Assembly and optimization of an infared quantitative phase-contrast microscope for semiconductor inspection

International audienceLaser-induced permanent modi cation inside silicon has been demonstrated by using tightly focused short pulses in the infared domain of the sepctrum, and has a broad eld of applications. These include the fabrication of devices in Silicon Photonics with for instance the writing of monolytic waveguides by changing the local refractive index with silicon modi cations. In order to characterize very precisely and quantitatively the accessible refractive index variations, we designed and assembled a microscope associated with an interferometer to apply the so-called phase-shifting measurement method with an infared wavelength. An interferometer close to a Mach-Zenhder con guration is rst set. An arrangement of imaging lenses are then installed to operate the interferometer while imaging samples in transmission mode. The sample is placed on the way of one arm of the interferometer, meanwhile the second one is the reference path. The presence of modi cations induces an optical path difference relative to the surrounding non-modi ed zone which can be quantitatively measured