New insights into fracture of Si in Cu-filled through silicon via during and after thermal annealing

Sonawane, D and Kumar, P (2020) New insights into fracture of Si in Cu-filled through silicon via during and after thermal annealing. In: Engineering Fracture Mechanics, 238 .

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Abstract

Copper (Cu)-filled through silicon (Si) via (CF-TSV) acts as an electrical conduit between different layers of circuitry in the advanced microelectronic devices. Due to wide difference in the coefficient of thermal expansion between Cu and Si, large thermal stresses get generated in both Si and Cu during the inevitable thermal excursions taking place during fabrication of microelectronic devices and their regular operation. This study examines the fracture of Si wafer in a CF-TSV due to annealing over the temperature range of 250�550 °C and the post-annealing natural ageing. Nucleation of micro-cracks in Si in the vicinity of the Cu pillars were observed, which propagated at a constant velocity during post-annealing room temperature ageing, thereby substantiating delayed fracture in Si. Microstructural examination revealed that the micro-cracks nucleated as a result of formation of a Cu-Si compound during annealing, whereas the crack propagated due to the oxidation of Si at the crack tip. Consistently, the micro-cracks did not propagate when the sample was stored in high vacuum. Furthermore, Raman spectroscopy and finite element method were used to gain insights into stress generation due to Cu-Si reaction, and nucleation and propagation of the crack. © 2020 Elsevier Ltd

Item Type:	Journal Article
Publication:	Engineering Fracture Mechanics
Publisher:	Elsevier Ltd
Additional Information:	The copyright of this article belongs to Elsevier Ltd
Keywords:	Annealing; Copper compounds; Copper metallography; Crack tips; Crystallization; Electronics packaging; Microelectronics; Nucleation; Silicon wafers; Thermal expansion; Three dimensional integrated circuits, Constant velocities; Electrical conduits; Micro-electronic devices; Microstructural examination; Regular operations; Temperature ageing; Thermal-annealing; Through-Silicon-Via, Silicon compounds
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	23 Sep 2020 07:15
Last Modified:	23 Sep 2020 07:15
URI:	http://eprints.iisc.ac.in/id/eprint/66597

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