The Model Of Scatterfield Microscope Based On Rigorous Coupled Wave Analysis

The rapid development of semiconductor and MEMS industries make an urgent request to develop the optical microscopy techniques that can improve or break the conventional diffraction limit to meet the measurement needs. Scatterfield microscopic measurement technique is currently the world’s hotspots for critical dimension measurement studies, mainly to solve the online, non-contact and fast size measurement for semiconductor processing, MEMS and other industries.Scatterfield measurement is a measurement approach based on model by comparison. The RCWA algorithm is chosen as the forward modeling method for the optical scattering measurement of one-dimensional micro and nano periodic structure. It strictly solves Maxwell’s equations in the grating region and then obtain the electromagnetic expression coupled by the characteristic function in the grating region by that Maxwell equations solution is looked as a problem to solve a characteristic function. Finally, the boundary conditions in the grating region and other regions of the junction surface are applied to solve the final value of the diffraction efficiencies.According to the characteristics of the algorithm theoretical derivation and computation, combined with the characteristics and advantages of the MATLAB language, the structure-oriented programming method is adopt to achieve rigorous coupled-wave analysis algorithms. The algorithm is evaluated in the three aspects:the accuracy, speed and the general characteristics of measurement. The results show that RCWA theory could achieve accurate and efficient purpose.The measurement characteristics of height, width and duty cycle for one-dimensional periodic structure in TE and TM mode are thoroughly discussed. Overall, the measurement characteristics in TE mode are better than that in TM mode. In theory, the linewidth measurement in TE mode could achieve nanometer resolution. The good measurement properties of RCWA theory for one-dimensional periodic micro and nano structure provide a scientific and feasible basis for scattering measurements.