Design and Study of an Electron Beam System for Silicon Recrystallization
The fabrication of Three-Dimensional Integrated Circuits (3D-ICs) is a key advancement in semiconductor technology. Technologies like Silicon-On-Insulator (SOI) can be used for the individual layers of a 3D-IC. 3D-ICs offer the potential to create more compact and powerful devices, which can be beneficial for fabricating advanced multi-core CPUs and intelligent high-performance sensors. The development of multi-core CPUs has enabled the efficient operation of modern multithreaded operating systems, allowing them to execute multiple tasks concurrently and improve overall system performance. This work was aimed at understanding and improving an electron beam recrystallization technique which is used for the fabrication of silicon on insulator substrates. In this technique, two electron beams are employed, one to provide general heating, the other to recrystallize the Silicon - On - Insulator material. The research focused on the design and characterization of a three-lens electron optical system for the column used for recrystallization. The initial work concerned the electron gun. The basic aim was to investigate the stability of the electron gun and to optimize its performance. Two different guns were tested, and a choice was made based on their relative performance. A computer simulation program and an analytical model were used to investigate space charge effects in the electron beam recrystallizer and to optimize the design of a three-lens electron optical system which would work under variable demagnification conditions and at nearly 100 % beam current transmission. The performance of the three-lens system was compared to that of a single lens electron optical system on the basis of pressure effects which are significant for the beam current and voltage regime that is used in the electron beam recrystallizer. The three-lens system showed a much greater tolerance to pressure changes. A numerical model for heat flow was developed for the recrystallization process. Results from the model were compared with experimental data from temperature measurements and the model was used to predict the beam power density required to recrystallize. Experiments on recrystallization were carried out as the ultimate test for proving the benefits of the three-lens system. Results were compared to those obtained in earlier work with the single lens system and significantly better control over the recrystallization process was demonstrated.
Silicon-On-Insulator, electron beam silicon recrystallization, Three-Dimensional Integrated Circuits, electron optics, heat flow simulations, silicon crystal defect characterization, VLSI technology
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