A de-coupled vibratory gyroscope using a mixed micro-machining technology

MEMS devices such as a vibratory gyroscope often suffer from a lower yield rate due to fabrication errors and external stress. In the decoupled vibratory gyroscope, the main factor that determines the yield rate is the frequency difference between the sensing and driving modes. The gyroscope, fabricated with a SOI (silicon-on-insulator) wafer and packaged using anodic bonding, has a large wafer bowing caused by thermal expansion mismatch as well as non-uniform surfaces of the structures caused by the notching effect. These effects result in a large distribution in the frequency difference, and thereby a lower yield rate. To improve the yield rate we propose a packaged SiOG (silicon-on-glass) technology. It uses a silicon wafer and two glass wafers to minimize the wafer bowing and a metallic membrane to avoid the notching. In the packaged SiOG gyroscope, the notching effect is eliminated and the warpage of the wafer is greatly reduced. Consequently, the frequency difference is more uniformly distributed and its variation is greatly improved. Therefore, we can achieve a more robust vibratory MEMS gyroscope with a higher yield rate.

Section: Vibratory Mems Gyroscope Using the Soi Processmentioning

confidence: 93%

A high yield rate MEMS gyroscope with a packaged SiOG process

Lee

Kang

Jung

et al. 2005

“…There are still many labs researching on decoupling gyroscopes, for example, Yokohama Technical Center of Japan [34], UC Berkeley [35,36], Seoul University of Korea [37], Samsung company [38], and so on. The comparison of some parameters is listed in table 7.…”

Section: Micro-gyroscope Based On Coriolis Effectmentioning

confidence: 99%

“…The USA has successfully picked up electrostatic gyroscope signals of the GP-B satellite, which obtains 10 −4 order of magnitude In terms of processes, MEMS gyroscopes still mainly adopt MEMS micromachined fabrication technologies, which are comprised of bulk fabrication and surface fabrication. For those gyroscopes in laboratory level, scientific researchers generally adopt bulk micromachined fabrication [8,10,13,18,30,31,33,34,38,59], surface micromachined fabrication [9,14,24] and mixed micromachined fabrication [12,22] to manufacture gyroscopes. Mixed micromachined fabrication means that the whole process includes not only bulk fabrication but also surface fabrication, and that method varied according to different gyroscope structures.…”

Section: Evaluations On Micro-gyroscopesmentioning

confidence: 99%

The development of micro-gyroscope technology

Zhang¹,

Chen²,

Li³

et al. 2009

196

This review reports an overview and development of micro-gyroscope. The review first presents different types of micro-gyroscopes. Micro-gyroscopes in this review are categorized into Coriolis gyroscope, levitated rotor gyroscope, Sagnac gyroscope, nuclear magnetic resonance (NMR) gyroscope according to the working principle. Different principles, structures, materials, fabrications and control technologies of micro-gyroscopes are analyzed. This review compares different classes of gyroscopes in the aspects such as fabrication method, detection axis, materials, size and so on. Finally, the review evaluates the key technologies on how to improve the precision and anti-jamming ability and to extend the available applications of the gyroscopes in the market and patents as well.

“…A design of a decoupled vertical gyroscope has been announced. It was fabricated and tested to have the right operation [5].…”

Section: Introductionmentioning

confidence: 99%

“…The Coriolis force proportional to the angular velocity causes displacements in the vertical direction. If the natural frequency in the sensing mode matches that in the driving mode, the displacements are exaggerated and sensing is easy [5]. Therefore, it is important to match the natural frequencies of the two vibration modes [6,7].…”

Section: Introductionmentioning

confidence: 99%

Robust design of a vibratory gyroscope with an unbalanced inner torsion gimbal using axiomatic design

Hwang

Lee

Park

et al. 2002

Recently, there has been considerable interest in micro gyroscopes made of silicon chips. It can be applied to many micro-electro-mechanical systems (MEMS): devices for stabilization, general rate control, directional pointing, autopilot systems, and missile control. The mechanical design of the gyroscope is carried out using axiomatic design, followed by the application of the Taguchi robust design method to determine the dimensions of the parts so as to accommodate the dimensional variations during fabrication. Functional requirements are defined twofold. One is the natural frequencies should have fixed values, and the other is the system should be robust to large tolerances. According to the Independence Axiom, design parameters are classified into a few groups. Then, the detailed design process is performed according to the sequence indicated by the design matrix. The dimensions of the structure are determined to have constant values for the difference of frequencies regardless of the tolerances. It is noted that the Taguchi concept is utilized as a unit process of the entire axiomatic approach.