Dry Gas Enclosure for Low Temperature Testing
Original Publication Date: 1988-Oct-01
Included in the Prior Art Database: 2005-Feb-15
By means of an enclosure around the normal test chuck and using the probe card as a wafer top cover, a low flow of dry gas, e.g., nitrogen, into the enclosure avoids moisture condensation on a wafer during and following low temperature testing. Referring to the figure, a wafer 2 under test is placed on temperature controlled chuck 4, as is usual. Installed around the normal chuck 4 is an enclosure 6 which has a lip 8 designed to direct dry gas flow inward toward the center of wafer 2. Probe card 10 forms a loose-fitting cover over most of the area over wafer 2. When dry gas is admitted to enclosure 6 via port 12, the gas flows throughout the cavity between chuck 4 and enclosure walls formed by the inner surface of enclosure 6, lip 8, and the lower surface of probe card 10 and exits mainly through opening 14 in probe card 10.