Use and generation of UHP steam has become widespread and has applications in critical processes in diverse markets.

THE FIRST STEAM ENGINE was developed in 1679, the steam boat in the 1780s, the steam locomotive in 1812, steam for sterilization in the 1890s, and steam for laundry in 2005. Steam generation is a mature technology. It is generated through multi-effect steel stills, with a wide range of flow rates, a wide range of feed stocks, and is common in industrial facilities. Yet until now, there has not been an easy, safe, economical way to produce ultra high purity(UHP) steam.

UHP steam can be used for diverse applications in many markets. High purity steam is the foundation of the medical and pharmaceutical industries. Its uses include sterilization of almost all components used in medicine, surgery, and pharmaceutical engineering. Almost all the water used for making drugs begins as steam and iscondensed back into a liquid.

UHP steam controls the humidity in a cleanroom. The humidity in semiconductor and medical clean-rooms requires very tight control of purity of the air. The humidity of the incoming air is controlled by injecting clean steam during cold and dry environmental conditions. If the steam contains contaminants, these get transferred into the air and into the cleanrooms, detrimentally affecting yield.

In the semiconductor industry, steam is commonly used as the source gas for generating oxide films on semiconductor wafers in diffusion and rapid thermal processing. Next generation films used in atomic layer deposition (nanotechnology) will require UHP steam for formation of the high-K layer. Clean steam can also effectively remove contaminants from next generation structures. As device feature sizes continue to shrink and aspect ratios increase, the ability to get sufficient energy into the bottom of the trench becomes less and less efficient with mega-sonics. Steam provides high energy and excellent contaminant removal capability, so is well poised to become the cleaning process of choice for next generation wafer cleaning. In addition, the move to immersion lithography will require water that is absolutely pure and bubble free. The power industry also depends on steam to provide the driving force for turbines that generate electricity. Dissolved silicon can deposit on the turbine blades shortening their life and reducing efficiency if high purity steam is not used.

Water in steam generator.

Steam enters purifier where water molecules (blue dots)
permeate the membraneand contaminants (other colors) are restricted.

Fuel cells depend on hydrogen, oxygen, and water vapor. Contamination in any of these process gases can lead to poisoning of the membrane catalyst and degradation of the proton exchange membrane (PEM). In addition, proper hydration of the PEM is critical for the performance of the fuel cell.