ULTRAUNIFORM CHEMICAL-MECHANICAL POLISHING (CMP) USING A HYDRO CHUCK,FEATURED BY WAFER MOUNTING ON A QUARTZ GLASS PLATE WITH FULLY FLAT, WATER-SUPPORTED SURFACE

For uniform device planarization by chemical mechanical polishing (CMP ), the effect of a wafer-chuck structure on the polishing uniformity i s examined. It is found that ''wafer mounting on a rigid plate (WOR)'' structure is superior to ''urafer mounting on an elastic film (WOE)'' structure for diminishing polishing fluctuation near the wafer perime ter. The WOR structure, however, generates abnormally polished spots i n the wafer due to abrasive particle inclusion in the region between t he rigid chucking plate and the wafer. A new WOR-type wafer chuck: cal led a ''hydro chuck'', is developed: the chuck is made of a quartz gla ss plate with a fully flat water-supported surface. Water is continuou sly supplied on the quartz glass plate to form an aqueous hydro film, which suppresses slurry penetration between the rigid quartz glass pla te and the wafer. Using the hydro chuck, an uniformity of +/-1200 Angs trom in a 6'' wafer is realized for CVD-SiO2 polishing.