UPW Process Optimization - Q&A

This article provides insight into an interview between Ultrapure water and Jill Wallin, a senior facilities engineer with WaferTech, and covers several areas such as the types of treatments systems and Metrology and Analytical Technology instruments implemented in WaferTech plants, troubleshooting tools and the main challenges in water treatment encountered at WaferTech.

Nanoparticles represent one of the most critical contaminations in ultrapure supplies for semiconductor fabrication addressing ultrapure water (UPW), gasses and chemicals as well as materials of construction decreasing yield on the wafer. Along the UPW generation process, there are sources (e.g. materials) and sinks (e.g. filter) for nanoparticles. As final barrier for nanoparticles in the polishing step, ultrafilters are commonly used on UPW plants. However, the performance of the ultrafilters in the field in terms of removal performance for particles need to be investigated to come up with pro-active approaches for particle removal. Especially for UPW, there is a lack of online particle metrologies down to particle size of sub 50 nm. This study aims to give an overview on different particle metrologies to better understand the particle removal performance by ultrafilters on the market.

Critical feature sizes of modern semiconductor devices have surpassed the capabilities of traditional optical-based methods to measure particle concentrations in process chemicals and on wafers. Without adequate metrology for quantifying particle and particle precursor concentration in process chemicals, device makers face challenges correlating component failures and fabrication steps. This is especially true for organic material released by Final Polish Ion Exchange resin during a rinse cycle, which is not detected efficiently using optical methods. In this work, we describe two state-of-the-art measurement methods that can detect organic particles and particle precursors to 3 nm using Aerosolization and Threshold Particle Counting (TPC) and defects from UPW deposited on a wafer surface down to 8 nm using Surfaced Enhanced Particle Sizing (SEPS)

UF even withstands episodic increase of particle numbers in the feed (e.g., caused by conditioning of ion-exchange resins) without negative effects for water quality and service lifetime. Such a particle challenge typically involves high concentrations of ~10-nanometer (nm) particles. On the other hand, current on-line particle counters approach their lower detection limit at about 10nm. Large numbers of particles nearby and below this limit remain undetected. Hence, the integrity of a UF membrane is essential to keep these small particles under control; it can hardly be evaluated by comparing particle counts upstream and downstream. Therefore, better test methods are needed to identify membrane damages, and to decide on service life and replacement of UF membranes.

This presentation was given as part of the Ultrapure Micro 2021 annual conference. It was given as part of the combined track, which contained presentations on airborne molecular contamination (AMC) and high purity gases, and ultra high purity chemicals.

This presentation was given as part of the Ultrapure Micro 2021 annual conference. It was given as part of the ultrapure water strand.

This presentation was given as part of the Ultrapure Micro 2021 annual conference. It was given as part of the water and wastewater management strand.

This presentation was given as part of the Ultrapure Micro 2021 annual conference. It was given as part of the airborne molecular contamination (AMC) and high purity gases control strand.

This presentation was given as part of the Ultrapure Micro 2021 annual conference. It was given as part of the ultrapure water strand.

This presentation was given as part of the Ultrapure Micro 2021 annual conference. It was given as part of the ultrapure water strand.