Despite advancements in cleanroom technology, particle contamination remains a persistent challenge in semiconductor manufacturing. Metrology tools, particularly, are susceptible to contamination due to their high wafer throughput and complex internal components. In addition, Metrology tools are highly vulnerable to fiber scratch defects, which can significantly impact wafer yield and overall process efficiency.
In order to implement corrective action to prevent reoccurring particle and fiber scratch excursions, a comprehensive understanding of particle contamination within metrology tools is crucial. While particle detection wafers (PDWs) offer some insights, fabs must comprehensively understand the contamination source.
Particle contamination on the KLA Stage after wiping with standard fab wipers.
Traditional methods for collecting surface contaminants, such as tape and swabbing, often fail to provide sufficient material for analysis. This is especially the case for organic sources of particle contamination. These methods can also introduce additional contaminants, further complicating the investigation process.
Foamtec’s PolyCHECK® offers a superior solution for collecting and analyzing surface contaminants. Unlike traditional methods, PolyCHECK® utilizes a more extensive sampling area, ensuring a more representative sample for analysis. PolyCHECK® is also cleaner, minimizing the risk of introducing extraneous contaminants that could interfere with the analysis.
Foamtec’s PolyCHECK® offers a revolutionary approach to particle analysis, enabling equipment engineers to pinpoint the root cause of contamination with unprecedented accuracy. By collecting larger sample volumes than traditional methods, PolyCHECK® facilitates more detailed analysis, including identifying particle composition and distribution.
The Limitations of Traditional Particle Analysis
PDWs provide valuable data on particle counts but offer limited information about particle composition. This makes it challenging to determine the source of contamination and implement practical corrective actions. For instance, while PDWs can detect the presence of fiber-shaped particles, they cannot identify the specific type of fiber, hindering root cause analysis.
An example of typical fiber contamination from standard fab wipers is found in KLA metrology tools.
PolyCHECK®: A Game-Changer for Particle Investigation
PolyCHECK® addresses the limitations of traditional methods by providing a comprehensive approach to particle analysis:
· Larger Sample Volume: PolyCHECK’s® sampling method captures more material, increasing the likelihood of detecting and analyzing critical contaminants.
· Particle Composition Analysis: By combining PolyCHECK® with techniques like FTIR, equipment engineers can accurately identify the composition of particles, including the type of fiber.
· Root Cause Identification: Pinpointing the source of contamination becomes more precise, enabling targeted corrective actions.
Case Study: Identifying Fiber Contamination in a KLA Tool
A leading semiconductor manufacturer was experiencing persistent fiber-related particle contamination in their KLA metrology tool. Despite rigorous cleaning procedures, the root cause remained elusive. By employing PolyCHECK®, the wafer fab identified polyester fibers as the primary contaminant. This discovery led to a thorough investigation of cleaning materials and processes. Standard fab wipers constructed of knitted polyester were identified as the source of the fibers. Moreover, the source of the fiber contamination was not limited to the direct cleaning of KLA tools but to their use throughout the fab in wafer environments. The fab implemented a woven non-stretch microfiber wiper and has been free of fiber scratch defect incidents for over 3 years.
Particles and fibers identified as polyester in the door area in a KLA metrology tool.
Surface contamination was collected by PolyCHECK on a KLA patterned wafer inspection tool.
Fiber contamination > 500 microns long was collected by PolyCHECK® and analyzed as polyester.
Polyester wipers were confirmed as the source of fiber and particle contamination in the tool.
Conclusion
PolyCHECK® empowers equipment engineers with the tools to address particle contamination challenges in metrology effectively. By providing a deeper understanding of particle composition and distribution, PolyCHECK® enables targeted corrective actions, leading to improved tool performance and higher wafer yields.
Contact Foamtec today to learn how PolyCHECK® can revolutionize particle contamination control efforts.