In situ monitoring and controlling technique for deep dry-etching of III-V multilayer structures

Deep reactive ion etching of III-V multilayer structures is an important issue especially for long wavelength VCSEL´s where full laser structures are usually very thick. However, as the etching rate is a complex function of many parameters, it changes from run to run. Commonly used methods have proved inadequate for controlling deep etching. We developed an appropriate method whereby we continuously match, experimental in situ laser reflectometry curves with the results of our numerical reflectivity model. The test structures, designed for the fabrication of wafer fused electrically pumped 1.55μm VCSELs, are carbon-doped Bragg mirrors, with 30 pairs of GaAs/AlGaAs layers.