Original Publication Date: 1985-Jan-01
Included in the Prior Art Database: 2005-Feb-18
The figure shows the mechanical design of an automatic chip tester for measuring currents in the picoampere range. For this purpose, effective shielding is required. As it is impractical to shield the entire tester, only the table carrying the wafer to be tested and the probe contacting the wafer are shielded. As the shielding must not interfere with the X-Y and the vertical table movements, an aluminum sliding plate is movably mounted between a carrier and a cover plate. The movable aluminum plate is arranged underneath the wafer table from which it is isolated by a TEFLON* foil, and whose movement it follows. The carrier and the cover plate are suitably recessed to permit the table to move freely. Carrier and cover plates are mounted on a stable frame which is fixed to the tester.