Aluminum-Germanium Eutectic Bonding for MEMS: Behaviour and Solidification of Liquid Al-Ge on Different Substrates. (24th August 2016)

• Record Type: Journal Article
• Authors: Lumineau, Victor; Fournel, Frank; Imbert, Bruno; Hodaj, Fiqiri
• Is Part Of: ECS transactions. Volume 75:Number 9(2016)
• Page Start: 273
• Page End: 281
• Publication Date: 2016-08-24
• Subjects: Electrochemistry -- Periodicals; Electrochemistry; Periodicals; Electronic journals; Electronic journal; 541.37
• DOI: 10.1149/07509.0273ecst
• Languages: English
• ISSNs: 1938-5862

Abstract

Abstract : In this paper we study the formation and behaviour of liquid Al-Ge alloy, its solidification, the resulting microstructures and the appearance of voids in bonded structure for MEMS packaging. The underneath layer influences the wettability of liquid Al-Ge as well as its solidification which can lead to undesirable Al dendrites. Each underneath layer imposes a critical value for the cooling rate above which dendrites are likely to appear. Blanket and patterned Al/Ge deposited wafers are bonded together with process parameters optimized thanks to previous results. The interfaces present a dendritic-free eutectic structure. Micro-voids are observed at the interfaces between Al and Ge phases. The Kirkendall effect and thermal stresses are two possible reasons for voiding phenomenon.