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Gatan Solarus Advanced Plasma Cleaning System

Optimal imaging and microanalysis in electron microscopy requires a clean, well-prepared specimen. This is especially important for field emission gun transmission electron microscope (FEGTEM), because specimen contamination rates tend to increase as probe size decreases and beam current density increases. The high performance now possible with the field emission scanning electron microscope (FESEM) underscores the need for eliminating hydrocarbon contamination, especially for those applications involving low voltage, high-resolution operation.

A RF-generated gas plasma cleaning process, originating within the semiconductor industry for wafer cleaning, has been known and available for some time. A version of this technique was adapted for EM applications by Nestor Zaluzek at Argonne National Laboratory and University of Chicago (US Patent 5,510,624, dated April 23, 1996).

The Solarus® advanced plasma system, model 950, expands this process to a new level. Solarus is a low power hydrogen and oxygen radical generator producing glow discharge plasma within the generator housing. The hydrogen and oxygen radicals disperse from the generator by convection, passing over and around the specimen/specimen holder tip to clean hydrocarbons from the surfaces. The process produces H2O, CO2, and CO gases that are pumped away by the vacuum system.

Solarus incorporates a multi-stage diaphragm pump backing a turbo molecular drag pump to assure fast, reliable pumping. The pump package enables pump and vent cycles of less than two minutes. With cleaning times of 1 – 2 min, the full Solarus cleaning cycle takes less than 4 min.

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