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Product Briefing Outline: RASIRC has revealed its next generation high-purity steam generation system called the ‘Steamer UHP 125.' With a reduced footprint, it can directly replace torches, bubblers, and direct water injection systems in 6", 8", and 12" furnaces as well as in other applications where flow rates of up to 12.5 slm of pure water vapor are needed. It has the ability to control flow into vacuum or atmospheric pressure systems. It generates Ultra High Purity steam from de-ionized water without hydrogen or oxygen.

Problem: Steamer UHP 125 is a safe, non-combustible system, as it does not require hydrogen and oxygen to generate water vapor. Water contaminants, including dissolved gases, metallic impurities, and particles are removed, resulting in purity equal to or better than pyrolytic steam created by burning oxygen and hydrogen. The RASIRC Steamer is claimed to show faster growth rates and better uniformity over torches, bubblers and direct liquid injection (DLI) systems by being able to deliver very high flow rates of 100 percent water vapor. In certain applications, such as thick oxide growth, overall process times have been reduced by almost 20 percent, freeing up an extra day of process time per week, according to the company.

Solution: The Steamer uses de-ionized water, which is inexpensive and widely available. A highly flexible system, it automatically controls delivery pressure, temperature, and the directly related mass flow rate so it can be adapted for many applications. It can be operated locally or remotely with an optional 0-5V ‘DeviceNet,' or ‘Modbus.'  A non-porous hydrophilic membrane selectively allows water vapor and steam to pass through it. Membrane selectivity is significant, as water molecules can pass through it 1,000,000 times faster than nitrogen molecules. In the vapor or steam phase, all other molecules are greatly restricted, and so contaminants in water such as dissolved gases, ions, total organic carbons (TOCs), particles, viruses, bacteria, pyrogens, and metals can be removed from the purified steam. According to the company, data from tests done on water vapor purified using the Steamer UHP 125 system show reduction of 67 different metals to below detectable limits. Some contaminants have been verified to less than 0.0005 parts per billion. Nitrogen and CO₂ contaminants can also be eliminated. Because the Steamer works with water at low pressures, alternative high purity piping material such as quartz and fluoropolymers can be used in the delivery system.

Applications: Water vapor is used with rapid thermal processing (RTP), atomic layer deposition (ALD), plasma stripping, immersion lithography, diffusion, wafer cleaning, and to control humidity in cleanrooms.

Platform: This next generation design has a footprint of 12" length by 6" width for a steamer that is 65 percent smaller than RASIRC's full-size steamer. At only 12" high the steamer is now small enough to fit on 6" diffusion furnace shelves and the purifier is integrated within the cabinet rather than being externally mounted. Volume is now 0.5 cu.ft. - a reduction of 75 percent.

Availability: May 2007 onwards.