Abstract
The bottom and sidewall profile reconstruction of microstructures with a high aspect ratio is a problem that urgently needs to be solved in the field of MEMS(Micro-Electro-Mechanical system). Microstructures profile reconstruction method is presented based on near-infrared light transmission reflection interferometry with optical path compensation(OPC), which is extended from white light to near-infrared light and from reflection interference to transmission interference. The near-infrared light transmission interferometry system is composed of a near-infrared light source, an interference microscope, an infrared light CCD, piezoelectric ceramics with high accuracy and a data acquisition system. A GaAs sample microstructure with two steps was designed and the method of vertical scanning interference of near-infrared light with OPC was adopted to reconstruct the internal profile of a microstructure, which was then compared with the results of scanning electron microscopy(SEM). Test results show that the relative heights of the measured microstructure steps using near-infrared light transmission reflection interferometry were 2.132 μm and 0.766 μm with 2.16% and 2.68% relative errors, respectively, which agree with the results of SEM and that of the near-infrared light reflection interferometer. The measurement system has the ability to reconstruct the bottom and sidewall profile of microstructures with a high aspect ratio.
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