Non-contact wafer thickness measurement of capacitance sensor circuit based on CAV424

Abstract

Non-contact wafer thickness measurement with the CAV424 capacitance sensor special integrated circuit and arc pole plate capacitor sensor has good stability and linearity under low capacity of the bottom of sensor and low&entity; C condition. This method has a high technical advantages and practical value. Two capacitance sensors Cb, Ca measurement spacing 4mm install at the same axis which constitutes the size condition for measuring thickness. The static capacity of Ca and Cb is a constant value. The capacity of Cb and Ca will change when the silicon wafer is involved. This change is checked by the CAV424 capacitive sensor which has better linearity and higher thickness resolution.

Keywords

• Circular planar capacitance sensors
• CAV424 application-specific integrated circuit for capacitance sensor
• Application design and non-contact thickness test