Research About Profile Measurement Of MEMS Devices Based On Infrared White Light Interferometry Technology

Profile measurement of microstructures is the important means to controlling, monitoring and diagnosing of microstructures process, so research about profile measurement of MEMS devices based on infrared white light interferometry technology have great influence on MEMS devices measurement. From the development and current station of profile measurement of microstructures, the full text analyses the limitation of current measurement about profile measurement of microstructures with high aspect ratio. Then, profile measurement of MEMS devices based on infrared white light interferometry technology is proposed. In the existing infrared white light interferometer, system performance is improved and compensation measurement of microstructures internal profile is proposed. And measurement is verified by profile measurement of typical samples. Results are as follows,1. According to Fourier transform infrared spectroscopy, infrared reflection spectrum of model-based methods and thick measurement based on whit-light interferometry, infrared white light transmission interferometry for profile measurement of MEMS devices is proposed.2. In the existing infrared white light interferometer, scanning samples method is selected by analyzing the advantages and disadvantages of other scanning methods and can shift accurately the position of microstructures with 100 nm level. Then, stability, optical sealing and collecting position of system are improved.3. In contrast with the traditional algorithms (VSI and PSI) and new algorithms (VSI and PSI combination algorithm, SEST algorithm and thick measurement based on whit-light interferometry), appropriate algorithm (infrared Stoilov algorithm) is proposed according to the project requirements. This algorithm not only can take arbitrary phase shift value, but also has a good inhibition to second and third order nonlinearity with 100 nm level vertical resolution. In order to operate easily, infrared Stoilov algorithm and operation interface are compiled by MATLAB and VB.4. Using white light interferometry, infrared interferometry and infrared transmission interferometry and combining with improved test system, interferometer is improved by optical compensation according to the distribution of transmission interference fringes. So as to verify reflection and transmission infterference, surface and internal profile with GaAs and Si typical samples is measured. The measurement results with micron lateral resolution and 100nm level vertical resolution are in good agreement with Micro System Analyzer.