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Navigating Polycellulose Fiber Contamination Challenges in Sub 14 nm Wafer Fabs: Unveiling Insights with Foamtec’s PolyCHECK® Process

by | Aug 22, 2023

Introduction: In the intricate world of sub 14 nm semiconductor fabs, meticulous contamination control reigns supreme. These facilities implement stringent protocols to ensure precision processes. Yet, a perplexing issue has emerged – the presence of Polycellulose fibers exceeding 500 microns in length within process chambers and wafer transport stations. This unsettling discovery has spotlighted the need for in-depth investigations into contamination sources. Here, Foamtec’s PolyCHECK® process has emerged as a guiding light, enabling several sub 14 nm fabs to uncover the enigma behind these unusual contaminations.

Delving into the Contamination Puzzle: PolyCHECK® stands as a formidable tool in the quest for answers. Employing static attraction, this innovative process captures particles, paving the way for meticulous analysis and the pinpointing of contamination sources. Through PolyCHECK®, sub 14 nm fabs are gaining unparalleled insights into the composition and origin of the identified Polycellulose fibers. The revelations garnered through this process play a pivotal role in crafting effective strategies to address the issue.

Unearthing the Polycellulose Mystery: The journey of PolyCHECK’s® analysis begins with the collaboration of engineers and the invaluable insights it offers. The process involves comprehensive sampling of surfaces within vacuum chambers, wafer transport stations, spare parts, and equipment across gown rooms, parts clean shops, and OEM tool assembly cleanrooms. Within these controlled environments, sophisticated tools like Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM EDX) and Fourier Transform Infrared Spectroscopy (FTIR) come into play.

SEM EDX: A Glimpse into Elemental Signatures: SEM EDX shines as a guiding light, offering elemental insights into the Polycellulose fibers captured by PolyCHECK®. This elemental map acts as a trail, guiding engineers through the intricacies of the fabrication process. By identifying potential sources of Polycellulose fiber contamination, engineers can initiate targeted adjustments and enhancements to eradicate the issue at its roots.

The resist polyester and polycellulose contamination captured from the P-Chuck & TSU are greater than 500 microns in size. The polyester fibers are a direct match with the wipers used in the track.

FTIR: Peering into Chemical Composition: FTIR complements SEM EDX by delving into the chemical composition of the identified fibers. This chemical analysis unveils the molecular fingerprint of the Polycellulose fibers, further narrowing down potential sources. This knowledge empowers engineers to make informed decisions about the materials, processes, and environments contributing to the contamination.

Using SEM/EDX & FTIR Technology, Foamtec was able to identify the source of contamination coming from the facility’s POR polyester wipe and polycellulose wipes.

Unveiling the Polycellulose Provenance: PolyCHECK’s® standout contribution is its ability to unveil the source of Polycellulose fiber contamination. By conducting a meticulous analysis of various elements, engineers uncovered an unexpected revelation. While polyester fibers were indeed present, the spotlight fell on the unintended culprit – Polycellulose non-woven wipers. These wipers, prohibited in modern 300mm fabs due to their migration tendencies, were identified as the primary cause of Polycellulose contamination. This migration extended from tools and spare parts to cleanroom gowns and even new tools, posing a significant risk of scratch defects in wafer transport systems.

Conclusion: Navigating the Challenges with Precision In the intricate landscape of sub 14 nm wafer fabs, Foamtec’s PolyCHECK® process emerges as a beacon of insight. By peeling back the layers of the Polycellulose fiber contamination enigma, sub 14 nm fabs are armed with the knowledge that steers effective solutions. With these revelations in hand, the industry can not only tackle Polycellulose contamination but also gain deeper insights into the intricacies of contamination migration, particularly the high risk of scratch defects in wafer transport systems. As sub 14 nm fabs march forward with unwavering precision, PolyCHECK® stands. 

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