Acid Chemical Thinning Apparatus
Original Publication Date: 1978-Jun-01
Included in the Prior Art Database: 2005-Feb-21
Chemical thinning is a technique used to remove process-induced crystallographic damage from sliced, lapped, or ground wafers. Known methods utilize rotating barrels, rotating open cups and stationary or oscillating open trays and tanks. The process is exothermic and copious amounts of nitrous oxides are evolved. The reaction is stopped at a predetermined time, depending on how much material is to be removed from the surface of the wafer by quenching with copious amounts of D.I. water. These processes generate large volumes of HF containing wastes. In addition, wafer staining is frequently observed due to the imprecise methods used to stop the reaction. Wafers chem-thinned with rotating barrels have rounded edges. Usable, undepleted acid mixtures are discarded, incurring added expense.