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Restriction of Wafer Drift in Parallel-Plate Plasma System

IP.com Disclosure Number: IPCOM000042385D
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Gut, GM: AUTHOR

Abstract

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.

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Restriction of Wafer Drift in Parallel-Plate Plasma System

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. After arranging the large product wafers 10 in a desired pattern on the parallel plate, place the small wafers 20 around the periphery of the pattern, as indicated in the figure. The volume of air trapped under the small wafers 20 is insufficient to float them; thus they will prevent the drift of the large wafers 10. This technique is an improvement over previous methods which use messy and possibly contaminating adhesives to restrict wafer motion.

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