MEMS Hermetic Packaging for Extremely Sensitive Accelerometers with In-Package Pressure Sensing Solution

Resource type
Thesis type
(Thesis) M.A.Sc.
Date created
2016-06-10
Authors/Contributors
Author: Zhang, Yuxi
Abstract
In Micro-Electro-Mechanical Systems packages, sealing pressure is one of the most important indicators of packaging quality. Traditional hermeticity testing methods are expensive and inconvenient. Solution for in-package pressure monitoring has long been appealing. Pirani sensor is a commonly used pressure sensor that can be integrated into Micro-Electro-Mechanical Systems packages. Our team is developing a hermetic packaging process for extremely sensitive and low noise accelerometers. A eutectic package sealing process is developed and evaluated. To verify the stability of environment inside the package, a lowcost, process flow compatible, space saving bondwire Pirani sensor has been explored. The sensing principle is based on resistance change of the filament is a function of pressure under constant electrical power. The feasibility of using the bondwire Pirani sensor has been thoroughly discussed. A novel four point measurement set up is implemented to achieve the accurate low resistance measurement. The bondwire Pirani sensor has a dynamic range from 0.1 Torr to about 50 Torr and is compatible with any micro-system such as resonators, gyroscopes, micro-mirrors, and micro-display systems among others. The sensor is applied to our own packaging process as pressure sensing element to detect pressure change. Long-term pressure stability for sealed packages is also measured by the bondwire Pirani sensor.
Document
Identifier
etd9628
Copyright statement
Copyright is held by the author.
Permissions
This thesis may be printed or downloaded for non-commercial research and scholarly purposes.
Scholarly level
Supervisor or Senior Supervisor
Thesis advisor: Bahreyni, Behraad
Attachment Size
etd9628_YZhang.pdf 10.02 MB