DI water tribocharging damage at CMP

A simple detection method for tribocharging of DI water (- 17M Ohm-cm) when traveling through PTFE, PVD and PVC tubing and exit nozzles is discussed. Tribocharge potentials between 10 and 200 volts are measured by direct probing of the DI water exit stream with an electrometer at low flow rates (-1 to 6 liters/minute) at the rinse station of a CMP tool used in the disk magnetic storage read head assembly process. The electrometer probe can be incorporated into the DI water conduit system for in situ measurement. A grounded metal exit nozzle is introduced and shown to eliminate the charge in the DI water without the addition of chemicals that may present integration or reliability problems.