing standard testing procedures for each gas, it has completed a testing and analysis service system covering all 15 gases. In addition, KRISS developed six certified reference materials for analyzing key impurities, each assigned an accurate reference value, to verify the measurement accuracy of on-site analytical instruments and to further improve the reliability and comparability of measurement results.

Building this analytical infrastructure required creating a safe testing environment for handling hazardous gases. The researchers equipped the facilities with specialized piping and safety cabinets, leak detection sensors, and exhaust gas treatment and air-conditioning systems to handle highly toxic, corrosive, and explosive semiconductor gases, and also set up a dedicated cleanroom for the precise analysis of metallic impurities.

The analysis of trace impurities draws on KRISS's gas analysis expertise, proven to be world-class through international comparisons, along with decades of accumulated know-how. Analyzing a semiconductor process gas with a purity of 99.9999% (6N grade) requires a high level of precision measurement capability to accurately identify, component by component, the trace impurities such as moisture, oxygen, hydrocarbons, and metals contained in the remaining 0.0001%.

Building on its established analysis system, KRISS has provided a total of 34 testing services to date. Demand has been particularly strong for hydrogen fluoride, a material undergoing active localization and supply diversification. The test results are used in various ways, including validating gas manufacturers' in-house analysis methods, improving manufacturing and purification processes, and comparing the quality of imported and domestic products. For semiconductor manufacturers, they serve as an objective basis for considering new gases as candidates for actual process testing.

Meanwhile, KRISS is also pursuing follow-up infrastructure in partnership with a private testing organization, aiming to expand the testing service to the private sector and broaden support for companies. KRISS is providing advisory support on the facility and equipment configuration, analysis methods, and development of testing procedures for the Semiconductor Gas Quality and Safety Evaluation Support Center, which the FITI Testing & Research Institute (FITI) is building with a target completion of 2030. Once the center is completed, companies are expected to access related services more conveniently through a specialized testing organization.

Dr. Oh Sang Hyub, Principal Research Scientist in the Gas Metrology Group at KRISS, said, "For the localization of semiconductor materials to translate into real industrial settings, it is essential to prove product quality with reliable, objective data.” He added, "Building on KRISS's world-class gas measurement standards and analytical capabilities, we will actively support domestic companies in their quality control and supply chain response.”