CATHODOLUMINESCENCE SPECTROSCOPY - AN ACCURATE TECHNIQUE FOR THE CHARACTERIZATION OF THE FABRICATION TECHNOLOGY OF GAALAS/GAAS HETEROJUNCTION BIPOLAR-TRANSISTORS

Cathodoluminescence (CL) spectroscopy and imaging performed at low temperature have been used to qualify the heterojunction bipolar transistor fabrication technology, particularly the etching and ion implantation steps. CL has been used to optimize low defect technological processes. The protection of the active region during the insulation process has been optimized. The best result is obtained when using a bilayer of silicon nitride and photoresist. In order to minimize it, the damage induced by the etching process has also been studied. The best result is obtained when combining Ar ion beam etching and chemical etching. The possibilities to perform localized spectroscopy, to visualize the different emitting regions and to achieve semiquantitative signal analysis, makes CL a powerful microcharacterization method.