Method of measuring oxide thickness during semiconductor fabrication

A measurement of thickness of a metal oxide layer on a solder ball connection during semiconductor fabrication is demonstrated by an in-situ capacitance measurement of the oxide layer. A linear relationship is shown between the reactance of the metal oxide and its thickness. This linearity is derived empirically, and correlated to Auger Spectroscopy test results for accuracy. The linear relationship demonstrated with these measurements exhibits a linear correlation coefficient, R2, greater than or equal to 0.974. This close, linear relationship allows for accurate testing of the oxide thickness using standard electrical parameter measurements during wafer fabrication.The method requires the determination of an analytical relationship between dielectric thickness and dielectric capacitance; the performance of an in-situ test of the dielectric layer capacitance including measuring the dielectric layer capacitance; and, the calculation of the dielectric layer thickness by using reactance values, calculated from the measured dielectric layer capacitance, as a variable within the analytical relationship.