Electrical Monitoring of Thicknesses of Semiconductor Wafers

A technique based on electrical-continuity measurements has been proposed as a means of monitoring and controlling the thicknesses of semiconductor wafers during lapping, polishing, and etching. The technique is expected to contribute to the development of microelectromechanical systems by making it possible to lap and polish wafers with precision greater than has been achieved previously, thereby further making it possible to fabricate wafers of unprecedented thinness (thicknesses of 5 µm or possibly even less). Unlike some prior techniques for measuring the thicknesses of semiconductor wafers, this technique does not entail the timeconsuming intermittent stopping of processing to take measurements. Also, in comparison with most prior techniques, this technique offers the potential for greater precision at lower cost.