ProcessesHCG-GaAs VCSEL Grating Etch

By replacing the upper DBR of the active layer with a diffraction grating, it is possible to improve the performance of the VCSEL. That is a high-refractive index sub-wavelength diffraction grating (HCG) -VCSEL, and is attracting attention as a next-generation VCSEL that not only thins the epi layer but also has a polarization control function.

This SEM shows an example of HCG processing of a ø6 inch GaAs wafer patterned with a resist mask. HCG samples with an etching depth of 340 nm and GaAs (190 nm) / Air-gap (275 nm) intervals were used for etch processing. The etching rate was about 50 nm / min, and the selectivity to a resist mask was about 5:1. A vertical and smooth side wall was obtained, and the ø6 inch in-plane uniformity was very good at ± 3.3%.