YieldUP Wins Cleaning and Drying Patent

By Lisa A. Karter

Mountain View, CA–YieldUP International Corp. was issued a patent for its Surface Tension Gradient (STG) cleaning and drying technology. The new YieldUP STG technology is primarily used to clean and dry patterned and unpatterned silicon wafers at various points in the IC manufacturing process, but it has also been used to clean and dry substrates in other defect-sensitive industries such as magnetic disks, flat panel displays and photomasks.

According to YieldUP, its process provides improvements over conventional spin rinse dryers (SRDs) and isopropyl alcohol (IPA) dryers. The STG cleaning technique uses ppm amounts of IPA in a nitrogen carrier gas that is introduced to wafers submerged in a deionized water bath. A subsequent drying sequence is completed using heated nitrogen gas. The technique is based on the “Marangoni Principle” of surface tension differential, named after the Italian scientist Marangoni, an early researcher in the field of fluid dynamics.

“With the issuance of this patent, and our previously patented CleanPoint technology, YieldUP has established itself as a technology leader in the semiconductor wet processing arena,” says Raj Mohindra, president and CEO of YieldUP. With the STG system, cleaning and drying is carried out in a single tank with no mechanical motion. The YieldUP process also reduces the use of Volatile Organic Compounds (VOCs) when compared to standard IPA dryers, says YieldUP.

The company is currently in litigation for patent infringement instituted by CFM Technologies, Inc. (West Chester, PA). YieldUP is countersuing CFM. n