A NEW DESIGN FOR OPTICALLY FLAT AND DAMAGE FREE POLISHING OF 3 INCH DIAMETER GAAS AND INP WAFERS

A POLISHING MACHINE CONCEPT WAS DEVISED FOR NON-ABRASIVE POLISHING OF THREE INCH DIAMETER (OR LARGER) SEMICONDUCTOR WAFERS OF GAAS, INP AND SIMILAR MATERIALS. THE POLISHING PRINCIPLE IS BASE ON A TECHNIQUE DEVELOPED BY MIT LINCOLN LABORATORY SCIENTISTS CALLED "HYDROPLANE POLISHING OF SEMICONDUCTOR CRYSTALS". THIS NEW CONCEPT, HOWEVER, DOES NOT DEPEND ON THE CENTRIFUGAL DISTRIBUTION OF THE POLISHING LIQUID, BUT RATHER ON A LEVITATION PROCESS WHICH ALLOWS FOR THE POLISHING OF VERY LARGE AREA WAFERS. THE NEW PROCESS FURTHERINFINITE CONTROL OF THE FORCE BETWEEN THE LIQUID AND THE SAMPLE TO BE POLISHED. THE ROTATION OF THE SAMPLE RELATIVE TO THE LIQUID MAY ALSO BE INDEPENDENTLY CONTROLLED. INITIAL TESTS HAVE SHOWN THAT THE LEVITATION, FORCE VARIATION BETWEEN THE SAMPLE AND LIQUID, AND INDEPENDENT SAMPLE-LIQUID ROTATION ARE SIMULTANEOUSLY FEASIBLE.