Oxide Thickness Profile Measurement by Dispersive White-Light Interferometry in CMP Process

Thickness profiles of CMPed oxide thin films are precisely measured by means of spectrally-resolved analysis based on dispersive white-light interferometry. This method allows not only the top surface profile but also the film thickness of an oxide film layer to be measured simultaneously with fine lateral and depth resolutions, leading to a complete 3-D tomographical reconstruction of the measured thin film. Besides, very thin films of less than 0.1 micrometer thickness can be accurately measured with precision in the nanometer range. No mechanical depth scanning is required during measurement, thus the proposed method is fast enough for the non-contact in-line inspection required for effective quality assurance of CMPed wafers.