Development of Metallic Hermetic Sealing for MEMS Packaging for Harsh Environment Applications

• Published in: Journal of electronic materials Vol. 41; no. 8; pp. 2256 - 2266
• Main Authors: Chidambaram, Vivek, Yeung, Ho Beng, Shan, Gao
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.08.2012; Springer; Springer Nature B.V
• Subjects: Applied sciences; Brazing. Soldering; Characterization and Evaluation of Materials; Chemistry and Materials Science; CMOS; Electronics; Electronics and Microelectronics; Eutectics; Exact sciences and technology; Instrumentation; Interfacial bonding; Joining, thermal cutting: metallurgical aspects; Materials; Materials Science; Metals. Metallurgy; Micro- and nanoelectromechanical devices (mems/nems); Microstructure; Optical and Electronic Materials; Parameter optimization; Sealing compounds; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Solid State Physics; Thin films; transient liquid-phase bonding; intermetallic compounds; eutectic bonding; die shear; composite; Hermeticity; Shear; Remelting; High temperature; Crystal defect; Aerospace industry; Composite material; Optimization; Thin film; Solder; Eutectic; Void; Microelectromechanical device; Semiconductor technology; High performance; Stacking sequence; Intermetallic compound; Ageing; Measurement sensor; Fusion welding; Mechanical properties; Solid state; Transient liquid phase bonding; Soldered joint; Germanium; Microstructure; Crystalline structure
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-012-2107-5

Hermetic sealing of microelectromechanical system sensors is indispensable to ensure their reliable operation and also to provide protection during fabrication. This work proposes two prospective candidates for hermetic sealing for rugged environment applications, i.e., Al-Ge and Pt-In. Al-Ge was chosen due to its compatibility with complementary metal–oxide–semiconductor technology. Pt-In possesses the highest remelting temperature among all the solder systems, which is desired for high-temperature applications in both the energy and aerospace industries. The various bonding parameters for Al-Ge eutectic bonding and Pt-In transient liquid-phase (TLP) bonding have been optimized, and their influence on the bond quality is reported. Optimization of bonding parameters has been carried out with the objective of ensuring void-free bonds. A new configuration for stacking Al-Ge thin films has been demonstrated to tackle the issue of loss of Ge prior to bonding, since native Ge oxides are soluble in deionized water. The impact of solid-state aging prior to Al-Ge eutectic bonding has been investigated. The method of tailoring the phases in the Pt-In joint is also discussed. The prospects and constraints of eutectic and TLP bonding from the hermeticity perspective are discussed in detail. Furthermore, changes in the microstructure under aging at 300°C up to 500 h and the resulting influence on the mechanical properties are presented. The overall finding of this work is that Al-Ge can achieve better mechanical and hermetic performance for high-temperature applications.