| dc.description.abstract | Metal organic chemical vapor deposition (MOCVD) is a source of reactants using precursors. The precursor is vaporized by a heater, and then transported by a carrier gas to generate a chemical reaction on the surface of the substrate, thereby forming a layer and a neat array. The densely packed film has become the main technology for producing large-size, composite semiconductor components. Therefore, in today′s diverse LED or semiconductor industries, the quality (non-uniformity, growth rate) of the grown film is more stringent.
This study will use the basic theoretical knowledge of the chemical mechanism and transport phenomena of GaN thin films to solve the factors affecting film quality (non uniformity, growth rate) by simulating software numerical values (including: length and diameter of the inlet, reactor pressure and rotational speed, etc.), respectively, to explore the relationship between process parameters and reactor geometry for film quality, and
analyze the chemical reactions, species transport and heat flow fields involved, and determine the parameters as control variables through the analysis results. The
optimization method ultimately found the optimal growth environment conditions for the GaN film.
Firstly, a steady-state model is established in which the reaction gases TMGa, NH3 and carrier gas H2 are mixed at the inlet, and the experimental results are compared with the experimental results. The relationship between the process parameters and the cavity geometry for the film quality can be known. The pressure, the intermediate inlet diameter and the inlet diameter have a significant influence on the non-uniformity and the growth rate. Therefore, it is decided to use these three parameters as the control variables. Finally, through the COMSOL simulation software and the Nelder-Mead algorithm-based optimization. Program integration to get the best value for the control variables. Non-uniformity decreased from 12.48% to 5.67%, film uniformity increased by 54%; growth rate decreased from 1.83 um/h to 1.52 um/h, and film growth rate decreased by 17%. Since the goal of optimization is to consider both the film uniformity and the growth rate, an optimum growth environment of the film is obtained on the overall objective function. | en_US |