New in-line metrology technique, powered by advanced THz near-field probes, offers faster, more accurate defect detection during chip manufacturing inside a semiconductor fab.
In a groundbreaking achievement for semiconductor manufacturing, researchers at Samsung Electronics, utilizing key technology from Protemics GmbH, have demonstrated the first-ever use of near-field terahertz (THz) time-domain spectroscopy (TDS) for in-line inspection within a semiconductor fab environment. This milestone, detailed in a recent Nature Communications Engineering article, promises to dramatically improve the speed and accuracy of identifying electrical defects during the critical integration processes of memory chip production.
A core innovation is the successful integration of THz-TDS with Protemics' advanced photo-conductive near-field microprobes. These specialized probes are crucial for achieving sub-10 µm spatial resolution, a level of detail that enables direct measurement of on-chip micro-patterns within individual cell units of DRAM. This represents a significant advancement over traditional methods, which often involve destructive testing of separate, less representative observation sites. This new technique, crucially, is non-contact and non-destructive.
While the challenge in semiconductor manufacturing, particularly with shrinking node sizes, is to quickly identify electrical defects without damaging the wafers undergoing integration, conventional methods are often too slow, destructive, or lack the resolution to measure individual cell structures.
The near-field THz-TDS system leverages the unique properties of THz waves to penetrate multiple layers of the semiconductor structure. This provides valuable information about both the sheet resistance of thin films (such as tungsten) and the critical interface properties between materials (like the gate oxide and silicon substrate). The system's versatility is demonstrated by its ability to detect variations in tungsten film deposition and, importantly, to identify nitrogen infiltration at the gate-oxide/Si-substrate interface during rapid thermal nitridation (RTN) processes – a direct indicator of threshold voltage changes.
Protemics' microprobes are the key enabling technology behind this world-first demonstration. Their robust design allows for precise positioning and rapid scanning of the wafer surface, even on the warped or bowed wafers typical in advanced manufacturing processes. The long-term stability and operational lifetime of the Protemics components were also critical for successful integration into the demanding, real-world environment of a high-volume memory production line, where the system demonstrated results consistent with traditional (but destructive) methods.
This represents not just a technological advancement, but a paradigm shift in semiconductor metrology. The ability to quickly and accurately assess electrical properties in-line provides rapid feedback for process control, leading to higher yields, improved reliability, and ultimately, better performing memory chips. The successful deployment of this Protemics-powered system within a working fab paves the way for widespread adoption of near-field THz metrology in the future of semiconductor fabrication.
Reference:
Jun, S., Baek, I., Park, S. et al. Near-field terahertz time-domain spectroscopy for in-line electrical metrology of semiconductor integration processes for memory. Commun Eng 4, 30 (2025). https://doi.org/10.1038/s44172-025-00356-y