Browse Prior Art Database

Holder for Flat Thin Elements

IP.com Disclosure Number: IPCOM000086905D
Original Publication Date: 1976-Nov-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 60K

Publishing Venue

IBM

Related People

Jaerisch, W: AUTHOR [+2]

Abstract

For contouring the surface of a flat thin element, e.g., semiconductor wafers 10a and 10b, a plurality of chucks 12 are supported on individually reciprocative shafts 14, grasping the lower surfaces of wafers 10a and 10b at selected areas. Sensors (not shown) are arranged adjacent to the opposite wafer surface and serve to sense the distances between reference plane 16 and selected individual wafer areas (points RP). Any difference in the distances between the various wafer areas detected by the sensors results in the actuation of means, e.g., step motors or piezo-electric drivers (not shown), for elevating or retracting the individual chuck shafts 14.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 74% of the total text.

Page 1 of 2

Holder for Flat Thin Elements

For contouring the surface of a flat thin element, e.g., semiconductor wafers 10a and 10b, a plurality of chucks 12 are supported on individually reciprocative shafts 14, grasping the lower surfaces of wafers 10a and 10b at selected areas. Sensors (not shown) are arranged adjacent to the opposite wafer surface and serve to sense the distances between reference plane 16 and selected individual wafer areas (points RP). Any difference in the distances between the various wafer areas detected by the sensors results in the actuation of means, e.g., step motors or piezo-electric drivers (not shown), for elevating or retracting the individual chuck shafts 14.

Generally, wafers are not absolutely plane and of uniform thickness In order to prevent the semiconductor wafer material from being tensioned during the above flattening process, each chuck 12 is mounted on its shaft 14 by means of a bearing, allowing a slight tilting of the chuck. Fig. 1A shows a convexly shaped wafer (in an exaggerated form) before the upper surface is flattened with respect to reference plane 16. Fig. 1B is a schematic representation of a conventional leveling system in which the chucks are rigidly mounted on their shafts, so that during leveling the boundary areas between the individual chucks are strained and, also, bent by the chuck. If, as shown in Fig. 1C, each : chuck 12 is mounted on its shaft 14 by a bearing, allowing the chuck to be tilted, then a continuou...