New method of measuring the permittivity of silicon wafer, with relevance to permittivity-based quality sensing

Abstract

A new method of measuring the permittivity of silicon wafers is provided. It removes the previously reported dependence of the measured permittivity on the silicon resistivity and on the electrode quality. Metal-semiconductor contacts or thin-film electrodes are not required. The method innovatively uses N-segment (e.g., N = 7) sandwiching aluminum-foil electrodes adhered to both surfaces of the wafer using double-sided adhesive tape, which provides adhesion and resistance enhancement (for ensuring that the meter measures the capacitance correctly). By measuring the capacitance C for various values of the capacitor area A (as provided by different numbers of segments) and plotting 1/C vs. 1/A, the permittivity is obtained from the slope and the effect of the electrode-specimen interface capacitance is removed. The relative permittivity (12) equals the conventionally obtained values. By using a sufficiently high value of N, the permittivity spatial distribution can be probed, thus enabling spatially resolved permittivity-based quality sensing.