Fault checking apparatus in electrostatic chuck

Abstract

Abstract PURPOSE:To reliably check the continuity between a sample and electrode by utilizing an AC signal through the use of static capacitance between a sample and basic panel. CONSTITUTION:When a switch 10 is turned ON for the predetermined period, a closed loop is formed by an AC generator 9, a switch 10, a detection transformer 8 (primary side), a capacitor between the basic panel 1 and sample 2, an equivalent resistor R of sample 2 and an electrode 3 and thereby an AC current flows. An AC signal is induced at the secondary side of the detection transformer 8, it is then amplified by a buffer amplifier 11 and inputted to a detection integrator 12. Thus, said signal is converted to a DC signal having an amplitude corresponding to such input. The converted DC signal is then inputted to a comparator 13. The comparator 13 compares an output signal of detection integrator 12 with the reference value. When the sample 2 is conductive with the electrode 3, an output signal of detection integrator 12 is inputted to a latch circuit 14 from the comparator 13 and a check signal is outputted from this latch circuit 14.

Inventors

• 👤 Kuniyoshi Tanaka
• 👤 田中　国義

Bibliographic Details