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A Japanese researcher developed a cleaning technique that uses only water and no chemical solution for industrial processes.

The technique was developed by Toshiyuki Sanada, assistant professor of the Department of Mechanical Engineering at Shizuoka University.

It injects water vapor and water at the same time. By using water vapor, which has a high condensation effect, it becomes possible to wet even an ultramicroscopic surface, realizing a high detergency performance. The technique can be used to remove foreign particles with a size of several nanometers without scratching an object to be cleaned.

With existing techniques, a different chemical solution is required to remove each of the light-sensitive film, polymer and so forth. But the new technique enables to remove them all at the same time, reducing the production cost. Also, the detergency performance can be further enhanced if an infinitesimal quantity of chemical solution is added.

Sanada expects that the cleaning technique will be used to clean semiconductor devices, printed boards, optical lenses and large glass plates in addition to medical apparatuses, foods and things to be cleaned at home.

In the manufacturing processes of semiconductor devices, there has been a need for a cleaning method that has a stable detergency performance and uses less chemical solution for cleaning a large number of wafers in order to scale down devices, introduce new materials and processes and address environmental problems.

RCA cleaning techniques, which use ammonia water, hydrochloric acid and hydrogen peroxide solution as cleaning fluids, have been commonly used in the manufacturing processes of semiconductor devices.

However, there are some problems such as a low cleaning performance, re-contamination caused by the reattachment of foreign particles, and large amounts of wastewater and
waste fluid because a large number of wafers are processed at the same time. On the other hand, the cleaning method of jetting air and water (or chemical solution) has a problem of scratching an object to be cleaned because it uses high-pressure air.