Study Of Measurement System For Micro-nano Deep Trench Structures

In the area of design and manufacturing process of micro-electronics and micro-electromechanical system (MEMS), deep trench structures with high-aspect ratio are widely used. As the conventional measurement methods are difficult or even impossible to measure the depth of the trenches, optical methods to extract the critical dimensions of deep trenches are proposed. The degree thesis supported by Hi-Tech Research and Development Program of China, study of model-based infrared reflectometry application for deep trench measurement. The main contents of this paper comprise:The method for measuring deep trench structures of dynamic random access memory (DRAM) based on fourier transform infrared (FTIR) reflectometry is proposed, the software and hardware for the measurement system is designed. The attention is focused on the regulation and correction of the optics. Combining with the special optical design, the suppression of the backside reflection of the silicon wafer is proposed. IR source, optics, Michelson interferometer and computer are integrated, establishing the infrared reflectometry prototype.In the environment of Matlab, the software of the system is developed. With the signal collection software, the spectrum with high signals-to-noise ratio (SNR) is collected by the system, completing the fitting of academic spectrum and measurement spectrum, and procuring the parameters.After accomplishing the hardware and software of the measurement system respectively, integrated regulation and performance optimization are developed. Routine samples with layered-film stack structures are measured; the feasibility and validity of the algorithm are analyzed and demonstrated. To optimize the optical design, deduce the errors of hardware system, the theoretical analysis of the errors of the system is necessary. The measurement system is calibrated after the analysis of standard sample, enhancing the stability and precision of the system.The paper provides the equipment development and research of model-based FTIR measurement for deep trench structures. Through the structural design of hardware and theoretical research of measurement, combining with experiments, we complete the preliminary equipment development and research of model-based FTIR system.