Improving Liquid Film Thickness Uniformity of Semiconductor Etching Equipment Using Flow Field Visualization and CFD Simulation

Abstract

With the rapid development of semiconductor-based products, semiconductor and integrated circuit (IC) design industries have become indicators of global technological advance in this field. As IC structure becomes smaller and smaller, improved process technology and equipment are necessary to maintain and improve wafer yield rates and quality. Among them, the etching technology in the process has a close relationship with the size of IC structure. According to extensive research and analyses put forward by predecessors, the etching process and methods that affect the yield rates and quality of wafers have been well characterized. This study investigates the spray etching method of the single nozzle and double nozzle. Using computational fluid dynamics software developed by Ansys Fluent, the fluid is injected from the center as the starting point at the same flow rate and speed, and according to 2, 4, and 8 seconds of a different cycle and nozzle forms, moving back and forth to supply liquid on the surface of the 300 mm disc. It is assumed that fluid properties do not change with temperature. Additionally, the chemical reaction and thermal reaction of the etching process are not considered. Changes in the surface flow field resulting from different nozzles and cycle conditions are observed. This study involved setting up a set of flow field visualization systems, replacing the etching liquid with colored water, using a digital camera to capture the relationship between the gray index and the thickness of the water film, and calculate the film thickness. The average film thickness deviation ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${t}_{avg}$ </tex-math></inline-formula> ) and variable quantity ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${dt}$ </tex-math></inline-formula> ) were characterized and used as a means to compare performance. The results show that the average film thickness deviation of the double nozzles is higher than the single nozzle, and variable quantity ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${dt}$ </tex-math></inline-formula> ) is lower than that of the single nozzles. In general, the double nozzles increase the thickness and stability of the liquid film thickness on the surface of the disc.