Technology Trends

Achieving IPA Removal In UPW From Marangoni Dryers In Semiconductor Production

By Yazdani et al.

Reuse Semiconductors Total Organic Carbon (TOC) UV Wastewater

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Drying of rinse water from parts is for many process engineers a final critical step of a process. Drying steps can be costly, energy and time consuming, and if not done properly, will leave a non-volatile residue of minerals, detergents, and ions on the surface of the part— not to mention water stains. 

There are various methods of drying that maybe employed; however, one of the best approaches is Marangoni drying for flat surfaces such as semiconductor wafers or disk drives. 

In a Marangoni dryer, wafers or disks are mounted in an open cassette box and immersed in DI water. The wafers submerged in water, are slowly passed through a thin layer of isopropyl alcohol (IPA) on the water surface.  The surface tension gradient between IPA and water dries the wafer and helps remove impurities and particles.

This article will focus on the removal efficiencies of the IPA from the rinse waters so the water can be recycled back to the dryer. Preliminary pilot-scale testing was conducted using an advanced electrodeionization technology platform, and a total organic carbon ultraviolet system.

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