|AVS 56th International Symposium & Exhibition|
|MEMS and NEMS||Thursday Sessions|
|Session:||MEMS and NEMS Poster Session|
|Presenter:||V. Rincon, University of Alabama|
|Authors:||V. Rincon, University of Alabama
H. Nampoori, University of Alabama
A.L. Highsmith, University of Alabama
S. Kotru, University of Alabama
|Correspondent:||Click to Email|
Piezoelectric materials are commonly used in micro electro mechanical systems (MEMS) due to the self-generating sensing, large actuation amplitude with low voltage, and compatibility to integrated circuit process. In this work we have used Nb-doped Pb(Zr20,Ti80)O3 (PZT) films for fabricating actuators and sensors for a micromachined vibratory gyroscope. PZT films exhibit higher values of effective transverse piezoelectric coefficient (e31,f) and effective longitudinal piezoelectric coefficient (d33,f) compared to any other available piezoelectric materials.
The complete gyroscope device consists of one active wafer, two handler wafers and a Si post bonded together. The active and handle wafers were fabricated using MEMS technology. Entire processing was done in a clean room environment using the state of art micro fabrication facility (MFF) at the University of Alabama . First, PNZT was deposited on both side of the active wafer resulting in PNZT/Pt/TiO2/SiO2/Si/SiO2/TiO2 /Pt/PNZT stack. This step was followed by SiO2/Ti/Au deposition using an e-beam evaporator. Processing the active wafer involves five masks and twenty four photolithography steps. Sine the device is on both sides of the wafers, one side was always protected with photoresist while the other side of the wafer was being processed. The final structures were released by etching away various film layers using a combination of dry and wet etching techniques. This includes three different etching techniques viz., ion mill, oxide etcher, and wet etch.
For the handle wafers Cr films were deposited on Si wafers using an e-beam evaporator. A photo-defineable polyimide was then spun on these wafers and patterned. These patterns were transferred using two masks and two photolithography steps. The active and handle wafers were then bonded together and the Si post attached to it to form the complete device. Details of the fabrication process of the device and its evaluation will be presented.