Characterization of Vapor HF Sacrificial Etching Through Submicron Relase Holes for Wafer-Level Vacuum Packaging Based on Silicon Migration Seal

Gong, Tianjiao; Suzuki, Yukio; Khan, Muhammad Jehanzeb; Hiller, Karla; Tanaka, Shuji

doi:10.1109/mems49605.2023.10052275

Cited by 2 publications

(1 citation statement)

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“…Therefore, the maximum diameter of 0.6 µ and the minimum aspect ratio of 8 for the release holes are applied. Five sets of multiple release holes are evenly distributed across the chip for effective sacrificial layer etching by vapor HF [29].…”

Section: A Design Of Sms-encapsulated Mems Resonatormentioning

confidence: 99%

Vacuum-Sealed MEMS Resonators Based on Silicon Migration Sealing and Hydrogen Diffusion

Gong,

Khan,

Suzuki

et al. 2024

J. Microelectromech. Syst.

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In this study, we introduce an innovative approach to vacuum-encapsulation of MEMS resonators using Silicon Migration Seal (SMS) technology, a novel wafer-level vacuum packaging method. SMS utilizes silicon reflow phenomena under high-temperature (>1000 • C) hydrogen environments to seal release holes effectively. We successfully demonstrated this technique on a MEMS resonator made on a standard SOI wafer, commonly used in inertial sensors and timing devices. After the encapsulation, hydrogen diffusion from the sealed cavity was performed through annealing at 430 • C for 27 hours in a nitrogen environment. Further analysis using focused ion beam (FIB) penetration outside the resonating element confirmed an impressive vacuum level improvement in the sealed cavity, estimated at ∼60 Pa. Notably, after additional air-baking at 145 • C, the maintained high Q factor suggests a potential vacuum level below 10 Pa. These findings not only illustrate the efficiency of SMS in wafer-level vacuum packaging but also open up possibilities for optimizing sealing pressure in MEMS packaging.

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Section: A Design Of Sms-encapsulated Mems Resonatormentioning

confidence: 99%