Restriction of Wafer Drift in Parallel-Plate Plasma System
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-03
Drifting of large semiconductor wafers over the surface of a parallel plate plasma system is commonly observed. This is caused by a layer of air trapped under the wafer, which supports the wafer and permits it to float during pumpdown of the chamber. Wafer floating causes problems, ranging from etch nonuniformity due to shifting of the wafer placement pattern, to difficulty in monitoring the etch process due to a shift of the monitor wafer from the proximity of a laser interferometer. These and associated problems are eliminated as follows. First, form a number of small round or square wafers 1/2" to 3/4" or so in diameter from a larger silicon wafer.