ROBUST REACTIVE ION ETCHING PROCESSES FOR GAAS ALGAAS/ALAS BY APPLICATION OF STATISTICAL CONCEPTS/

Reactive ion etching of AlGaAs/GaAs was investigated using chlorine-co ntaining gases. We defined a remarkably stable process exhibiting very good process parameters: smooth surfaces, rectangular side walls, and good selectivity against photoresist, but almost no difference in etc h rates due to a different aluminum content. These response variables depend on the process parameters RF power, total gas pressure, total g as flow, and mixing ratio of reactive to nonreactive gases. The etch r ate mainly depends linearly on dc-bias and the flow of BCl3. The devia tion from linearity for bias is attributed to the chemical part of mat erial removal. About three quarters of the observed response variables can be explained by the chosen model. The inclination angle of the si de walls which are free of redeposits is almost rectangular to the etc hed surfaces, which are extremely smooth. This is compared with glow d ischarges of neutral atoms.