Modeling high power magnetron copper seed deposition: Effect of feature geometry on coverage

Abstract

The deposition of copper using a high power magnetron (HPM) has been studied using reactor and feature scale models. Discussed are results for Cu seed HPM deposition on trench, via, and dual inlaid features with different geometries (aspect ratio and side wall angles). At low wafer powers the Cu seed feature coverage is characterized by geometric shadowing due to the broad angular distribution of the dominant Cu athermal. At high wafer powers the metal deposited at feature bottom is sputtered by Ar+ and redistributed to the side walls. The deposition rate within a feature is nonlinear with time as metal deposited at the feature opening obstructs incoming metal from reaching the inside of the feature. Competing trends of higher copper flux at wafer center versus edge and higher Ar+ flux at wafer center versus edge result in a transition of the field thickness heights from edge>center at low wafer powers to center