CAPACITANCE MEASUREMENT SYSTEM WITH DIFFERENTIAL COUPLES Russian patent published in 2015 - IPC G01B7/14 

FIELD: instrumentation.

SUBSTANCE: invention relates to instrumentation, namely, to a capacitance sensor for distance measurement, in particular, to a target in a lithographic device. Substance: a capacitance measurement system comprises two or more capacitance sensors (30a, 30b), one or more sources (306a, 306b) of AC power for supply of power to capacitance sensors and a circuit of signal processing for processing of signals from sensors. The sensors are arranged in pairs. One or more sources of AC power are made as capable of energizing the first sensor from the pair of sensors with AC (307) or voltage with a phase shift of 180 degrees relative to current or voltage for the second sensor from the pair of sensors. The signal processing circuit is made as capable of processing the received output signals for generation of a single measured value of the distance corresponding to the average distance between the metering block and the target. The signal processing circuit is made as capable of generation of the result of differential measurement by summation of output signals from the measurement block during the first half-period of the supply signal and during the second half-period of the supply signal separately, and subtraction of the summed values.

EFFECT: development of a capacitance sensor for distance measurement.

15 cl, 32 dwg