Abstract
VCSEL layer structures are among the most complicated ones in compound semiconductor device production. Re-establishing growth conditions for a new epi campaign after chamber maintenance can be challenging and time consuming. This work is about how to tackle this challenge by applying in-situ optical metrology during growth and processing of GaAs-based VCSEL devices as well as post-growth ex-situ wafer mapping. We demonstrate how to efficiently combine in-situ and ex-situ white light reflectance (WLR) measurements and modelling in order to increase the target wavelength accuracy.
Fitting the in-situ reflectance transient or the ex-situ WLR is used to generate a target reflectance trace for the subsequent plasma etching of the VCSEL mesa enabling automated end pointing.
