| dc.description.abstract | Metal organic chemical vapor deposition (MOCVD), one of the important techniques in the manufacturing process of light emitting diode (LED), is a method of growing film on semiconductor. The uniformity of the film is relevant to efficiency and quality of LED. The study investigates GaN growth from trimethyl-gallium and ammonia. It also simulates the 2D axisymmetric and 3D Veeco E400LDM vertical rotation reactor by using commercial computational software, COMSOL. Simulations were performed to study the effect of key design parameters of GaN film growth rate and uniformity, such as chemical reactions, process parameters and design of gas inlet.
In order to simplify the simulation and to find the main chemical reactions leading to film growth, the study was first conducted to explore the gas-phase reactions mechanism.
After that, the study investigated the effect of tuning these manufacturing parameters, such as gas flow rate (50-200 slm), wafer carrier rotation rate (500-1500 rpm), chamber pressure (10-70 Torr), and growth temperature (900-1100℃), on the growth rate and film thickness uniformity. The results showed no significant effects of heating temperature on the growth rate and uniformity. The increase of gas flow rate improves the growth rate of the film but makes deterioration of uniformity. Moreover, enhancing the wafer carrier rotation rate and chamber pressure can allow the boundary layer thinning and accelerate the diffusion of specie, to get a better growth rate and film thickness uniformity. However, the higher speed and higher pressure easily induced the vortex in the side wall and the entrance. It cause instability in the flow field.
Finally, the study of optimization of the gas inlets was done. The results show that increasing the number of slot jets, the fluid flow can be significantly stabilized. The arrangement of species was also been studied. The symmetric arrangement design doesn’t enhance any diffusion of gas. It reduced the growth rate of the film. However, the staggered design can solve this problem. | en_US |