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Many customers require wafer surface cleanliness to sub-micron particle size levels, defined as the number of particles greater than a specified size on a wafer surface. To provide our customers the low particle counts they often specify, we have developed a multi-step cleaning process based on the use of baths of a heated mixture of very pure deionized water, ammonium hydroxide and hydrogen peroxide, our adaptation of the proven "SC-1"clean, followed by machine scrubbing. Recirculating filtered over-flow baths and mega-sonic cleaning stations loosen and remove most of the particles from the wafer surfaces. Finally, the wafers are scrubbed by machines using soft sponge brushes to remove more of the loose particles. At this point the wafers are ready for final inspection.
