Abstract:

Lowering organic contamination in ultrapure water (UPW) is becoming increasingly important to maintain a robust manufacturing process with high product yield in semiconductor device fabrication. Acceptable levels of organics in production, and consequently, allowable limits in UPW continue to reduce in the International Roadmap for Devices and Systems (IRDS) in anticipation of advanced devices with smaller dimensions and increasingly complex three-dimensional structures. In addition, the ability to speciate organic contamination is needed in order to identify potential source(s) of contamination and potentially improve materials of construction and to support appropriate mitigation technologies.

Prior testing in support of latest SEMI F57 update has indicated that some piping materials may have difficulty achieving the TOC and fluoride extraction requirements in hot UPW applications in the time frame desired by end users. A robust and predictive extraction method is needed to allow manufactures to improve their products and for end users to accurately determine their startup schedules.

This paper presents a method for determining Total Organic Carbon (TOC) extraction and extraction rate from polymeric piping materials in 85oC UPW (HUPW). The method continuously circulates the HUPW over an extended exposure period, allow TOC contamination to build over time. TOC was monitored in-situ using a TOC monitor and by grab samples for off-line analysis. By calculating the change in TOC as a function of time, TOC extraction rate can be calculated and used to estimate the operating time required to meet the extraction rate target by the IRDS Roadmap. Fluoride ion extraction rate can simultaneously be measured during this procedure.

While having TOC extraction rate data is valuable in establishing installation and qualification timing, it does not provided data on the nature or source of the organic contamination. It also does not provide data on the particle and particle precursor extraction. To this end, the extract was analyzed for particle size distribution using Liquid Nanoparticle Sizing and Scanning Threshold Particle Counter (STPC). Additionally, particles from the extract were collected for SEM and TOF-SIM analysis using Focused Aerosol Deposition (FAD). Particles as small as 4 nm were isolated and imaged. Additional results will be provided in the paper.