Development of test structures and methods for characterization of MEMS materials

Yıldırım, Ender
This study concerns with the testing methods for mechanical characterization at micron scale. The need for the study arises from the fact that the mechanical properties of materials at micron scale differ compared to their bulk counterparts, depending on the microfabrication method involved. Various test structures are designed according to the criteria specified in this thesis, and tested for this purpose in micron scale. Static and fatigue properties of the materials are aimed to be extracted through the tests. Static test structures are analyzed using finite elements method in order to verify the results. Test structures were fabricated by deep reactive ion etching of 100 æm thick (111) silicon and electroplating 18 æm nickel layer. Performance of the test structures are evaluated based on the results of tests conducted on the devices made of (111) silicon. According to the results of the tests conducted on (111) silicon structures, elastic modulus is found to be 141 GPa on average. The elastic modulus of electroplated nickel is found to be 155 GPa on average, using the same test structures. It is observed that while the averages of the test results are acceptable, the deviations are very high. This case is related to fabrication faults in general. In addition to the tests, a novel computer script utilizing image processing is also developed and used for determination of the deflections in the test structures.


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Citation Formats
E. Yıldırım, “Development of test structures and methods for characterization of MEMS materials,” M.S. - Master of Science, Middle East Technical University, 2005.