Title :
Silicon Micromachined Device Testing by Infrared Low-Coherence Reflectometry
Author :
Carpignano, Francesca ; Surdo, Salvatore ; Barillaro, Giuseppe ; Merlo, Sabina
Author_Institution :
Dipt. di Ing. Ind. e dell´Inf., Univ. degli Studi di Pavia, Pavia, Italy
Abstract :
With the development of silicon micromachining technologies, non-contact measurement techniques for in-depth non-destructive inspection of layered and microstructured samples are becoming increasingly relevant. In this paper, we apply optical low-coherence reflectometry (OLCR) to detect the optical path between the interfaces of several silicon devices with characteristic distance in the range 3-17 μm. The implemented configuration is based on a fiberoptic Michelson interferometer that exploits infrared broadband radiation in the wavelength range of 1.2-1.7 μm, with coherence length shorter than 2 μm, for performing spot tomographic measurements. OLCR enabled out-of-plane measurements on a MEMS linear accelerometer and in-plane measurements on vertical periodic silicon/air microstructures. The optical distance between hidden interfaces was found well in agreement with the design parameters.
Keywords :
Michelson interferometers; accelerometers; elemental semiconductors; fibre optic sensors; micromachining; micromechanical devices; reflectometry; silicon; MEMS linear accelerometer; OLCR; Si; distance 3 mum to 17 mum; fiber-optic Michelson interferometer; in-depth nondestructive inspection; in-plane measurements; infrared broadband radiation; infrared low-coherence reflectometry; layered samples; microstructured samples; noncontact measurement; optical low-coherence reflectometry; out-of-plane measurements; silicon devices; silicon micromachined device testing; silicon micromachining technology; spot tomographic measurements; vertical periodic silicon-air microstructures; wavelength 1.2 mum to 1.7 mum; Optical imaging; Optical interferometry; Optical refraction; Optical sensors; Optical variables control; Optical variables measurement; Silicon; Optical low-coherence reflectometry; distance measurements; infrared sensor; non-destructive testing; silicon micromachined device; silicon micromachined device.; time-domain analysis;
Journal_Title :
Microelectromechanical Systems, Journal of
DOI :
10.1109/JMEMS.2015.2453367