Interferometric <i>in-situ</i> III/V semiconductor dry-etch depth-control with ±0.8 nm best accuracy using a quadruple-Vernier-scale measurement

Semiconductor multilayer and device fabrication is a complex task in electronics opto-electronics. Layer dry etching one of the process steps to achieve specific lateral design. In situ real-time monitoring etch depth will be necessary if high precision required. Nondestructive optical techniques are methods choice. Reflectance anisotropy spectroscopy equipment has been used monitor accurate during reactive ion III/V semiconductor samples real time. For this purpose, temporal Fabry–Perot oscillations due etch-related shrinking thickness uppermost layer have exploited. Earlier, we already reported an etch-depth resolution ±16.0 nm. By use quadruple-Vernier-scale measurement evaluation protocol, now even improve by factor 20, i.e., nominally down ±0.8