Research on Wafer-Level MEMS Packaging with Through-Glass Vias

Research on Wafer-Level MEMS Packaging with Through-Glass Vias

Citation

Yang, F.; Han, G.; Yang, J.; Zhang, M.; Ning, J.; Yang, F.; Si, C. Research on Wafer-Level MEMS Packaging with Through-Glass Vias. Micromachines 2019, 10, 15. 

Keywords

  • Wafer-level packaging
  • Through-glass vias (TGVs)
  • Laser drilling
  • Anodic bonding
  • MEMS devices
  • Reliability
  • Cost-effective 

Brief

This article presents a method for fabricating microelectromechanical systems (MEMS) devices using through-glass vias (TGVs) created by laser drilling, offering a reliable and cost-effective approach to wafer-level packaging. This method involves anodically bonding a glass wafer with laser-drilled vias to a silicon wafer containing MEMS structures, and then using electron beam evaporation to deposit metal onto the sides of the vias for electrical interconnection.

Summary

This article presents a method for MEMS (Microelectromechanical Systems) fabrication using through-glass vias (TGVs) created by laser drilling. The sources explain that wafer-level packaging is essential for the lifespan and reliability of MEMS devices, and electrical interconnection and bonding are two major aspects of this type of packaging. The article emphasizes that while through-silicon via (TSV) technology is a common approach for interconnection, TGV technology offers advantages such as glass's superior mechanical, thermal, and chemical resistance, as well as its low dielectric constant.

The article outlines a process for creating TGVs using a picosecond laser to drill holes in Pyrex 7740 glass. The researchers experimented with various laser parameters to optimize drilling efficiency and hole quality. The sources detail how different laser path diameters, scan times, step depths, and step times affected the resulting holes. They also note that using a concentric circular laser path allowed them to drill different via hole sizes in glass of varying thicknesses.

After drilling the TGVs, the researchers used anodic bonding to bond the glass to silicon structures. They confirmed the effectiveness of this method, observing a clean bonding area suitable for MEMS packaging. The sources further explain how they achieved electrical interconnection by depositing a thin metal film onto the sides of the via holes, ensuring contact between the silicon structure and the outside.

The researchers successfully packaged a ring-type MEMS gyroscope and a comb micro-accelerometer using this TGV-based fabrication process. The gyroscope, which used a getter, maintained a stable vacuum under 1 Pa for over two years. The article concludes that this approach to MEMS fabrication is cost-effective, reliable, and suitable for both prototyping and mass production.

Origin: https://pdfs.semanticscholar.org/50c1/46ed3774b60621d651fec8eac023367685f9.pdf

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