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A robust lateral shift free (LSF) electrothermal micromirror with flexible multimorph beams
Hengzhang Yang1, Anrun Ren1, Yingtao Ding1
1School of Integrated Circuits and Electronics, Beijing Institute of Technology, Beijing, 100081 China.
Microsystems & Nanoengineering
|September 1, 2023
Summary
This study introduces robust electrothermal micromirrors using photosensitive polyimide (PSPI) instead of brittle silicon dioxide. The new PSPI micromirrors demonstrate significantly improved durability against impacts and drops, expanding their practical applications.
Area of Science:
- MEMS technology
- Materials science
- Optical engineering
Background:
- Standard electrothermal micromirrors use silicon dioxide (SiO2) for isolation, which is brittle and limits device robustness.
- Device fragility restricts the application range of current micromirror technologies.
Purpose of the Study:
- To enhance the robustness of electrothermal micromirrors by incorporating a polymer material.
- To investigate the performance and durability of micromirrors utilizing photosensitive polyimide (PSPI).
Main Methods:
- Designed and fabricated electrothermal micromirrors using PSPI as an isolation and anchor material, partially replacing SiO2.
- Conducted optical scanning angle and displacement tests.
- Performed impact, drop, and vibration tests to assess device survivability.
Main Results:
- PSPI-type micromirrors achieved an optical scan angle of ±19.6° and 370 μm vertical displacement at 4 Vdc.
- Micromirrors survived >200g accelerations (impact), falls from 21 cm (drop test), and significant vibration accelerations (21g vertical, 29g lateral).
- PSPI micromirrors exhibited at least 4x greater robustness compared to SiO2-based micromirrors from the same fabrication batch.
Conclusions:
- Photosensitive polyimide (PSPI) is a viable material for enhancing the robustness of electrothermal micromirrors.
- The developed PSPI-based micromirrors offer superior durability, overcoming limitations of traditional SiO2-based designs.
- These robust micromirrors have expanded application potential in demanding environments.
