High Force Z Sense Mechanism
Original Publication Date: 1980-Sep-01
Included in the Prior Art Database: 2005-Feb-13
Fig. 1 shows a typical cycle for a wafer chuck. The Z elevator stroke (needed to accommodate an optical alignment system) is achieved by using an inflatable diaphragm. The programmable Z will be energized to perform the pad sense stroke. Upon pad sensing, the Z motor will "freeze" by a holding current. At this point the deflection cylinders are depleted, allowing the diaphragm to expand further, providing the necessary deflection force.