The Volatile Component Loss and the Surface Morphology of the Gold-Palladium Metallizations to the Compound Semiconductor Structures

Abstract

ABSTRACTPalladium based metal systems can be used to make ohmic contacts to AIIIBV compound semiconductors. A covering layer of gold is advantageous even from the point of view of bonding. Gold, palladium, Au/Pd layers were studied on InP and GaAs substrates. The samples were annealed in the vacuum chamber of the scanning electron microscope (SEM) and the volatile component losses (arsenic or phosphorus) were monitored by a quadrupole mass spectrometer. The changes of the surface morphology were studied using the SEM images. In the case of Pd/AIIIBV samples a single characteristic peak due to the interaction taking place between the palladium and the substrate was observed on the volatile component loss vs. temperature curve. In the case of Au/Pd/AIIIBv samples a second peak appeared on the evaporation vs. temperature curve due to the interaction between gold and AIIIBV substrate. The temperature of that second peak is about 50–60°C higher than in the case of a single gold layer on AIIIBV substrates because gold had to diffuse through the palladium layer, what hindered the reaction of gold with AIIIBV materials.