The research of zno metal organic chemical vapor deposition operating environment and experimental verification

Abstract

Currently, metal oganic chemical vapor deposition (MOCVD) is the most suitable technology for large-scale preparation of thin-film materials, with the advantage of large expitaxial area, good repeatability, precise componential control, deposition rate, etc. It is a multi-disciplinary complex system, and MOCVD process contains a large number of complex physical and chemical processes with complicated reaction mechanism and growth kinetics. The core part of MOCVD system is reactor. In order to grow high-quality thinfilm by MOCVD, the flow fields, thermal fields and chemical reactions mechanism of MOCVD reactor must be studied in depth. In this paper, MOCVD was 3D numerically simulated by computational fluid dynamics software. The flow field, the thermal field and the gas -phase pre-reaction that affect the structure and properties of thin-films have been intensively studied, and the experimental results and the simulation results under same operating condition are compared to verify the reliability of the simulation results. Achievements are as follows: 1.Use home-made MOCVD equipment to grow thin-films which can be used to machine semiconductor LED chip on polished silicon substrate and collect parameters in the process as boundary conditions of numerical simulation. The N & K versatile film tester is also used to measure the thickness of the sample and to analysis the thickness distribution trends of thin film on a substrate, preparing to verify the reliability of the simulation results. 2. Establish the geometric model and grid model of MOCVD reactor chamber, and import to computational fluid dynamics software Fluent for numerical simulation, and then compare the results of numerical simulation and experimental results. It is found that the simulation deposition rate distribution curve after fitting with an empirical formula generally coincides with the experimental distribution curve. 3. Analyze the distribution of temperature, velocity, mass fraction, deposition rate and the pre-reaction conditions which seriously affect the quality of films, and get to know the state of thermal and flow fields in the reaction chamber and the conditions and regions of pre-reactions. Due to the low gas velocity in the area near the center of the substrate, it more greatly subjects to DEZn and O2 reaction and 'decomposition reaction of DEZn, which also explains the film's thinner deposition on the inner circumference of the substrate, namely, consumption of raw materials being not promptly replenished.