Browse Prior Art Database

Flatness Controlled Wafer Clamping Pedestal

IP.com Disclosure Number: IPCOM000078756D
Original Publication Date: 1973-Mar-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Rottmann, HR: AUTHOR [+2]

Abstract

The degradation of masks by contact printing can be reduced by flattening of the wafer surface. This can achieved in a number of ways: 1) In. Fig. 1, the topography of the wafer surface is sensed by a two-dimensional array of sensors (e.g. fiber bundles). In accordance with the sensing signals, a two-dimensional array of studs is activated and adjusted such that the sensor signals are equalized. The counterforce to the studs is provided by vacuum grooves or holes which are located between the studs. 2) The studs can be activated and adjusted by either mechanical means, or more precisely by piezoelectric translators.

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Flatness Controlled Wafer Clamping Pedestal

The degradation of masks by contact printing can be reduced by flattening of the wafer surface. This can achieved in a number of ways:
1) In. Fig. 1, the topography of the wafer surface is

sensed by a two-dimensional array of sensors

(e.g. fiber bundles). In accordance with the

sensing signals, a two-dimensional array of studs is activated and adjusted such that the sensor signals are equalized. The

counterforce to the studs is provided by vacuum grooves

or holes which are located between the studs.
2) The studs can be activated and adjusted by either

mechanical means, or more precisely

by piezoelectric translators. In the case of

piezoelectric translators, the stud is

fabricated by cementing together thin piezoelectric

ceramic wafers with appropriate electric connections

as shown in Fig. 2. Precise movement, in the order

of microinches, of the stud can be controlled

by the voltage applied to the stud assembly.

By applying the proper voltages to individual stud assemblies

in accordance with the signals from the flatness sensor

array, and with one end of the studs fixed to the

base, the other end provides the

necessary movement to achieve a flat wafer surface.

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