Stress evolution in the metal layers of TSVs with Bosch scallops

• We have studied the stress evolution in the metal thin film of an open TSV technology.
• We describe a new FEM simulation scheme for thin-films.
• The stress inside the TSV follows a particular evolution due to the geometry.
• Valleys between Bosch scallops in the middle of the TSV are critical points.
• During heating of the structure the stress reach maximum value around 420 °C.

We have studied the stress evolution in the tungsten film of a particular open TSV technology during the thermal processing cycle. The film is attached to the via’s wall, where scallops were observed as a result of the Bosch processing. Our work describes a scheme which considers the scallops on the TSV and conjugates a stress model for thin-films with the traditional mechanical FEM approach. The results reveal potential reliability issues and a specific evolution of the stress in the tungsten layer.