Atomic layer deposition (ALD) is a promising method in semiconductor industry for high quality of thin films. As a view point of equipment development, the control of internal flow in ALD chamber is an inevitable part of engineering design process to improve the quality of thin films. However, during the process, it is difficult to measure the internal flow inside the chamber. Therefore, computational fluid dynamics (CFD) is a useful tool in predicting the uniformity of thin films by ALD chamber with various operating conditions. In this talk, we will perform CFD analysis in a specific chamber of ALD equipment to find the correlation between the flow pattern and the quality of uniformity of thin films. As a result, our simulation shows high magnitudes of vortices in the internal flow affect on the quality and yield of thin films. Additionally, we will discuss the simulation results with experimental measurements and suggest a new design to enhance the performance of ALD chamber.