Study On White Light Spectral Interferometry: Measurement Method And System

The development of micro-nano manufacturing technology promotes the detectiontechnology to march on the field of micro-nano technology. As two important parts ofmicro-nano component, micro-structure and thin film have been widely applied in the field ofsemiconductor, medical, aerospace and modern manufacturing. As their tiny and fine features,the traditional detection methods cannot satisfy the requirements. White light interferometrycan realize fast, non-contact and high precision measurement, and it is now widely used in thefield of micro-nano detection, with the high efficiency of spectrum measurement, white lightspectral interferometry measurement technology has been put forward and system has beenbuilt in this dissertation. Compared with white light scanning interferometry, this technologyhas strong ability in resistance environmental noise and high speed. The main research in thisdissertation is listed as follows:1. The state-of-art research situation about measuring technology of geometry parameter ofmicro-structure and thin film were described in detail. White light spectral interferometrymeasurement technology has been put forward, which combined the high precision of whitelight interferometry and the high efficiency of spectrum measurement.2. The measurement principle of white light spectral interferometry was analyzed. Firstly,the character of white light interferometry signal has been described, and white lightinterferometry spectrum signals have been focused on. Then several phase extractionalgorithms have been introduced, emphasized on time phase shifting algorithm. At last,different measurement models have been established for measuring micro-structure and thinfilm.3. The measurement system has been built. It mainly includes three parts: the microscopicinterference optical system, mechanical support and movement devices, measurementsoftware. Light source, optical microscopy, micro interference object, fiber and spectrometerare included in microscopic interference optical system, which is used to extract the opticalsignal. Mechanical support and movement devices were for fixing the optical system on,adjusting position and shifting phase. The software of system included the following two parts:control acquisition interface developed by Labview and data processing programmed byMatlab.4. Experiments of system performance test have been conducted. The measuring range of system has been determined and the repeatability has been verified. The accuracy of systemhas been validated by measuring the standard step structure. For measuring the thin filmstructure, firstly, the impact of nonlinear phase and data processing algorithm of thin filmhave been analyzed. Then several different films have been measured by reflectance spectrumof white light and white light spectral interferometry technology. The measuring results areconsistent with the simulation.