Design and Fabrication of a MEMS Device to Characterize Electromechanical Coupling in Thin Films
Author
Pérez Millan, Alba
Term
4. semester
Education
Publication year
2023
Submitted on
2023-06-01
Pages
47
Abstract
This thesis develops a practical method to make free-standing micro-beams (cantilevers) that serve as a test platform for the electromechanical behavior of thin films. Electromechanical coupling here refers to how mechanical deformation produces electrical signals—and vice versa. The process combines electron-beam lithography and anisotropic etching to release the beams. A silicon nitride (Si3N4) layer is added to study flexoelectricity—electric polarization caused by bending or strain gradients—and to manage film stress. The work demonstrates successful cantilever fabrication and shows that fine-tuning the etch is essential to achieve a reliable etch stop. The Si3N4 layer yielded excellent film quality and favorable stress levels. However, the method used to create electrical contacts was flawed, leading to material overlap and leakage. As a result, device testing could not be completed within the available timeframe. An alternative contact fabrication approach is proposed, and an experimental plan is outlined to guide future measurements and performance evaluation.
Dette speciale udvikler en praktisk metode til at fremstille fritstående mikrobjælker (cantilevere), der fungerer som en testplatform for tyndfilms elektromekaniske egenskaber. Elektromekanisk kobling betyder her, hvordan mekanisk deformation skaber elektriske signaler – og omvendt. Processen kombinerer elektronstrålelitografi og anisotrop ætsning for at frigøre bjælkerne. Et lag siliciumnitrid (Si3N4) tilføjes for at undersøge flexoelektricitet—elektrisk polarisering forårsaget af bøjning eller spændingsgradienter—og for at styre films spænding. Arbejdet viser, at cantilevere kan fremstilles med succes, og at finjustering af ætsningen er afgørende for at opnå et pålideligt ætstop. Si3N4‑laget gav fremragende filmkvalitet og gunstige spændingsniveauer. Den anvendte metode til at lave elektriske kontakter var dog mangelfuld og medførte materialeoverlap og lækage. Derfor kunne enheden ikke testes inden for den afsatte tidsramme. En alternativ kontaktfremstillingsmetode foreslås, og et forsøgsdesign skitseres som grundlag for fremtidige målinger og evaluering af enhedens ydeevne.
[This apstract has been rewritten with the help of AI based on the project's original abstract]
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