Vapour HF Release of Airgap-based UV-visible Optical Filters. (2015)

• Record Type: Journal Article
• Authors: Ghaderi, M.; Ayerden, N.P.; de Graaf, G.; Wolffenbuttel, R.F.
• Is Part Of: Procedia engineering. Volume 120(2015)
• Page Start: 816
• Page End: 819
• Publication Date: 2015
• Subjects: Distributed Bragg reflector -- airgap filters -- Fabry-Perot filters -- vapour HF etching -- UV-visible range.; Engineering -- Congresses; Engineering -- Periodicals; Engineering; Conference proceedings; Periodicals; 620.005
• DOI: 10.1016/j.proeng.2015.08.674
• Languages: English
• ISSNs: 1877-7058

Abstract

Abstract: The design and CMOS-compatible fabrication of airgap-based optical filters in a surface micromachining process with sacrificial release using thevapour phase is presented. An airgap-dielectric layer combination offers a higher refractive index contrast, as compared to the conventional all-dielectriclayer based filters, which results in a higher peak reflectance and a wider bandwidth in a distributed Bragg reflector (DBR). Several DBRs and Fabry-Perot filters with multiple (low-n) airgap layers separating a stack of (high-n) layers of a dielectric material were designed for operation in the UV-visible spectrum. The fabrication was based on an Al2 O3 and SiO2 system. The lateral design includes a set of anchor points and access holes. Finally, a vapour phase HF etching was used to remove the SiO2 layers and release the Al2 O3 membranes. This method prevents the stiction of the membranes and provides a higher control and uniformity over the filter area.