Abstract

Hyperspectral imaging is a powerful technique offering spectrally- and spatially-resolved measurements with many potential benefits in the monitoring of semiconductor devices process [1]. In this work, we propose a method based on hyperspectral imaging applied to the fabrication of Vertical-cavity Surface-Emitting Lasers (VCSELs). VCSEL performances largely relies on the selective thermal oxidation of a thin layer of semiconducting AlGaAs into an insulating oxide (AlOx). This oxidized layer is buried in the middle of the VCSEL vertical stack, forming an aperture that controls both electrical and optical confinements, and thus the VCSEL properties [2]. The optical observation of the oxide aperture from the top surface, based on slight changes on the reflectivity spectra between the oxidized and unoxidized regions of the stack, can be challenging specially in-situ inside an oxidation oven and at high temperature depending on the VCSEL structure. To-date, the practical implementations used near-infrared camera with either a white-light broad or a single narrow-band illumination spectrum [3].

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