Advanced Microscopy for Quantification and Identification in UPW, Process Chemicals, and Industrial Gases

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)

This provides greater visibility to the material manufacturing process, which complements a risk-based approach to material disposition and facilitates timely response to inline material signals. Gases have not historically resulted in the same level of fab process impact at legacy nodes; however, excursion impact of raw materials has increased exponentially at smaller and smaller nodes. More frequently, gas excursions have resulted from isolated process, raw material, and cylinder-level abnormalities not characterized on the COA. This impact has driven the need for a similar COA expansion approach within high purity gases, for quality assurance. In preparation for EUV nodes, the overall gap in analytical capability, characterization, and control between the Asian and US markets, further drives the need for this supply chain visibility. Therefore, investment and innovation in US high purity gas supply chains will be critical to achieving yield ramp in EUV nodes.

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 ultrapure water 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 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 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.