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Subject: Growth of particles on copper masks in CD-R manufacturing
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Date: 02/06/02 at 5:14 AM
Posted by: Jeroen van 't Erve
We're using a DC-magnetron sputter unit for depositing silver on dye coated polycarbonate CD-R substrates. To prevent the outer edge and the center hole from being covered with silver we use copper masks. The masks get covered with silver and usually after about 15,000 discs we have to clean the masks. However, recently we're having problems with particles growing on the masks, particulary the innermask. Because the particles cause shadowing on the sputter image on the CD-R we're forced to clean the maskers after approximately 4,000 discs. When looking through a microscope the particles look like two-dimensional leafs, growing parallel to the substrate surface. The leafs start to grow from the edge of the innermask where the disc touches the mask. We would like to know what these leafs are and how to get rid of them. If you have similar experiences, please respond!
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