Microfabrication Principles LearningSpace



Microfabrication Principles LearningSpace will help you study Microfabrication processes used for VLSI and other technologies. Starting with the basic understanding of semiconductor properties and wafer preparation, the fundamentals of microfabrication processes, including solid state diffusion, ion implantation, thermal oxidation, and material etching are presented. The learningSpace is organized in the following section:


Learning Unit One: Semiconductor Properties & Wafer Preparation


Learning Unit One covers fundamental issues relating to crystalline material properties including the three major types of crystalline materials and common cubic structures. You will learn to evaluate crystal structures in terms of crystal planes and directions as well the various types of defects and impurities that can exist within these structures during fabrication. Finally, you will also learn the process by which the raw material for creating single-crystal silicon wafers is first purified and then with many subsequent steps transformed into high-purity, polished, single crystal wafers.


Learning Unit 2: Solid State Diffusion


Learning Unit Two covers issues relating to thermal diffusion and includes both theory and the practical applications of the fabrication process step. You will gain an understanding of how dopants/impurities are introduced into the silicon substrate and how these dopants in turn affect the electrical properties of the silicon. It also covers how these dopants move within the material and how this leads to the formation of p-n junctions. Calculations of junction depth and surface impurity concentration are shown.


Learning Unit Three: Ion Implantation


Learning Unit Three addresses the ideas and theories related to Ion-Implantation. You will be given the mathematical foundation of the theories behind this modern process so that you may be able to design depth profiles and calculate device junctions as well as calculate impurity concentration levels. The advantages and disadvantages of ion-implantation, channeling, lattice damage and annealing are also described.


Learning Unit Four: Thermal Oxidation


Learning Unit Four covers both the theory behind the oxidation of silicon (i.e. surface reaction rate, diffusion of dopants through an oxide layer, how steam oxidation and dry oxidation differ in term of diffusion coefficients) and the calculation of the projected thickness of oxide layers grown under various conditions. You will learn the uses for oxide layer and factors, which influence oxidation, and formation of thin oxides, and their uses.


Learning Unit Five: Material Etching


Learning Unit Five covers the difference between wet and dry etching, the equipment that is used for each type of etching process and the theory behind both wet and dry etching.