Vapour HF release of airgap-based UV-visible optical filters

Vapour HF release of airgap-based UV-visible optical filters

Ghaderi, M.
Ayerden, N.P.
De Graaf, G.
Wolffenbuttel, R.F.

Electrical Engineering, Mathematics and Computer Science

Microelectronics

2015-11-01

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 Al2O3 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 Al2O3 membranes. This method prevents the stiction of the membranes and provides a higher control and uniformity over the filter area.

distributed Bragg reflector
airgap filters
Fabry-Perot filters
vapour HF etching
UV-visible range

http://resolver.tudelft.nl/uuid:88cea531-4bd3-43da-99ca-6202b91f32e1

Elsevier

1877-7058

https://doi.org/10.1016/j.proeng.2015.08.674

Procedia Engineering, 120, 2015; Eurosensors 2015. 1st YAWL Symposium 2013, Sankt Augustin, Germany, 7 June 2013

Institutional Repository

conference paper

© 2015 The Authors
This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)