August 24, 2005 – Tokyo Seimitsu Co. has developed a special grinding and polishing procedure that can process silicon wafers down to a thickness of just 5 microns. The new technology opens the door on wafers that can bend like a piece of paper. In comparison, the wafers now used for semiconductor mass-production are 75 microns at the thinnest, according to a story in the Nikkei English News.
Wafers this thin will significantly reduce the space taken up by semiconductor devices in multichip packages for cellular phones and other applications where size and weight are important selling factors.
Tokyo Seimitsu designed the technology for use with its polisher grinders, which trim the wafer from the underside after the circuits have been placed on the silicon. The wafer, which has an initial thickness of 725 microns, is first ground down to a thickness of around 10 microns using two kinds of diamond whetstones. They are then further polished using silicon oxide in a process that involves finely adjusted concentrations of polishing agents and cleaning fluids.
Wafers that are 50 microns thick will be used for semiconductor mass-production starting around the end of this year. The new procedure from Tokyo Seimitsu promises even thinner wafers. The company thus plans to adopt the procedure for its mainline PG300RM Series of polisher grinders with the goal of doubling sales to 60 units in fiscal 2005.