Microfabricated Heteroepitaxial Oxide Structures on Silicon for Bolometric Arrays

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To realize high sensitive bolometer, new material with higher TCR value is needed including the low thermal mass : small pixel size and very thin thermally isolated membrane. Mixed-valent manganese, perovskite La0.67(Sr, Ca)0.33MnO3 (LSCMO) films on oxide buffered Si substrate with huge 4.4 %_K-1 TCR value in room temperature was demonstrated due to semiconductor-metal transition. For the epitaxial LSCMO microbolometer, free standing microstructure on isolated membrane is key processing for micro-fabrication. The epitaxial grown oxide buffer layer is another good candidate for new type membrane instead of thicker amorphous Si3N4 and SiO2 membrane The etching rate of all layers was investigated by Ar ion beam etching (IBE) The LSCMO film and oxide buffer layers etched by Ar IBE had a similar etching rate, 16~17nm/min. To prevent from burning of photoresist as a protective layer on LSCMO films against Ar IBE etching process, pre-annealed photoresist mask (Shipley 5740) was investigated. Finally, the free standing hetero epitaxial LSCMO thin films on Silicon substrate was realized for bolometric application by Ar IBE and inductively coupled plasma (ICP) with SF6 gas for etching.

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Journal: TechConnect Briefs
Volume: 3, Technical Proceedings of the 2005 NSTI Nanotechnology Conference and Trade Show, Volume 3
Published: May 8, 2005
Pages: 521 - 524
Industry sector: Sensors, MEMS, Electronics
Topic: MEMS & NEMS Devices, Modeling & Applications
ISBN: 0-9767985-2-2