Etching performance of silicon wafers with redesigned etching drum

Etching process involves various chemical reactions and reflects significantly on silicon wafer quality. Design of Experiments (DOE) with full factorial design is employed for optimization purpose. Etching factors namely the bubbling flow rate, wafer rotation, and etchant temperature had been randomized with additional three center points to observe any curvature. The responses studied are etching removal, total thickness variation (TTV) and wafer brightness. Additionally, the etchant temperature and bubbling flow rate provide interaction effect on both etching removal and wafer brightness. A higher bubbling flow rate is required to ensure etching removal and brightness within specification. Besides studying these three responses, the wafer surface after etching is analyzed using ADE Infotool software which captures the etched surface profile and its thickness. Finally, the removal uniformity throughout the redesigned etching drum is observed. Etching performance is enhanced with the optimized value of bubbling flow rate, etchant temperature and wafer rotation to achieve the optimum etching removal distribution.