A technique for drift compensation of an area-varying capacitive displacement sensor for nano-metrology

Abstract Area-varying capacitive displacement sensors can overcome the short measurable range of widely-used gap-varying sensors. However, the output signal of the area-varying sensor may have an apparent drift. The drift in the signal is thought to be caused by several parameters, such as alignment error, thermal effect, external electric waves, etc. Since these parameters are difficult to control, so is reducing the drift. In this study, a model using two sets of electrodes in a single sample is proposed for reducing the drift while improving SNR (signal to noise ratio). The model is applied to an area variation type capacitive device to achieve drift and common noise reduction.