PROCESS OF POLISHING WAFERS

摘要

THE INVENTION CONCERNS A PROCESS OF POLISHING WAFERS, IN WHICH A SILICON WAFER HELD ON A WAFER SUPPORT PLATE ROTATABLE UNDER A PREDETERMINED APPLIED PRESSURE, IS POLISHED BY MECHANOCHEMICAL POLISHINING IN A PLURALITY OF POLISHING STEPS WITH AN ABRASIVE MATERIAL INTERPOSED BETWEEN THE WAFER AND A POLISHING PAD CLOTH APPLIED TO A POLISHING SURFACE PLATE MOVED RELATIVE TO THE WAFER SUPPORT PLATE AT A PREDETERMINED RELATIVE SPEED. QUALITY COMPARABLE TO THAT OF WAFERS OBTAINABLE BY A PRIOR ART THREE-STEP POLISHING PROCESS CAN BE OBTAINED WITH A TWO-STEP WAFER POLISHING STEP COMPRISING A PRIMARY POLISHING STEP AND A FINAL POLISHING STEP. THE PRIMARY POLISHING STEP IS PERFORMED BY SETTING A HIGH POLISHING PRESSURE OF 300 TO 700 G/CM2 AND A REFERENCE RELATIVE SPEED OF 50 TO 150 M/MIN., AND QUICK INCREASE OF THE RELATIVE SPEED TO 2 TO 4 TIMES AND QUICK REDUCTION OF THE POLISHING PRESSURE DOWN TO 1/2 TO 1/10 ARE CAUSED IN A FINAL STAGE OF THE PRIMARY POLISHING STEP. THE FINAL POLISHING STEP IS PERFORMED BY SETTING A REFERENCE POLISHING PRESSURE OF 100 TO 400 G/CM2 AND A REFERENCE RELATIVE SPEED OF 50 TO 150 M/MIN., AND IN ITS FINAL STAGE THE RELATIVE SPEED IS QUICKLY REDUCED TO 1/2 TO 1/5.