Modeling and optimization for circumferential uniformity of MOCVD showerhead hole arrangement

This paper presents a method for modeling and analyzing the circumferential uniformity of MOCVD showerhead hole arrangement. The coordinate expressions of MOCVD showerhead hole are derived from the initial position of the radial hole on the helix curve. Through rotating the strip observation window around the center of the showerhead face plate at an equal angle, a data set is obtained by computing the total area of holes in the strip observation window. The circumferential uniformity of hole layout is measured according to the standard deviation of this dataset, and then an optimal layout model of the holes is established. The result indicates that the sampling rotating angle has limited impact on the ultimate hole arrangement, which verifies the robustness of the proposed method. Finally, optimal parameter of the helix curve is built using the genetic algorithm (GA), and the optimal layout of showerhead holes is illustrated correspondingly.