Simulation and optimization of reactor airflow and magnetic field for enhanced thin film uniformity in physical vapor deposition

Abstract

Planar magnetron sputtering reactors are widely utilized in the semiconductor industry due to their high deposition rate, low substrate temperature, and capability for large-area coating. Careful control of the reactor's flow field and magnetic field is essential to ensure appropriate thickness uniformity of the thin film and uniform etching of the target. Utilizing finite element analysis software, simulations were conducted to obtain numerical solutions for the airflow and magnetic field. An increase in the inlet diameter from 4 mm to 5 mm resulted in a 63.4 % decrease in the gas distribution unevenness coefficient. Conversely, increasing the outlet diameter from 1 mm to 2 mm led to a 636.6 % increase in the coefficient. At a pitch of 11.7 mm, the horizontal magnetic field component on the target surface peaked at 0.24 T, covering a larger area. A dual-runway structure reduced the circumferential component of the horizontal magnetic field by more than half. Analysis of the results precipitated the optimization of key component structures, resulting in an optimal solution: an air ring diameter of 5 mm, an outlet diameter of 1 mm, outlet spacing of 12 mm, double inlets, and 38 outlets on each side of the air ring. Further optimization determined the optimal magnet-to-target surface spacing of 11.7 mm, with the dual-runway structure effectively improving the uniformity of the radial magnetic field distribution and increasing the target etching area. This study provides a theoretical basis for optimizing planar magnetron sputtering reactors.