About Wafer Recycling: With the continuing shortage of certain types and sizes of Silicon wafers and their associated high cost, used wafer reprocessing or Recycling is not only a good idea, in some cases like with 300mm it is an absolute must! Wafer Recycling is not a grinding or polishing process and as such it will not remove scratches, scribe marks, silicon haze or other related defects. However, it does not thin the Silicon wafer or change the flatness characteristics of good prime wafers and best of all it can be repeated many times. We do recommend Reclaiming for badly damaged wafers Process Specialties can also handle this work for our customers as well. Please remember wafers can only be reclaimed two to three times before they are to thin and not usable. On the other hand we have Recycled some customer wafers over 10 times with no real detectable change in flatness or apparent damage to the silicon. This is because in our process we use a combination of wet and dry stripping processes, methods and chemistries developed by us over the years to strip used films and patterns off the Silicon wafers. In most cases revealing a fresh new Silicon surface ready for subsequent processing.

Removable films: Within certain limits the following films can be recycled: Thermal Oxide, TEOS Oxide, BPSG, Polysilicon, Aluminum/Cu, Cu, TiN, Ti, TiW, W, Ni, Co and others ( patterns OK ).

Non removable films: There are a few films we will not Recycle: Platinum (Pt), Vanadium (V), Gold (Au) and Silicides (any). Also Silicon Nitride and Poly Silicon cannot be Recycled unless they have Thermal Oxide as a base layer to protect the Silicon surface. The same chemistries that remove Nitride and Poly also attack Silicon and if the wafer is not protected by Oxide the polished surface can be damaged and ruined during the removal process. For this reason unless you know that your Nitride is indeed on at least 500A Oxide we will not be able to Recycle these wafers.