Mechanical Effects of the Volmer-Weber Growth in the TSV Sidewall

Open Through Silicon Vias (TSVs) are interconnections in three dimensional technologies. The tungsten material is usually employed as conductor line and it has high value of tensile intrinsic stress. The stress generated during the deposition process needs to be studied in order to avoid the mechanical failure of the TSV. We simulated the tungsten Volmer-Weber growth for a full plate sample. Subsequently, the sidewall area of the Open TSV was investigated. Due to the etch process, a formation of a surface roughness along the sidewall, called scallops, characterizes the Open TSVs. This particular structure lead to a different stress distribution in the tungsten layer. We reproduced the tungsten growth process on a scallops surface demonstrating an important decrease of the film stress compared to the full plate sample. The simulations of the Volmer-Weber growth can be an important tool for the design optimization of TSV.