Wafer release method and apparatus

Details Wafer release method and apparatus Wafer release method and apparatus

1993-03-10

1995-08-22

Pellinen, A. D.

Electricity: electrical systems and devices

Electric charge generating or conducting means

Use of forces of electric charge or field

H02N 1300

Patent

active

054445973

ABSTRACT:
A wafer position and clamp sensor. A circuit monitors capacitance between two electrodes within a wafer support. With no wafer on the support, the capacitance falls in one range, with the wafer in place but not clamped, the capacitance falls in a second range and with the wafer held in place by an electrostatic attraction the capacitance falls in a third range. The sensed capacitance is converted to a frequency and then a D.C. voltage level that can easily be sensed and used to confirm wafer placement and then wafer clamping. After the wafer has been treated, the wafer is removed and a next subsequent wafer treated. A clamping voltage applied to clamp the wafer to its support is reversed at a controlled frequency to release the wafer. The voltage reversal disrupts the electrostatic attraction between the wafer and its support.

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