Microelectromechanical systems (MEMS) is an evolution and expansion of micromachining technology. MEMS builds on the processes, thin film technology and materials used in VLSI technology, but with structures suspended or released and can move. With MEMS, engineers can build minute mechanical structures like sensors and actuators using the silicon-based manufacturing process in IC technology. Micromechanical devices and systems are inherently smaller, lighter, and faster than their macroscopic counterparts, and are usually more precise....[ Read more ]

Microelectromechanical systems (MEMS) is an evolution and expansion of micromachining technology. MEMS builds on the processes, thin film technology and materials used in VLSI technology, but with structures suspended or released and can move. With MEMS, engineers can build minute mechanical structures like sensors and actuators using the silicon-based manufacturing process in IC technology. Micromechanical devices and systems are inherently smaller, lighter, and faster than their macroscopic counterparts, and are usually more precise.

Gyroscopes (gyros) are used as angular velocity sensors. Conventional gyros are composed of mechanical parts. However these gyros tend to be large and heavy, and they consume large quantities of power. They are also expensive and easily wear out after only a few thousand hours of operation, thus they are limited in their applications. To compensate the disadvantages of conventional gyros, MEMS is used to fabricate gyros to realize integrated micromechanical gyros.

In this research an integrated micromechanical gyroscope with large precision to cost ratio is under consideration. The working principle of this gyro is based on the coupling of Coriolis force and piezoelectricity. Piezoelectric materials PZT, ZnO and AlN are chosen and the preparation techniques of these films are investigated. ZnO and AlN films are-prepared by sputtering method, while PZT film is obtained by sol-gel method. Depositing a crack-free PZT film on silicon substrate is very difficult because of the great difference in thermal expansion coefficients between PZT and silicon, much effort has been paid to solve this problem. To integrate the preparation of the crack-free PZT film with existing IC technology, and also to allow the measuring circuit for gyro to be fabricated with the device, a thorough process flow for the fabrication is designed.